Changes in cortico-spinal excitability following uphill versus downhill treadmill exercise

Area of Science:

• Neuroscience
• Exercise Physiology
• Motor Control

Background:

• Aerobic exercise and paired associative stimulation (PAS) are known to induce neuroplasticity in the motor cortex.
• The influence of different exercise modes on neuroplasticity remains unclear.

Purpose of the Study:

• To investigate the effects of uphill versus downhill treadmill exercise on corticospinal (CS) excitability.
• To examine if exercise mode influences neuroplastic changes induced by PAS.

Main Methods:

• Subjects performed 30-min treadmill exercises at 60% maximal heart rate (uphill or downhill).
• Paired associative stimulation (PAS25) was applied post-exercise.
• Motor evoked potentials (MEPs) were recorded from the abductor pollicis brevis (APB) muscle.

Main Results:

• Both uphill and downhill exercises increased MEP amplitude 30 minutes post-exercise.
• MEP amplitude increased after PAS25 only following downhill exercise.
• No significant difference in CS excitability was observed between exercise modes without PAS.

Conclusions:

• Sub-maximal aerobic exercise enhances CS excitability for at least 30 minutes.
• Downhill exercise, potentially due to its muscle contraction mode, may prime the motor cortex for greater neuroplasticity when combined with PAS.
• Exercise-induced homeostatic mechanisms may interact with PAS protocols to induce specific neuroplastic changes.