The Effect of Crank Length Changes from Cycling Rehabilitation on Muscle Behaviors.

BACKGROUND: Many sports and physical activities can result in lower limb injures. Pedaling is an effective exercise for lower extremity rehabilitation, but incorrect technique may cause further damage. To some extent, previous experiments have been susceptible to bias in the sample recruited for the study. Alternatively, methods used to simulation activities can enable parametric studies without the influence of noise. In addition, models can facilitate the study of all muscles in the absence of the effects of fatigue. This study investigated the effects of crank length on muscle behavior during pedaling. METHODS: Six muscles (soleus, tibialis anterior, vastus medialis, vastus lateralis, gastrocnemius, and rectus femoris), divided into three groups (ankle muscle group, knee muscle group, and biarticular muscle group), were examined under three cycling crank lengths (100 mm, 125 mm, and 150 mm) in the present study. In addition, the relationship between crank length and muscle biological force was analyzed with the AnyBody Modeling System™, a human simulation modeling software based on the Hill-type model. Findings. Based on inverse kinematic analysis, the results indicate that muscle activity and muscle force decrease in varying degrees with increases in crank length. The maximum and minimum muscular forces were attained in the tibialis anterior and vastus lateralis, respectively. Interpretation. Studying the relationship between muscle and joint behavior with crank length can help rehabilitation and treating joint disorders. This study provides the pedal length distribution areas for patients in the early stages of rehabilitation.

The effect of sitting position changes from pedaling rehabilitation on muscle activity.

Sports injuries or traffic accidents make the individuals bedridden for a long duration, easily causing the disuse of lower limb muscles. Exercise rehabilitation is an effective method to improve muscle activity; however, currently, exercise therapy mainly relies on the experience of rehabilitation physicians for determining the rehabilitation parameters. In this paper, we establish a human-machine coupling system model for disuse atrophy of lower limb muscles. We analyze the influence of sitting position on pedaling rehabilitation. The relationship between the sitting position and muscle effect of lower limb muscle is calculated. We optimized the parameters to analyze muscle force and activity distribution in the muscle group during different sitting positions, and the rehabilitation risk area and the invalid area were identified from the distribution map, which helps quantify the maximal exercise of muscles without causing secondary muscle damage. The mapping relationship between sitting position and muscle force was established in this study. Further, muscle activity mapping is performed for overall assessment. Muscle activity assessment considered the training intensity of small muscles and avoids secondary injury of small muscle. The corresponding designated sitting posture improved the intensity of muscle training and shortened the rehabilitation cycle. Systematic distribution areas for different rehabilitation effects in pedal exercises are presented and provide the sitting position distribution areas for patients in the early, middle, and late stages. The proposed model provides theoretical guidance for rehabilitation physicians.

Motion Trajectory of 3-PH/R Ankle Rehabilitation Robot / 医用生物力学

Objective To study the influence of different trajectories of 3-PH/R ankle rehabilitation robot on joints and muscles. Methods The 3-PH/R ankle rehabilitation robot was simplified and imported into biomechanical modeling software by analyzing the kinematics principles. Using the actual motion trajectory of ankle rehabilitation robot as model driving, the joint and muscle forces were compared under three different trajectories, namely, dorsiflexion/plantarflexion, inversion/eversion and nutation. The correlation analysis on three motion trajectories was conducted. Results Nutation could satisfy the function of both plantar dorsiflexion/plantarflexion, and inversion/eversion, and made the ankle muscles fully exercised. The maximum difference in joint force under three different rehabilitation trajectories was 0.3 N. Different muscles had different sensitivity to trajectories. Conclusions The continuous dynamic analysis of muscle force and joint force under three kinds of rehabilitation trajectories was implemented. The results have certain theoretical significance and clinical reference value for the clinical application of ankle rehabilitation robot and the formulation of rehabilitation trajectory.