Muscle fatigue in a standing heel-rise test

Area of Science:

• Biomechanics
• Exercise Physiology
• Muscle Physiology

Background:

• The triceps surae muscle group, composed of the gastrocnemius and soleus, is crucial for ankle plantarflexion.
• Understanding muscle fatigue patterns is essential for diagnosing and managing neuromuscular disorders.
• The standing heel-rise test is a common functional assessment, but its fatigue characteristics require further elucidation.

Purpose of the Study:

• To investigate the fatigue process of the triceps surae (gastrocnemius and soleus) during a maximal standing heel-rise test.
• To analyze changes in mechanical work and electromyographic (EMG) activity (mean power frequency and root mean square) during fatiguing contractions.
• To differentiate the fatigue patterns between the gastrocnemius and soleus muscles.

Main Methods:

• Ten healthy women (mean age 24 years) performed a standing heel-rise test to exhaustion.
• Mechanical work and EMG signals (root mean square, mean power frequency) of the gastrocnemius and soleus were recorded.
• Data were analyzed to assess changes during eccentric and concentric muscle actions throughout the test.

Main Results:

• Overall work output significantly decreased as the test progressed.
• Mean power frequency significantly decreased in both gastrocnemius and soleus muscles during both contraction phases.
• The decrease in mean power frequency was significantly greater in the gastrocnemius than the soleus during the eccentric phase; root mean square showed no significant change except for a decrease in the soleus during the eccentric phase.

Conclusions:

• The gastrocnemius and soleus muscles exhibit differential fatigue patterns during a standing heel-rise test.
• These findings provide a reference for evaluating muscle fatigue in clinical settings.
• Standardization of the heel-rise test is recommended for consistent clinical application.