Differences in in vivo muscle fascicle and tendinous tissue behavior between the ankle plantarflexors during running.
The primary human ankle plantarflexors, soleus (SO), medial gastrocnemius (MG), and lateral gastrocnemius (LG) are typically regarded as synergists and play a critical role in running. However, due to differences in muscle-tendon architecture and joint articulation, the muscle fascicles and tendinous tissue of the plantarflexors may exhibit differences in their behavior and interactions during running. We combined in vivo dynamic ultrasound measurements with inverse dynamics analyses to identify and explain differences in muscle fascicle, muscle-tendon unit, and tendinous tissue behavior of the primary ankle plantarflexors across a range of steady-state running speeds. Consistent with their role as a force generator, the muscle fascicles of the uniarticular SO shortened less rapidly than the fascicles of the MG during early stance. Furthermore, the MG and LG exhibited delays in tendon recoil during the stance phase, reflecting their ability to transfer power and work between the knee and ankle via tendon stretch and storage of elastic strain energy. Our findings add to the growing body of evidence surrounding the distinct mechanistic functions of uni- and biarticular muscles during dynamic movements.
['Lai|A K M|AKM|http://orcid.org/0000-0002-8931-0878', 'Lichtwark|G A|GA|', 'Schache|A G|AG|', 'Pandy|M G|MG|']
D000328:Adult D000842:Ankle D001696:Biomechanical Phenomena D003198:Computer Simulation D004576:Electromyography D005260:Female D006801:Humans D008297:Male D018482:Muscle, Skeletal D016059:Range of Motion, Articular D012420:Running D013710:Tendons D014463:Ultrasonography D055815:Young Adult
muscle fascicles running tendon biarticular muscle function