Ipsilateral resistance exercise prevents exercise-induced central sensitization in the contralateral limb: a...

Area of Science:

• Exercise Physiology
• Neuroscience
• Sports Medicine

Background:

• Eccentric exercise (ECC) can induce muscle damage and alter nociception.
• The repeated bout effect (RBE) describes the protective adaptations following prior exercise.
• Understanding RBE in spinal nociception and muscle oxygenation is crucial for training protocols.

Purpose of the Study:

• To test if a second eccentric exercise bout (ECC2) reduces spinal nociceptive sensitivity and muscle oxygenation changes compared to the first bout (ECC1).
• To determine if the RBE is greater for ipsilateral (same leg) versus contralateral (opposite leg) exercise.
• To investigate the role of muscle blood oxygenation in the RBE.

Main Methods:

• Twenty-six healthy men underwent two high-intensity eccentric exercise (ECC) bouts of the tibialis anterior (TA) muscle, separated by two weeks.
• Participants were divided into ipsilateral (IPSI) and contralateral (CONTRA) groups for the second bout (ECC2).
• Nociceptive withdrawal reflex threshold (NWRT) and muscle oxygenation were measured before and after each ECC bout.

Main Results:

• ECC1 significantly decreased NWRT and muscle oxygenation; ECC2 did not alter NWRT in either group.
• Muscle oxygenation decreased less after ECC2 than ECC1 in both IPSI and CONTRA groups.
• Increased muscle oxygen re-perfusion was observed before ECC2 only in the IPSI group.

Conclusions:

• The RBE significantly reduces spinal nociceptive potentiation after repeated eccentric exercise.
• Contralateral RBE appears mediated by spinal facilitation at homologous innervation levels.
• Improved oxygen re-perfusion is unlikely to be the primary mechanism behind the contralateral RBE.