Relationship between Achilles Tendon Moment Arm and Plantarflexor Muscle Architecture
Open Access
- Author:
- Faux-Dugan, Logan
- Graduate Program:
- Kinesiology
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- October 26, 2022
- Committee Members:
- Jonathan Dingwell, Professor in Charge/Director of Graduate Studies
Stephen Piazza, Thesis Advisor/Co-Advisor
Jonas Rubenson, Committee Member
John Henry Challis, Committee Member - Keywords:
- Achilles tendon moment arm
Plantarflexors
Muscle Architecture
Regression Analysis
Ultrasonography
3D Ultrasonography
Motion Capture System - Abstract:
- Sufficient plantarflexor muscle moment is critical to locomotor function, so the direct determinants of this moment, plantarflexor force, and the plantarflexor moment arm of the Achilles tendon (ATMA), are also of great importance. The primary plantarflexor muscles – the lateralis gastrocnemius (LG), medialis gastrocnemius (MG), and soleus – transmit force through the Achilles tendon (AT) to generate a plantarflexion moment about the ankle as the foot pushes off from the ground during locomotion. The plantarflexor moment may be thought of as the product of the AT force and the ATMA, which determines the leverage of the AT force about the ankle joint axis. Muscle architecture parameters – such as fascicle length (FL), pennation angle (PA), muscle volume (MV), and physiologic cross-sectional area (PCSA) – influence plantarflexor force through the force-length (F-L) and force-velocity (F-V) properties of muscle. Several recent studies have reported differences in the relationships between ATMA and plantarflexor architecture between groups with different functional demands (e.g., sprinters and non-sprinters) and associations have been found between ATMA and functional capacity in terms of energetic efficiency during distance running. The purpose of this thesis was to investigate the relationship between ATMA and architecture of plantarflexor muscles (LG and MG) in a healthy, adult, non-athlete population. Therefore, measurements were taken of the ATMA and architecture (FL, PA, MV, & PCSA) of the LG and MG. Significant positive correlations were observed between ATMA and LG fascicle length, MG PCSA, and MVs of the LG and MG, and there are implications for these associations. With all else equal, a larger ATMA increases muscle contraction velocity which decreases muscle force according to the F-L and F-V properties. Although this research cannot answer questions about the cause of these associations, it is possible that larger fascicle lengths, PCSAs, and muscle volumes of the plantarflexors might reduce the force lost from the larger ATMA. Future studies should investigate the relationship between ATMA and plantarflexor architecture in different populations to see if similar relationships exist.