Strength profile of the superior and inferior rotator cuff: A comparison between painful and non-painful participants aged between 18 and 75 years.

Strength profile of the superior and inferior rotator cuff: A comparison between painful and non-painful participants aged between 18 and 75 years. | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Strength profile of the superior and inferior rotator cuff: A comparison between painful and non-painful participants aged between 18 and 75 years. Sonia Briel, Corlia Brandt, Benita Olivier This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5414162/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background: The ideal force couple ratio of the superior cuff, supraspinatus versus anterior deltoid is yet to be determined in both an athletic and non-athletic population. Objective: To determine the muscle force and muscle force couple ratios of the superior cuff, between the supraspinatus and the anterior deltoid and of the inferior cuff, between the external rotators and the internal rotators in painful and non- painful shoulders in an adult non-athletic population. Methods: This was an analytical cross-sectional study. The shoulders of both painful and non-painful shoulders of adults, females and males aged between 18 years and 75 years of age were tested. The ratios of the superior cuff (supraspinatus versus anterior deltoid) and of the inferior cuff (external versus the internal rotators) were determined. Results: Specific force couple ratio of supraspinatus versus anterior deltoid was determined. Higher values for the force couple’s ratios were concluded in the non-painful group of supraspinatus: anterior deltoid of 1.25 (0.20) versus the lower value of the painful group of supraspinatus: anterior deltoid of 1.20 (0.23). Statistically significant difference was determined between supraspinatus: anterior deltoid in males (1.25) versus females of (1.16) ( p > 0.12) with a small effect size of (0.27). Statistically significant difference ( p < 0.001) of the external rotators force values between the non-painful and the painful participants were determined. No significant difference of the internal rotator force values between the non-painful and the painful participants were determined. Conclusions: All force couple ratios should be considered in the evaluation and rehabilitation of all population groups. Force couple ratios supraspinatus anterior deltoid external internal. Figures Figure 1 Figure 2 1. Background The shoulder is the most mobile joint of the human body and is a good example of controlled mobility and stability brought about predominantly by muscular forces [1–3]. The shoulder joint can perform a large range of motion despite noncongruent joint surfaces [4,5] The interplay between osseous structures (scapula, clavicle and humeral head) and muscular and capsular (capsular, ligaments, labral and muscular) structures are finely coordinated and balanced to ensure a large range of motion of the shoulder joint [4,5]. The prevalence of shoulder pain in the general population has been established to be as high as 16% [ 6]. Through extensive research conducted by numerous authors, the association between decreased external rotator force and the development of shoulder pain has been established [7–9] An increased risk of developing shoulder pain has also been identified as a decrease in the ratio of the external rotator force to the internal rotator force [7–9]. These studies have primarily been conducted in athletic populations, predominantly in overhead athletes [10–12]. The deficits previously mentioned have not been explored extensively in non-athletic populations. This raises the question of whether these deficits are adaptive or protective phenomena specific to athletic populations and/or whether they also occur in non-athletic populations. Inman et al. (1944) [13] initially proposed the force couple between the supraspinatus and deltoid. A paucity of evidence exists in literature on the role and ideal force balance ratio of the superior force couple between the supraspinatus and anterior deltoid, in both the athletic and non-athletic population groups in the development of shoulder pain. Rotator cuff pathology contributing to shoulder dysfunction is complex and multifaceted and is often difficult to diagnose [14]. The rotator cuff has been implicated in the development of shoulder dysfunction by numerous authors [15,16,17]. An imbalance in the rotator cuff’s musculature can be the result of altered force couple vectors. Instability of the glenohumeral head on the glenoid cavity can occur if the balanced rotator force couples are disturbed, and in total disruption of the rotator cuff, anterior dislocation of the humeral head can result [5]. Furthermore, if centering of the humeral head on the glenoid fossa is lost due to imbalanced force couples of the rotator cuff, abnormal joint kinematics will follow [18,19]. Disturbed balance of the force couple of the rotator cuff can result in upward migration of the humeral head and can have a knock effect on loading of the long head of biceps (LHB) with increased labral tissue strain [20]. The anterior-posterior force couple of the inferior cuff comprises the anteriorly placed subscapularis (internal rotator) and the posteriorly placed infraspinatus and teres minor (external rotators). The infraspinatus, subscapularis, and teres minor force couple act synergistically, creating a compressive force in the coronal plane, directing the head of the humerus into the glenoid cavity [19,21,22]. This force couple counterbalances the superiorly directed force couple of the supraspinatus and deltoid [23]. The general consensus among numerous authors is that stronger external rotators contribute to shoulder stability and decrease the development of shoulder pain [10,24]. Moreover, several authors agree that no real left- side-to-right-side force difference in the rotator cuff musculature exists in non-painful shoulders [11,9,12]. To our knowledge, no studies have been conducted on the force couple between the supraspinatus and anterior deltoid in either the athletic or non-athletic populations. The investigation and determination of both the force values and ratios of the supraspinatus and the anterior deltoid of the superior force couple, the supraspinatus versus the anterior deltoid and the inferior force couple, between the subscapularis and the infraspinatus/ teres minor will therefore be investigated. To draw clinical conclusions from these results, the force couple ratios were determined in participants with both non-painful and painful shoulders. The force couple values in the group of participants with non-painful shoulders were used for comparisons between females and males to determine side-to-side differences. The relationship between the force couples on the non-painful side and painful side of participants with painful shoulders were explored to help clarify the role that disruption of these force couples may play in the development of pain. The present study therefore explored the previously mentioned force couples and the associated changes in both non-painful and painful shoulders in a non-athletic population. The null hypothesis is rejected, and the alternative hypothesis is accepted in that a definite relationship will exist between the concluded force couple ratios of the supraspinatus versus the anterior deltoid between the females and males, and between the external versus the internal, in the non-painful and painful shoulders of participants with painful shoulders. 2. Methods Ethical approval was obtained from the University of xxxxxx Human Research Ethics (Medical) number (M190984) Committee of the xxxxxxxxx. Study design and setting: An analytical cross-sectional study. 2.1 Participants: Sampling method: A sample of convenience from the public was used. Potential participants were invited to participate from the and xxxxxxx area. A priory sample size calculation, with rotator cuff muscle strength as the variable, using inferential statistics with a medium effect (0.50), SD (1.0) alpha of (p < 0.05) and power (80%) yielded a sample of (n = 60). To provide for any fallouts a sample of 85 participants were recruited. Eighty-five participants were recruited and tested. The Inclusion and exclusion criteria were as follows: The study included 45 participants with non-painful shoulders and 40 participants with painful shoulders, both females and males, aged between 18 and 75 years of age (Table 1 , 2 ), (Fig. 1 ). Table 1 Demographics of participants with and without painful shoulders. Painful Non-painful Gender N Gender N F 17 F 22 M 23 M 23 Dominance Dominance L 2 L 10 R 38 R 35 F = female, M = male, L = left, R = right. For the group of participants with pain-free shoulders, inclusion criteria for recruitment were defined as participants without: any previous shoulder surgery, any pain in the shoulders for a period of three months, any previous dislocation of the shoulders, and any cervical pathology (pins and needles or numbness in the shoulder or arm). For the group of participants with painful shoulders, the recruitment criteria were as follows; participants with: shoulder pain present for longer than a month but without any previous dislocation of the shoulder and without any previous shoulder or cervical surgery. Testing procedure: 2.2 Instruments and data collection: A handheld dynamometer (HHD Micro-FET3) was used for the force measurements of the shoulder muscles (Health Industries Inc., West Jordan, UT, USA). The reliability and validity of HHD has been demonstrated in clinical by various researchers [8,24,25,26]. The participants were weighed using a commercially available electronic bath scale (Camry) and were measured using a statue meter (Easycare wall mounted statue meter). To collect isometric force measurements of the pain-free shoulders, the “make test” was used. Resistance was slowly increased until maximum voluntary effort was achieved and then until the participant matched the force applied by the primary researcher. The force was maintained for five seconds, until giving way of the movement [27,28]. Resistance was applied to the painful shoulders until onset of discomfort. The range of movement was limited to the onset of discomfort experienced in the painful shoulder. Full strength was not applied to the painful shoulders to prevent further tissue damage. Bias was limited by using self-reported pain as the guiding factor. The use of maximal voluntary isometric strength testing, in which the muscle-tendon unit remains at a constant length, is a recognized technique in testing participants with rotator cuff pathology [24,26]. Force is applied at specific joint angles and is better controlled than isotonic contractions. High reliability was demonstrated thereof [24,26]. 2.2.3 Data collection procedure: A pilot study comprising eight participants (four pain free and four painful shoulders) was conducted. The aim of the pilot study was to estimate the time needed to collect data. The results obtained reflected the first testing procedure to produce the best force value for the non-painful participants. Only one testing procedure could be performed on the participants with painful shoulders, as they became more tender after only one testing procedure. The results collected during the pilot study were found to be reliable and are included in the results section. The same procedure as described in the main study was followed and no changes were implemented following the pilot. The main study procedures were as follows. Participants read the information sheet, completed and signed the consent form to participate in the study. The participants were weighed, measured, and demographic and anthropometric information was collected and recorded by the primary researcher. Force measurement data was collected and recorded on the data collection sheets by the primary researcher (Online supplement 1). The testing sequence and measurements were explained to the participants before the onset of the actual testing to ensure that they fully understood the testing procedure. Measurements were performed once on both the painful and non-painful shoulders. One testing procedure has been established in the literature to be adequate for data collection [28,29]. The principal researcher verbally counted “1-2-3-go” before the measurement started and then encouraged the participant verbally with a “push-push-push-keep-pushing and relax” command. This process was repeated for all the testing positions. For the force production measurements, the participants were standing with legs spread apart and their elbow flexed to 90 degrees, for internal and external rotation testing [30]. The HHD was positioned 2 cm proximal to the ulnar styloid process on the dorsal and volar surfaces of the forearm [8,31]. The elbow was kept straight for supraspinatus and anterior deltoid testing (Table 2 ). A novel testing position for the testing of supraspinatus was used; the arm is in 30 degrees of scaption with external rotation of the arm and the thumb pointing up (Table 2 ). Based on the electromyographic (EMG) study conducted on the best position to isolate the SS from the AD, the authors of the present study, proposed the position of abduction in 30-degree scaption with external rotation of the arm to best isolate the supraspinatus muscle [32]. For the testing of the anterior deltoid, the testing position proposed by Daniel’s and Worthingham was used [33]. The HHD was positioned laterally on the radius 2 cm above the wrist line (Table 2 ). The left side was tested first, followed by the right side. Force measurements were collected from the external rotators (ERs) and internal rotators (IRs) in (neutral rotation, 45-degree rotation, abduction, and external rotation (ABDER, external rotation in the flexion (ERF) positions. Force measurements of the SS at 30 degrees of scaption and AD at 90 degrees of sagittal flexion were collected (Table 2 ). The ratio between external: internal rotators (ER:IR) and SS: AD was mathematically calculated. Range of motion measurements were taken and recorded using the digital goniometer EasyAngle® inclinometer ( https://meloqdevices.com/pages/easyangle-digital-goniometer ). For the range of motion measurements, participants stood with their arms hanging by their sides, and their legs were spread comfortably apart (Table 3 ). The inclinometer was placed along the lateral surface of the humerus for sagittal flexion measurements and along the posterior surface of the humerus for frontal plane measurements (Table 3 ). The range of motion was taken from neutral to the end of range in both sagittal flexion and frontal abduction (Table 3 ). The reliability and validity of the digital goniometer have been reported by numerous authors in clinical practice [34–36]. 3. Statistical analyses Statistical analysis was performed using the Statistical Package for the Social Sciences (SPSS Statistics 240 28.01.1.1, (15) IBM Corp., Armonk, NY, USA) package. Normality of data was tested with the Shapiro- Wilk ( p < 0.05). Some data was concluded to be of a non-normal distribution and some data of a normal distribution. For descriptive statistics, the means and standard deviation (SD) for normally distributed data, and the median and interquartile range (IQR) for non-normal distributed data, were calculated and reported for all continuous variables. The confidence level (Cl) was set at 95%, and statistical significance at p < 0.05 The isometric force measurements were normalized to body weight (force/kg*100) for all force measurements with allometric normalization to account for anthropometric differences between participants [37]. The normalized data could then be used for comparisons between different participants. For paired non-normally distributed data, the Wilcoxon signed rank test was used and for the independent groups the Kruskal -Wallis test was used. The t -test was used for normally distributed data. Frequency data were reported using the median and the (IQR). For the correlation between participants with non- painful shoulders and those with painful shoulders, the Spearman correlation test was used for non-normally distributed data and the Pearson correlation test for normally distributed data. Levene’s test for Equality of variance was used to determine the effects of age and gender on muscle force. 4. Results Force measurements: The demographics and the results of participants with both non-painful and painful shoulders are presented next. Table 4 Demographics of participants with non-painful shoulders (n = 45) and participants with painful shoulders (n = 40). Painful Non-painful N Mean SD N Mean SD Age (years) 40 51.74 11.95 45 41.17 12.87 Height (cm) 168.81 10.67 168.23 16.93 Weight (kg) 77.72 16.56 78.26 17.20 BMI 22.93 4.88 26.01 32.72 P = painful, NP = non-painful, SD = standard deviation, BMI = body mass index, L = left, R = right, SD = standard deviation. Table 5 Median (IQR) of the force values of participants with non-painful shoulders (n = 125) and painful shoulders (n = 45). SubscapNP SubscapP SSNP (kg/f) SSP (kg/f) ADNP (kg/f) ADP (kg/f) ER0NP (kg/f) ER0P (kg/f) ER45NP (kg/f) ER45P (kg/f) ERABD/ERNP (kg/f) ERABD/ERP (kg/f) ERFNP (kg/f) ERFP (kg/f) n 125 45 125 45 125 45 125 45 125 45 125 45 125 45 Percentiles 25 3,46 0,99 8,22 5,77 6,88 4,16 7,05 5,13 5,00 3,09 4,17 2,69 4,68 3,25 50 4,64 2,64 10,45 8,13 8,65 7,17 9,29 7,82 6,35 5,00 5,30 4,36 5,76 5,25 75 6,06 4,00 13,70 12,04 11,50 9,68 11,44 10,56 7,92 6,70 6,67 5,79 7,07 6,14 Measurements were performed in kg/force. NP = non- painful; P = painful; Subscap = subscapularis; ss = supraspinatus; ER0 = external rotation in neutral, ER45 = external rotation in 45-degrees; ERABD/ER = external rotation in abduction at external rotation; ERF = external rotation during flexion. Table 6 Means (SD), standard error of measurement and effect sizes of the ratios of all variables for non-painful shoulders (n = 125). Ratios N Mean SD SE d = p = SS: AD 125 1,20 0,21 0,02 0,21 < 0.001 ER: IR0 125 1,24 0,47 0,04 0,47 < 0.001 ER: IR45 125 1,29 0,23 0,02 0,23 < 0.001 ER: IRABD 125 1,25 0,25 0,02 0,25 < 0.001 ER: IRF 125 1,17 0,21 0,02 0,21 < 0.001 SS = supraspinatus; AD = anterior deltoid; ER0 = external rotation in neutral, ER45 = external rotation at 45 degrees; ERABD/ER = external rotation in abduction at external rotation; ERF = external rotation in flexion; IR0 = internal rotation in neutral; IR45 = internal rotation in 45- degrees; IRABD/ER = internal rotation abduction in external rotation; IR F = internal rotation during flexion, SD = standard deviation. SE = standard measurement of error, d = effect size. Statistically significant ratios of all force variables were determined (p < 0.001) using the t-test (Fig. 2 ) and (Table 4 ). Left and right sides of the group with non-painful shoulders (n = 90) (Online supplement 1): No statistically significant difference was observed between the left and right sides of the participants with bilateral non-painful shoulders (n = 90) with the related samples using Friedman’s Two-Way Analysis of Variance by Ranks test. A strong positive correlation was determined between the left and right force values using Spearman’s rank correlation coefficient, ranging from ( r = 0.54–0.81). (Appendix 1). Table 7 Means (SD), correlations, and effect sizes of the ratios of all variables between females (n = 22) and males (23) of participants with non-painful shoulders (n = 90). N Mean SD SE r M and F p d Pair 1 SS:ADM 23 1,25 0,19 0,03 0,11 0,39 0.27 SS: ADF 22 1,16 0,21 0,03 Pair 2 ER:IR0M 23 1,18 0,26 0,03 -0,03 0,85 0.67 ER:IR0F 22 1,28 0,61 0,08 Pair 3 ER:IR45M 23 1,30 0,22 0,03 0,07 0,58 0.34 ER:IR45F 22 1,31 0,24 0,03 Pair 4 ER: IRABDM 23 1,26 0,20 0,03 0,07 0,61 0.34 ER: IRABDF 22 1,23 0,29 0,04 Pair 5 ER: IRFM 23 1,17 0,23 0,03 -0,02 0,85 0.30 ER: IRFF 22 1,16 0,19 0,03 SS = supraspinatus; AD = anterior deltoid; ER0 = external rotation in neutral, ER45 = external rotation at 45 degrees; ERABD/ER = external rotation in abduction at external rotation; ERF = external rotation in flexion; IR0 = internal rotation in neutral; IR45 = internal rotation at 45 degrees; IRABD/ER = internal rotation abduction in external rotation; IRF = internal rotation in flexion. M = males; F = females. SD = standard deviation, d = effect size, SE = standard, r = correlation. error of measurement, statistically significance = *. Weak negative ( r = -0.03) to a weak positive correlation ( r = 0.07) was determined between females and males. Cohen’s d calculation between the female and male groups revealed a small effect size of d = 0.27 for the SS: AD ratio, and a large effect size of d = 0.67 for the ER: IR ratio (in neutral). Statistically significant differences between the muscle force values of the females and males ( p < 0.001) were determined using Levene’s test for Equality of variance. Table 8 Means (SD), correlations, and effect sizes of the ratios between the non-painful sides (n = 35) and painful sides (n = 35) of participants with painful shoulders (n = 70). Ratios N Mean SD r p d NP SS/AD 70 1,26 0,18 -0,14 0,45 0.31 P SS/AD 70 1,20 0,23 NP ER/IR0 70 1,23 0,21 0,04 0,83 0.29 P ER/IR0 70 1,15 0,21 NP ER/IR45 70 1,32 0,21 0,22 0,25 0.78 P ER/IR45 70 1,05 0,24 NP ERABD/IR 70 1,21 0,21 0,08 0,67 1.70 P ERABD/IR 70 0,99 0,27 NP ERF/IRF 70 1,18 0,21 0,01 0,94 0.31 P ERF/IRF 70 0,99 0,22 SS = supraspinatus; AD = anterior deltoid; NP = non- painful; P = painful; ER0 = external rotation in neutral, ER45 = external rotation at 45 degrees; ERABD/IR = external rotation in abduction versus internal rotation; ERF = external rotation in flexion; IR0 = internal rotation in neutral; IR45 = internal rotation at 45 degrees; IRF = internal rotation in flexion, SD = standard deviation, d = effect size, r = correlation. Weak negative (r= -0.14) to weak positive (r = 0.22) correlations between the non-painful and painful sides, of the ratios of the participants with painful shoulders, were determined using Pearson’s correlation coefficient. A small correlation (r = 0.22) with a large effect size ( d = 0.78) was observed of the ER/IR (45-degree position) between participants with non-painful and painful shoulders. Pairwise comparison of the muscle force values between the non-painful sides (n = 35) versus painful sides (n = 35) of the participants (n = 70) with shoulder pain, was conducted using related-samples Friedman's two-way analysis of variance by rank statistics. A statistically significant difference of p < 0.001 between the non-painful sides and the painful sides of the participants with painful shoulders for the variables SS, AD, and (ERs), but not of the (IRs) force measurements were concluded (Online supplement 1). The effects of age and sex on muscle force were determined using the Independent-sample-Mann-Whitney U test. No significant effect of age on muscle force was determined when the force measurements were normalized to the body weight. Statistically significant differences between force measures of females versus males was determine (p = 0.001). Force measures were stronger in male participants than in the female participants in the non-painful group (Appendix 1). Table 9 Median (IQR) of range of motion (in degrees) of both the painful shoulders (n = 45) (unilateral pain = 35, bilateral pain n = 10) and non-painful shoulders (n = 125) (unilateral no pain n = 35, bilateral no pain n = 90). Total shoulders (n = 170). ROM degrees SFNP FABDNP SFP FABDP N 125 125 45 45 Percentiles 25 160 163 119 85 50 168 170 152 156 75 173 176 164,50 170,50 ROM = range of motion, SFNP = sagittal plane flexion; NP = non-painful; FABD = frontal plane abduction; P = painful. Decreased range of motion was present in both the sagittal plane of flexion and the frontal plane of abduction in the painful shoulders, but more so in the frontal plane of abduction in the painful shoulders. This finding was most noticeable in the first 25% (IQR), where decreased sagittal plane flexion of 119 degrees in the painful shoulders compared with 160 degrees in the non-painful shoulders was present. Decreased frontal plane abduction of 85 degrees was observed in painful shoulders versus 163 degrees in non-painful shoulders. 5. Discussion A fine balance between shoulder musculature mobility and stability must co-exist to provide stable shoulder function [2]. Monitoring the rotator cuff using isometric force measurements has been proven useful in the clinical setting. Clinical guidelines have supported the use thereof [38,39]. Our study explored all force couples of the ER:IR and SS:AD in a population aged 18–75 years in a non-athletic population (Tables 5 – 9 ) and online supplements 1,2. Age and Gender: The results of the age analysis did not reflect any statistically significant difference in strength between age groups for either females or males in the non-painful group. Previous research using HHD in overhead athletes has revealed that sex differences are absent once force measurements are normalized to body weight [8]. In contrast to this, our study still found differences between genders with normalized weight of males versus females using Friedman’s Two-way Analysis of Variance by Ranks ( p < 0.001) (Online supplement 1). Males had higher force values than females (Online supplement 1). This finding has been reiterated by other authors [40,41]. Possible explanations have been linked to the presence of different muscle morphologies and lean body mass, which are more pronounced in the upper body of males than in females [40,41]. SS: AD force couple ratio: Historically, Inman (1944) [13] proposed the force couple between the SS and AD. Our study was the first study, to the authors’ knowledge, to explore the force measures of the SS and AD using isometric dynamometry. Our study found decreased muscle strength in participants with painful shoulders in both the SS and AD groups, but the SS was weakened more so in comparison to the AD (Tables 5 ). . The concluded force values are as follows: In the non-painful group, the SS was 10.62 kg versus AD was 8.65 kg (Table 5 ). In the painful group, the SS was 8.12 kg versus the AD 7.17 kg (Table 5 ), and a definite decrease in force of both variables was observed. Specific forces couple ratios were determined in both the participants with non-painful shoulders SS:AD 1.25 (± 0.20) and in the participants with painful shoulders, SS:AD 1.20 (± 0.23) with a weak negative correlation (r=-0.142) between the values (Tables 6 , 8 ). From the expressed results, it can be seen that the SS force was significantly decreased compared with the AD force. In essence, this could translate into a decreased compressive force provided by the SS and a potentially increased superior anterior translation force provided by the AD Increased deltoid activation has been demonstrated in shoulders with compromised supraspinatus and infraspinatus muscle forces [42,43,44]. This in turn led to increased cranial migration of the humeral head and painful subacromial impingement [42,43,44]. Furthermore, the unopposed action of deltoid caused the cranial migration to occur [45,46]. Proximal migration of the humeral has been confirmed previously by radiology, and increased loading of the arm has been shown to increase this migration [45,46]. This phenomenon is not age-related and occurs in all age groups [43]. It can therefore be surmised that combined with the observed decreased strength of the external rotators versus the internal rotators in the painful group, as reflected in our study, the action of the deltoid may be amplified, and increased cranial migration of the humeral head may result in subacromial impingement. The known values of all the variables can be used to tailor rehabilitation protocols to correct the affected variables. External rotators: Our study concluded that the ER of the participants with painful shoulders was weaker than that of the participants with non-painful shoulders, with a statistical significance of p < 0.001 (Table 5 ). The concluded results of the study by Lang (2021) [47] emphasized the importance of the known values of the ER, not only in neutral but also in higher ranges. Their study concluded that increased external rotator activity with increased degrees of elevation was present but not increased internal rotator activity [47]. The finding of decreased external rotator cuff strength but not internal rotator cuff strength, in painful shoulders in our study, might therefore, be a confirmation of their findings [47]. The concluded results for the weaker (ERs) rotators but not for the (IRs) rotators may accelerate the de-centering of the humeral head and lead to pain or secondary pathology. Weaker ER strength was determined in participants with painful shoulders compared with those with non-painful shoulders (Table 5 ) as well as a reduced ER:IR strength ratio (Table 6 , 8 ). These findings are in agreement with results of a study by Maestroni (2020) [31]. Their study was also conducted on a non-athletic population with strength normalized to body weight. However, the test was conducted in the prone position, potentially limiting the gravitational scapular control. In the current study, the participant was standing in a more functional position, that required more scapular control. In Maestroni’ (2020) [31] study, testing was conducted in the 90-degree abducted shoulder position, and in our study different angles were incorporated into measurement (neutral, 45 degrees, ABD/ER, ER/F). Decreased external rotation strength has been linked to shoulder pathology in both the athletic and non-athletic populations [48,49,7]. Furthermore, previous studies have shown that stronger external rotators enhance shoulder stability [48,49,7]. It was their opinion that stronger external rotators and a higher ER:IR ratio can decrease the development of shoulder dysfunction. ER:IR force couple ratios: Lower strength ratios of ER:IR were determined in participants with painful shoulders (Table 8 ). This indicates that the external rotator muscle strength was decreased in comparison to the internal rotator muscle strength. This concurs with other authors’ findings of decreased strength ratios of the ER: IR forces [48,12,31]. Studies conducted on asymptomatic shoulders of both athletes and non-athletes did not reveal real differences in strength between sides [8,9,24,50]. Similar results were expressed in our study, with no statistically significant difference between sides in the non-painful group regardless of arm dominance (Online supplement 1). Given the previously mentioned results of lower ER force values and lower strength ratios of the ER:IR in painful shoulders, it could be postulated that the presence of these altered variables may predispose shoulders to dysfunction. Therefore, theoretically, correction of these altered variables, decreased external rotation strength, and decreased ER:IR strength ratios should lead to less shoulder dysfunction. The same trend of decreased the ER force compared with the IR force was observed in neutral and higher ranges of movement (Table 5 and online supplement 1). Decreased strength ratios were also observed in the ER:IR force couple ratios, and not just in neutral (Table 8 ). Therefore, disruption of the subscapularis/ infraspinatus and teres minor force couple may produce an anterior or posterior shearing force that destabilizes the humeral head articulation on the glenoid fossa, and perhaps contributes to shoulder dysfunction. Internal rotators: Another interesting finding was that the (IRs) force values (Table 5 ) were not significantly decreased in the painful shoulders. This finding was reiterated in their studies by several authors [12,31,48]. The practical application of the proposed method can therefore be that strengthening should focus more on the weakened (ERs) and not be applied with equal importance to both strength components (ER and IR). With the presence of decreased (ERs) strength and unchanged (IRs) strength, and decreased ER:IR ratio, disruption of the inferior anterior-posterior force couple can be anticipated. Theoretically, this imbalance can start the destabilizing of the humeral head on the glenoid surface due to increased translatory shear forces across the glenoid. This finding perhaps echoes the viewpoint of Ellenbecker and Rotert (2003) [51] that the strength of individual muscles in the rotator cuff is important, but more so the external versus the internal rotator strength ratio for balanced joint motion. Left and Right sides of participants with non-painful shoulders: In the non-painful group, no statistically significant difference was observed between the left and right sides of the same participant in our study. Hence, in practice, comparisons may be made of the same individual’s left and right sides for evaluation and rehabilitation purposes. This finding was also reflected in other studies of asymptomatic participants in both the athletic and non-athletic populations [8, 9, 24, 50.7]. Strength differences: Differences in the observed strength of participants with painful shoulders (Table 5 ) cannot be solely attributed to pain inhibition. [52]. Ellenbecker (2020) visually observed infraspinatus atrophy in the dominant arm of male tennis players. The presence of infraspinatus atrophy correlated with weakness of the ERs [52] (Ellenbecker (2020). Manske (2024) [53] with the use of musculoskeletal ultrasound (MSK-US) confirmed visually observed atrophy to be linked to decreased cross-sectional muscle volume of the infraspinatus. Lajtai (2009) [54] observed atrophy in the painful shoulders of beachball volley ballplayers, and Benitez- Martinez (2017) [55] observed a decrease in the cross-sectional area of the supraspinatus in the presence of painful shoulders in their respective studies. The conclusion drawn from these observations therefore, cast doubt on the decreased muscle force stemming from pain inhibition. Furthermore, disruption of both the anterior: posterior (ER:IR) and superior (SS:AD) force couple, can potentially predispose the shoulder to dysfunction. In lieu of the findings by Werner (2006) [56] that concluded isolated induced palsy of the SS muscle does not lead to superior migration of the humeral head, all muscles and force couples of the rotator cuff should be considered and not just the supraspinatus muscle in isolation. It is known in the current literature that the whole cuff contributes to elevation; therefore, the concluded values of all force couples can lead to better informed diagnosis and treatment strategies for the shoulder [56, 57,23]. Evidence-based Practice (EBP): EBP is becoming increasingly important in all spheres of medical practices. The use of isometric evaluation for strength testing and rehabilitation program progression has been recommended for practice [38, 39]. Approaching shoulder evaluation and treatment using objective evaluation measurements will be meaningful for both patients and clinicians. To echo the viewpoint of Ellenbecker and Roetert (2003) [51] the strength of the individual muscles of the rotator cuff is important, but more so, for balanced joint motion, the external versus internal rotator cuff strength ratio. Adding information on all the concluded force couples provides a more comprehensive overview of the primary stabilizers of the glenohumeral joint. 6. Implication Limitation: Our study was an analytical cross-sectional study and causation of pain was not determined. Only the muscle force and force couple ratios of SS and AD were determined. However, investigation of the force couple ratios between the supraspinatus and middle deltoid and between the supraspinatus and posterior deltoid are recommended in all population groups. Investigation of the above-mentioned factors, with both observational cross-sectional and longitudinal cohort study designs are recommended. Causality of pain development in the presence of altered force couple ratios should be explored with randomized control trials. 7. Clinical message Strengthening of weakened (ERs), and SS and restoration of all affected force couple ratios of both the superior cuff and inferior cuff, in painful shoulders among all age groups, may be beneficial to pain relieve. Therefore, applying the results of our study to both clinical and research practices may help evaluate shoulder dysfunction and tailor rehabilitation principles. Specific force values were determined for the SS and AD. The determined SS: AD force couple ratios shed more light on the biomechanical functioning of the rotator cuff. The concluded ER:IR force couple ratios in all ranges, not just in neutral range, provide a holistic overview of the inferior rotator cuff musculature. Moreover, (ERs) were more weakened than (IRs) in painful shoulders in a non-athletic population. The expressed results were determined in a broad general population group and are applicable to practice. Abbreviations AD Anterior deltoid ABDER Abduction external ABDIR Abduction internal BMI Body mass index EBP Evidence based practice EMG Electromyographic ER External ERF External rotation flexion HHD Hand held dynamometer IR Internal IRF Internal flexion NP Non-painful P Painful ROM Range of motion SD Standard deviation SS Supraspinatus Declarations 9. Data Availability Statement: The authors xxxxxx declare that the data supporting the findings of this study are available within the paper and in the supplementary online information files. 10. Funding: Funding was received from the xxxxxxx. 11. Disclosure of Interest: All authors xxxxxxxxx declare that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript. 12. Ethics declaration: Ethical approval was obtained from the Approval Committee of the University of the xxxx Internal Review Board: Human Research Ethics Committee (Medical) number (M190984). Clinical trial number not applicable. Consent to participate: Voluntary informed signed consent was obtained from all participants prior to the testing session. Consent to publish: Written informed consent for publication was obtained by the participant used, for the use of the images that will be freely available on the internet and may be seen by the general public. References Engin AE, Chen SM.(a) Statistical data base for the biomechanical properties of the human shoulder complex--I: Kinematics of the shoulder complex. 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Supplementary Files Onlinesupplement1.docx Onlinesupplement2.docx table2and3.docx Appendices.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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rotators.\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5414162/v1/f351f2fccad77bb33ada0bd0.jpg"},{"id":76071384,"identity":"2e7970fb-9a7c-47b1-8853-4f7a44ea0da9","added_by":"auto","created_at":"2025-02-12 04:32:04","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1050050,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5414162/v1/a1eb71e8-6915-4e5b-868a-85b73e2bcac8.pdf"},{"id":71608580,"identity":"8ebc471c-332f-4039-b260-35cec9398a49","added_by":"auto","created_at":"2024-12-17 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06:36:15","extension":"docx","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":140018,"visible":true,"origin":"","legend":"","description":"","filename":"table2and3.docx","url":"https://assets-eu.researchsquare.com/files/rs-5414162/v1/1b36e7399ffae846ab4fee11.docx"},{"id":71612308,"identity":"e629a02e-2b53-4818-b113-f61e8ab411ca","added_by":"auto","created_at":"2024-12-17 07:00:15","extension":"docx","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":18353,"visible":true,"origin":"","legend":"","description":"","filename":"Appendices.docx","url":"https://assets-eu.researchsquare.com/files/rs-5414162/v1/89d246db13d4725a07f1a706.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Strength profile of the superior and inferior rotator cuff: A comparison between painful and non-painful participants aged between 18 and 75 years.","fulltext":[{"header":"1. Background","content":"\u003cp\u003eThe shoulder is the most mobile joint of the human body and is a good example of controlled mobility and stability brought about predominantly by muscular forces [1\u0026ndash;3]. The shoulder joint can perform a large range of motion despite noncongruent joint surfaces [4,5] The interplay between osseous structures (scapula, clavicle and humeral head) and muscular and capsular (capsular, ligaments, labral and muscular) structures are finely coordinated and balanced to ensure a large range of motion of the shoulder joint [4,5]. The prevalence of shoulder pain in the general population has been established to be as high as 16% [ 6]. Through extensive research conducted by numerous authors, the association between decreased external rotator force and the development of shoulder pain has been established [7\u0026ndash;9] An increased risk of developing shoulder pain has also been identified as a decrease in the ratio of the external rotator force to the internal rotator force [7\u0026ndash;9]. These studies have primarily been conducted in athletic populations, predominantly in overhead athletes [10\u0026ndash;12]. The deficits previously mentioned have not been explored extensively in non-athletic populations. This raises the question of whether these deficits are adaptive or protective phenomena specific to athletic populations and/or whether they also occur in non-athletic populations. Inman et al. (1944) [13] initially proposed the force couple between the supraspinatus and deltoid. A paucity of evidence exists in literature on the role and ideal force balance ratio of the superior force couple between the supraspinatus and anterior deltoid, in both the athletic and non-athletic population groups in the development of shoulder pain.\u003c/p\u003e \u003cp\u003eRotator cuff pathology contributing to shoulder dysfunction is complex and multifaceted and is often difficult to diagnose [14]. The rotator cuff has been implicated in the development of shoulder dysfunction by numerous authors [15,16,17]. An imbalance in the rotator cuff\u0026rsquo;s musculature can be the result of altered force couple vectors. Instability of the glenohumeral head on the glenoid cavity can occur if the balanced rotator force couples are disturbed, and in total disruption of the rotator cuff, anterior dislocation of the humeral head can result [5]. Furthermore, if centering of the humeral head on the glenoid fossa is lost due to imbalanced force couples of the rotator cuff, abnormal joint kinematics will follow [18,19]. Disturbed balance of the force couple of the rotator cuff can result in upward migration of the humeral head and can have a knock effect on loading of the long head of biceps (LHB) with increased labral tissue strain [20].\u003c/p\u003e \u003cp\u003eThe anterior-posterior force couple of the inferior cuff comprises the anteriorly placed subscapularis (internal rotator) and the posteriorly placed infraspinatus and teres minor (external rotators). The infraspinatus, subscapularis, and teres minor force couple act synergistically, creating a compressive force in the coronal plane, directing the head of the humerus into the glenoid cavity [19,21,22]. This force couple counterbalances the superiorly directed force couple of the supraspinatus and deltoid [23]. The general consensus among numerous authors is that stronger external rotators contribute to shoulder stability and decrease the development of shoulder pain [10,24]. Moreover, several authors agree that no real left- side-to-right-side force difference in the rotator cuff musculature exists in non-painful shoulders [11,9,12].\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eTo our knowledge, no studies have been conducted on the force couple between the supraspinatus and anterior deltoid in either the athletic or non-athletic populations. The investigation and determination of both the force values and ratios of the supraspinatus and the anterior deltoid of the superior force couple, the supraspinatus versus the anterior deltoid and the inferior force couple, between the subscapularis and the infraspinatus/ teres minor will therefore be investigated. To draw clinical conclusions from these results, the force couple ratios were determined in participants with both non-painful and painful shoulders. The force couple values in the group of participants with non-painful shoulders were used for comparisons between females and males to determine side-to-side differences. The relationship between the force couples on the non-painful side and painful side of participants with painful shoulders were explored to help clarify the role that disruption of these force couples may play in the development of pain. The present study therefore explored the previously mentioned force couples and the associated changes in both non-painful and painful shoulders in a non-athletic population. The null hypothesis is rejected, and the alternative hypothesis is accepted in that a definite relationship will exist between the concluded force couple ratios of the supraspinatus versus the anterior deltoid between the females and males, and between the external versus the internal, in the non-painful and painful shoulders of participants with painful shoulders.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"2. Methods","content":"\u003cp\u003e \u003cstrong\u003eEthical approval\u003c/strong\u003e \u003cp\u003e was obtained from the University of xxxxxx Human Research Ethics (Medical) number (M190984) Committee of the xxxxxxxxx.\u003c/p\u003e \u003c/p\u003e \u003cp\u003eStudy design and setting:\u003c/p\u003e \u003cp\u003eAn analytical cross-sectional study.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Participants:\u003c/h2\u003e \u003cp\u003eSampling method:\u003c/p\u003e \u003cp\u003eA sample of convenience from the public was used. Potential participants were invited to participate from the and xxxxxxx area. A priory sample size calculation, with rotator cuff muscle strength as the variable, using inferential statistics with a medium effect (0.50), SD (1.0) alpha of (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) and power (80%) yielded a sample of (n\u0026thinsp;=\u0026thinsp;60). To provide for any fallouts a sample of 85 participants were recruited. Eighty-five participants were recruited and tested.\u003c/p\u003e \u003cp\u003eThe Inclusion and exclusion criteria were as follows:\u003c/p\u003e \u003cp\u003eThe study included 45 participants with non-painful shoulders and 40 participants with painful shoulders, both females and males, aged between 18 and 75 years of age (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDemographics of participants with and without painful shoulders.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003ePainful\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003eNon-painful\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGender\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGender\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eF\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eF\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eM\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eM\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDominance\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eDominance\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eL\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eL\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eR\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eR\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e35\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eF\u0026thinsp;=\u0026thinsp;female, M\u0026thinsp;=\u0026thinsp;male, L\u0026thinsp;=\u0026thinsp;left, R\u0026thinsp;=\u0026thinsp;right.\u003c/p\u003e \u003cp\u003eFor the group of participants with pain-free shoulders, inclusion criteria for recruitment were defined as participants without: any previous shoulder surgery, any pain in the shoulders for a period of three months, any previous dislocation of the shoulders, and any cervical pathology (pins and needles or numbness in the shoulder or arm).\u003c/p\u003e \u003cp\u003eFor the group of participants with painful shoulders, the recruitment criteria were as follows; participants with: shoulder pain present for longer than a month but without any previous dislocation of the shoulder and without any previous shoulder or cervical surgery.\u003c/p\u003e\u003cp\u003eTesting procedure:\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Instruments and data collection:\u003c/h2\u003e \u003cp\u003eA handheld dynamometer (HHD Micro-FET3) was used for the force measurements of the shoulder muscles (Health Industries Inc., West Jordan, UT, USA). The reliability and validity of HHD has been demonstrated in clinical by various researchers [8,24,25,26]. The participants were weighed using a commercially available electronic bath scale (Camry) and were measured using a statue meter (Easycare wall mounted statue meter). To collect isometric force measurements of the pain-free shoulders, the \u0026ldquo;make test\u0026rdquo; was used. Resistance was slowly increased until maximum voluntary effort was achieved and then until the participant matched the force applied by the primary researcher. The force was maintained for five seconds, until giving way of the movement [27,28].\u003c/p\u003e \u003cp\u003eResistance was applied to the painful shoulders until onset of discomfort. The range of movement was limited to the onset of discomfort experienced in the painful shoulder. Full strength was not applied to the painful shoulders to prevent further tissue damage. Bias was limited by using self-reported pain as the guiding factor. The use of maximal voluntary isometric strength testing, in which the muscle-tendon unit remains at a constant length, is a recognized technique in testing participants with rotator cuff pathology [24,26]. Force is applied at specific joint angles and is better controlled than isotonic contractions. High reliability was demonstrated thereof [24,26].\u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section3\"\u003e \u003ch2\u003e2.2.3 Data collection procedure:\u003c/h2\u003e \u003cp\u003eA pilot study comprising eight participants (four pain free and four painful shoulders) was conducted. The aim of the pilot study was to estimate the time needed to collect data. The results obtained reflected the first testing procedure to produce the best force value for the non-painful participants. Only one testing procedure could be performed on the participants with painful shoulders, as they became more tender after only one testing procedure. The results collected during the pilot study were found to be reliable and are included in the results section. The same procedure as described in the main study was followed and no changes were implemented following the pilot.\u003c/p\u003e \u003cp\u003eThe main study procedures were as follows. Participants read the information sheet, completed and signed the consent form to participate in the study. The participants were weighed, measured, and demographic and anthropometric information was collected and recorded by the primary researcher. Force measurement data was collected and recorded on the data collection sheets by the primary researcher (Online supplement 1).\u003c/p\u003e \u003cp\u003eThe testing sequence and measurements were explained to the participants before the onset of the actual testing to ensure that they fully understood the testing procedure. Measurements were performed once on both the painful and non-painful shoulders. One testing procedure has been established in the literature to be adequate for data collection [28,29].\u003c/p\u003e \u003cp\u003e The principal researcher verbally counted \u0026ldquo;1-2-3-go\u0026rdquo; before the measurement started and then encouraged the participant verbally with a \u0026ldquo;push-push-push-keep-pushing and relax\u0026rdquo; command. This process was repeated for all the testing positions.\u003c/p\u003e \u003cp\u003eFor the force production measurements, the participants were standing with legs spread apart and their elbow flexed to 90 degrees, for internal and external rotation testing [30]. The HHD was positioned 2 cm proximal to the ulnar styloid process on the dorsal and volar surfaces of the forearm [8,31]. The elbow was kept straight for supraspinatus and anterior deltoid testing (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). A novel testing position for the testing of supraspinatus was used; the arm is in 30 degrees of scaption with external rotation of the arm and the thumb pointing up (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Based on the electromyographic (EMG) study conducted on the best position to isolate the SS from the AD, the authors of the present study, proposed the position of abduction in 30-degree scaption with external rotation of the arm to best isolate the supraspinatus muscle [32]. For the testing of the anterior deltoid, the testing position proposed by Daniel\u0026rsquo;s and Worthingham was used [33]. The HHD was positioned laterally on the radius 2 cm above the wrist line (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The left side was tested first, followed by the right side.\u003c/p\u003e \u003cp\u003eForce measurements were collected from the external rotators (ERs) and internal rotators (IRs) in (neutral rotation, 45-degree rotation, abduction, and external rotation (ABDER, external rotation in the flexion (ERF) positions. Force measurements of the SS at 30 degrees of scaption and AD at 90 degrees of sagittal flexion were collected (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The ratio between external: internal rotators (ER:IR) and SS: AD was mathematically calculated.\u003c/p\u003e \u003cp\u003eRange of motion measurements were taken and recorded using the digital goniometer EasyAngle\u0026reg; inclinometer (\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://meloqdevices.com/pages/easyangle-digital-goniometer\u003c/span\u003e\u003cspan address=\"https://meloqdevices.com/pages/easyangle-digital-goniometer\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e). For the range of motion measurements, participants stood with their arms hanging by their sides, and their legs were spread comfortably apart (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The inclinometer was placed along the lateral surface of the humerus for sagittal flexion measurements and along the posterior surface of the humerus for frontal plane measurements (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The range of motion was taken from neutral to the end of range in both sagittal flexion and frontal abduction (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The reliability and validity of the digital goniometer have been reported by numerous authors in clinical practice [34\u0026ndash;36].\u003c/p\u003e "},{"header":"3. Statistical analyses","content":"\u003cp\u003eStatistical analysis was performed using the Statistical Package for the Social Sciences (SPSS Statistics 240 28.01.1.1, (15) IBM Corp., Armonk, NY, USA) package. Normality of data was tested with the Shapiro- Wilk (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Some data was concluded to be of a non-normal distribution and some data of a normal distribution. For descriptive statistics, the means and standard deviation (SD) for normally distributed data, and the median and interquartile range (IQR) for non-normal distributed data, were calculated and reported for all continuous variables. The confidence level (Cl) was set at 95%, and statistical significance at \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05\u003c/p\u003e \u003cp\u003eThe isometric force measurements were normalized to body weight (force/kg*100) for all force measurements with allometric normalization to account for anthropometric differences between participants [37]. The normalized data could then be used for comparisons between different participants. For paired non-normally distributed data, the Wilcoxon signed rank test was used and for the independent groups the Kruskal -Wallis test was used. The \u003cem\u003et\u003c/em\u003e-test was used for normally distributed data. Frequency data were reported using the median and the (IQR).\u003c/p\u003e \u003cp\u003eFor the correlation between participants with non- painful shoulders and those with painful shoulders, the Spearman correlation test was used for non-normally distributed data and the Pearson correlation test for normally distributed data. Levene\u0026rsquo;s test for Equality of variance was used to determine the effects of age and gender on muscle force.\u003c/p\u003e"},{"header":"4. Results","content":"\u003cp\u003eForce measurements:\u003c/p\u003e \u003cp\u003eThe demographics and the results of participants with both non-painful and painful shoulders are presented next.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDemographics of participants with non-painful shoulders (n\u0026thinsp;=\u0026thinsp;45) and participants with painful shoulders (n\u0026thinsp;=\u0026thinsp;40).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cp\u003ePainful\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003eNon-painful\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eMean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eSD\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAge (years)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e51.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e11.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e41.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e12.87\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHeight\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(cm)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e168.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e10.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e168.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e16.93\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eWeight\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(kg)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e77.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e16.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e78.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e17.20\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBMI\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e22.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e26.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e32.72\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eP\u0026thinsp;=\u0026thinsp;painful, NP\u0026thinsp;=\u0026thinsp;non-painful, SD\u0026thinsp;=\u0026thinsp;standard deviation, BMI\u0026thinsp;=\u0026thinsp;body mass index, L\u0026thinsp;=\u0026thinsp;left, R\u0026thinsp;=\u0026thinsp;right, SD\u0026thinsp;=\u0026thinsp;standard deviation.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMedian (IQR) of the force values of participants with non-painful shoulders (n\u0026thinsp;=\u0026thinsp;125) and painful shoulders (n\u0026thinsp;=\u0026thinsp;45).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"16\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c15\" colnum=\"15\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c16\" colnum=\"16\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSubscapNP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSubscapP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSSNP\u003c/p\u003e \u003cp\u003e(kg/f)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSSP\u003c/p\u003e \u003cp\u003e(kg/f)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eADNP\u003c/p\u003e \u003cp\u003e(kg/f)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eADP\u003c/p\u003e \u003cp\u003e(kg/f)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eER0NP\u003c/p\u003e \u003cp\u003e(kg/f)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eER0P\u003c/p\u003e \u003cp\u003e(kg/f)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003eER45NP\u003c/p\u003e \u003cp\u003e(kg/f)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e \u003cp\u003eER45P\u003c/p\u003e \u003cp\u003e(kg/f)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c13\"\u003e \u003cp\u003eERABD/ERNP\u003c/p\u003e \u003cp\u003e(kg/f)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c14\"\u003e \u003cp\u003eERABD/ERP\u003c/p\u003e \u003cp\u003e(kg/f)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c15\"\u003e \u003cp\u003eERFNP\u003c/p\u003e \u003cp\u003e(kg/f)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c16\"\u003e \u003cp\u003eERFP\u003c/p\u003e \u003cp\u003e(kg/f)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e \u003cp\u003e125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c16\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003ePercentiles\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3,46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8,22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5,77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6,88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4,16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e7,05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e5,13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e5,00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e3,09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e \u003cp\u003e4,17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e2,69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e4,68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c16\"\u003e \u003cp\u003e3,25\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4,64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2,64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10,45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e8,13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e8,65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e7,17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e9,29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e7,82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e6,35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e5,00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e \u003cp\u003e5,30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e4,36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e5,76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c16\"\u003e \u003cp\u003e5,25\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6,06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4,00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e13,70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e12,04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e11,50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e9,68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e11,44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e \u003cp\u003e10,56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e7,92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e6,70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e \u003cp\u003e6,67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e5,79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e7,07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c16\"\u003e \u003cp\u003e6,14\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eMeasurements were performed in kg/force. NP\u0026thinsp;=\u0026thinsp;non- painful; P\u0026thinsp;=\u0026thinsp;painful; Subscap\u0026thinsp;=\u0026thinsp;subscapularis; ss\u0026thinsp;=\u0026thinsp;supraspinatus; ER0\u0026thinsp;=\u0026thinsp;external rotation in neutral, ER45\u0026thinsp;=\u0026thinsp;external rotation in 45-degrees; ERABD/ER\u0026thinsp;=\u0026thinsp;external rotation in abduction at external rotation; ERF\u0026thinsp;=\u0026thinsp;external rotation during flexion.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMeans (SD), standard error of measurement and effect sizes of the ratios of all variables for non-painful shoulders (n\u0026thinsp;=\u0026thinsp;125).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRatios\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSE\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003ed\u003c/em\u003e=\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e=\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSS: AD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1,20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0,21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eER: IR0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1,24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0,47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eER: IR45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1,29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0,23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eER: IRABD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1,25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0,25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eER: IRF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1,17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0,21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eSS\u0026thinsp;=\u0026thinsp;supraspinatus; AD\u0026thinsp;=\u0026thinsp;anterior deltoid; ER0\u0026thinsp;=\u0026thinsp;external rotation in neutral, ER45\u0026thinsp;=\u0026thinsp;external rotation at 45 degrees; ERABD/ER\u0026thinsp;=\u0026thinsp;external rotation in abduction at external rotation; ERF\u0026thinsp;=\u0026thinsp;external rotation in flexion; IR0\u0026thinsp;=\u0026thinsp;internal rotation in neutral; IR45\u0026thinsp;=\u0026thinsp;internal rotation in 45- degrees; IRABD/ER\u0026thinsp;=\u0026thinsp;internal rotation abduction in external rotation; IR F\u0026thinsp;=\u0026thinsp;internal rotation during flexion, SD\u0026thinsp;=\u0026thinsp;standard deviation. SE\u0026thinsp;=\u0026thinsp;standard measurement of error, d\u0026thinsp;=\u0026thinsp;effect size.\u003c/p\u003e \u003cp\u003eStatistically significant ratios of all force variables were determined (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) using the t-test (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) and (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eLeft and right sides of the group with non-painful shoulders (n\u0026thinsp;=\u0026thinsp;90) (Online supplement 1):\u003c/p\u003e \u003cp\u003eNo statistically significant difference was observed between the left and right sides of the participants with bilateral non-painful shoulders (n\u0026thinsp;=\u0026thinsp;90) with the related samples using Friedman\u0026rsquo;s Two-Way Analysis of Variance by Ranks test. A strong positive correlation was determined between the left and right force values using Spearman\u0026rsquo;s rank correlation coefficient, ranging from (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.54\u0026ndash;0.81). (Appendix 1).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab7\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMeans (SD), correlations, and effect sizes of the ratios of all variables between females (n\u0026thinsp;=\u0026thinsp;22) and males (23) of participants with non-painful shoulders (n\u0026thinsp;=\u0026thinsp;90).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSE\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003er\u003c/em\u003e\u003c/p\u003e \u003cp\u003eM and\u003c/p\u003e \u003cp\u003eF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u003cem\u003ed\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePair 1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSS:ADM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0,03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0,11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0,39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.27\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSS: ADF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0,03\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePair 2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eER:IR0M\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0,03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e-0,03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0,85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.67\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eER:IR0F\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0,08\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePair 3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eER:IR45M\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0,03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0,07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0,58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.34\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eER:IR45F\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0,03\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePair 4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eER: IRABDM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0,03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0,07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0,61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.34\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eER: IRABDF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0,04\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePair 5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eER: IRFM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0,03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e-0,02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0,85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eER: IRFF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1,16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0,19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0,03\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eSS\u0026thinsp;=\u0026thinsp;supraspinatus; AD\u0026thinsp;=\u0026thinsp;anterior deltoid; ER0\u0026thinsp;=\u0026thinsp;external rotation in neutral, ER45\u0026thinsp;=\u0026thinsp;external rotation at 45 degrees; ERABD/ER\u0026thinsp;=\u0026thinsp;external rotation in abduction at external rotation; ERF\u0026thinsp;=\u0026thinsp;external rotation in flexion; IR0\u0026thinsp;=\u0026thinsp;internal rotation in neutral; IR45\u0026thinsp;=\u0026thinsp;internal rotation at 45 degrees; IRABD/ER\u0026thinsp;=\u0026thinsp;internal rotation abduction in external rotation; IRF\u0026thinsp;=\u0026thinsp;internal rotation in flexion. M\u0026thinsp;=\u0026thinsp;males; F\u0026thinsp;=\u0026thinsp;females. SD\u0026thinsp;=\u0026thinsp;standard deviation, d\u0026thinsp;=\u0026thinsp;effect size, SE\u0026thinsp;=\u0026thinsp;standard, r\u0026thinsp;=\u0026thinsp;correlation. error of measurement, statistically significance = *.\u003c/p\u003e \u003cp\u003eWeak negative (\u003cem\u003er\u003c/em\u003e = -0.03) to a weak positive correlation (\u003cem\u003er\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.07) was determined between females and males. Cohen\u0026rsquo;s d calculation between the female and male groups revealed a small effect size of \u003cem\u003ed\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.27 for the SS: AD ratio, and a large effect size of \u003cem\u003ed\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.67 for the ER: IR ratio (in neutral).\u003c/p\u003e \u003cp\u003eStatistically significant differences between the muscle force values of the females and males (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) were determined using Levene\u0026rsquo;s test for Equality of variance.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab8\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 8\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMeans (SD), correlations, and effect sizes of the ratios between the non-painful sides (n\u0026thinsp;=\u0026thinsp;35) and painful sides (n\u0026thinsp;=\u0026thinsp;35) of participants with painful shoulders (n\u0026thinsp;=\u0026thinsp;70).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRatios\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003er\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003ed\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNP SS/AD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1,26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e-0,14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0,45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.31\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP SS/AD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1,20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNP ER/IR0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1,23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0,04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0,83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.29\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP ER/IR0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1,15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNP ER/IR45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1,32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0,22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0,25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.78\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP ER/IR45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1,05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNP ERABD/IR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1,21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0,08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0,67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1.70\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP ERABD/IR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0,99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNP ERF/IRF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1,18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0,01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0,94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.31\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP ERF/IRF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0,99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0,22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eSS\u0026thinsp;=\u0026thinsp;supraspinatus; AD\u0026thinsp;=\u0026thinsp;anterior deltoid; NP\u0026thinsp;=\u0026thinsp;non- painful; P\u0026thinsp;=\u0026thinsp;painful; ER0\u0026thinsp;=\u0026thinsp;external rotation in neutral, ER45\u0026thinsp;=\u0026thinsp;external rotation at 45 degrees; ERABD/IR\u0026thinsp;=\u0026thinsp;external rotation in abduction versus internal rotation; ERF\u0026thinsp;=\u0026thinsp;external rotation in flexion; IR0\u0026thinsp;=\u0026thinsp;internal rotation in neutral; IR45\u0026thinsp;=\u0026thinsp;internal rotation at 45 degrees; IRF\u0026thinsp;=\u0026thinsp;internal rotation in flexion, SD\u0026thinsp;=\u0026thinsp;standard deviation, d\u0026thinsp;=\u0026thinsp;effect size, r\u0026thinsp;=\u0026thinsp;correlation.\u003c/p\u003e \u003cp\u003eWeak negative (r= -0.14) to weak positive (r\u0026thinsp;=\u0026thinsp;0.22) correlations between the non-painful and painful sides, of the ratios of the participants with painful shoulders, were determined using Pearson\u0026rsquo;s correlation coefficient. A small correlation (r\u0026thinsp;=\u0026thinsp;0.22) with a large effect size (\u003cem\u003ed\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.78) was observed of the ER/IR (45-degree position) between participants with non-painful and painful shoulders.\u003c/p\u003e \u003cp\u003ePairwise comparison of the muscle force values between the non-painful sides (n\u0026thinsp;=\u0026thinsp;35) versus painful sides (n\u0026thinsp;=\u0026thinsp;35) of the participants (n\u0026thinsp;=\u0026thinsp;70) with shoulder pain, was conducted using related-samples Friedman's two-way analysis of variance by rank statistics. A statistically significant difference of \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001 between the non-painful sides and the painful sides of the participants with painful shoulders for the variables SS, AD, and (ERs), but not of the (IRs) force measurements were concluded (Online supplement 1).\u003c/p\u003e \u003cp\u003eThe effects of age and sex on muscle force were determined using the Independent-sample-Mann-Whitney U test. No significant effect of age on muscle force was determined when the force measurements were normalized to the body weight. Statistically significant differences between force measures of females versus males was determine \u003cem\u003e(p\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001). Force measures were stronger in male participants than in the female participants in the non-painful group (Appendix 1).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab9\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 9\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMedian (IQR) of range of motion (in degrees) of both the painful shoulders (n\u0026thinsp;=\u0026thinsp;45) (unilateral pain\u0026thinsp;=\u0026thinsp;35, bilateral pain n\u0026thinsp;=\u0026thinsp;10) and non-painful shoulders (n\u0026thinsp;=\u0026thinsp;125) (unilateral no pain n\u0026thinsp;=\u0026thinsp;35, bilateral no pain n\u0026thinsp;=\u0026thinsp;90). Total shoulders (n\u0026thinsp;=\u0026thinsp;170).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eROM degrees\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSFNP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFABDNP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSFP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eFABDP\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e45\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003ePercentiles\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e160\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e163\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e119\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e85\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e168\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e170\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e152\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e156\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e173\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e176\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e164,50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e170,50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eROM\u0026thinsp;=\u0026thinsp;range of motion, SFNP\u0026thinsp;=\u0026thinsp;sagittal plane flexion; NP\u0026thinsp;=\u0026thinsp;non-painful; FABD\u0026thinsp;=\u0026thinsp;frontal plane abduction; P\u0026thinsp;=\u0026thinsp;painful.\u003c/p\u003e \u003cp\u003eDecreased range of motion was present in both the sagittal plane of flexion and the frontal plane of abduction in the painful shoulders, but more so in the frontal plane of abduction in the painful shoulders. This finding was most noticeable in the first 25% (IQR), where decreased sagittal plane flexion of 119 degrees in the painful shoulders compared with 160 degrees in the non-painful shoulders was present. Decreased frontal plane abduction of 85 degrees was observed in painful shoulders versus 163 degrees in non-painful shoulders.\u003c/p\u003e"},{"header":"5. Discussion","content":"\u003cp\u003eA fine balance between shoulder musculature mobility and stability must co-exist to provide stable shoulder function [2]. Monitoring the rotator cuff using isometric force measurements has been proven useful in the clinical setting. Clinical guidelines have supported the use thereof [38,39]. Our study explored all force couples of the ER:IR and SS:AD in a population aged 18\u0026ndash;75 years in a non-athletic population (Tables\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan refid=\"Tab9\" class=\"InternalRef\"\u003e9\u003c/span\u003e) and online supplements 1,2.\u003c/p\u003e \u003cp\u003eAge and Gender:\u003c/p\u003e \u003cp\u003eThe results of the age analysis did not reflect any statistically significant difference in strength between age groups for either females or males in the non-painful group. Previous research using HHD in overhead athletes has revealed that sex differences are absent once force measurements are normalized to body weight [8]. In contrast to this, our study still found differences between genders with normalized weight of males versus females using Friedman\u0026rsquo;s Two-way Analysis of Variance by Ranks (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) (Online supplement 1). Males had higher force values than females (Online supplement 1). This finding has been reiterated by other authors [40,41]. Possible explanations have been linked to the presence of different muscle morphologies and lean body mass, which are more pronounced in the upper body of males than in females [40,41].\u003c/p\u003e \u003cp\u003eSS: AD force couple ratio:\u003c/p\u003e \u003cp\u003eHistorically, Inman (1944) [13] proposed the force couple between the SS and AD. Our study was the first study, to the authors\u0026rsquo; knowledge, to explore the force measures of the SS and AD using isometric dynamometry. Our study found decreased muscle strength in participants with painful shoulders in both the SS and AD groups, but the SS was weakened more so in comparison to the AD (Tables\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e.\u003c/p\u003e \u003cp\u003eThe concluded force values are as follows: In the non-painful group, the SS was 10.62 kg versus AD was 8.65 kg (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). In the painful group, the SS was 8.12 kg versus the AD 7.17 kg (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e), and a definite decrease in force of both variables was observed. Specific forces couple ratios were determined in both the participants with non-painful shoulders SS:AD 1.25 (\u0026plusmn;\u0026thinsp;0.20) and in the participants with painful shoulders, SS:AD 1.20 (\u0026plusmn;\u0026thinsp;0.23) with a weak negative correlation (r=-0.142) between the values (Tables\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, \u003cspan refid=\"Tab8\" class=\"InternalRef\"\u003e8\u003c/span\u003e). From the expressed results, it can be seen that the SS force was significantly decreased compared with the AD force. In essence, this could translate into a decreased compressive force provided by the SS and a potentially increased superior anterior translation force provided by the AD\u003c/p\u003e \u003cp\u003eIncreased deltoid activation has been demonstrated in shoulders with compromised supraspinatus and infraspinatus muscle forces [42,43,44]. This in turn led to increased cranial migration of the humeral head and painful subacromial impingement [42,43,44]. Furthermore, the unopposed action of deltoid caused the cranial migration to occur [45,46]. Proximal migration of the humeral has been confirmed previously by radiology, and increased loading of the arm has been shown to increase this migration [45,46]. This phenomenon is not age-related and occurs in all age groups [43].\u003c/p\u003e \u003cp\u003eIt can therefore be surmised that combined with the observed decreased strength of the external rotators versus the internal rotators in the painful group, as reflected in our study, the action of the deltoid may be amplified, and increased cranial migration of the humeral head may result in subacromial impingement. The known values of all the variables can be used to tailor rehabilitation protocols to correct the affected variables.\u003c/p\u003e \u003cp\u003eExternal rotators:\u003c/p\u003e \u003cp\u003eOur study concluded that the ER of the participants with painful shoulders was weaker than that of the participants with non-painful shoulders, with a statistical significance of p\u0026thinsp;\u0026lt;\u0026thinsp;0.001 (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). The concluded results of the study by Lang (2021) [47] emphasized the importance of the known values of the ER, not only in neutral but also in higher ranges. Their study concluded that increased external rotator activity with increased degrees of elevation was present but not increased internal rotator activity [47]. The finding of decreased external rotator cuff strength but not internal rotator cuff strength, in painful shoulders in our study, might therefore, be a confirmation of their findings [47]. The concluded results for the weaker (ERs) rotators but not for the (IRs) rotators may accelerate the de-centering of the humeral head and lead to pain or secondary pathology.\u003c/p\u003e \u003cp\u003eWeaker ER strength was determined in participants with painful shoulders compared with those with non-painful shoulders (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e) as well as a reduced ER:IR strength ratio (Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, \u003cspan refid=\"Tab8\" class=\"InternalRef\"\u003e8\u003c/span\u003e). These findings are in agreement with results of a study by Maestroni (2020) [31]. Their study was also conducted on a non-athletic population with strength normalized to body weight. However, the test was conducted in the prone position, potentially limiting the gravitational scapular control. In the current study, the participant was standing in a more functional position, that required more scapular control. In Maestroni\u0026rsquo; (2020) [31] study, testing was conducted in the 90-degree abducted shoulder position, and in our study different angles were incorporated into measurement (neutral, 45 degrees, ABD/ER, ER/F).\u003c/p\u003e \u003cp\u003eDecreased external rotation strength has been linked to shoulder pathology in both the athletic and non-athletic populations [48,49,7]. Furthermore, previous studies have shown that stronger external rotators enhance shoulder stability [48,49,7]. It was their opinion that stronger external rotators and a higher ER:IR ratio can decrease the development of shoulder dysfunction.\u003c/p\u003e \u003cp\u003eER:IR force couple ratios:\u003c/p\u003e \u003cp\u003eLower strength ratios of ER:IR were determined in participants with painful shoulders (Table\u0026nbsp;\u003cspan refid=\"Tab8\" class=\"InternalRef\"\u003e8\u003c/span\u003e). This indicates that the external rotator muscle strength was decreased in comparison to the internal rotator muscle strength. This concurs with other authors\u0026rsquo; findings of decreased strength ratios of the ER: IR forces [48,12,31]. Studies conducted on asymptomatic shoulders of both athletes and non-athletes did not reveal real differences in strength between sides [8,9,24,50]. Similar results were expressed in our study, with no statistically significant difference between sides in the non-painful group regardless of arm dominance (Online supplement 1). Given the previously mentioned results of lower ER force values and lower strength ratios of the ER:IR in painful shoulders, it could be postulated that the presence of these altered variables may predispose shoulders to dysfunction. Therefore, theoretically, correction of these altered variables, decreased external rotation strength, and decreased ER:IR strength ratios should lead to less shoulder dysfunction.\u003c/p\u003e \u003cp\u003eThe same trend of decreased the ER force compared with the IR force was observed in neutral and higher ranges of movement (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and online supplement 1). Decreased strength ratios were also observed in the ER:IR force couple ratios, and not just in neutral (Table\u0026nbsp;\u003cspan refid=\"Tab8\" class=\"InternalRef\"\u003e8\u003c/span\u003e). Therefore, disruption of the subscapularis/ infraspinatus and teres minor force couple may produce an anterior or posterior shearing force that destabilizes the humeral head articulation on the glenoid fossa, and perhaps contributes to shoulder dysfunction.\u003c/p\u003e \u003cp\u003eInternal rotators:\u003c/p\u003e \u003cp\u003eAnother interesting finding was that the (IRs) force values (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e) were not significantly decreased in the painful shoulders. This finding was reiterated in their studies by several authors [12,31,48]. The practical application of the proposed method can therefore be that strengthening should focus more on the weakened (ERs) and not be applied with equal importance to both strength components (ER and IR).\u003c/p\u003e \u003cp\u003eWith the presence of decreased (ERs) strength and unchanged (IRs) strength, and decreased ER:IR ratio, disruption of the inferior anterior-posterior force couple can be anticipated. Theoretically, this imbalance can start the destabilizing of the humeral head on the glenoid surface due to increased translatory shear forces across the glenoid. This finding perhaps echoes the viewpoint of Ellenbecker and Rotert (2003) [51] that the strength of individual muscles in the rotator cuff is important, but more so the external versus the internal rotator strength ratio for balanced joint motion.\u003c/p\u003e \u003cp\u003eLeft and Right sides of participants with non-painful shoulders:\u003c/p\u003e \u003cp\u003eIn the non-painful group, no statistically significant difference was observed between the left and right sides of the same participant in our study. Hence, in practice, comparisons may be made of the same individual\u0026rsquo;s left and right sides for evaluation and rehabilitation purposes. This finding was also reflected in other studies of asymptomatic participants in both the athletic and non-athletic populations [8, 9, 24, 50.7].\u003c/p\u003e \u003cp\u003eStrength differences:\u003c/p\u003e \u003cp\u003eDifferences in the observed strength of participants with painful shoulders (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e) cannot be solely attributed to pain inhibition. [52]. Ellenbecker (2020) visually observed infraspinatus atrophy in the dominant arm of male tennis players. The presence of infraspinatus atrophy correlated with weakness of the ERs [52] (Ellenbecker (2020). Manske (2024) [53] with the use of musculoskeletal ultrasound (MSK-US) confirmed visually observed atrophy to be linked to decreased cross-sectional muscle volume of the infraspinatus. Lajtai (2009) [54] observed atrophy in the painful shoulders of beachball volley ballplayers, and Benitez- Martinez (2017) [55] observed a decrease in the cross-sectional area of the supraspinatus in the presence of painful shoulders in their respective studies. The conclusion drawn from these observations therefore, cast doubt on the decreased muscle force stemming from pain inhibition.\u003c/p\u003e \u003cp\u003eFurthermore, disruption of both the anterior: posterior (ER:IR) and superior (SS:AD) force couple, can potentially predispose the shoulder to dysfunction. In lieu of the findings by Werner (2006) [56] that concluded isolated induced palsy of the SS muscle does not lead to superior migration of the humeral head, all muscles and force couples of the rotator cuff should be considered and not just the supraspinatus muscle in isolation. It is known in the current literature that the whole cuff contributes to elevation; therefore, the concluded values of all force couples can lead to better informed diagnosis and treatment strategies for the shoulder [56, 57,23].\u003c/p\u003e \u003cp\u003eEvidence-based Practice (EBP):\u003c/p\u003e \u003cp\u003eEBP is becoming increasingly important in all spheres of medical practices. The use of isometric evaluation for strength testing and rehabilitation program progression has been recommended for practice [38, 39]. Approaching shoulder evaluation and treatment using objective evaluation measurements will be meaningful for both patients and clinicians. To echo the viewpoint of Ellenbecker and Roetert (2003) [51] the strength of the individual muscles of the rotator cuff is important, but more so, for balanced joint motion, the external versus internal rotator cuff strength ratio. Adding information on all the concluded force couples provides a more comprehensive overview of the primary stabilizers of the glenohumeral joint.\u003c/p\u003e"},{"header":"6. Implication","content":"\u003cp\u003eLimitation:\u003c/p\u003e \u003cp\u003eOur study was an analytical cross-sectional study and causation of pain was not determined. Only the muscle force and force couple ratios of SS and AD were determined. However, investigation of the force couple ratios between the supraspinatus and middle deltoid and between the supraspinatus and posterior deltoid are recommended in all population groups. Investigation of the above-mentioned factors, with both observational cross-sectional and longitudinal cohort study designs are recommended. Causality of pain development in the presence of altered force couple ratios should be explored with randomized control trials.\u003c/p\u003e"},{"header":"7. Clinical message","content":"\u003cp\u003eStrengthening of weakened (ERs), and SS and restoration of all affected force couple ratios of both the superior cuff and inferior cuff, in painful shoulders among all age groups, may be beneficial to pain relieve. Therefore, applying the results of our study to both clinical and research practices may help evaluate shoulder dysfunction and tailor rehabilitation principles. Specific force values were determined for the SS and AD. The determined SS: AD force couple ratios shed more light on the biomechanical functioning of the rotator cuff. The concluded ER:IR force couple ratios in all ranges, not just in neutral range, provide a holistic overview of the inferior rotator cuff musculature. Moreover, (ERs) were more weakened than (IRs) in painful shoulders in a non-athletic population. The expressed results were determined in a broad general population group and are applicable to practice.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eAD\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAnterior deltoid\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eABDER\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAbduction external\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eABDIR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAbduction internal\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eBMI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eBody mass index\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eEBP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eEvidence based practice\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eEMG\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eElectromyographic\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eER\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eExternal\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eERF\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eExternal rotation flexion\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eHHD\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eHand held dynamometer\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eInternal\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIRF\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eInternal flexion\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eNP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eNon-painful\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePainful\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eROM\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eRange of motion\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSD\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eStandard deviation\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSupraspinatus\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e9. Data Availability Statement:\u003c/p\u003e\n\u003cp\u003eThe authors xxxxxx declare that the data supporting the findings of this study are available within the paper and in the supplementary online information files.\u003c/p\u003e\n\u003cp\u003e10. Funding:\u003c/p\u003e\n\u003cp\u003eFunding was received from the xxxxxxx.\u003c/p\u003e\n\u003cp\u003e11. Disclosure of Interest:\u003c/p\u003e\n\u003cp\u003eAll authors xxxxxxxxx declare that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript.\u003c/p\u003e\n\u003cp\u003e12. Ethics declaration:\u003c/p\u003e\n\u003cp\u003eEthical approval was obtained from the Approval Committee of the University of the xxxx Internal Review Board: Human Research Ethics Committee (Medical) number (M190984).\u003c/p\u003e\n\u003cp\u003eClinical trial number not applicable.\u003c/p\u003e\n\u003cp\u003eConsent to participate:\u003c/p\u003e\n\u003cp\u003eVoluntary informed signed consent was obtained from all participants prior to the testing session.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eConsent to publish:\u003c/p\u003e\n\u003cp\u003eWritten informed consent for publication was obtained by the participant used, for the use of the images that will be freely available on the internet and may be seen by the general public. \u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eEngin AE, Chen SM.(a) Statistical data base for the biomechanical properties of the human shoulder complex--I: Kinematics of the shoulder complex. 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American volume\u003c/em\u003e, \u003cem\u003e74\u003c/em\u003e(9), 1320\u0026ndash;1333.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables 2 and 3 are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Force couple ratios, supraspinatus, anterior deltoid, external, internal.","lastPublishedDoi":"10.21203/rs.3.rs-5414162/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5414162/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground:\u003c/h2\u003e \u003cp\u003eThe ideal force couple ratio of the superior cuff, supraspinatus versus anterior deltoid is yet to be determined in both an athletic and non-athletic population.\u003c/p\u003e\u003ch2\u003eObjective:\u003c/h2\u003e \u003cp\u003eTo determine the muscle force and muscle force couple ratios of the superior cuff, between the supraspinatus and the anterior deltoid and of the inferior cuff, between the external rotators and the internal rotators in painful and non- painful shoulders in an adult non-athletic population.\u003c/p\u003e\u003ch2\u003eMethods:\u003c/h2\u003e \u003cp\u003eThis was an analytical cross-sectional study. The shoulders of both painful and non-painful shoulders of adults, females and males aged between 18 years and 75 years of age were tested. The ratios of the superior cuff (supraspinatus versus anterior deltoid) and of the inferior cuff (external versus the internal rotators) were determined.\u003c/p\u003e\u003ch2\u003eResults:\u003c/h2\u003e \u003cp\u003eSpecific force couple ratio of supraspinatus versus anterior deltoid was determined. Higher values for the force couple\u0026rsquo;s ratios were concluded in the non-painful group of supraspinatus: anterior deltoid of 1.25 (0.20) versus the lower value of the painful group of supraspinatus: anterior deltoid of 1.20 (0.23). Statistically significant difference was determined between supraspinatus: anterior deltoid in males (1.25) versus females of (1.16) (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.12) with a small effect size of (0.27). Statistically significant difference (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) of the external rotators force values between the non-painful and the painful participants were determined. No significant difference of the internal rotator force values between the non-painful and the painful participants were determined.\u003c/p\u003e\u003ch2\u003eConclusions:\u003c/h2\u003e \u003cp\u003eAll force couple ratios should be considered in the evaluation and rehabilitation of all population groups.\u003c/p\u003e","manuscriptTitle":"Strength profile of the superior and inferior rotator cuff: A comparison between painful and non-painful participants aged between 18 and 75 years.","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-12-17 06:36:11","doi":"10.21203/rs.3.rs-5414162/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"47af4c75-d142-498f-98ce-220829a1ee6c","owner":[],"postedDate":"December 17th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-02-12T04:23:54+00:00","versionOfRecord":[],"versionCreatedAt":"2024-12-17 06:36:11","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5414162","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5414162","identity":"rs-5414162","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}