Gender Differences of Achilles tendon Cross-sectional Area during Loading

Area of Science:

• Biomechanics
• Musculoskeletal research
• Human physiology

Background:

• The Achilles tendon (AT) is known to be larger and stiffer in males than females.
• AT stiffness is influenced by length changes during loading, but transverse collagen fibers suggest cross-sectional area (CSA) changes also occur.
• Understanding gender-specific AT mechanics during contraction is crucial for injury prevention and performance optimization.

Purpose of the Study:

• To investigate gender differences in Achilles tendon cross-sectional area (AT-CSA) during maximal voluntary isometric contraction (MVIC).
• To quantify AT-CSA deformation, compliance, and strain in males and females.
• To explore the implications of observed gender differences in AT mechanics.

Main Methods:

• Sonographic assessment of AT-CSA in 15 males and 15 females during rest and MVIC (plantar flexion).
• Calculation of AT-CSA maximal deformation, compliance (CSA deformation/peak torque), and strain (CSA deformation/CSA at rest).
• Statistical analysis using independent sample t-tests with Bonferroni correction (α=0.01) to compare gender differences.

Main Results:

• Males exhibited significantly larger AT-CSA at rest and during MVIC, along with higher peak torque.
• Females demonstrated significantly greater AT-CSA deformation, strain, and compliance compared to males.
• CSA reduction during loading was more pronounced in females, indicating higher CSA compliance.

Conclusions:

• Despite larger overall size in males, the Achilles tendon exhibits greater cross-sectional area compliance in females during maximal contraction.
• Higher CSA compliance in females may indicate enhanced adaptability to loading.
• This increased compliance could potentially serve as a protective factor against tendon injuries.