Effect of cooling on force oscillations during maximal voluntary eccentric exercise

Area of Science:

• Exercise Physiology
• Motor Control
• Neuromuscular Function

Background:

• Force oscillations are observed during maximal eccentric muscle contractions.
• The underlying mechanisms of these oscillations, particularly their relationship to neural activity, are not fully understood.

Purpose of the Study:

• To investigate the effect of superficial cooling on force oscillations during maximal eccentric exercises of the quadriceps femoris.
• To explore the potential neural mechanisms contributing to force oscillations during eccentric contractions.

Main Methods:

• Ten adult participants performed maximal concentric and eccentric quadriceps exercises at 120 degrees/s.
• Surface electromyography (EMG) of the vastus medialis was recorded.
• Superficial cooling was applied to the experimental group, while a control group rested.

Main Results:

• Force oscillations (12.4 +/- 2.8 Hz) were present in all subjects during initial eccentric exercises.
• Superficial cooling eliminated or reduced oscillations in 40% of the experimental group.
• Control subjects showed no significant change in oscillations after rest.

Conclusions:

• Force oscillations during maximal eccentric exercise resemble physiological action tremor.
• The alteration of force oscillations and EMG patterns by cooling suggests a neural component in their initiation.
• Superficial cooling may modulate neural pathways involved in generating force oscillations during eccentric contractions.