Cycling Kinematics in Healthy Adults for Musculoskeletal Rehabilitation Guidance

Background: Stationary cycling is commonly used for postoperative rehabilitation of physical disabilities, but few studies have focused on the three-dimensional (3D) kinematics of rehabilitation. This study aimed to elucidate the three-dimensional lower limb kinematics of musculoskeletally healthy people and the effect of sex and age on kinematics using a controlled bicycle configuration. Methods: : Thirty-one healthy adults participated in the study. The stationary cycle positioning was standardized using the LeMond method by setting the saddle height to 85.5% of the participant’s inseam. The participants maintained a pedaling rate of 10–12 km/h, and the average value of three successive cycles of the right leg was used for analysis. The pelvis, hip, knee, and ankle joint motions during cycling were evaluated in the sagittal, coronal, and transverse planes. Kinematic data were normalized to 0–100% of the cycling cycle. The Kolmogorov-Smirnov test, Mann-Whitney U test, Kruskal-Wallis test, and k-fold cross-validation were used to analyze the data. Results: : In the sagittal plane, the cycling ranges of motion (ROMs) were 1.6° (pelvis), 43.9° (hip), 75.2° (knee), and 26.9° (ankle). The coronal plane movement was observed in all joints, and the specific ROMs were 6.6° (knee) and 5.8° (ankle). There was significant internal and external rotation of the hip (ROM: 11.6°), knee (ROM: 6.6°), and ankle (ROM: 10.3°) during cycling. There was no difference in kinematic data of the pelvis, hip, knee, and ankle between sexes (p = 0.12 to 0.95) and among ages (p = 0.11 to 0.96) in all anatomical planes. Conclusions: : The kinematic results support the assertion that cycling is highly recommended for comprehensive musculoskeletal rehabilitation. These results may help clinicians choose a target recovery ROM based on healthy and non-elite individuals and issue suitable guidelines to patients.