High-intensity interval exercise affects explicit sequential motor consolidation with both physical and mental practice

High-intensity interval exercise (HIIE) is known to enhance motor consolidation following physical practice (PP), but its effects on sequential motor learning (SML) through PP or motor imagery (MI) remain unclear. We examined whether HIIE modulates SML consolidation in 48 participants who learned an explicit SML task through PP or MI. Performance was assessed before and after acquisition, after HIIE or rest, and at 24 hours and 7 days. Both PP and MI improved performance, with greater gains for PP (p = 0.042), and both induced intracortical disinhibition (p = 0.03). HIIE increased BDNF (p = 0.044) and lactate levels (p < 0.001), markers typically linked to neuroplasticity, yet unexpectedly impaired SML at early (p < 0.01) and late consolidation (p < 0.05), without affecting excitability. These findings challenge the presumed coupling between exercise-induced biomarkers and behavioral gains, suggesting that HIIE may hinder consolidation when explicit components of motor learning are involved. Significance StatementHIIE is increasingly proposed as a tool to boost neuroplasticity and enhance motor learning. However, whether its benefits extend to all forms of learning remains unclear. Here, we show that both physical and motor imagery practice improve SML and induce intracortical disinhibition, a neurophysiological signature of plasticity. Surprisingly, HIIE impaired SML consolidation at both early and late stages, despite increases in BDNF and lactate, biomarkers typically linked to learning facilitation. This deterioration was observed across both practice modalities and is likely driven by the explicit, cognitively demanding nature of the task. These findings challenge the generalizability of HIIEs beneficial effects and highlight the need to align exercise-based interventions with the specific cognitive-motor demands of the learning task. Such insights are critical for optimizing motor learning strategies in both athletic training and neurorehabilitation.