Morphological, Physical and Biomechanical Characteristics of the Achilles Tendon in the Dromedary Camel (Camelus dromedarius)

Morphological, Physical and Biomechanical Characteristics of the Achilles Tendon in the Dromedary Camel (Camelus dromedarius) | 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 Article Morphological, Physical and Biomechanical Characteristics of the Achilles Tendon in the Dromedary Camel (Camelus dromedarius) Gamal M Allouch, Fahad A Alshanbari This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9484450/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract This study investigates the anatomy and biomechanics of the camel’s Achilles tendon and associated hindlimb muscles to better understand their functional roles during movement such as walking, running, and kicking. Ten healthy adults camel hindlimbs, collected from both males and females aged Five camels are aged 1–3 years, were examined from anatomy laboratories and slaughterhouses in Saudi Arabia. Detailed dissections were performed to analyze the structure of the semitendinosus, gastrocnemius, and superficial digital flexor muscles, along with their tendons. A comprehensive set of measurements was recorded, including muscle fiber length, total muscle length and weight, muscle mass and volume, density, physiological cross‑sectional area (PCSA), cross‑sectional area (CSA), maximum isometric force, stress, torque, and kinetic energy. The findings revealed that the semitendinosus and gastrocnemius muscles, which contribute to flexion and abduction of the hindlimb, exhibited similar physical and biomechanical properties. In contrast, the superficial digital flexor muscle showed distinct and higher biomechanical values, attributed to its string‑like tendinous structure. These biomechanical differences highlighted the specialized roles of each muscle in facilitating efficient hindlimb movement. Overall, the research demonstrates that every muscle possesses unique physical characteristics that contribute to the camel’s locomotor performance. Health sciences/Anatomy Biological sciences/Physiology Biological sciences/Zoology Morphology Stress Animals Adult Energy transfer Camel Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Introduction The Achilles tendon plays a major role not only in movement but also in reflecting the animal’s overall musculoskeletal health [1,2]. Despite the camel’s distinctive hindlimb function, few studies have explored how different locomotor behaviors relate to musculoskeletal morphology [3], and detailed analyses of the camel Achilles tendon remain limit. Key anatomical and biomechanical parameters such as physiological cross‑sectional area (PCSA), tendon cross‑sectional area (TCSA), tendon power (TP), torque, and kinetic energy. These measurements are critical for understanding joint loading and tendon stress [4, 5]. In many ruminants and horses, the Achilles tendon includes contributions from the superficial digital flexor and gastrocnemius muscles, supported by the biceps femoris, semitendinosus, and gracilis, all inserting on the calcaneal tuberosity [6]. Similar anatomical descriptions have been reported for camels [7] , while ultrasonographic findings show the plantaris tendon as a thick, hyperechoic band measuring 15–20 mm [8]. Understanding tendon mechanical properties is vital because elasticity influences muscle output and force control, a principle consistent across vertebrates [9] .In many species, the Achilles tendon runs nearly parallel to the tibia [10], and its formation involves the fusion of the gastrocnemius and soleus muscles with contributions from the plantaris [11]. Accurate PCSA estimation is crucial for determining muscle force, as errors can significantly affect tendon load assessments [12]. While PCSA is extensively documented [13], methodological accuracy is crucial; maximal isometric force (MIF) must be estimated from PCSA rather than assumed to be equivalent. Measuring tendon CSA is fundamental for evaluating tendon biomechanics because stress is defined as force relative to CSA. This measurement varies with species, age, sex, and anatomical location [14.15,16,17]), and resting CSA is typically used for stress analysis [18]. This research aims to characterize the physical and biomechanical properties of the Achilles tendon in camels, a structure essential for interpreting their unique locomotor behaviors including walking, running, and kicking. Material and methods Study Design and Animals Ten healthy adult dromedaries camel hindlimbs, collected from animals aged Five camels are aged 1–3 years, of both sexes, were obtained from the Anatomy Laboratory, Department of Medical Biosciences, College of Veterinary Medicine, Qassim University. The limbs were used to investigate the structural organization of the gastrocnemius, superficial digital flexor, and semitendinosus muscles, along with their tendons, which collectively contribute to the formation of the Achilles tendon. Sample Preparation and Dissection The hindlimbs were preserved in 10% formalin in an extended position to maintain anatomical integrity. Detailed dissections were performed to expose each muscle from origin to insertion, along with associated tendons. Standard dissection tools were used to isolate the components of the Achilles tendon. In five specimens, 10% formalin was injected into the external carotid arteries to enhance tissue fixation and maintain tendon morphology during examination. Morphometric and Architectural Measurements Five hindlimbs were dedicated to the physical and biochemical properties of the Achilles tendon. Measurements of the physical properties included weight, length, volume, mass of the muscles and tendons and their percentages (Table 1 , 2 ). Water displacement was used to determine volume, from which mass was calculated using the formula: Mass = Volume × Gravity (9.8 m/s²). Density was 1.06 (g/cm³) to [ 19 ]. Muscle fiber length was estimated as 70% of total muscle length, based on [ 20 , 21 ], because direct sarcomere measurements were considered impractical for this study. Pennation angles were quantified using calipers (Mitutoyo N20, Japan) in accordance with the procedures outlined by) [ 22 ] and other investigations focused on muscle architectural stability. Physiological cross‑sectional area (PCSA), a key determinant of muscle force‑generating potential, was calculated using the formula: PCSA = (Muscle mass × cos θ) / (Muscle density × Fiber length) following [ 12 , 23 , 24 ]. Tendon Biomechanics: Tendon cross‑sectional area (TCSA) was estimated according to tendon shape, applying standard geometric equations by : 𝑇𝐶𝑆𝐴=𝑊𝑖𝑑𝑡ℎ×𝑇ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠;. Elliptical tendons: CSA = ¼ πab, and Circular tendons: CSA = πr². Measurements were taken at rest, consistent with [ 18 ]. Maximum isometric tendon force was estimated as 2 × TCSA. Tendon stress was calculated using: Stress (σ) = Force / Area (N/m²). Force production was derived from gravitational load and measured mass: Force = Mass × 9.8 m/s². Kinetic energy and Torque: Muscular torque (T) was determined using the equation: T = F × d, where d is the perpendicular distance from the force line of action to the joint axis [ 25 ]. Kinetic energy (KE) of muscle movement was calculated as: KE = ½ m v², with velocity derived from displacement over time [ 26 ]. Human muscle speed data were used as a comparative standard. Further, anatomical measurements included distances from the stifle joint to the hindlimb’s lateral extremities during movement, focusing on the roles of the semitendinosus, gastrocnemius, and superficial digital flexor muscles during contraction. Inclusion Criteria Camels were included in this study due to the functional significance of the Achilles tendon, particularly its role in facilitating movement, with an emphasis on lateral motion. The specimens were categorized based on anatomical features, type, age, and a range of physical and biochemical characteristics. Ethical Approval Because all samples were collected from camels slaughtered for human consumption at a commercial slaughterhouse, no ethical approval was required for this study. No live animals were handled, used, or subjected to any experimental procedures; therefore, no animal experimentation or intervention was involved. Results Semitendinosus Muscle and Tendon (Fig. 1, 2 and 3): The semitendinosus muscle is the largest contributor to the Achilles tendon group in camels. It lies between the semimembranosus and the biceps femoris muscles, originating from the ischiatic tubercle. Its fibers extend caudoventrally at an angle of approximately 30° (Fig. 3), producing a long tendon that overlays the dorsal side of the Achilles tendon. Functionally, the semitendinosus muscle plays key roles in forward propulsion, walking, running, and producing lateral kicks and inward rotation of the hindlimb. Its PCSA was calculated at 24.30 cm², with an estimated maximum force-generating capacity of 48.60 cm².The muscle generates a force of 6.69 N, which is responsible for moving the hindlimb in cranial, caudal, and medial directions ( Table.3). Its tendon, which contributes to the upper portion of the calcaneal insertion, transmits a force of 3.06 N, roughly half that produced by the muscle (Table 4 and Fig 4). The torque generated by the semitendinosus muscle was 6.48 Nm (table.3), while the tendon torque was 4.02 Nm (Table. 4). These values reflect the influence of fiber orientation on mechanical leverage. The kinetic energy required to activate the muscle for movement was 2.32 Joules (Table 3), while the tendon required 0.72 Joules (Table 4), representing the energy needed to shift the muscle mass from rest to action and back. Tendon pressure remained constant at 2, indicating structural stability against daily mechanical loads without risk of injury (Table 4). Gastrocnemius Muscle and Tendon (Fig 1, 2 and 3): The gastrocnemius muscle is located in the proximal hindlimb region and consists of two heads medial and lateral (Fig. 2 and 3) that originate from the supracondylar tubercle of the femur. The two heads merge near the stifle joint, forming a spiraled tendon that wraps from medial to lateral around the plantaris muscle before inserting on the calcaneal tubercle. Its fibers exhibit a caudolateral orientation at an angle of 50° (Fig. 3), enabling rapid limb extension, running, and kicking. Additionally, the gastrocnemius plays a major role in posture maintenance and balance. The PCSA of the gastrocnemius was 17.95 cm², with a potential force generating capacity of 35 cm², while the muscle creates a force of 5.59 N (Table 3), enabling multidirectional hindlimb motion. The tendon force was 5.24 N (Table 4), reflecting a nearly equal force transfer from muscle to calcaneus. The torque values demonstrate strong mechanical leverage: 7.48 Nm for the muscle and 6.86 Nm for the tendon (Table 3,4). kinetic energy activation values were 1.64 Joules for the muscle and 1.97 Joules for the tendon (Table, 3,4 ) representing the energy required to transition between rest and active states. Superficial Digital Flexor (Plantaris) Muscle and Tendon (Fig 1, 2 and 3) The plantaris muscle in camels is entirely tendinous and located proximally, fully enclosed in its upper region by the gastrocnemius muscle. It arises from the lateral supracondylar tuberosity of the femur. The plantaris fibers run in a straight, ventral trajectory, maintaining a parallel alignment without angle (0°) (Fig. 3). This unique morphology contributes significantly to torque production. The plantaris integrates with fascial slips from other flexor tendons and merges with the gastrocnemius tendon to form part of the shared Achilles tendon. It spirals medially around the gastrocnemius before inserting into the calcaneal tuberosity. Its PCSA was 1.79 cm² the lowest among the three muscles, despite its relatively large mass(Table 3),. The TCSA was 2.11 mm², enabling a transmission capacity of approximately 4.22 cm² (Table, 4). The plantaris produced a force of 9.98 N, its muscle and tendon forces are identical since the entire structure is functionally tendinous (Fig.4). The torque generated was 13.25 Nm, the highest among the three muscles (Table 3,4). This significant value is attributed to its straight fiber orientation, which enhances mechanical leverage for both flexion and extension movements. The KE needed to activate the muscle was 3 Joules, reflecting the energy demand for transitioning its mass during movement (Table 3,4). The tendon of semitendinosus M and the tendons of the gastrocnemius and plantaris muscles contribute a role in creating the Achilles tendon, attaching to the tuberosity of calcaneus. The first layer comprises the fascicular tendons from gastrocnemius' two medial and lateral heads contributing to the tendon’s dorsal, lateral, and medial portions. The lateral head's tendon partially connects to the tuber calcanei’s surfaces, while the medial head’s tendon lies deeper. The plantaris muscle forms the deepest layer, partially joining with gastrocnemius tendons, and is enclosed proximally within the gastrocnemius muscle. All tendon bundles from Achilles tendon terminate on the calcaneal tuberosity. Each of the three tendons has unique fiber arrangements, reflecting specific local mechanical loads (Fig. 1,2). Discussion The camel hindlimb is supported by a highly specialized and robust Achilles tendon apparatus that plays a critical role in locomotor functions such as walking, running, lateral kicking, and maintaining body stability. In this study, we examined the anatomical, morphological, physical, and biomechanical characteristics of the camel Achilles tendon and the three major muscles contributing to its formation: the semitendinosus, gastrocnemius, and superficial digital flexor (plantaris). Together, these components form an integrated muscle–tendon system that supports propulsion, weight bearing, and controlled hindlimb movement during both routine and high‑intensity activities. Camel locomotion combines high endurance with efficient sprinting while minimizing energy expenditure [27]. Evolutionary specializations—elongated hindlimb metatarsals and relatively shortened forelimbs—support upright posture with minimal muscular effort [28], enhancing energy conservation and shock absorption for desert locomotion [29].The caudal thigh muscles show distinctive architecture essential for hindlimb movement [30], with primary roles in knee flexion and hip extension and semitendinosus involvement in medial tibial rotation [31, 32]. In camels, the hamstrings facilitate walking, running, and powerful kicking [33] Váczi et al., 2022; [34], consistent with integrated muscle–tendon systems observed in highly mobile species such as horses [35]. The semitendinosus is notably large and contributes substantially to the Achilles tendon, with fibers oriented caudoventrally [36]. Its rounded contour resembles that of ungulates and differing from the more angular form reported in dogs and oxen [6] and bovines [37]. The Achilles tendon was the strongest tendon in the body attaches to the tuber calcanei and functions as an energy‑saving, force‑transmitting structure that enables rapid locomotion, including kicking and running [29,38,39]. Our findings support the interconnected nature of tendon components [40] and diverge from [36] who proposed contributions from the biceps portion of the superficial digital flexor and the gastrocnemius that were not substantiated here. Notably, no soleus muscle was identified in any specimen, contradicting report [7], who described its presence in camels. The findings align more closely with descriptions by [6,41,42] in horse who recorded that the Achilles tendon is primarily formed by the gastrocnemius, superficial digital flexor (SDFT), and plantaris muscles. Findings also sured [37,43] on tendon contributions in bovines. The plantaris tendon is an efficient energy‑storage structure, recovering over 90% of stored elastic energy [9,44, 45]. Comparative equine anatomy notes the spiral path of the gastrocnemius tendon around the SDFT before insertion on the tuber calcanei [46]. In the present study, semitendinosus fibers extended caudoventrally at roughly 30°, gastrocnemius fibers coursed caudomedially at about 50°, and SDF and plantaris fibers ran straight ventrally [47,48], paralleling observations in cattle where fibers run caudoventrally and more parallel to the long axis [49]. These differing orientations indicate that fiber direction guides extension, flexion, and lateral motion. Histologically, the camel semitendinosus contains rounded and polyhedral fiber profiles, supporting long‑distance efficiency [50]. Fiber lengths in semitendinosus exceed those in the gastrocnemius [51]. While horses exhibit short‑fibered, multipennate SDF muscles [52], camels show longer fibers, and the SDFT runs alongside the deep digital flexor tendon [8,53] .Region‑specific variations in tendon thickness and width across the Achilles complex indicate heterogeneous mechanical loading [54, 55, 56,57] Cross‑sectional shapes vary by region—oval proximally, semi‑oval mid‑tendon, and ring‑shaped distally as described in horses and cattle [58] 59,60] and observed in reindeer [61]. Small but measurable pennation angles were identified: 30° in semitendinosus and 50° in gastrocnemius, confirming their pennate architecture, whereas SDF showed no pennation (α = 0°). Correspondingly, physiological cross‑sectional areas (PCSA) differed 24.30 cm² (semitendinosus), 17.95 cm² (gastrocnemius), and 1.79 cm² (superficial digital flexor) supporting the principle that pennate muscles possess greater PCSA and thus higher force‑generating capacity than non‑pennate muscles [62]. The relationship between muscle mass, length, and pennation angle underpins maximum isometric force, consistent with prior reports [63]. In line with optimal musculoskeletal design, muscle volume maximizes force and mechanical work [64]. We observed a clear association between fascicle length and PCSA: long fascicles (e.g., SDF at 52 cm) corresponded to low PCSA (18 cm²), indicating specialization for body‑mass support and efficient locomotion but reduced physiological power, Our results were consistent with [64, 65]. PCSA remains a primary determinant of maximal force, and dynamic changes in pennation with limb motion further modulate effective force transmission, to date, detailed PCSA measurements are better documented in the equine forelimb [66]. We documented notable variation in tendon morphology and cross sectional area (CSA) within the camel Achilles complex (0.59 cm² semitendinosus; 1.06 cm² gastrocnemius; 2.77 cm² SDFM), consistent with reports that tendon cross sections near insertions can be flat, cylindrical, fan shaped, or ribbon like [358], reflecting uneven stress distribution [54, 60]. The accuracy of stress depends, in part, upon the determination of the cross-sec-tional area (CSA). The accuracy of stress depends partly on the accurate determination of the cross-sectional area (CSA) [67]. Our findings also align with the principle that the maximum force a muscle can generate depends on cross sectional area and its placement within the musculoskeletal system [68]. An inverse relationship between CSA and tendon stress was evident: the largest CSA (superficial digital flexor muscle, 2.77 cm²) showed the lowest stress ratio, whereas the smallest CSA (semitendinosus, 0.59 cm²) showed the highest, with gastrocnemius intermediate—consistent with the notion that reduced CSA during elongation elevates localized stress ; [3]. Tendons operate in concert with muscle and bone, creating localized mechanical specializations, in line with evidence for region‑specific tendon properties [69, 70]. Functionally, the camel Achilles tendon complex is central to locomotion especially running and kicking supporting weight and enabling efficient force transmission, and its mechanical properties scale with CSA [3,71] The activation of Achilles‑associated muscles facilitates tensile strength for weight support [72]. Based on anatomical and mechanical indicators, the plantaris produced the greatest force (9.89 N), followed by the semitendinosus (6.69 N) and gastrocnemius (5.59 N), matching general mammalian patterns despite interspecific differences in size and structure. Although mammalian feet share similar mechanisms for transmitting locomotor forces, their size, structure, and composition vary considerably [45, 73]. Muscle force production was strongly influenced by length and mass, emphasizing optimal length–tension relationships and the need for sufficient muscle mass to generate forces required for hindlimb motions [74]. Consistent with equine data, the SDF can reach high peak forces [75]. Maximum isometric force values varied among muscles: the semitendinosus reached 48 N/cm², and the gastrocnemius 35 N/cm², reflecting architectural differences particularly pennation that influence force transmission (Table 3). Total ankle torque reached 26 Nm; the SDF produced the highest torque (13.25 Nm), whereas the semitendinosus contributed the least (6.48 Nm). Torque decreased as attachment area increased, consistent with mechanical principles [76]. Variability in fiber length‑to‑moment torque ratios among functionally similar muscles [77, 78] This is represented by )Figure 5, (underscores how fiber architecture and pennation shape performance [52],and how physiological and morphological specializations not size alone govern torque output [61]. Tendon pressure remained constant (value = 2) across Achilles regions, suggesting structural adaptation to daily mechanical loads and resilience against injury, in line with intratendinous pressure mechanisms that shape tendon behavior [79, 80]. Kinetic energy (KE) profiles showed the Achilles complex generated the highest KE (7.83 J), followed by SDF (3.54 J), semitendinosus (2.32 J), and gastrocnemius (1.97 J), with fleshy muscles collectively producing more KE than the tendinous SDF [81]. Tendons store and release mechanical energy [82] and the long, compliant 52‑cm SDF tendon stored 3.08 J—nearly double the 1.62 J in the shorter 41‑cm gastrocnemius (fig.5 ) illustrating elastic energy‑saving roles [52, 83]. Flexor tendons exhibit energy‑storing characteristics with fiber organizations tailored for efficient force generation and elastic return [84, 85]. Accurate anatomical identification is essential for achieving optimal clinical outcomes in cases involving the Achilles tendon [86, 87]. Injury to this tendon may manifest as a partial tear, affecting specific component tendons, or as a complete rupture involving all of the structures that form the Achilles tendon [88] . Conclusions This study presents the general the anatomy, biomechanics, and physical characteristics of Achilles tendon muscles, Its effect on movement of camels. The muscles contraction and force generation are influenced by fiber arrangement, length, it clarified these discrepancies by illustrating physical biomechanics, variations in PCSA, TCSA, maximum isometric force, stress, torque, and kinetic energy affecting hindlimb movement. Database comprising biomechanical variables obtained from healthy camels was essential to study the primary features of normal movement and the alterations in velocity n velocity during movement. Declarations Author contributions: GA conceived and designed the study. GA, FA executed the experiment. GA and FA analyzed the data. All authors interpreted the data, critically revised the manuscript for important intellectual contents and approved the final version. Ethical Approval Because all samples were collected from camels slaughtered for human consumption at a commercial slaughterhouse, no ethical approval was required for this study. No live animals were handled, used, or subjected to any experimental procedures; therefore, no animal experimentation or intervention was involved. Funding : The researchers would like to thank the Deanship of Graduate Studies and Scientific Research at Qassim University for financial support (QU-APC 2026). Data availability The relevant information, including raw data, has been included in the manuscript. Consent to Publish Declaration Not applicable. Informed Consent Statement: Not applicable Data Availability Statement: All data presented in this study are available on request from the corresponding authors. Competing interests The authors declare no competing interests. Competing interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Acknowledgements The authors would like to thank the Deanship of Scientific Research, Qassim University for financially aiding in the publication of this project. Author details 1 Departement of Medical Biosciences, College of Veterinary Medicine, Qassim University, P.O. Box 6622, Buraydah, 51452, Saudi Arabia . References Blazevich J,Fletcher J R . More than energy cost: multiple benefits of the long Achilles tendon in human walking and running. Biological Reviews.2023;98:6: 2210-2225. https://doi.org/10.1111/brv.13002 Demiraslan D, Gürbüz Y, Dayan İ, Akbulut M, Aslan Ya, Kadir ÖS. Structural and Functional Properties of the Distal Muscles of Front and Hind Legs of Malakan Horses (Equus caballus) . KafKas Universitesi veteriner faKUltesi Dergisi Journal 2015 http://vetdergikafkas.org DOI: 10.1186/1757-1146-7-26 · Smart RR, O’Connor B, Jakobi JM. Resting tendon cross-sectional area underestimates biceps brachii tendon stress: importance of measuring during a contraction. Frontiers in physiology 2021. 654231. doi: 10.3389/fphys.2021.654231 Albracht K, Arampatzis A, Baltzopoulos V, Assessment of muscle volume and physiological cross-sectional area of the human triceps surae muscle in vivo. J Biomech 2008. 41(10):2211–2218. doi: 10.1016/j.jbiomech.2008.04.020 Maarleveld R, Veeger HEJ, Helm van der, Son FCT, Lieber J, Kruk RL.. What the PCSA? Addressing diversity in lower-limb musculoskeletal models: age-and sex-related differences in PCSA and muscle mass. Journal of Biomechanics 2025.. 193 112976 https://doi.org/10.1016/j.jbiomech.2025.112976. Dyce K, ,Sack M, Wolfgang O. Textbook of Veterinary Anatomy, 4th ed.; Elsevier Health Sciences , MO, USA, 2010; 71: p. 78. 15. Sadan M, Achilles tendon rupture in camel (Camelus dromedarius): Radiographic and Ultrasonographic findings, Journal of Camel Health.,2019 1:1-5. https://camel.health Abu Seida AM, Mostafa AM and Tolba AR. Anatomical And Ultrasonographical Studies On Tendons And Digital Cushions Of Normal Phalangeal Region In Camels (Camelus dromedarius) Journal of Camel Practice and Research. 2012; 19 : 2: p 169-175.https://doi:10.5455/OVJ.2021.v11.12.8 Alexande RMN. Tendon elasticity and muscle function. Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 2002:133: 4: Pages 1001-1011https://doi.org/10.1016/S1095-6433(02)00143-5 Mizuno F, Fujiwara S. Estimating ankle joint angle from skeletal geometry: a mechanical model of the calcaneal lever in terrestrial mammals. Peer J. 2025:13:P. e20056 DOI 10.7717/peerj.20056 Mahan J, Damodar D, Trapana E, Barnhill S, Nuno AU, Smyth NA, Aiyer A, Jose J. Achilles tendon complex: The anatomy of its insertional footprint on the calcaneus and clinical implications. Journal of orthopaedics 2020: 17:221–227. doi: 10.1016/j.jor.2019.06.008 Furuuchi K, Koyabu D, Mori K, Endo H. Physiological cross-sectional area of the masticatory muscles in the giraffe (Giraffa camelopardalis). Mammal Study. 2013; 38 (1): 67-71. DOI: 10.3106/041.038.0109 Son J, Ward SR, Lieber RL. Scaling relationships between human leg muscle architectural properties and body size. J. Exp. Biol. , 2024: 227 (6), jeb246567. https://doi. org/10.1242/jeb.246567. Vergari C , Pourcelot Ph , Holden L, Ravary-Plumioën, B,Gerard, G,Laugier, P,Mitton, D,Crevier-Denoix N. True stress and Poisson's ratio of tendons during loading. Journal of Biomechanics. 2011:44: 4: 719-724 https://doi.org/10.1016/j.jbiomech.2010.10.038 Lepley AS, Joseph M F, Daigle N R, Digiacomo J E,Galer J,Rock E,Rosier SB,Sureja PB. Sex Differences in Mechanical Properties of the Achilles Tendon. 2018: The Journal of Strength & Conditioning Research.218; 32:11: 3070-3079. DOI: 10.1519/JSC.0000000000002386 Ristaniemi A, Stenroth L, Mikkonen S, Korhonen RK. Comparison of elastic, viscoelastic and failure tensile material properties of knee ligaments and patellar tendon. Journal of Biomechanics. 2018: 79: Pages 31-38. https://doi.org/10.1016/j.jbiomech.2018.07.031 Wu SY, Kim W, Kremen TJ, Thomas J. In Vitro Cellular Strain Models of Tendon Biologyand Tenogenic Differentiation. Front. Bioeng. Biotechnol. 2022: 10 : 826748. https://doi.org/10.3389/fbioe.2022.826748 Stenroth L, Peltonen J, Cronin NJ, Sipilä S, Finni T.Age-related differences in Achilles tendon properties and triceps surae musclearchitecture in vivo. Journal of applied physiology 2012: 113: 1537–1544,.doi:10.1152/japplphysiol.00782.2012.8750-7587/12 Ward SR & Lieber RL. Density and hydration of fresh and fixed human skeletal muscle. J Biomech. 2005: 38:11:2317–2320. https://doi.org/10.1016/j.jbiomech.2004.10.001 Biewener A A. Musculoskeletal design in relation to body size. Journal of Biomechanics. 1991; 24:1: 19-29. https://doi.org/10.1016/0021-9290(91)90374-V Persad LS, Wang Z, Pino PA, Binder-Markey B, Kaufman K R, Lieber RL.. Specific tension of human muscle in vivo: a systematic review. J Appl Physiol. 2024;137(4):945–962. https://doi.org/10.1152/japplphysiol.00296.2024 Taylor AB,| Terhune CE, Ross C F, Vinyard ChJ. The impact of measurement technique and samplingon estimates of skeletal muscle fibre architecture. The Anatomical Record 2024:307:3071–3084. https://doi.org/10.1002/ar.25415 Santana SE, Dumont ER, Davis JL, 2010. Mechanics of bite force production and its relationship to diet in bats. Functional Ecology 2010; 24 :4: 776-784. DOI: 10.1111/j.1365-2435.2010.01703.x FukunagaT, Roy RR, Shellock FG, Hodgson JA, Day MK, Lee PL, Kwong‐Fu H, Edgerton VR.Physiological cross‐sectional area of human leg muscles based on magnetic resonance imaging. J Orthop Res. 1992:10 :6: 926-934. DOI: 10.1002/jor.1100100623 Smart R, Richardson CM, Wile DJ, Dalton BH, Jakobi J M. Importance of Maximal Strength and Muscle-Tendon Mechanics for Improving Force Steadiness in Persons with Parkinson’s Disease . Brain Sci. 2020: 10: 8: 471; https://doi.org/10.3390/brainsci10080471 Gindy M , Nassif HH, Velde J. Bridge Displacement Estimates from Measured Acceleration Records. Transportation Research Record.2007: 2028:136-1451 https://doi.org/10.3141/2028-15 Mascoli GJD, 2002. Will that be one hump or two? Science IQ.com www.scienceiq.com/facts/humps.cfm. Accessed On 17/9/2010. Jones ME, Travouillon K, Janis CM. Proportional variation and scaling in the hindlimbs of hopping mammals, including convergent evolution in argygrolagids and jerboas. Journal of Mammalian Evolution 2024:31:1:1–16 DOI 10.1007/s10914-023-09699-9. Alves ALG , Dudhia J , Rosa GS, Smith RKW.The The veterinarian perspective: Comparative anatomy, equine models and in vivo bioengineering of tendons Chapter 9 - 359-380 https://doi.org/10.1016/B978-0-443-15916-9.00016-4 Sinulingga AR, and Zemková E. Maximal isometric and eccentric hamstring strength is influenced by body mass and additional load: Does the critical point at which peak knee flexor force is achieved play a role? Frontiers in Physiology. 2025;16:1654030 9 https://doi.org/10.3389/fphys.2025.1654030 Rodgers CD and Raja A. Anatomy, bony pelvis and lower limb, hamstring muscle .2026 : Stat Pearls Publishing Treasure Island ; American Nurses Association ID: NBK546688PMID: 3153629. DOI:10.6084/m9.figshare.16682479.v1 Takeda K, Kato K, Ichimura K, Sakai T. Unique morphological architecture of the hamstring muscles and its functional relevance revealed by analysis of isolated muscle specimens and quantification of structural parameters. J. Anat. 2023: 243 (2), 284–296. doi:10.1111/JOA.13860 Váczi M, Fazekas G, Pilissy T, Cselkó A,Trzaskoma L, Sebesi B,Tihanyi J.The effects of eccentric hamstring exercise training in young female handball players. European journal of applied physiology. 2022; 122:4: 955–964. doi:10.1007/S00421-022 04888-5 Markovic G, Sarabon N, Boban F, ZoricI, Jelcic M, Sos K, Scappaticci M.. Nordic hamstring strength of highly trained youth football players and its relation to sprint performance. The Journal of Strength & Conditioning Research. 2020:34 :3: 800–807. doi:10.1519/jsc.0000000000002800 Dutto D, Hoyt DF, Cogger EA, Wickler S J.34. Ground reaction forces in horses trotting up an incline and on the level over a range of speeds. Journal of Experimental Biology.2007; 20: 3507-3514 .DOI:10.1242/jeb.01171 Hamoda H, Elsaid FG, Eldesoqui M, Al-Mosaibih, MA, Fayad, E, Hussein, MK, Hamed, MA, Farrag F, Abumandour M, Shukry, M.. Imaging-based observation of the pes region in the dromedary camel (Camelus dromedarius): computed tomography, 3D volume rendering, magnetic resonance imaging, and ultrasonography. Front. Vet. Sci. 202;12:1558954. doi: 10.3389/fvets.2025.1558954 Burdras KD and Habel RE. 2011. Bovine anatomy, an illustrated text, 1st ed. Hannover, Germany: Schlütersche, Verlag Gesellschaft.112-120. Malvankar S and Khan WS. Evolution of the Achilles tendon: The athlete's Achilles heel?? Foot 2011; 21:4:193–197. https://doi.org/10.1016/j.foot.2011.08.004 Raichlen DA, Armstrong H, Lieberman DE. Calcaneus length deter mines running economy: implications for endurance running perfor mance in modern humans and Neandertals. J Hum Evol , 2011;60: 3:: 299–308. https://doi.org/10.1016/j.jhevol.2010.11.002 Szaro P, Witkowski G , Smigielski R , Krajewski P.Ciszek B.. Fascicles of the adult human Achilles tendon - an anatomical study. Ann Anat.2009; 191:6:586-93. DOI: 0.1016/j.aanat.2009.07.006 Budras K D,Sack W O, Rock S, Horowitz, A, Berg, R. Anatomy of the Horse. Schlütersche Verlagsgesellschaft GmbH and Co. KG: Hanover, Germany, 2017; pp. 3–25. https://doi.org/10.1201/9783842683686 Schreiber K, Haudiquet Ph, Hamon M. Achilles Tendon Rupture Treated with Flexor Digitorum Lateralis Tendon Transposition and Transarticular External Skeletal Fixator in Ouessant Sheep CC BY 4.0 · VCOT Open 2024; :7:1: e46-e51. DOI: 10.1055/s-0044-1786187 Wahengbam P, Pathak R, Hajam IA, Shah MA, Basha MA, Verma NK, Pawde AM . Clinical Management of Achilles Tendon Injury with Tendon Gap Defect in a Horse Using Tissue Engineering: A Case Report Acta Scientific Veterinary Sciences; 2023;5:7;64-68 DOI:10.31080/ASVS.2023.05.0690. Proudman CJ. Common calcaneal tendinitis in a horse. Equine Veterinary Education . 1992;4:6: 277-279. https://doi.org/10.1111/j.2042-3292..tb00965.x Biewener AA. Muscle Function in vivo: A Comparison of Muscles used for Elastic Energy Savings versus Muscles Used to Generate Mechanical Power. American Zoologis.1998; 703-717. Doi: 10.1093/icb/38.4.703 Dyson SJ , Kidd L. Five cases of gastrocnemius tendinitis in the horse . Equine Veterinary Journal ,1992; 24:5, Pages 351-356 https://doi.org/10.1111/j.2042-3306..tb02854.x. Azhari H..Basics of Biomedical Ultrasound for Engineers. Published by John Wiley & Sons Inc. Hobok, New Jersy published simultaneously in Canda. 2010. PP 83-142 Zhou Y, Li JZ , Zhou G, Zheng YP. Dynamic measurement of pennation angle of gastrocnemius muscles during contractions basedon ultrasound imagingBiomedical engineering online. 2012; 11:63: 10 doi:10.1186/1475-925X-11-63 Senaratne LS, Calkins CR, deMello Jr AS, Pokharel S,Hinkle JB.Mapping of Intramuscular Tenderness and Muscle Fiber Orientation of Muscles in the Beef Round. Journal of animal science;2010;88;9;3084-3106. https://doi.org/10.2527/jas.2009-2683 Oyelowo FO, Sonfada ML Muscle fibre types in hamstring muscles of one-humped camel Camelus dromedaries. Oyelowo/ Journal of Camelid Science 2013; 6:72-80 https://doi.org/10.2527/jas.2009-2683 Watanabe K, Otsuki S, Hisa T, Nagaoka M, Functional difference between the proximal and distal compartments of the semitendinosus muscle. Journal of Physical Therapy Science. 2016 ; 28: 5: 1511–1517. https://doi.org/10.1589/jpts.28.1511 52 . Butcher MT , Chase PB , Hermanson J W Clark AN,Brunet NM,Bertram, JEA.. Contractile properties of muscle fibers from the deep and superficial digital flexors of horses. : American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 2010; 299;4; R996-R1005.4 https://doi.org/10.1152/ajpregu.00510. Franchi M, Trirè A, Quaranta M Orsini E, Ottani V.Collagen Structure of Tendon Relates to Function. The Scientific World Journal.2007; 7:1; 404–420. https://doi.org/10.1100/tsw.2007.92 Magnusson SP, Hansen P, Kjaer M, 2003. Tendon properties in relation to muscular activity and physical training. Scand. Scandinavian journal of medicine & science in sports.2003; 4: 211-223. https://doi.org/10.1034/j.1600-0838.2003.00308.x Çelimli N, Seyrek D, and Kaya M. Morphometric measurements of flexor tendons and ligaments in Arabian horses by ultrasonographic examination and comparison with other breeds. Equine vet. Educ. . 2004; 16 (2) 81-85. DOI 10.2298/VETGLA0402095K Biewener AA, 2005. Biomechanical consequences of scaling. Journal of Experimental Biology2005;208:9: 1665–1676. https://doi.org/10.1242/jeb.01520 Watanabe T, Hosaka Y, Yamamoto E, Ueda H,Sugawara K,Takahashi H,Takehana, K. Control of the collagen fibril diameter in the equine superficial digital flexor tendon in horses by decorin. J. Vet. Med. Sci. 2005; 67: 9:855-860. https://doi.org/10.1292/jvms.67.855 Kannus P. Structure of the tendon connective tissue. Scand. J. Med. Sci. Sports.2000; 10: 6; 312-320. https://doi.org/10.1034/j.1600-0838.2000.010006312.x Watanabe T, Imamura Y, Hosaka, Y, UedaH,iTakehana, K. Graded arrangement of collagen fibrils in the equine superficial digital flexor tendon. Connect. Tissue Res.2007; 48:6; 332-337. https://doi.org/10.1080/03008200701692800 Takahashi N, Hirose T, Minaguchi JA, Ueda H,Tangkawattana P,Takehana, K. Fibrillar architecture at three different sites of the bovine superficial digital flexor tendon . J. Vet. Med. Sci. 2018 ; 80: 3: 405–412, 2018 doi: 10.1292/jvms.17-0562 Wareing k, Tickle PG, Stokkan KA, Codd JR,Sellers WI.The musculoskeletal anatomy of the reindeer (Rangifer tarandus): fore and hindlimb Polar Biology. 2011;34:10:1071-1578. DOI 10.1007/s00300-011-1017-y 123 Rockenfeller R, Günther M, Clemente CJ, Dick T JM. Rethinking the physiological cross-sectional area of skeletal muscle reveals the mechanical advantage of pennation. R. Soc. Open Sci.2024; 11:9. https://doi.org/10.1098/rsos.240037 Sopher RS, Amis AA, Davies DC, Jeffers J RT.The Influence of muscle pennation angle and cross-sectional area on contact forces in the ankle joint. J. Strain Anal. Eng. Des. 2017; 52: 1: 12–23. (doi:10.1177/0309324716669250 Labonte D. A theory of physiological similarity in muscle-driven motion. Proceedings of the National Academy of Sciences..2023;120:24: e2221217120 https://doi.org/10.1073/pnas.2221217120 PP 1 - 11. Leonardo Alexandre PT, Marcelo C.Locomotion as a Powerful Model to Study Integrative Physiology: Efficiency, Economy, and Power Relationship. Front. Physiol.2018; 9:1789. doi: 10.3389/fphys.2018.01789 Watson J C and Wilson A M. Muscle architecture of biceps brachii, triceps brachii and supraspinatus in the horse. Journal of Anatomy. 2006;210: 1: 32-40 https://doi.org/10.1111/j.1469-7580.2006.00669.x Ge Xj , Zhang L, Xiang G, Hu Y ch, Lun Dx.2020 Cross-Sectional Area Measurement Techniques of Soft Tissue: A Literature Review. Orthopaedic Surgery.2020;12:6:1547–1566 • DOI: 10.1111/os.12757 Clemente ChJ , Groote F, Dick TJM, 2024. Predictive musculoskeletal simulations reveal the mechanistic link between speed, posture and energetics among extant mammals. Nature Communications.2024;15:1: 8594. https://doi.org/10.1038/s41467-024-52924-z Nakamichi R , Asahara H.The role of mechanotransduction in tendon. Journal of Bone and Mineral Research.2024;39:7: 814-820. doi: 10.1093/jbmr/zjae074. Gehwolf R, Tempfer H, Cesur NP, Wagner A,Traweger A,LehnerCh. Tendinopathy: The Interplay between Mechanical Stress,Inflammation, and Vascularity. Advanced Science.2025;12:36e06440. DOI: 10.1002/advs.202506440 Thorpe CT, Riley GP, Birch H L, Clegg PD,Screen H RC. Fascicles and the interfascicular matrix show decreased fatigue life with ageing in energy storing tendons. Acta Biomater. 2017; 56: 58–64. doi: 10.1016/j.actbio.2017.03.024 Spinella G, Tamburro R, Loprete G, Vilar JM, Valentini S. Surgical repair of Achilles tendon rupture in dogs: a review of the literature, a case report and new perspectives. Veterinarni Medicina.2010;55: 303-310. DOI:10.17221/2926-VETMED Wearing SC , Smeathers JE. The heel fat pad: mechanical properties and clinical applications. Journal of Foot and Ankle Research.2011; 4:Suppl 1: I14 doi: 10.1186/1757-1146-4-S1-I14 Clemente Ch J, Dick TJM, Glen Ch L, Panagiotopoulou Ol. Biomechanical insights into the role of foot pads during locomotion in camelid species Scientific Reports.2020; 10:1:3856. 10.1038/s41598-020-60795-9 Harrison SM, Whitton RCh, Kawcak ChE Stover, SM,Pandy MG. Relationship between muscle forces, joint loading and utilization of elastic strain energy in equine locomotion The Journal of experimental biology.2010 ;213:23: 3998-4009. https://doi.org/10.1242/JEB.044545 Serway RA, Jewett JW, Peroomian V. Physics for scientists and engineers. 6th Ed. Philadelphia: Saunders college publishing Philadelphia;. 2: 0-534- 40842-7. Lieber RL and Brown CG. Sarcomere length-joint angle relationships of seven frog hindlimb muscles. Cells Tissues Organs. 1992; 4:145, 289–295. https://doi.org/10.1159/000147380 Lieber R.L and Shoemaker D. Muscle, joint, and tendon contributions to the torque profile of frog hip-joint. American Journal of Physiology.1992; 263, R586–R590. https://doi.org/10.1152/ajpregu.1992.263.3.R586 Pringels L, Cook J, Witvrouw E, Burssens, A,Vanden Bossche L,Wezenbeek E. Exploring the role of intratendinous pressure in the pathogenesis of tendon pathology: a narrative review and conceptual framework. Br. J. Sports Med. 2023; 57:16: 1042–1048. doi:10.1136/bjsports-2022-106066 Bossuyt FM, Leonard TR, Scott WM, Taylor WR,Herzog W.In-vivo and in-vitro environments affect the storage and release of energy in tendons. Front. Physiol.2024; 15:1443675. doi: 10.3389/fphys.2024.1443675. Patterson-Kane JC,Rich T. Achilles Tendon Injuries in Elite Athletes: Lessons in Pathophysiology from Their Equine Counterparts. ILAR Journal.2014; 55: 1: 86-99 https://doi.org/10.1093/ilar/ilu004. Sasaki K, Neptune RR. Muscle mechanical work and elastic energy utilization during walking and running near the preferred gait transition speed. Gait & posture. 2006; 23 :3: 383-390. https://doi.org/10.1016/j.gaitpost.2005.05.002 Biewener, AA. Muscle-tendon stresses and elastic energy storage during locomotion in the horse. Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology.1998; 120:1: 73-87. https://doi.org/10.1016/S0305-0491(98)00024-8 Gsell KY, Veres SP, Kreplak,L. Single collagen fibrils isolated from high stress and low stress tendons show differing susceptibility to enzymatic degradation by the interstitial collagenase matrix metalloproteinase-1 (MMP-1). Matrix Biology Plus. 2023; 18: 100129 https://doi.org/10.1016/j.mbplus..100129 Hefferan SA, Blaker CL, Ashton DM Little Chr B,Clarke El C. Structural Variations of Tendons: A Systematic Searchand Narrative Review of Histological DifferencesBetween Tendons, Tendon Regions, Sex, and Age. Journal of Orthopedic Research. 2025; 43:5:994–1053 https://doi.org/10.1002/jor.26060 Dik KJ, 1993. Ultrasonography Of The Equine Tarsus. Veterinary Radiology and Ultrasound.1993;34:1: 36-43.https://doi.org/10.1111/j.1740-8261.1993.tb01991.x Longo U G, Ronga M,Maffulli N. Acute Ruptures of the Achilles Tendon . Sports Medicine and Arthroscopy Review .2009; 17:2::127-138. DOI: 10.1097/JSA.0b013e3181a3d767 Gamble LJO, Canapp DA, Canapp Sh O. Evaluation of Achilles Tendon Injuries with Findings from Diagnostic Musculoskeletal Ultrasound in Canines – 43 Cases. Veterinary Evidence. 2017; 2 :3: 1-23 DOI: http://dx.doi.org/10.18849/ve.v2i3.92. Tables Table 1. Results of measuring the Physical properties of muscles contributing to the Achilles tendon (means; standardized units). Muscle Weight (g) Volume (cm³) Muscle mass (g) Density (g/cm³) Muscle length (cm) Fiber length (cm) Weight (%) Volume (%) Muscle mass (%) Semitendinosus (Muscle) 673±6.26 70±1.78 683±19.50 9.8±0 31±2.7 22.83±1.43 47.87% 30.30 8 COS 30 Gastrocnemius (Muscle) 593±10.28 58±1.36 571±15.27 9.8±0 18±1.78 13.83±1.80 42.18% 25.11 25.23% COS 50 Plantaris (Muscle) 140±9.0 103±6.75 100,9±74.49 9.8±0 52±7.15 52±19.95 9.96% 44.59 44.58% COS 0 Total 1406 231 2263 nan nan nan 100.00 100.00 100.00 Table 2. Results of measuring the Physical properties of Achilles tendon components (means; standardized units). Tendon Weight (g) Volume (cm³) Tendon mass (g) Density (g/cm³) Tendon length (cm) Fiber length (cm) Weight (%) Volume (%) Tendon mass (%) Semitendinosus (Tendon) 82±7.15 32±3.57 313.6±39.2 9.8±0 50±9.95 50±9.95 23.42% 16.93% 16.88% Gastrocnemius (Tendon) 125±6.28 54±4.50 535±49.3 9.8±0 41±3.22 41±3.22 35.71% 28.57% 28.80% Plantaris (Tendon) 143±6.28 103±6.75 100.9±69.5 9.8±0 52±7.15 52±7.15 40.85% 54.50% 54.32% Total 350 189 1857.60 nan nan nan 100.00 100.00 100.00 Table 3. Physical and Biochemical properties of muscles (PCSA, force , MIF, torque, kinetics energy and Maximum isometric force) (means; standardized units). Muscle Muscle length (cm) Fiber length (cm) Density (g/cm³) Weight (g) Muscle mass (g) Volume (cm³) PCSA (cm²) Force (N) Torque (N·m) KE (J) MIF (N) Semitendinosus (Muscle) 31±2.7 22.83±1.4 1.06 673±6.2 683±19.5 70±1.7 24.30±2.68 6.69±0.07 6.48±4.7 2.32±0.50 48.6 Gastrocnemius (Muscle) 18±1.78 13.83±1.80 1.06 593±10 571±15.27 58±1.36 17.95±1.36 5.59±0.07 7.84±7.6 1.97±0.39 35.9 Plantaris (Muscle) 52±7.15 52±7.15 1.06 140±9.0 100.4±74.49 104 ±6.75 1.79±3.89 9.89±0.08 13.25±20 3.54±0.88 3.59 Total nan nan nan 1406 2263 231 60 22.17 27.57 7.83 88 Table 4. Physical and Biochemical properties of tendons (Force, MIF, TCSA, CSA , torque, kinetics energy, Tendon pressure and stress) (means; standardized units) Not: MIF of tendon is Maximum isometric force-transferring capability (Ncm²). Tendon Tendon length (cm) Fiber length (cm) Density (g/cm³) Weight (g) Tendon mass (g) Volume (cm³) Force (N) MIF TCSA (mm²) CSA=A Torque (N·m) KE (J) TP (arb) Stress (N/mm²) Semitendinosus (Tendon) 50±9.95 50±9.95 1.12 82±7.15 313.6±39.2 32±3.57 3.06±0.38 1.16±0.26 0.58±0.03 0.59±0.34 4.02±0.8 0.72±0.56 2±0 6.39±3.47 Gastrocnemius (Tendon) 41±3.22 41±3.22 1.12 125±6.28 535±49.3 54±4.50 5.24 ±0.48 2.6±0.04 1.3±0.04 1.06±0.48 6.86 ± 1.26 1.64±0.24 2±0 5.56±2.12 Plantaris (Tendon) 52±7.15 52±7.15 1.12 143±6.28 100.4±69.5 103±6.75 9.89±0.72 4.22±0.11 2.11±0.12 2.77±0.91 13.25±2.21 3.08±0.43 2±0 3.75±0.90 Total nan nan nan 350 1857.60 189 18.19 7.98 3.99 4.42 24.13 5.44 6 15.7 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviewers invited by journal 04 May, 2026 Editor invited by journal 28 Apr, 2026 Editor assigned by journal 22 Apr, 2026 Submission checks completed at journal 22 Apr, 2026 First submitted to journal 21 Apr, 2026 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. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9484450","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":637027168,"identity":"99dbb991-dcb5-4af2-9c93-f2e3a0380953","order_by":0,"name":"Gamal M Allouch","email":"","orcid":"","institution":"Qassim University","correspondingAuthor":false,"prefix":"","firstName":"Gamal","middleName":"M","lastName":"Allouch","suffix":""},{"id":637027169,"identity":"c2199c48-a733-4d8b-9427-4d1fcf719b92","order_by":1,"name":"Fahad A Alshanbari","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAvklEQVRIiWNgGAWjYDACCQY2IGkDZZOgJY10LYdJ0CI/u/fY48q287IbDjAfvM3DUCdPUIvBnXPphmfbbhtvOMCWbM3DcNiwgaAWiRwzyca224kbDvCYSfMwHGAkqEV+BljLOaAW/m9ALXX2BLUw3ABrOQCyhQ2ohTmRsMNu5JgbNpxLNp55mM3Yco7B4WSiHPawocxOtu9488MbbyrqbAk7DAQY2RgYG5jBlhKlHgT+MBAOqFEwCkbBKBi5AAAd4Tse4TkzOwAAAABJRU5ErkJggg==","orcid":"","institution":"Qassim University","correspondingAuthor":true,"prefix":"","firstName":"Fahad","middleName":"A","lastName":"Alshanbari","suffix":""}],"badges":[],"createdAt":"2026-04-21 12:53:13","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9484450/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9484450/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":109117845,"identity":"e1dbaef9-946b-4f73-b63f-22677c64cb55","added_by":"auto","created_at":"2026-05-12 16:43:23","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":161745,"visible":true,"origin":"","legend":"\u003cp\u003ePhotograph of caudolateral view of the camel Achilles tendon shows Semitendinosus muscle (1), Gastrocnemius muscle (2), Tendon of semitendinosus muscle (3) Tendon of semitendinosus muscle and gastrocnemius muscle. Please note the continuation of the tendon (4), Superficial digital flexor muscle (5), Insertion site of Achilles tendon (6), Calcaneus tuber (7), Biceps femoris muscle please that it is not share in the Achilles tendon (8), Cranial tibial muscle (9) Caudal tibial muscle (10).\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9484450/v1/aa256eb70cbfcd2f971c6ff6.png"},{"id":109204916,"identity":"12b1f3de-785b-4337-b825-993e1bb7bc0b","added_by":"auto","created_at":"2026-05-13 15:02:50","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":194456,"visible":true,"origin":"","legend":"\u003cp\u003ePhotograph shows lateral view of the Achilles tendon in camel. The semitendinosus tendon (separated) (1). Superficial digital flexor) muscle (Plantaris) (2). Lateral head (belly) of gastrocnemius muscle (3) Tendon of medial head (belly) of gastrocnemius muscle (4). Tendon of lateral head (belly) of gastrocnemius muscle (5). Insertion of Achilles tendons (6). Calcaneus Tuber (7).\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9484450/v1/5cdc6e4d499fae53918795fc.png"},{"id":109204915,"identity":"23cac7de-78d8-4c6e-8e02-ebd6e7d7b2ab","added_by":"auto","created_at":"2026-05-13 15:02:49","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":355636,"visible":true,"origin":"","legend":"\u003cp\u003ePennation angles of the semitendinosus, medial head of the gastrocnemius, and superficial digital flexor muscles in the camel hindlimb. The semitendinosus muscle exhibits a pennation angle of approximately 30°, the medial head of the gastrocnemius displays a larger pennation angle of 50°, and the superficial digital flexor muscle shows a parallel‑fiber arrangement with a 0° pennation angle.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-9484450/v1/1ceee7a8327e02e709fd984c.png"},{"id":109204629,"identity":"a5cef0ca-8e90-4214-8c6a-1aee15416473","added_by":"auto","created_at":"2026-05-13 15:01:33","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":14686,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of muscle‑generated force and tendon‑transmitted force for the semitendinosus, gastrocnemius, and plantaris muscles. Yellow bars represent the force produced by each muscle, while blue bars represent the corresponding force transmitted through their tendons. The final pair of bars shows the total combined muscle force versus total tendon force.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-9484450/v1/5d16c7c86ac921555880b762.png"},{"id":109204769,"identity":"aabd6821-b711-4d2c-9ab0-482c1f5c1e0f","added_by":"auto","created_at":"2026-05-13 15:02:05","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":13785,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of muscle fiber length and torque production in the semitendinosus, gastrocnemius, and superficial digital flexor muscles. Blue bars represent muscle fiber length, while orange bars represent the torque generated by each muscle.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-9484450/v1/760dc5fbdcb539649a2442b2.png"},{"id":109205066,"identity":"ca40a123-a315-4fc9-9278-22f3f6c7ac11","added_by":"auto","created_at":"2026-05-13 15:03:14","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":17850,"visible":true,"origin":"","legend":"\u003cp\u003eComparative biomechanical parameters of the semitendinosus, gastrocnemius, and superficial digital flexor muscles, along with their combined totals. Bars represent each muscle’s physiological cross‑sectional area (PCSA), maximum force, generated force (N), torque (N·m), and kinetic energy (KE, J). The green bars indicate the sum of all three muscles for each parameter.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-9484450/v1/44673f0196baac59bdd3d760.png"},{"id":109117846,"identity":"5293e094-04ef-4fa5-b18a-a4c36d064faf","added_by":"auto","created_at":"2026-05-12 16:43:23","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":16725,"visible":true,"origin":"","legend":"\u003cp\u003eComparative tendon biomechanical parameters of the semitendinosus, gastrocnemius, and superficial digital flexor tendons. The bar chart illustrates tendon force, tendon cross‑sectional area (TCSA), calculated cross‑sectional area (CSA), tendon stress, maximum isometric force transmitted through the tendon (MIFF‑T), torque, kinetic energy (KE), and total power (TP) for each tendon. Blue bars represent the semitendinosus tendon, orange bars the gastrocnemius tendon, and gray bars the superficial digital flexor tendon.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-9484450/v1/7490433aa6e321383047365d.png"},{"id":109117847,"identity":"b3fb1fa9-693c-4b63-822c-a80d8226e24e","added_by":"auto","created_at":"2026-05-12 16:43:23","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":109917,"visible":true,"origin":"","legend":"\u003cp\u003eOverview of illustrating the physical and biomechanical parameters of Achilles tendon , the morphological characteristics of the muscle length and fiber length contribute to determining its physical properties, density, weight, volume and mass . These physical attributes, in turn, influence the biomechanical loading of Achilles tendon and ultimately shape the biomechanical properties of the Achilles tendon\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-9484450/v1/a7a214fd72e8c7fa34fa7820.png"},{"id":109207845,"identity":"09ff90ad-857d-4797-ac0b-67207d13a373","added_by":"auto","created_at":"2026-05-13 15:22:04","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1317877,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9484450/v1/d2216f73-8ffd-4d11-a56e-00ebd9c35bf8.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Morphological, Physical and Biomechanical Characteristics of the Achilles Tendon in the Dromedary Camel (Camelus dromedarius)","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe Achilles tendon plays a major role not only in movement but also in reflecting the animal’s overall musculoskeletal health [1,2]. Despite the camel’s distinctive hindlimb function, few studies have explored how different locomotor behaviors relate to musculoskeletal morphology [3], and detailed analyses of the camel Achilles tendon remain limit. Key anatomical and biomechanical parameters such as physiological cross‑sectional area (PCSA), tendon cross‑sectional area (TCSA), tendon power (TP), torque, and kinetic energy. These measurements are critical for understanding joint loading and tendon stress [4, 5]. In many ruminants and horses, the Achilles tendon includes contributions from the superficial digital flexor and gastrocnemius muscles, supported by the biceps femoris, semitendinosus, and gracilis, all inserting on the calcaneal tuberosity [6]. Similar anatomical descriptions have been reported for camels [7] , while ultrasonographic findings show the plantaris tendon as a thick, hyperechoic band measuring 15–20 mm [8].\u003c/p\u003e\n\u003cp\u003eUnderstanding tendon mechanical properties is vital because elasticity influences muscle output and force control, a principle consistent across vertebrates [9] .In many species, the Achilles tendon runs nearly parallel to the tibia [10], and its formation involves the fusion of the gastrocnemius and soleus muscles with contributions from the plantaris [11]. Accurate PCSA estimation is crucial for determining muscle force, as errors can significantly affect tendon load assessments [12]. While PCSA is extensively documented [13], methodological accuracy is crucial; maximal isometric force (MIF) must be estimated from PCSA rather than assumed to be equivalent. Measuring tendon CSA is fundamental for evaluating tendon biomechanics because stress is defined as force relative to CSA. This measurement varies with species, age, sex, and anatomical location [14.15,16,17]), and resting CSA is typically used for stress analysis\u0026nbsp; [18]. This research aims to characterize the physical and biomechanical properties of the Achilles tendon in camels, a structure essential for interpreting their unique locomotor behaviors including walking, running, and kicking.\u0026nbsp;\u003c/p\u003e"},{"header":"Material and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Design and Animals\u003c/h2\u003e \u003cp\u003eTen healthy adult dromedaries camel hindlimbs, collected from animals aged Five camels are aged 1\u0026ndash;3 years, of both sexes, were obtained from the Anatomy Laboratory, Department of Medical Biosciences, College of Veterinary Medicine, Qassim University. The limbs were used to investigate the structural organization of the gastrocnemius, superficial digital flexor, and semitendinosus muscles, along with their tendons, which collectively contribute to the formation of the Achilles tendon.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSample Preparation and Dissection\u003c/h3\u003e\n\u003cp\u003eThe hindlimbs were preserved in 10% formalin in an extended position to maintain anatomical integrity. Detailed dissections were performed to expose each muscle from origin to insertion, along with associated tendons. Standard dissection tools were used to isolate the components of the Achilles tendon. In five specimens, 10% formalin was injected into the external carotid arteries to enhance tissue fixation and maintain tendon morphology during examination.\u003c/p\u003e\n\u003ch3\u003eMorphometric and Architectural Measurements\u003c/h3\u003e\n\u003cp\u003eFive hindlimbs were dedicated to the physical and biochemical properties of the Achilles tendon. Measurements of the physical properties included weight, length, volume, mass of the muscles and tendons and their percentages (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e,\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Water displacement was used to determine volume, from which mass was calculated using the formula: Mass\u0026thinsp;=\u0026thinsp;Volume \u0026times; Gravity (9.8 m/s\u0026sup2;). Density was 1.06 (g/cm\u0026sup3;) to [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Muscle fiber length was estimated as 70% of total muscle length, based on [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], because direct sarcomere measurements were considered impractical for this study. Pennation angles were quantified using calipers (Mitutoyo N20, Japan) in accordance with the procedures outlined by) [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] and other investigations focused on muscle architectural stability. Physiological cross‑sectional area (PCSA), a key determinant of muscle force‑generating potential, was calculated using the formula: PCSA = (Muscle mass \u0026times; cos θ) / (Muscle density \u0026times; Fiber length) following [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTendon Biomechanics: Tendon cross‑sectional area (TCSA) was estimated according to tendon shape, applying standard geometric equations by : \u0026#119879;\u0026#119862;\u0026#119878;\u0026#119860;=\u0026#119882;\u0026#119894;\u0026#119889;\u0026#119905;ℎ\u0026times;\u0026#119879;ℎ\u0026#119894;\u0026#119888;\u0026#119896;\u0026#119899;\u0026#119890;\u0026#119904;\u0026#119904;;. Elliptical tendons: CSA = \u0026frac14; πab, and Circular tendons: CSA\u0026thinsp;=\u0026thinsp;πr\u0026sup2;. Measurements were taken at rest, consistent with [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Maximum isometric tendon force was estimated as 2 \u0026times; TCSA. Tendon stress was calculated using: Stress (σ) = Force / Area (N/m\u0026sup2;). Force production was derived from gravitational load and measured mass: Force\u0026thinsp;=\u0026thinsp;Mass \u0026times; 9.8 m/s\u0026sup2;. Kinetic energy and Torque: Muscular torque (T) was determined using the equation: T\u0026thinsp;=\u0026thinsp;F \u0026times; d, where \u003cem\u003ed\u003c/em\u003e is the perpendicular distance from the force line of action to the joint axis [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Kinetic energy (KE) of muscle movement was calculated as: KE = \u0026frac12; m v\u0026sup2;, with velocity derived from displacement over time [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Human muscle speed data were used as a comparative standard. Further, anatomical measurements included distances from the stifle joint to the hindlimb\u0026rsquo;s lateral extremities during movement, focusing on the roles of the semitendinosus, gastrocnemius, and superficial digital flexor muscles during contraction.\u003c/p\u003e\n\u003ch3\u003eInclusion Criteria\u003c/h3\u003e\n\u003cp\u003eCamels were included in this study due to the functional significance of the Achilles tendon, particularly its role in facilitating movement, with an emphasis on lateral motion. The specimens were categorized based on anatomical features, type, age, and a range of physical and biochemical characteristics.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eEthical Approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBecause all samples were collected from camels slaughtered for human consumption at a commercial slaughterhouse, no ethical approval was required for this study. No live animals were handled, used, or subjected to any experimental procedures; therefore, no animal experimentation or intervention was involved.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eSemitendinosus Muscle and Tendon\u0026nbsp;(Fig. 1, 2 and 3):\u0026nbsp;\u003c/em\u003e\u003c/strong\u003eThe semitendinosus muscle is the largest contributor to the Achilles tendon group in camels. It lies between the semimembranosus and the biceps femoris muscles, originating from the ischiatic tubercle. Its fibers extend caudoventrally at an angle of approximately 30° (Fig. 3), producing a long tendon that overlays the dorsal side of the Achilles tendon.\u0026nbsp;Functionally, the semitendinosus muscle plays key roles in forward propulsion, walking, running, and producing lateral kicks and inward rotation of the hindlimb. Its PCSA was calculated at 24.30 cm², with an estimated maximum force-generating capacity of 48.60 cm².The muscle generates a force of 6.69 N, which is responsible for moving the hindlimb in cranial, caudal, and medial directions ( Table.3). Its tendon, which contributes to the upper portion of the calcaneal insertion, transmits a force of 3.06 N, roughly half that produced by the muscle (Table 4 and Fig 4).\u003c/p\u003e\n\u003cp\u003eThe torque generated by the semitendinosus muscle was 6.48 Nm (table.3), while the tendon torque was 4.02 Nm (Table. 4). These values reflect the influence of fiber orientation on mechanical leverage. The kinetic energy \u0026nbsp;required to activate the muscle for movement was 2.32 Joules (Table 3), while the tendon required 0.72 Joules (Table 4), representing the energy needed to shift the muscle mass from rest to action and back. Tendon pressure remained constant at 2, indicating structural stability against daily mechanical loads without risk of injury (Table 4).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eGastrocnemius Muscle and Tendon (Fig 1, 2 and 3):\u0026nbsp;\u003c/em\u003e\u003c/strong\u003eThe gastrocnemius muscle is located in the proximal hindlimb region and consists of two heads\u0026nbsp;medial and lateral (Fig. 2 and 3) that originate from the supracondylar tubercle of the femur. The two heads merge near the stifle joint, forming a spiraled tendon that wraps from medial to lateral around the plantaris muscle before inserting on the calcaneal tubercle. Its fibers exhibit a caudolateral orientation at an angle of 50° (Fig. 3), enabling rapid limb extension, running, and kicking. Additionally, the gastrocnemius plays a major role in posture maintenance and balance.\u003c/p\u003e\n\u003cp\u003eThe PCSA of the gastrocnemius was 17.95 cm², with a potential force generating capacity of 35\u003c/p\u003e\n\u003cp\u003ecm², while the muscle creates a force of 5.59 N (Table 3), enabling multidirectional hindlimb motion. The tendon force was 5.24 N (Table 4), reflecting a nearly equal force transfer from muscle to calcaneus.\u003c/p\u003e\n\u003cp\u003eThe torque values demonstrate strong mechanical leverage: 7.48 Nm for the muscle and 6.86 Nm for the tendon (Table 3,4). kinetic energy activation values were 1.64 Joules for the muscle and \u0026nbsp;1.97 Joules for the tendon (Table, 3,4 ) representing the energy required to transition between rest and active states.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eSuperficial Digital Flexor (Plantaris) Muscle and Tendon (Fig 1, 2 and 3)\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe plantaris muscle in camels is entirely tendinous and located proximally, fully enclosed in its upper region by the gastrocnemius muscle. It arises from the lateral supracondylar tuberosity of the femur. The plantaris fibers run in a straight, ventral trajectory, maintaining a parallel alignment without angle (0°) (Fig. 3). \u0026nbsp;This unique morphology contributes significantly to torque production.\u0026nbsp;The plantaris integrates with fascial slips from other flexor tendons and merges with the gastrocnemius tendon to form part of the shared Achilles tendon. It spirals medially around the gastrocnemius before inserting into the calcaneal tuberosity.\u003c/p\u003e\n\u003cp\u003eIts PCSA was 1.79 cm² the lowest among the three muscles, despite its relatively large mass(Table 3),. The TCSA was 2.11 mm², enabling a transmission capacity of approximately 4.22 cm² (Table, 4). The plantaris produced a force of 9.98 N, its muscle and tendon forces are identical since the entire structure is functionally tendinous (Fig.4).\u003c/p\u003e\n\u003cp\u003eThe torque generated was 13.25 Nm, the highest among the three muscles (Table 3,4). This significant value is attributed to its straight fiber orientation, which enhances mechanical leverage for both flexion and extension movements. The KE needed to activate the muscle was 3 Joules, reflecting the energy demand for transitioning its mass during movement (Table 3,4).\u003c/p\u003e\n\u003cp\u003eThe tendon of semitendinosus M and the tendons of the gastrocnemius and plantaris muscles contribute a role in creating the Achilles tendon, attaching to the tuberosity of calcaneus. The first layer comprises the fascicular tendons from gastrocnemius' two medial and lateral heads contributing to the tendon’s dorsal, lateral, and medial portions. The lateral head's tendon partially connects to the tuber calcanei’s surfaces, while the medial head’s tendon lies deeper. The plantaris muscle forms the deepest layer, partially joining with gastrocnemius tendons, and is enclosed proximally within the gastrocnemius muscle. All tendon bundles from Achilles tendon terminate on the calcaneal tuberosity. Each of the three tendons has unique fiber arrangements, reflecting specific local mechanical loads (Fig. 1,2).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe camel hindlimb is supported by a highly specialized and robust Achilles tendon apparatus that plays a critical role in locomotor functions such as walking, running, lateral kicking, and maintaining body stability. In this study, we examined the anatomical, morphological, physical, and biomechanical characteristics of the camel Achilles tendon and the three major muscles contributing to its formation: the semitendinosus, gastrocnemius, and superficial digital flexor (plantaris). Together, these components form an integrated muscle–tendon system that supports propulsion, weight bearing, and controlled hindlimb movement during both routine and high‑intensity activities.\u003c/p\u003e\n\u003cp\u003eCamel locomotion combines high endurance with efficient sprinting while minimizing energy expenditure [27]. Evolutionary specializations—elongated hindlimb metatarsals and relatively shortened forelimbs—support upright posture with minimal muscular effort [28], enhancing energy conservation and shock absorption for desert locomotion [29].The caudal thigh muscles show distinctive architecture essential for hindlimb movement [30], with primary roles in knee flexion and hip extension and semitendinosus involvement in medial tibial rotation [31, 32]. In camels, the hamstrings facilitate walking, running, and powerful kicking [33] Váczi et al., 2022; [34], consistent with integrated muscle–tendon systems observed in highly mobile species such as horses [35].\u003c/p\u003e\n\u003cp\u003eThe semitendinosus is notably large and contributes substantially to the Achilles tendon, with fibers oriented caudoventrally [36]. Its rounded contour resembles that of ungulates and differing from the more angular form reported in dogs and oxen [6] and bovines [37]. The Achilles tendon was the strongest tendon in the body attaches to the tuber calcanei and functions as an energy‑saving, force‑transmitting structure that enables rapid locomotion, including kicking and running [29,38,39]. Our findings support the interconnected nature of tendon components [40] and diverge from [36] who proposed contributions from the biceps portion of the superficial digital flexor and the gastrocnemius that were not substantiated here.\u003c/p\u003e\n\u003cp\u003eNotably, no soleus muscle was identified in any specimen, contradicting report \u0026nbsp;[7], who described its presence in camels. The findings align more closely with descriptions by [6,41,42] \u0026nbsp;in horse who recorded that the Achilles tendon is primarily formed by the gastrocnemius, superficial digital flexor (SDFT), and plantaris muscles. Findings also sured [37,43] on tendon contributions in bovines.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe plantaris tendon is an efficient energy‑storage structure, recovering over 90% of stored elastic energy [9,44, 45]. Comparative equine anatomy notes the spiral path of the gastrocnemius tendon around the SDFT before insertion on the tuber calcanei [46]. In the present study, semitendinosus fibers extended caudoventrally at roughly 30°, gastrocnemius fibers coursed caudomedially at about 50°, and SDF and plantaris fibers ran straight ventrally [47,48], paralleling observations in cattle where fibers run caudoventrally and more parallel to the long axis [49]. These differing orientations indicate that fiber direction guides extension, flexion, and \u0026nbsp; \u0026nbsp;lateral motion.\u003c/p\u003e\n\u003cp\u003eHistologically, the camel semitendinosus contains rounded and polyhedral fiber profiles, supporting long‑distance efficiency [50]. Fiber lengths in semitendinosus exceed those in the gastrocnemius [51]. While horses exhibit short‑fibered, multipennate SDF muscles [52], camels show longer fibers, and the SDFT runs alongside the deep digital flexor tendon [8,53] .Region‑specific variations in tendon thickness and width across the Achilles complex indicate heterogeneous mechanical loading [54, 55, 56,57] Cross‑sectional shapes vary by region—oval proximally, semi‑oval mid‑tendon, and ring‑shaped distally as described in horses and cattle [58] 59,60] and observed in reindeer [61].\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;Small but measurable pennation angles were identified: 30° in semitendinosus and 50° in gastrocnemius, confirming their pennate architecture, whereas SDF showed no pennation (α = 0°). Correspondingly, physiological cross‑sectional areas (PCSA) differed 24.30 cm² (semitendinosus), 17.95 cm² (gastrocnemius), and 1.79 cm² (superficial digital flexor) supporting the principle that pennate muscles possess greater PCSA and thus higher force‑generating capacity than non‑pennate muscles [62]. The relationship between muscle mass, length, and pennation angle underpins maximum isometric force, consistent with prior reports [63]. In line with optimal musculoskeletal design, muscle volume maximizes force and mechanical work [64]. We observed a clear association between fascicle length and PCSA: long fascicles (e.g., SDF at 52 cm) corresponded to low PCSA (18 cm²), indicating specialization for body‑mass support and efficient locomotion but reduced physiological power, Our results were consistent with [64, 65].\u003c/p\u003e\n\u003cp\u003ePCSA remains a primary determinant of maximal force, and dynamic changes in pennation with limb motion further modulate effective force transmission, to date, detailed PCSA measurements are better documented in the equine forelimb [66]. We documented notable variation in tendon morphology and cross sectional area (CSA) within the camel Achilles complex (0.59 cm² semitendinosus; 1.06 cm² gastrocnemius; 2.77 cm² SDFM), consistent with reports that tendon cross sections near insertions can be flat, cylindrical, fan shaped, or ribbon like [358], reflecting uneven stress distribution [54, 60].\u003c/p\u003e\n\u003cp\u003eThe accuracy of stress depends, in part, upon the determination of the cross-sec-tional area (CSA). The accuracy of stress depends partly on the accurate determination of the cross-sectional area (CSA) [67]. Our findings also align with the principle that the maximum force a muscle can generate depends on cross sectional area and its placement within the musculoskeletal system [68].\u003c/p\u003e\n\u003cp\u003eAn inverse relationship between CSA and tendon stress was evident: the largest CSA (superficial digital flexor muscle, 2.77 cm²) showed the lowest stress ratio, whereas the smallest CSA (semitendinosus, 0.59 cm²) showed the highest, with gastrocnemius intermediate—consistent with the notion that reduced CSA during elongation elevates localized stress ; [3]. Tendons operate in concert with muscle and bone, creating localized mechanical specializations, in line with evidence for region‑specific tendon properties [69, 70]. Functionally, the camel Achilles tendon complex is central to locomotion especially running and kicking supporting weight and enabling efficient force transmission, and its mechanical properties scale with CSA [3,71] \u0026nbsp;The activation of Achilles‑associated muscles facilitates tensile strength for weight support [72].\u003c/p\u003e\n\u003cp\u003eBased on anatomical and mechanical indicators, the plantaris produced the greatest force (9.89 N), followed by the semitendinosus (6.69 N) and gastrocnemius (5.59 N), matching general mammalian patterns despite interspecific differences in size and structure. Although mammalian feet share similar mechanisms for transmitting locomotor forces, their size, structure, and composition vary considerably [45, 73]. Muscle force production was strongly influenced by length and mass, emphasizing optimal length–tension relationships and the need for sufficient muscle mass to generate forces required for hindlimb motions [74]. Consistent with equine data, the SDF can reach high peak forces [75].\u003c/p\u003e\n\u003cp\u003eMaximum isometric force values varied among muscles: the semitendinosus reached 48 N/cm², and the gastrocnemius 35 N/cm², reflecting architectural differences particularly pennation that influence force transmission (Table 3). Total ankle torque reached 26 Nm; the SDF produced the highest torque (13.25 Nm), whereas the semitendinosus contributed the least (6.48 Nm). Torque decreased as attachment area increased, consistent with mechanical principles [76]. Variability in fiber length‑to‑moment torque ratios among functionally similar muscles [77, 78] This is represented by )Figure 5, (underscores how fiber architecture and pennation shape performance [52],and how physiological and morphological specializations not size alone govern torque output [61].\u003c/p\u003e\n\u003cp\u003eTendon pressure remained constant (value = 2) across Achilles regions, suggesting structural adaptation to daily mechanical loads and resilience against injury, in line with intratendinous pressure mechanisms that shape tendon behavior [79, 80]. Kinetic energy (KE) profiles showed the Achilles complex generated the highest KE (7.83 J), followed by SDF (3.54 J), semitendinosus (2.32 J), and gastrocnemius (1.97 J), with fleshy muscles collectively producing more KE than the tendinous SDF [81]. Tendons store and release mechanical energy [82] and the long, compliant 52‑cm SDF tendon stored 3.08 J—nearly double the 1.62 J in the shorter 41‑cm gastrocnemius (fig.5 ) illustrating elastic energy‑saving roles [52, 83]. Flexor tendons exhibit energy‑storing characteristics with fiber organizations tailored for efficient force generation and elastic return [84, 85]. Accurate anatomical identification is essential for achieving optimal clinical outcomes in cases involving the Achilles tendon [86, 87]. Injury to this tendon may manifest as a partial tear, affecting specific component tendons, or as a complete rupture involving all of the structures that form the Achilles tendon [88] .\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThis study presents the general the anatomy, biomechanics, and physical characteristics of Achilles tendon muscles, Its effect on movement of camels. \u0026nbsp;The muscles contraction and force generation are influenced by fiber arrangement, length, it clarified these discrepancies by illustrating physical biomechanics, variations in PCSA, TCSA, maximum isometric force, stress, torque, and kinetic energy affecting hindlimb movement. Database comprising biomechanical variables obtained from healthy camels was essential to study the primary features of normal movement and the alterations in velocity n velocity during movement.\u0026nbsp;\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAuthor contributions:\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eGA conceived and designed the study. GA, FA executed the experiment. GA and FA analyzed the data. All authors interpreted the data, critically revised the manuscript for important intellectual contents and approved the final version.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical Approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBecause all samples were collected from camels slaughtered for human consumption at a commercial slaughterhouse, no ethical approval was required for this study. No live animals were handled, used, or subjected to any experimental procedures; therefore, no animal experimentation or intervention was involved.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003eThe researchers would like to thank the Deanship of Graduate Studies and Scientific Research at Qassim University for financial support (QU-APC 2026).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eData availability\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe relevant information, including raw data, has been included in the\u003c/p\u003e\n\u003cp\u003emanuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Publish Declaration\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInformed Consent Statement:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Not applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability Statement:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data presented in this study are available on request from the corresponding authors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eAcknowledgements\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors would like to thank the Deanship of Scientific Research, Qassim University for financially aiding in the publication of this project.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor details\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003csup\u003e1\u003c/sup\u003e\u003c/em\u003e\u003cem\u003eDepartement of Medical Biosciences, College of Veterinary Medicine, Qassim University, P.O. Box 6622, Buraydah, 51452, Saudi Arabia\u003c/em\u003e\u003cem\u003e.\u003c/em\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBlazevich J,Fletcher J R\u003cspan dir=\"RTL\"\u003e.\u003c/span\u003e More than energy cost: multiple benefits of the long Achilles tendon in human walking and running. Biological Reviews.2023;98:6: 2210-2225. \u003cstrong\u003ehttps://doi.org/10.1111/brv.13002\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eDemiraslan D, G\u0026uuml;rb\u0026uuml;z Y, Dayan İ, Akbulut M, Aslan Ya, Kadir \u0026Ouml;S. Structural and Functional Properties of the Distal Muscles of\u003cspan dir=\"RTL\"\u003e \u003c/span\u003eFront and Hind Legs of Malakan Horses (Equus caballus) . KafKas Universitesi veteriner faKUltesi Dergisi Journal 2015 http://vetdergikafkas.org DOI: 10.1186/1757-1146-7-26 \u0026middot;\u003c/li\u003e\n\u003cli\u003eSmart RR, O\u0026rsquo;Connor B, Jakobi JM. Resting tendon cross-sectional area underestimates biceps brachii tendon stress: importance of measuring during a contraction. Frontiers in physiology 2021. 654231. doi:\u003cstrong\u003e10.3389/fphys.2021.654231\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eAlbracht K, Arampatzis A, Baltzopoulos V, Assessment of muscle volume and physiological cross-sectional area of the human triceps surae muscle in vivo. J Biomech 2008. 41(10):2211\u0026ndash;2218. doi: 10.1016/j.jbiomech.2008.04.020\u003c/li\u003e\n\u003cli\u003eMaarleveld R, Veeger HEJ, Helm van der, Son FCT, Lieber J, Kruk RL.. What the PCSA? Addressing diversity in lower-limb musculoskeletal models: age-and sex-related differences in PCSA and muscle mass. Journal of Biomechanics 2025.. 193 112976 https://doi.org/10.1016/j.jbiomech.2025.112976. \u003c/li\u003e\n\u003cli\u003eDyce K, ,Sack M, Wolfgang O. Textbook of Veterinary Anatomy, 4th ed.; Elsevier Health Sciences , MO, USA, 2010; 71: p. 78. 15. \u003c/li\u003e\n\u003cli\u003eSadan M, Achilles tendon rupture in camel (Camelus dromedarius): Radiographic and Ultrasonographic findings, Journal of Camel Health.,2019 1:1-5. https://camel.health\u003c/li\u003e\n\u003cli\u003eAbu Seida AM, Mostafa AM and Tolba AR. Anatomical And Ultrasonographical Studies On Tendons And Digital Cushions Of Normal Phalangeal Region In Camels (Camelus dromedarius) Journal of Camel Practice and Research. 2012; 19 : 2: p 169-175.https://doi:10.5455/OVJ.2021.v11.12.8\u003c/li\u003e\n\u003cli\u003eAlexande RMN. Tendon elasticity and muscle function. Comparative Biochemistry and Physiology Part A: Molecular \u0026amp; Integrative Physiology 2002:133: 4: Pages 1001-1011https://doi.org/10.1016/S1095-6433(02)00143-5\u003c/li\u003e\n\u003cli\u003eMizuno F, Fujiwara S. Estimating ankle joint angle from skeletal geometry: a mechanical model of the calcaneal lever in terrestrial mammals. Peer J. 2025:13:P. e20056 DOI 10.7717/peerj.20056\u003c/li\u003e\n\u003cli\u003eMahan J, Damodar D, Trapana E, Barnhill S, Nuno AU, Smyth NA, Aiyer A, Jose J. Achilles tendon complex: The anatomy of its insertional footprint on the calcaneus and clinical implications. Journal of orthopaedics 2020: 17:221\u0026ndash;227. doi: 10.1016/j.jor.2019.06.008\u003c/li\u003e\n\u003cli\u003eFuruuchi K, Koyabu D, Mori K, Endo H. Physiological cross-sectional\u003cspan dir=\"RTL\"\u003e \u003c/span\u003earea of the masticatory muscles in the giraffe (Giraffa camelopardalis).\u003cspan dir=\"RTL\"\u003e \u003c/span\u003eMammal Study. 2013; 38 (1): 67-71. DOI: 10.3106/041.038.0109\u003c/li\u003e\n\u003cli\u003eSon J, Ward SR, Lieber RL. Scaling relationships between human leg muscle architectural properties and body size. J. Exp. Biol. , 2024: 227 (6), jeb246567. https://doi. org/10.1242/jeb.246567.\u003c/li\u003e\n\u003cli\u003eVergari C , Pourcelot Ph , Holden L, Ravary-Plumio\u0026euml;n, B,Gerard, G,Laugier, P,Mitton, D,Crevier-Denoix N. True stress and Poisson\u0026apos;s ratio of tendons during loading. Journal of Biomechanics. 2011:44: 4: 719-724 https://doi.org/10.1016/j.jbiomech.2010.10.038\u003c/li\u003e\n\u003cli\u003eLepley AS, Joseph M F, Daigle N R, Digiacomo J E,Galer J,Rock E,Rosier SB,Sureja PB. Sex Differences in Mechanical Properties of the Achilles Tendon. 2018: The Journal of Strength \u0026amp; Conditioning Research.218; 32:11: 3070-3079. DOI: 10.1519/JSC.0000000000002386\u003c/li\u003e\n\u003cli\u003eRistaniemi A, Stenroth L, Mikkonen S, Korhonen RK. Comparison of elastic, viscoelastic and failure tensile material properties of knee ligaments and patellar tendon. Journal of Biomechanics. 2018: 79: Pages 31-38. https://doi.org/10.1016/j.jbiomech.2018.07.031\u003c/li\u003e\n\u003cli\u003eWu SY, Kim W, Kremen TJ, Thomas J. \u003cem\u003eIn Vitro\u003c/em\u003e Cellular Strain Models of Tendon Biologyand Tenogenic Differentiation. \u003cem\u003eFront. Bioeng. Biotechnol.\u003c/em\u003e 2022:\u003cstrong\u003e 10\u003c/strong\u003e: 826748. https://doi.org/10.3389/fbioe.2022.826748\u003c/li\u003e\n\u003cli\u003eStenroth L, Peltonen J, Cronin NJ, Sipil\u0026auml; S, Finni T.Age-related differences in Achilles tendon properties and triceps surae musclearchitecture in vivo. Journal of applied physiology 2012: 113: 1537\u0026ndash;1544,.doi:10.1152/japplphysiol.00782.2012.8750-7587/12 \u003c/li\u003e\n\u003cli\u003eWard SR \u0026amp; Lieber RL. Density and hydration of fresh and fixed human skeletal muscle. J Biomech. 2005: 38:11:2317\u0026ndash;2320. https://doi.org/10.1016/j.jbiomech.2004.10.001 \u003c/li\u003e\n\u003cli\u003eBiewener A A. Musculoskeletal design in relation to body size. Journal of Biomechanics. 1991; 24:1: 19-29. https://doi.org/10.1016/0021-9290(91)90374-V\u003c/li\u003e\n\u003cli\u003ePersad LS, Wang Z, Pino PA, Binder-Markey B, Kaufman K R, Lieber RL.. Specific tension of human muscle in vivo: a systematic review. J Appl Physiol. 2024;137(4):945\u0026ndash;962. https://doi.org/10.1152/japplphysiol.00296.2024\u003c/li\u003e\n\u003cli\u003eTaylor AB,| Terhune CE, Ross C F, Vinyard ChJ. The impact of measurement technique and samplingon estimates of skeletal muscle fibre architecture. The Anatomical Record 2024:307:3071\u0026ndash;3084. \u003cstrong\u003ehttps://doi.org/10.1002/ar.25415\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eSantana SE, Dumont ER, Davis JL, 2010. Mechanics of bite force production\u003cspan dir=\"RTL\"\u003e \u003c/span\u003eand its relationship to diet in bats. Functional Ecology 2010; 24 :4: 776-784.\u003cspan dir=\"RTL\"\u003e \u003c/span\u003eDOI: 10.1111/j.1365-2435.2010.01703.x\u003c/li\u003e\n\u003cli\u003eFukunagaT, Roy RR, Shellock FG, Hodgson JA, Day MK, Lee PL, Kwong‐Fu H, Edgerton VR.Physiological cross‐sectional area of human leg muscles based on magnetic resonance imaging. J Orthop Res. 1992:10 :6: 926-934. DOI: 10.1002/jor.1100100623\u003c/li\u003e\n\u003cli\u003eSmart R, Richardson CM, Wile DJ, Dalton BH, Jakobi J M. Importance of Maximal Strength and Muscle-Tendon Mechanics for Improving Force Steadiness in Persons with Parkinson\u0026rsquo;s Disease .\u003cem\u003eBrain Sci.\u003c/em\u003e 2020: \u003cem\u003e10:\u003c/em\u003e8: 471; https://doi.org/10.3390/brainsci10080471 \u003c/li\u003e\n\u003cli\u003eGindy M , Nassif HH, Velde J. Bridge Displacement Estimates from Measured Acceleration Records. Transportation Research Record.2007: 2028:136-1451 https://doi.org/10.3141/2028-15\u003c/li\u003e\n\u003cli\u003eMascoli GJD, 2002. Will that be one hump or two? Science IQ.com www.scienceiq.com/facts/humps.cfm. Accessed On 17/9/2010.\u003c/li\u003e\n\u003cli\u003eJones ME, Travouillon K, Janis CM. Proportional variation and scaling in the hindlimbs of hopping mammals, including convergent evolution in argygrolagids and jerboas. Journal of Mammalian Evolution 2024:31:1:1\u0026ndash;16 DOI 10.1007/s10914-023-09699-9.\u003c/li\u003e\n\u003cli\u003eAlves ALG , Dudhia J , Rosa GS, Smith RKW.The The veterinarian perspective: Comparative anatomy, equine models and in vivo bioengineering of tendons Chapter 9 - 359-380 https://doi.org/10.1016/B978-0-443-15916-9.00016-4\u003c/li\u003e\n\u003cli\u003eSinulingga AR, and Zemkov\u0026aacute; E. Maximal isometric and eccentric hamstring strength is influenced by body mass and additional load: Does the critical point at which peak knee flexor force is achieved play a role? Frontiers in Physiology. 2025;16:1654030 9 https://doi.org/10.3389/fphys.2025.1654030\u003c/li\u003e\n\u003cli\u003eRodgers CD and Raja A. Anatomy, bony pelvis and lower limb, hamstring muscle .2026 : Stat Pearls Publishing\u003cstrong\u003e Treasure Island \u003c/strong\u003e; American Nurses Association ID: NBK546688PMID: 3153629. DOI:10.6084/m9.figshare.16682479.v1\u003c/li\u003e\n\u003cli\u003eTakeda K, Kato K, Ichimura K, Sakai T. Unique morphological architecture of the hamstring muscles and its functional relevance revealed by analysis of isolated muscle specimens and quantification of structural parameters. \u003cem\u003eJ. Anat.\u003c/em\u003e 2023: 243 (2), 284\u0026ndash;296. doi:10.1111/JOA.13860\u003c/li\u003e\n\u003cli\u003eV\u0026aacute;czi M, Fazekas G, Pilissy T, Cselk\u0026oacute; A,Trzaskoma L, Sebesi B,Tihanyi J.The effects of eccentric hamstring exercise training in young female handball players. European journal of applied physiology. 2022; 122:4: 955\u0026ndash;964. doi:10.1007/S00421-022 04888-5\u003c/li\u003e\n\u003cli\u003eMarkovic G, Sarabon N, Boban F, ZoricI, Jelcic M, Sos K, Scappaticci M.. Nordic hamstring strength of highly trained youth football players and its relation to sprint performance. The Journal of Strength \u0026amp; Conditioning Research. 2020:34 :3: 800\u0026ndash;807. doi:10.1519/jsc.0000000000002800\u003c/li\u003e\n\u003cli\u003eDutto D, Hoyt DF, Cogger EA, Wickler S J.34. Ground reaction forces in horses trotting up an incline and on the level over a range of speeds. Journal of Experimental Biology.2007; 20: 3507-3514 .DOI:10.1242/jeb.01171\u003c/li\u003e\n\u003cli\u003eHamoda H, Elsaid FG, Eldesoqui M, Al-Mosaibih, MA, Fayad, E, Hussein, MK, Hamed, MA, Farrag F, Abumandour M, Shukry, M.. Imaging-based observation of the pes region in the dromedary camel (Camelus dromedarius): computed tomography, 3D volume rendering, magnetic resonance imaging, and ultrasonography. Front. Vet. Sci. 202;12:1558954. doi: 10.3389/fvets.2025.1558954\u003c/li\u003e\n\u003cli\u003eBurdras KD and Habel RE. 2011. Bovine anatomy, an illustrated text, 1st ed. Hannover, Germany: Schl\u0026uuml;tersche, Verlag Gesellschaft.112-120.\u003c/li\u003e\n\u003cli\u003eMalvankar S and Khan WS. Evolution of the Achilles tendon: The athlete\u0026apos;s Achilles heel?? Foot 2011; 21:4:193\u0026ndash;197. https://doi.org/10.1016/j.foot.2011.08.004\u003c/li\u003e\n\u003cli\u003eRaichlen DA, Armstrong H, Lieberman DE. Calcaneus length deter mines running economy: implications for endurance running perfor mance in modern humans and Neandertals. J Hum Evol , 2011;60: 3:: 299\u0026ndash;308. https://doi.org/10.1016/j.jhevol.2010.11.002\u003c/li\u003e\n\u003cli\u003eSzaro P, Witkowski G , Smigielski R , Krajewski P.Ciszek B.. Fascicles of the adult human Achilles tendon - an anatomical study. Ann Anat.2009; 191:6:586-93. DOI: 0.1016/j.aanat.2009.07.006\u003c/li\u003e\n\u003cli\u003eBudras K D,Sack W O, Rock S, Horowitz, A, Berg, R. Anatomy of the Horse. Schl\u0026uuml;tersche Verlagsgesellschaft GmbH and Co. KG: Hanover, Germany, 2017; pp. 3\u0026ndash;25. https://doi.org/10.1201/9783842683686\u003c/li\u003e\n\u003cli\u003eSchreiber K, Haudiquet Ph, Hamon M. Achilles Tendon Rupture Treated with Flexor Digitorum Lateralis Tendon Transposition and Transarticular External Skeletal Fixator in Ouessant Sheep CC BY 4.0 \u0026middot; VCOT Open 2024; :7:1: e46-e51. DOI: 10.1055/s-0044-1786187\u003c/li\u003e\n\u003cli\u003eWahengbam P, Pathak R, Hajam IA, Shah MA, Basha MA, Verma NK, Pawde AM . Clinical Management of Achilles Tendon Injury with Tendon Gap Defect in a Horse Using Tissue Engineering: A Case Report Acta Scientific Veterinary Sciences; 2023;5:7;64-68 DOI:10.31080/ASVS.2023.05.0690.\u003c/li\u003e\n\u003cli\u003eProudman CJ. Common calcaneal tendinitis in a horse. Equine Veterinary Education . 1992;4:6: 277-279. https://doi.org/10.1111/j.2042-3292..tb00965.x \u003c/li\u003e\n\u003cli\u003eBiewener AA.\u003cspan dir=\"RTL\"\u003e \u003c/span\u003e Muscle Function in vivo: A Comparison of Muscles used for Elastic Energy Savings versus Muscles Used to Generate Mechanical Power. American Zoologis.1998; 703-717. Doi: \u003cstrong\u003e10.1093/icb/38.4.703\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eDyson SJ , Kidd L. Five cases of gastrocnemius tendinitis in the horse . Equine Veterinary Journal\u003cem\u003e,1992; \u003c/em\u003e24:5, Pages 351-356 https://doi.org/10.1111/j.2042-3306..tb02854.x.\u003c/li\u003e\n\u003cli\u003eAzhari H..Basics of Biomedical Ultrasound for Engineers. Published by John Wiley \u0026amp; Sons Inc. Hobok, New Jersy published simultaneously in Canda. 2010. PP 83-142\u003c/li\u003e\n\u003cli\u003eZhou Y, Li JZ , Zhou G, Zheng YP. Dynamic measurement of pennation angle of gastrocnemius muscles during contractions basedon ultrasound imagingBiomedical engineering online. 2012; 11:63: 10 doi:10.1186/1475-925X-11-63\u003c/li\u003e\n\u003cli\u003eSenaratne LS, Calkins CR, deMello Jr AS, Pokharel S,Hinkle JB.Mapping of Intramuscular Tenderness and Muscle Fiber Orientation of Muscles in the Beef Round. Journal of animal science;2010;88;9;3084-3106. https://doi.org/10.2527/jas.2009-2683\u003c/li\u003e\n\u003cli\u003eOyelowo FO, Sonfada ML Muscle fibre types in hamstring muscles of one-humped camel Camelus dromedaries. Oyelowo/ Journal of Camelid Science 2013; 6:72-80 https://doi.org/10.2527/jas.2009-2683\u003c/li\u003e\n\u003cli\u003eWatanabe K, Otsuki S, Hisa T, Nagaoka M, Functional difference between the proximal and distal compartments of the semitendinosus muscle. Journal of Physical Therapy Science. 2016 ; 28: 5: 1511\u0026ndash;1517. https://doi.org/10.1589/jpts.28.1511\u003c/li\u003e\n\u003cli\u003e\u003cstrong\u003e52\u003c/strong\u003e. Butcher MT , Chase PB , Hermanson J W Clark AN,Brunet NM,Bertram, JEA.. \u003cspan dir=\"RTL\"\u003e \u003c/span\u003eContractile properties of muscle fibers from the deep and superficial digital flexors of horses. : American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 2010; 299;4; R996-R1005.4 https://doi.org/10.1152/ajpregu.00510.\u003c/li\u003e\n\u003cli\u003eFranchi M, Trir\u0026egrave; A, Quaranta M Orsini E, Ottani V.Collagen Structure of Tendon Relates to Function. The Scientific World Journal.2007; 7:1; 404\u0026ndash;420. https://doi.org/10.1100/tsw.2007.92\u003c/li\u003e\n\u003cli\u003eMagnusson SP, Hansen P, Kjaer M, 2003. Tendon properties in relation to muscular activity and physical training. Scand. Scandinavian journal of medicine \u0026amp; science in sports.2003; 4: 211-223. https://doi.org/10.1034/j.1600-0838.2003.00308.x\u003c/li\u003e\n\u003cli\u003e\u0026Ccedil;elimli N, Seyrek D, and Kaya M. Morphometric measurements of flexor tendons and ligaments in Arabian horses by ultrasonographic examination and comparison with other breeds. Equine vet. Educ. . 2004; 16 (2) 81-85. DOI 10.2298/VETGLA0402095K\u003c/li\u003e\n\u003cli\u003eBiewener AA, 2005. Biomechanical consequences of scaling. Journal of Experimental Biology2005;208:9: 1665\u0026ndash;1676. https://doi.org/10.1242/jeb.01520\u003c/li\u003e\n\u003cli\u003eWatanabe T, Hosaka Y, Yamamoto E, Ueda H,Sugawara K,Takahashi H,Takehana, K. Control of the collagen fibril diameter in the equine superficial digital flexor tendon in horses by decorin. J. Vet. Med. Sci. 2005; 67: 9:855-860. https://doi.org/10.1292/jvms.67.855\u003c/li\u003e\n\u003cli\u003eKannus P. Structure of the tendon connective tissue. Scand. J. Med. Sci. Sports.2000; 10: 6; 312-320. https://doi.org/10.1034/j.1600-0838.2000.010006312.x\u003c/li\u003e\n\u003cli\u003eWatanabe T, Imamura Y, Hosaka, Y, UedaH,iTakehana, K. Graded arrangement of collagen fibrils in the equine superficial digital flexor tendon. Connect. Tissue Res.2007; 48:6; 332-337. https://doi.org/10.1080/03008200701692800\u003c/li\u003e\n\u003cli\u003eTakahashi N, Hirose T, Minaguchi JA, Ueda H,Tangkawattana P,Takehana, K. Fibrillar architecture at three different sites of the bovine superficial digital flexor tendon . J. Vet. Med. Sci. 2018 ; 80: 3: 405\u0026ndash;412, 2018 doi: 10.1292/jvms.17-0562\u003c/li\u003e\n\u003cli\u003eWareing k, Tickle PG, Stokkan KA, Codd JR,Sellers WI.The musculoskeletal anatomy of the reindeer (Rangifer tarandus): fore and hindlimb Polar Biology. 2011;34:10:1071-1578. DOI 10.1007/s00300-011-1017-y 123\u003c/li\u003e\n\u003cli\u003eRockenfeller R, G\u0026uuml;nther M, Clemente CJ, Dick T JM. Rethinking the physiological cross-sectional area of skeletal muscle reveals the mechanical advantage of pennation. R. Soc. Open Sci.2024; 11:9. https://doi.org/10.1098/rsos.240037\u003c/li\u003e\n\u003cli\u003eSopher RS, Amis AA, Davies DC, Jeffers J RT.The Influence of muscle pennation angle and cross-sectional area on contact forces in the ankle joint. J. Strain Anal. Eng. Des. 2017; 52: 1: 12\u0026ndash;23. (doi:10.1177/0309324716669250\u003c/li\u003e\n\u003cli\u003eLabonte D. A theory of physiological similarity in muscle-driven motion. Proceedings of the National Academy of Sciences..2023;120:24: e2221217120 https://doi.org/10.1073/pnas.2221217120 PP 1 - 11.\u003c/li\u003e\n\u003cli\u003eLeonardo Alexandre PT, Marcelo C.Locomotion as a Powerful Model to Study Integrative Physiology: Efficiency, Economy, and Power Relationship. Front. Physiol.2018; 9:1789. doi: 10.3389/fphys.2018.01789\u003c/li\u003e\n\u003cli\u003eWatson J C and Wilson A M. Muscle architecture of biceps brachii, triceps brachii and supraspinatus in the horse. Journal of Anatomy. 2006;210: 1: 32-40\u003cspan dir=\"RTL\"\u003e \u003c/span\u003ehttps://doi.org/10.1111/j.1469-7580.2006.00669.x \u003c/li\u003e\n\u003cli\u003eGe Xj , Zhang L, Xiang G, Hu Y ch, Lun Dx.2020 Cross-Sectional Area Measurement Techniques of Soft Tissue: A Literature Review. Orthopaedic Surgery.2020;12:6:1547\u0026ndash;1566 \u0026bull; DOI: 10.1111/os.12757\u003c/li\u003e\n\u003cli\u003eClemente ChJ , Groote F, Dick TJM, 2024. Predictive musculoskeletal simulations reveal the mechanistic link between speed, posture and energetics among extant mammals. Nature Communications.2024;15:1: 8594. https://doi.org/10.1038/s41467-024-52924-z\u003c/li\u003e\n\u003cli\u003eNakamichi R , Asahara H.The role of mechanotransduction in tendon. Journal of Bone and Mineral Research.2024;39:7: 814-820. doi: 10.1093/jbmr/zjae074. \u003c/li\u003e\n\u003cli\u003eGehwolf R, Tempfer H, Cesur NP, Wagner A,Traweger A,LehnerCh. Tendinopathy: The Interplay between Mechanical Stress,Inflammation, and Vascularity. Advanced Science.2025;12:36e06440. DOI: 10.1002/advs.202506440\u003c/li\u003e\n\u003cli\u003eThorpe CT, Riley GP, Birch H L, Clegg PD,Screen H RC. Fascicles and the interfascicular matrix show decreased fatigue life with ageing in energy storing tendons. Acta Biomater. 2017; 56: 58\u0026ndash;64. doi: 10.1016/j.actbio.2017.03.024\u003c/li\u003e\n\u003cli\u003eSpinella G, Tamburro R, Loprete G, Vilar JM, Valentini S. Surgical repair of Achilles tendon rupture in dogs: a review of the literature, a case report and new perspectives. Veterinarni Medicina.2010;55: 303-310. DOI:10.17221/2926-VETMED\u003c/li\u003e\n\u003cli\u003eWearing SC , Smeathers JE. The heel fat pad: mechanical properties and clinical applications. Journal of Foot and Ankle Research.2011; 4:Suppl 1: I14 doi: 10.1186/1757-1146-4-S1-I14\u003c/li\u003e\n\u003cli\u003eClemente Ch J, Dick TJM, Glen Ch L, Panagiotopoulou Ol. Biomechanical insights into the role of foot pads during locomotion in camelid species\u003cspan dir=\"RTL\"\u003e \u003c/span\u003eScientific \u003cspan dir=\"RTL\"\u003e \u003c/span\u003eReports.2020; 10:1:3856. \u003cstrong\u003e10.1038/s41598-020-60795-9\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eHarrison SM, Whitton RCh, Kawcak ChE Stover, SM,Pandy MG. Relationship between muscle forces, joint loading and utilization of elastic strain energy in equine locomotion The Journal of experimental biology.2010 ;213:23: 3998-4009. https://doi.org/10.1242/JEB.044545\u003c/li\u003e\n\u003cli\u003eSerway RA, Jewett JW, Peroomian V. Physics for scientists and engineers. 6th Ed. Philadelphia: Saunders college publishing Philadelphia;. 2: 0-534- 40842-7.\u003c/li\u003e\n\u003cli\u003eLieber RL and Brown CG. Sarcomere length-joint angle relationships of seven frog hindlimb muscles. Cells Tissues Organs. 1992; 4:145, 289\u0026ndash;295. https://doi.org/10.1159/000147380\u003c/li\u003e\n\u003cli\u003eLieber R.L and Shoemaker D. Muscle, joint, and tendon contributions to the torque profile of frog hip-joint. American Journal of Physiology.1992; 263, R586\u0026ndash;R590. https://doi.org/10.1152/ajpregu.1992.263.3.R586\u003c/li\u003e\n\u003cli\u003ePringels L, Cook J, Witvrouw E, Burssens, A,Vanden Bossche L,Wezenbeek E. Exploring the role of intratendinous pressure in the pathogenesis of tendon pathology: a narrative review and conceptual framework. \u003cem\u003eBr. J. Sports Med.\u003c/em\u003e 2023; 57:16: 1042\u0026ndash;1048. doi:10.1136/bjsports-2022-106066\u003c/li\u003e\n\u003cli\u003eBossuyt FM, Leonard TR, Scott WM, Taylor WR,Herzog W.In-vivo and in-vitro environments affect the storage and release of energy in tendons. Front. Physiol.2024; 15:1443675. doi: 10.3389/fphys.2024.1443675.\u003c/li\u003e\n\u003cli\u003ePatterson-Kane JC,Rich T. Achilles Tendon Injuries in Elite Athletes: Lessons in Pathophysiology from Their Equine Counterparts. ILAR Journal.2014; 55: 1: 86-99 https://doi.org/10.1093/ilar/ilu004.\u003c/li\u003e\n\u003cli\u003eSasaki K, Neptune RR. Muscle mechanical work and elastic energy utilization during walking and running near the preferred gait transition speed. Gait \u0026amp; posture. 2006; 23 :3: 383-390. https://doi.org/10.1016/j.gaitpost.2005.05.002\u003c/li\u003e\n\u003cli\u003eBiewener, AA. Muscle-tendon stresses and elastic energy storage during locomotion in the horse. Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology.1998; 120:1: 73-87. https://doi.org/10.1016/S0305-0491(98)00024-8\u003c/li\u003e\n\u003cli\u003eGsell KY, Veres SP, Kreplak,L. Single collagen fibrils isolated from high stress and low stress tendons show differing susceptibility to enzymatic degradation by the interstitial collagenase matrix metalloproteinase-1 (MMP-1). Matrix Biology Plus. 2023; 18: 100129 https://doi.org/10.1016/j.mbplus..100129\u003c/li\u003e\n\u003cli\u003eHefferan SA, Blaker CL, Ashton DM Little Chr B,Clarke El C. Structural Variations of Tendons: A Systematic Searchand Narrative Review of Histological DifferencesBetween Tendons, Tendon Regions, Sex, and Age. Journal of Orthopedic Research. 2025; 43:5:994\u0026ndash;1053 https://doi.org/10.1002/jor.26060\u003c/li\u003e\n\u003cli\u003eDik KJ, 1993. Ultrasonography Of The Equine Tarsus. Veterinary Radiology and Ultrasound.1993;34:1: 36-43.https://doi.org/10.1111/j.1740-8261.1993.tb01991.x\u003c/li\u003e\n\u003cli\u003eLongo U G, Ronga M,Maffulli N. Acute Ruptures of the Achilles Tendon\u003cstrong\u003e.\u003c/strong\u003e\u003cem\u003e \u003c/em\u003eSports Medicine and Arthroscopy Review\u003cem\u003e.2009;\u003c/em\u003e 17:2::127-138.\u003cem\u003eDOI: \u003c/em\u003e10.1097/JSA.0b013e3181a3d767\u003c/li\u003e\n\u003cli\u003eGamble LJO, Canapp DA, Canapp Sh O. Evaluation of Achilles Tendon Injuries with Findings from Diagnostic Musculoskeletal Ultrasound in Canines \u0026ndash; 43 Cases. Veterinary Evidence. 2017; 2 :3: 1-23 DOI: http://dx.doi.org/10.18849/ve.v2i3.92.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1.\u003c/strong\u003e Results of measuring the Physical properties of muscles contributing to the Achilles tendon (means; standardized units).\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"624\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMuscle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eWeight (g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eVolume (cm\u0026sup3;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMuscle mass (g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eDensity (g/cm\u0026sup3;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMuscle length (cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eFiber length (cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eWeight (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eVolume (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMuscle mass (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cimg width=\"23\" height=\"22\" src=\"data:image/png;base64,R0lGODlhIwAhAHcAMSH+GlNvZnR3YXJlOiBNaWNyb3NvZnQgT2ZmaWNlACH5BAEAAAAALAAABwATAAcAhQAAAAAAAAAAOgA6kABmtjoAADoAZjo6ADpmkDpmtjqQtjqQ22YAAGY6AGZmtmaQ22a222a2/5A6AJBmOpDb/7ZmALb//9uQOtuQZtu2Ztv/29v///+2Zv+2kP/bkP/btv//tv//2wECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwECAwZSQEBoEggQNqBGMQEAYAoBQSQkWQAyA00V4GFEPAZKqPI1WJpcc/NCADEgaPC5KV8TuA3BIz3n2+NeblYfDlQKGx9eHEdJEXgBCBuPegAdB0sbQQA7\" v:shapes=\"_x0000_i1025\" alt=\"image\"\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSemitendinosus (Muscle)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e673\u0026plusmn;6.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e70\u0026plusmn;1.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e683\u0026plusmn;19.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e9.8\u0026plusmn;0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e31\u0026plusmn;2.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e22.83\u0026plusmn;1.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e47.87%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e30.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCOS 30\u003cimg width=\"3\" height=\"22\" src=\"data:image/png;base64,R0lGODlhBQAhAHcAMSH+GlNvZnR3YXJlOiBNaWNyb3NvZnQgT2ZmaWNlACH5BAEAAAAALAAABAAFAAQAgwAAAAAAAAA6ZgA6kDqQ25BmOrb//9u2Ztv///+2Zv//2wECAwECAwECAwECAwECAwQNUJUgTCLgkJuJDAMSAQA7\" v:shapes=\"_x0000_i1025\" alt=\"image\"\u003e\u003c/p\u003e\n \u003cp\u003e\u003cimg width=\"27\" height=\"22\" src=\"data:image/png;base64,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\" v:shapes=\"_x0000_i1025\" alt=\"image\"\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eGastrocnemius (Muscle)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e593\u0026plusmn;10.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e58\u0026plusmn;1.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e571\u0026plusmn;15.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e9.8\u0026plusmn;0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e18\u0026plusmn;1.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e13.83\u0026plusmn;1.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e42.18%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e25.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e25.23%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCOS 50\u003cimg width=\"3\" height=\"22\" src=\"data:image/png;base64,R0lGODlhBQAhAHcAMSH+GlNvZnR3YXJlOiBNaWNyb3NvZnQgT2ZmaWNlACH5BAEAAAAALAAABAAFAAQAgwAAAAAAAAA6ZgA6kDqQ25BmOrb//9u2Ztv///+2Zv//2wECAwECAwECAwECAwECAwQNUJUgTCLgkJuJDAMSAQA7\" v:shapes=\"_x0000_i1025\" alt=\"image\"\u003e\u003c/p\u003e\n \u003cp\u003e\u003cimg width=\"27\" height=\"22\" src=\"data:image/png;base64,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\" v:shapes=\"_x0000_i1025\" alt=\"image\"\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePlantaris (Muscle)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e140\u0026plusmn;9.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e103\u0026plusmn;6.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e100,9\u0026plusmn;74.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e9.8\u0026plusmn;0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e52\u0026plusmn;7.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e52\u0026plusmn;19.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e9.96%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e44.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e44.58%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCOS \u0026nbsp;0\u003cimg width=\"3\" height=\"22\" src=\"data:image/png;base64,R0lGODlhBQAhAHcAMSH+GlNvZnR3YXJlOiBNaWNyb3NvZnQgT2ZmaWNlACH5BAEAAAAALAAABAAFAAQAgwAAAAAAAAA6ZgA6kDqQ25BmOrb//9u2Ztv///+2Zv//2wECAwECAwECAwECAwECAwQNUJUgTCLgkJuJDAMSAQA7\" v:shapes=\"_x0000_i1025\" alt=\"image\"\u003e\u003c/p\u003e\n \u003cp\u003e\u003cimg width=\"15\" height=\"22\" src=\"data:image/png;base64,R0lGODlhFgAhAHcAMSH+GlNvZnR3YXJlOiBNaWNyb3NvZnQgT2ZmaWNlACH5BAEAAAAALAAABAAVAAoAgwAAAAAAAAAAOgBmtjo6ADpmtjqQ22YAAJDb/7aQZtuQOtuQZtu2Zv//tgECAwECAwQqEMhJq2TF6qrC2GCCKB8IklJzBGwbGBpqbvJsyarbwndpc74fYEFgCQoRADs=\" v:shapes=\"_x0000_i1025\" alt=\"image\"\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1406\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e231\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2263\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003enan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003enan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003enan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e100.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e100.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e100.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2.\u003c/strong\u003e Results of measuring the Physical properties of Achilles tendon components (means; standardized units).\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTendon\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eWeight (g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eVolume (cm\u0026sup3;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTendon mass (g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eDensity (g/cm\u0026sup3;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTendon length (cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eFiber length (cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eWeight (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eVolume (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTendon mass (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSemitendinosus (Tendon)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e82\u0026plusmn;7.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e32\u0026plusmn;3.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e313.6\u0026plusmn;39.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e9.8\u0026plusmn;0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e50\u0026plusmn;9.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e50\u0026plusmn;9.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e23.42%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e16.93%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e16.88%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eGastrocnemius (Tendon)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e125\u0026plusmn;6.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e54\u0026plusmn;4.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e535\u0026plusmn;49.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e9.8\u0026plusmn;0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e41\u0026plusmn;3.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e41\u0026plusmn;3.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e35.71%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e28.57%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e28.80%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePlantaris (Tendon)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e143\u0026plusmn;6.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e103\u0026plusmn;6.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e100.9\u0026plusmn;69.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e9.8\u0026plusmn;0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e52\u0026plusmn;7.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e52\u0026plusmn;7.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e40.85%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e54.50%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e54.32%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e350\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e189\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1857.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003enan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003enan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003enan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e100.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e100.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e100.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3.\u003c/strong\u003e Physical and \u0026nbsp;Biochemical properties of muscles (PCSA, force , MIF, torque, kinetics energy and Maximum isometric force) (means; standardized units).\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"642\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMuscle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMuscle length (cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eFiber length (cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eDensity (g/cm\u0026sup3;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eWeight (g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMuscle mass (g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eVolume (cm\u0026sup3;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePCSA (cm\u0026sup2;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eForce (N)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTorque (N\u0026middot;m)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eKE (J)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMIF (N)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSemitendinosus (Muscle)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e31\u0026plusmn;2.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e22.83\u0026plusmn;1.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e673\u0026plusmn;6.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e683\u0026plusmn;19.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e70\u0026plusmn;1.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e24.30\u0026plusmn;2.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.69\u0026plusmn;0.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.48\u0026plusmn;4.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2.32\u0026plusmn;0.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e48.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eGastrocnemius (Muscle)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e18\u0026plusmn;1.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e13.83\u0026plusmn;1.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;593\u0026plusmn;10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e571\u0026plusmn;15.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e58\u0026plusmn;1.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e17.95\u0026plusmn;1.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5.59\u0026plusmn;0.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e7.84\u0026plusmn;7.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.97\u0026plusmn;0.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e35.9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePlantaris (Muscle)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e52\u0026plusmn;7.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e52\u0026plusmn;7.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;140\u0026plusmn;9.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e100.4\u0026plusmn;74.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e104\u003c/p\u003e\n \u003cp\u003e\u0026plusmn;6.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.79\u0026plusmn;3.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e9.89\u0026plusmn;0.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e13.25\u0026plusmn;20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3.54\u0026plusmn;0.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3.59\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003enan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003enan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003enan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1406\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2263\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e231\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e22.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e27.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e7.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4.\u003c/strong\u003e Physical and Biochemical properties of tendons (Force, MIF, TCSA, CSA , torque, kinetics energy, Tendon pressure and stress) (means; standardized units) Not: MIF of tendon is Maximum isometric force-transferring capability (Ncm\u0026sup2;).\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"642\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTendon\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTendon length (cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eFiber length (cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eDensity (g/cm\u0026sup3;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eWeight (g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTendon mass (g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eVolume (cm\u0026sup3;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eForce (N)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMIF\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTCSA (mm\u0026sup2;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCSA=A\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTorque (N\u0026middot;m)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eKE (J)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTP (arb)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eStress (N/mm\u0026sup2;)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSemitendinosus (Tendon)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e50\u0026plusmn;9.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e50\u0026plusmn;9.95\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e82\u0026plusmn;7.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e313.6\u0026plusmn;39.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e32\u0026plusmn;3.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3.06\u0026plusmn;0.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.16\u0026plusmn;0.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.58\u0026plusmn;0.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.59\u0026plusmn;0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e4.02\u0026plusmn;0.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.72\u0026plusmn;0.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2\u0026plusmn;0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.39\u0026plusmn;3.47\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eGastrocnemius (Tendon)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e41\u0026plusmn;3.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e41\u0026plusmn;3.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e125\u0026plusmn;6.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e535\u0026plusmn;49.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e54\u0026plusmn;4.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5.24 \u0026plusmn;0.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2.6\u0026plusmn;0.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.3\u0026plusmn;0.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.06\u0026plusmn;0.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6.86 \u0026plusmn; 1.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.64\u0026plusmn;0.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2\u0026plusmn;0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5.56\u0026plusmn;2.12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePlantaris (Tendon)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e52\u0026plusmn;7.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e52\u0026plusmn;7.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e143\u0026plusmn;6.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e100.4\u0026plusmn;69.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e103\u0026plusmn;6.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e9.89\u0026plusmn;0.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e4.22\u0026plusmn;0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2.11\u0026plusmn;0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2.77\u0026plusmn;0.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e13.25\u0026plusmn;2.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3.08\u0026plusmn;0.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2\u0026plusmn;0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3.75\u0026plusmn;0.90\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003enan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003enan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003enan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e350\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1857.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e189\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e18.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e7.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e4.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e24.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e5.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e15.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Morphology, Stress, Animals, Adult, Energy transfer, Camel","lastPublishedDoi":"10.21203/rs.3.rs-9484450/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9484450/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study investigates the anatomy and biomechanics of the camel\u0026rsquo;s Achilles tendon and associated hindlimb muscles to better understand their functional roles during movement such as walking, running, and kicking. Ten healthy adults camel hindlimbs, collected from both males and females aged Five camels are aged 1\u0026ndash;3 years, were examined from anatomy laboratories and slaughterhouses in Saudi Arabia. Detailed dissections were performed to analyze the structure of the semitendinosus, gastrocnemius, and superficial digital flexor muscles, along with their tendons. A comprehensive set of measurements was recorded, including muscle fiber length, total muscle length and weight, muscle mass and volume, density, physiological cross‑sectional area (PCSA), cross‑sectional area (CSA), maximum isometric force, stress, torque, and kinetic energy. The findings revealed that the semitendinosus and gastrocnemius muscles, which contribute to flexion and abduction of the hindlimb, exhibited similar physical and biomechanical properties. In contrast, the superficial digital flexor muscle showed distinct and higher biomechanical values, attributed to its string‑like tendinous structure.\u003c/p\u003e \u003cp\u003eThese biomechanical differences highlighted the specialized roles of each muscle in facilitating efficient hindlimb movement. Overall, the research demonstrates that every muscle possesses unique physical characteristics that contribute to the camel\u0026rsquo;s locomotor performance.\u003c/p\u003e","manuscriptTitle":"Morphological, Physical and Biomechanical Characteristics of the Achilles Tendon in the Dromedary Camel (Camelus dromedarius)","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-12 16:43:17","doi":"10.21203/rs.3.rs-9484450/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewersInvited","content":"","date":"2026-05-04T16:59:50+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-04-28T16:36:35+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-22T09:56:31+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-22T09:56:10+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2026-04-21T12:37:35+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"18db6c6c-bc34-4f77-9902-d184627399dc","owner":[],"postedDate":"May 12th, 2026","published":true,"recentEditorialEvents":[{"type":"reviewersInvited","content":"6","date":"2026-05-04T16:59:50+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":67807696,"name":"Health sciences/Anatomy"},{"id":67807697,"name":"Biological sciences/Physiology"},{"id":67807698,"name":"Biological sciences/Zoology"}],"tags":[],"updatedAt":"2026-05-12T16:43:17+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-12 16:43:17","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9484450","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9484450","identity":"rs-9484450","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}