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Updated: Jun 10, 2026
07:44
Construction of Constant-Load (Isotonic) and Constant-Velocity (Isokinetic) Torque-Velocity-Power Profiles In vivo for the Rat Plantar Flexors
Published on: October 3, 2025
Velocity-dependent muscle strategy during plantarflexion in humans
A Carpentier1, J Duchateau, K Hainaut
1Laboratory of Biology, Université Libre de Bruxelles, Brussels, Belgium.
Summary
The knee joint
Area of Science:
- Biomechanics
- Human Physiology
- Motor Control
Background:
- Understanding muscle contributions to movement is crucial for biomechanical analysis.
- The triceps surae and tibialis anterior are key muscles in plantarflexion.
- Knee joint position influences muscle mechanics and neural activation.
Purpose of the Study:
- To investigate the roles of triceps surae and tibialis anterior in plantarflexion.
- To analyze muscle activation and tension development at different velocities and knee positions.
- To determine factors contributing to maximal plantarflexion velocity.
Main Methods:
- Electromyography (EMG) recorded voluntary activity of plantarflexors and dorsiflexors.
- Maximal M-wave and Hoffmann reflex assessed motoneuron excitability.
- Plantarflexion performed at various velocities with knee extended and flexed.
Main Results:
- Maximal plantarflexion velocity was greater with the knee flexed.
- Increased movement velocity enhanced triceps surae integrated EMG (IEMG) activity.
- Soleus IEMG/gastrocnemii IEMG ratio was higher in the flexed knee at low velocity.
- Agonist-antagonist co-activation increased with movement velocity.
Conclusions:
- Maximal plantarflexion velocity differences between knee positions are primarily due to muscle mechanical properties, not neural drive.
- Co-activation of agonist and antagonist muscles aids rapid movement strategies.
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