On muscle, tendon and high heels

Area of Science:

• Biomechanics
• Musculoskeletal adaptations
• Human physiology

Background:

• The calf muscle-tendon unit (MTU) is adaptable to chronic loading.
• High heel (HH) wear maintains the MTU in a shortened position.
• Potential for structural and functional changes in the calf MTU from chronic HH use.

Purpose of the Study:

• To investigate the effects of chronic high heel wear on the calf MTU.
• To compare structural and functional parameters between HH users and a control group.
• To determine if HH use alters muscle fascicle length, tendon properties, or plantarflexion mechanics.

Main Methods:

• Recruited 11 women regularly wearing HH and 9 controls.
• Assessed gastrocnemius medialis (GM) fascicle length, pennation angle, and PCSA.
• Measured Achilles tendon (AT) length, CSA, and mechanical properties.
• Evaluated plantarflexion torque-angle and torque-velocity relationships.

Main Results:

• Shorter GM fascicle lengths observed in the HH group (49.6+/-5.7 mm vs 56.0+/-7.7 mm).
• Increased AT CSA and higher AT stiffness in the HH group (136.2+/-26.5 N mm(-1) vs 111.3+/-20.2 N mm(-1)).
• No significant differences in GM PCSA to AT CSA ratio or torque-velocity relationships.

Conclusions:

• Long-term high heel use induces GM muscle fascicle shortening.
• Chronic HH use increases AT stiffness, reducing ankle active range of motion.
• Observed adaptations appear to functionally counteract each other, maintaining torque output.