Effect of High-Intensity Interval Treadmill Exercise on Subsequent Lower and Upper Limb Strength Performance.

: The aim of this study was to analyze the acute effect of a treadmill high-intensity interval protocol on subsequent upper body and lower body strength exercise performance. : Sixteen young men had their maximal aerobic capacity and one-repetition maximum (1RM) determined and underwent four randomized conditions: a half-squat control session; a bench press control session; a treadmill interval protocol followed by a half-squat experimental session; and a treadmill interval protocol followed by a bench press experimental session. During the control sessions, four sets to failure for each exercise were performed at 80% of 1RM. In the experimental sessions, participants performed eight sprints of 40 s at 100% velocity of maximal oxygen uptake with 20 s of passive interval between them, followed by the same strength exercise protocol of the control sessions. The number of repetitions during each protocol and participants' heart rate (HR),and blood lactate concentration ([lac]) were compared pre and post protocols and exercises. : Fewer repetitions were completed in the experimental session compared to the control sessions ( < .001). Moreover, the reduction in number of repetitions performed was more evident in half-squat compared to bench press ( = .018). HR was higher at the end of sessions with the interval protocol for both exercises ( < .001). The [lac] was higher at the end of session with the interval protocol for half-squat ( = .003). : These findings suggest that previous high-intensity interval running may impair subsequent strength exercise performance, but the magnitude of the negative effect is greater in the lower limbs.