Background: Diminished respiratory muscle strenght has been shown following a strenuous bout of sit-ups; however, there is a paucity of evidence for this effect following a strenuous upper and lower body resistance training session. This study investigated the acute effect of a high-volume compared to a low-volume resistance exercise session on respiratory muscle strength.
Methods: Twenty resistance-trained males (age 25.1±7.4 y) participated in this randomized and cross-over design study. Participants completed two resistance training protocols (high- and low-volume) and a control session (no exercise). Sessions involved 5 sets (high-volume) and 2 sets (low-volume) of 10 repetitions at 65% one-repetition maximum for each exercise (bench press, squat, seated shoulder press, and deadlift) with 90 s recovery between sets. Maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) was assessed pre- and post-session and respiratory gases were measured during the recovery between sets.
Results: Following the high-volume session MIP and MEP decreased by a median of 10.0% (interquartile range, IQR=-15.2 to -2.6%) and 12.1% (IQR=-22.2 to -3.9%), respectively, which was significant compared to the low-volume (P<0.001) and control sessions (P≤0.001). At 20 min post-high-volume session MEP returned to baseline whereas MIP returned to baseline values at 40 min. Greater metabolic stress was associated with the higher-volume session as demonstrated by a lower recovery end-tidal CO<inf>2</inf> partial pressure across the majority of exercises (P≤0.008).
Conclusions: Findings suggest that respiratory muscle strength is impaired following a high-volume resistance exercise session, however it appears to be restored within an hour post-exercise.