Resistance Exercise And Caffeine On Performance, Hemodynamics, And Pulse Wave Reflection Measure In Resistance-trained Women

Abstract

PURPOSE: To investigate the effects of caffeine ingestion in conjunction with acute resistance exercise in resistance-trained women on resistance exercise performance, cardiovascular hemodynamics, and pulse wave reflection. METHODS: Eleven resistance-trained women (Mean Age±SD=24±4yrs) ingested either a placebo (PL) or caffeine (4mg/kg), separated by 72hrs, in a double-blind, crossover design. Heart rate (HR), mean arterial pressure (MAP), and pulse wave reflection measures were assessed at rest (Rest1), 45 minutes post-consumption (Rest2), immediately post-exercise (Post1), and 10 minutes post-exercise (Post2). Participants performed two sets of 10 repetitions at 75% 1-repetition maximum (1RM), and one set with repetitions to failure at 70% 1RM on the squat and bench press. Paired t-tests were used to analyze total volume the across conditions. Hemodynamics and pulse wave reflection were analyzed with repeated measures ANOVAs to determine the effects of condition (PL and caffeine) across time (Rest1, Rest2, Post1, Post2). RESULTS: There was no statistical differences for total volume on the squat (p=0.9) or bench press (p=0.4). There were no significant two-way interactions for any variable. There was no main effect of time for MAP (p=0.09). There were significant main effects of time for HR (p=0.0001), augmentation index (AIx, p=0.001), and for AIx normalized to 75bpm ([email protected], p=0.0001). HR increased significantly at Rec1 and Rec2 compared to Rest1 and Rest 2 (PL: Rest1: 61±9bpm, Rest2: 59±10bpm: Rec1: 87±16bpm, Rec2: 83±14bpm; Caffeine: Rest1: 58±7bpm, Rest2: 58±10bpm, Rec1: 86±18bpm, Rec2: 82±15bpm). This was also seen for AIx (PL: Rest1: 6.8±8.5%, Rest2: 2.3±11.6%, Rec1: 26.5±9%, Rec2: 19.1±9.1%; Caffeine: Rest1: 9.6±10.2%, Rest2: 7.2±10%, Rec1: 27.8±16.2%, Rec2: 22.2±12.2%) and [email protected] (PL: Rest1: 1.7±9.1%, Rest2: -5.7±14%, Rec1: 32.3±10.8%, Rec2: 24.2±12%; Caffeine: Rest1: 1.2±11.5%, Rest2: -0.8±11.2%, Rec1: 28.9±19.8%, Rec2: 23.6±17%). CONCLUSIONS: These data suggest that the ingestion of 4mg/kg of caffeine provides no ergogenic effect in resistance-trained women. Additionally, caffeine consumption, in addition to performing resistance exercise, does not demonstrate alter hemodynamics or pulse wave reflection in resistance-trained women.