Fatiguing unilateral handgrip influences force during force-matching task with lower limb.

Area of Science:

• Neuroscience
• Motor Control
• Human Physiology

Background:

• Unilateral fatiguing contractions can induce neuroplastic changes.
• The influence of handgrip fatigue on lower limb corticomotor excitability is not fully understood.
• Investigating cross-limb effects of fatigue is crucial for understanding motor control.

Purpose of the Study:

• To investigate asymmetrical changes in corticomotor excitability of lower limbs following fatiguing unilateral handgrip contractions.
• To determine if changes in corticomotor excitability in non-fatigued lower limbs influence force production based on the sense of effort.

Main Methods:

• Ten healthy males performed fatiguing unilateral handgrip contractions.
• Motor-evoked potentials (MEPs) in the tibialis anterior (TA) muscles (ipsilateral and contralateral to the fatigued hand) were measured.
• Force-matching tasks involving static dorsiflexion were conducted before, immediately after, and 10 minutes after handgrip fatigue.

Main Results:

• Fatiguing handgrip contractions led to significantly increased MEPs in the contralateral TA muscle compared to the ipsilateral TA muscle.
• The contralateral TA muscle showed greater MEPs post-fatigue (158 ± 60%) than the ipsilateral TA muscle (111 ± 30%).
• Torque output in the force-matching task significantly increased in the contralateral ankle post-fatigue.

Conclusions:

• Unilateral handgrip fatigue induces asymmetric alterations in corticomotor excitability in the tibialis anterior muscles.
• Enhanced corticomotor excitability in the TA muscle correlates with increased force production during a force-matching task.
• These findings highlight complex interhemispheric and interlimb interactions in response to localized fatigue.