Unilaterally Induced Quadriceps Fatigue during Sustained Submaximal Isometric Exercise Does Not Alter Contralateral...

Area of Science:

• Exercise Physiology
• Neuromuscular Function
• Human Performance

Background:

• Unilateral exercise can induce fatigue in the exercised limb.
• The impact of unilateral exercise on the contralateral limb and potential sex differences are not fully understood.

Purpose of the Study:

• To investigate the effects of fatiguing unilateral exercise on ipsilateral and contralateral limb performance.
• To examine sex-dependent differences in fatigue response and neurophysiological outcomes.

Main Methods:

• Ten males and ten females performed unilateral isometric leg extensions to fatigue.
• Maximal voluntary isometric contractions (MVIC), surface electromyography (sEMG), and mechanomyography (sMMG) were measured.
• Amplitude (AMP) and mean power frequency (MPF) of the vastus lateralis were recorded.

Main Results:

• No significant sex differences in time to task failure or ipsilateral fatigability.
• MVIC force decreased in the exercised limb but not the non-exercised limb.
• Fatigue affected sEMG MPF, suggesting neural influences on both limbs, independent of sex.

Conclusions:

• Fatigability from submaximal unilateral isometric exercise is similar between males and females.
• There was no clear crossover effect observed in limb performance.
• Neurophysiological changes suggest neural competition may influence performance in both limbs post-unilateral fatigue.