Abstract
Objective: To determine the influence of fatigue on active and passive muscle stiffness when the muscle/tendon complex has been exposed to high-intensity dynamic exercises of a short duration.
Subjects and methods: Fifteen (see: Methods: 2.1 subjects) healthy women aged 23 ± 2 years participated. Active and passive stiffness of the calf muscle was measured on an isokinetic dynamometer using electrical stimulation and passive stretch (200°/s). The stiffness test was conducted before and immediately after high-intensity dynamic exercises of the plantar flexors performed until exhaustion.
Results: The forces generated by the same electrical stimulation level were significantly higher before than after the fatigue test. No significant changes could be demonstrated regarding active or passive stiffness before and after the fatigue protocol. However individual changes in active stiffness of about 40% were noted.
Conclusion: Even though no significant changes in stiffness were apparent after the fatiguing exertion large individual changes could be noted. This is an indication that stiffness in the calf muscle after high-intensity dynamic exercises may not correspond to the peripheral fatigue.