High‐Intensity Interval Exercise Affects Explicit Sequential Motor Consolidation With Both Physical and Motor Imagery Practice

High-intensity interval exercise (HIIE) has been shown to improve motor skill consolidation when performed after physical practice (PP), but it remains unclear whether similar benefits extend to motor sequence learning (MSL) with both physical and motor imagery practice (MI). In this study, we examined the effects of HIIE on the consolidation of an explicit MSL task learned through PP or MI. Forty-eight participants were randomized into four groups based on the type of practice used to acquire the MSL task and whether they performed HIIE or rested before consolidation. Performance on the MSL task was assessed before and after acquisition, following HIIE or REST (early consolidation), and after 24 h and 7 days of late consolidation. Lactate and brain-derived neurotrophic factor (BDNF) levels, as well as corticospinal and intracortical excitability were examined to determine the mechanisms underpinning MSL acquisition and the effects of HIIE on consolidation. We found that both PP and MI increased performance during acquisition, with PP outperforming MI (p = 0.042), while both practices induced intracortical disinhibition right after acquisition (p = 0.02). Following HIIE, BDNF (p = 0.044) and lactate (p < 0.001) levels increased, but corticospinal and intracortical excitability remained unchanged. Importantly, our study suggests that MSL performance could be impaired by HIIE during both early and late consolidation (p < 0.01 and p < 0.05, respectively). Therefore, the HIIE-induced deterioration in MSL consolidation for both types of practice is likely due to the task's explicit demands, emphasizing the need to consider this factor when incorporating HIIE as an optimization approach into motor learning strategies in both sport and clinical contexts.