Presenter: Ayooluwa Popoola – Human Physiology
Faculty Mentor(s): Austin Ricci, Damien Callahan
Session: (In-Person) Poster Presentation
Skeletal muscle is a complex tissue, comprised at the whole tissue level of contractile structures, adipose and connective tissue. The relationships between composition and biological sex are important because composition likely affects muscle contractile performance. However, the mechanisms through which composition and stiffness interdependently influence function between men and women remain largely unclear.
Purpose: to investigate the differences in active and passive stiffness of the vastus lateralis muscle (VL) and patellar tendon (PT) in young men and women.
Methods: We recruited 14 young healthy participants, 9 men and 5 women. Participants performed 3 maximum voluntary isometric contractions (MVIC) of the knee extensor muscles (KE) to determine peak torque. Passive stiffness was measured at the VL and PT using digital palpation (DP) prior to MVIC measurements. Active stiffness was measured at 25%, 50%, and 100% MVIC during ramped contractions using DP and ultrasound.
Results: Passive stiffness was not different between sexes at the PT or VL. Active stiffness was less in women at the VL [0.19] and PT [0.03]. Women had higher subcutaneous adipose thickness (SAT) [<0.001] and echogenicity [<0.001] with similar muscle thickness.
Conclusion: Data suggests muscle activation comparatively alters stiffness in women. Despite similar muscle thickness, women have higher SAT and echogenicity, two characteristics known to reduce stiffness.