Combining Blood Flow Restriction Training With Heat To Maximize Hypertrophy And Strength In Rugby Players

Abstract

PURPOSE: We assessed whether blood flow restriction (BFR) training with the addition of heat stress (BFRH) improves hypertrophy, muscle strength and sport-specific physical performance in rugby union players, compared to BFR training alone. METHODS: Nineteen elite U23 rugby union male players were randomly assigned to BFRH (n = 7), BFR (n = 6) or traditional high-load resistance training (CON, n = 6) groups. BFRH and BFR groups trained twice weekly for 3 weeks using BFR exercise (half squat, 4 sets of 30-15-15-15 repetitions at 30% 1 maximum repetition (1RM) with 30 s of passive recovery; 50% of resting arterial occlusion pressure) in hot (37°C) and cool (22°C) conditions, respectively. Before and after the intervention, thigh circumference, half squat 1RM, squat jump force-velocity profile, and performance in vertical jump, sprint and repeated-sprint ability (RSA) tasks were measured. Muscle damage marker (creatine kinase) was measured before and after (0.1-24 h) the first and last training session. RESULTS: Thigh circumference significantly increased (P<0.001) from pre- to post-training in both BFRH (+6%, P<0.001) and BFR (+4%, P<0.05). Significant time × group interaction revealed improvement in half squat 1RM (+12% and +19%, P<0.01) and maximal force component (+102% and +116%, P<0.001) of the force-velocity profile for BFRH and BFR. Vertical jump performance did not change. 10-m sprint (-5% and -3%, P<0.001) and RSA best and total times (both -2%, both P≤0.001) improved similarly in BFRH and BFR. Although not significant, muscle damage was lowered after the last session in BFRH only. No pre- to post-training changes occurred in CON. CONCLUSIONS: Combining BFR training with heat stress can potentially induce hypertrophy and improve rugby union-specific physical performance while also inducing lower muscle damage than BFR training alone. Such gains could be of benefit during competitive period or rehabilitative setting.