Finger tapping at maximal speed evokes crossover fatigability in the other hand

Area of Science:

• Neuroscience
• Exercise Physiology
• Motor Control

Background:

• Crossover fatigability (CF) is the reduced capacity of a non-exercised muscle due to exertion in the contralateral limb.
• The existence and mechanisms of CF are debated, potentially influenced by the exercise protocol.
• Fast repetitive movements can induce supraspinal fatigue and motor slowing.

Purpose of the Study:

• To investigate if CF can be evoked using fast, maximal-speed repetitive movements.
• To determine if motor slowing paradigms can induce CF.
• To explore the underlying mechanisms of CF in this context.

Main Methods:

• Two independent cohorts (n=16, n=30) performed maximal speed unilateral finger tapping.
• Fatigability was induced via brief (10s) maximal effort on one hand.
• Contralateral hand performance was assessed for changes in tapping speed and movement reserve.

Main Results:

• Crossover fatigability was successfully induced using the motor slowing paradigm.
• CF manifested as reduced initial tapping speed in the non-exercised hand.
• A reduced "movement reserve" was observed in the contralateral limb.
• Even brief maximal effort was sufficient to elicit CF.

Conclusions:

• Fast repetitive movements at maximal speed can effectively induce crossover fatigability.
• The findings suggest that CF evoked by motor slowing is primarily mediated by supraspinal mechanisms.
• CF is not solely a peripheral phenomenon and can be influenced by central nervous system fatigue.