Abstract
ABSTRACTDespite the robust findings linking plantar flexor muscle structure to gross function within athletes, the elderly and patients following Achilles tendon ruptures, the link between natural variation in plantar flexor structure and function in healthy adults is unclear. In this study, we determined the relationship between medial gastrocnemius structure and peak torque and total work about the ankle during maximal effort contractions. We measured resting fascicle length and pennation angle using ultrasound in healthy adults (N=12). Subjects performed maximal effort isometric and isokinetic contractions on a dynamometer. We found that longer fascicles were positively correlated with higher peak torque and total work (R2>0.41, P<0.013) across all isokinetic velocities, ranging from slow (30°/s) to fast (210°/s) contractions. Higher pennation angles were negatively correlated with peak torque and total work (R2>0.296, P<0.067). These correlations were not significant in isometric conditions. We further explored this relationship using a simple computational model to simulate isokinetic contractions. These simulations confirmed that longer fascicle lengths generate more joint torque and work throughout a greater range of motion. This study provides evidence that ankle function is strongly influenced by muscle structure in healthy adults.
Highlights
Plantar flexor function is a critical parameter for human movement in athletes, aging and patient populations
More than half of the variability in plantar flexor work (R2=0.599, P=0.003) and peak torque (R2=0.521, P=0.008) during 30°/s isokinetic contractions was explained by resting fascicle length
The correlation between resting fascicle length and plantar flexor work and peak torque decreased during faster isokinetic contractions at 120°/s (0.413>R2>0.415, PR2>0.494, P
Summary
Plantar flexor function is a critical parameter for human movement in athletes, aging and patient populations. The triceps surae muscles, comprised of the soleus, lateral gastrocnemius and medial gastrocnemius, support and accelerate the body during ambulation. These plantar flexors appear small relative to knee and hip musculature, plantar flexor function is critical during walking (Graf et al, 2005; JudgeRoy et al, 1996), stair climbing (Suzuki et al, 2001), running (Ellis et al, 2014; Nesser et al, 1996), and jumping (Bobbert et al, 1986).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
