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THE INFLUENCE OF PRE-EXERCISE BLOOD FLOW RESTRICTION ON MUSCLE SIZE AND STRENGTH ADAPTATIONS

Abstract

Enrique N. Moreno, William B. Hammert, Cole C. Martin, Samuel L. Buckner. University of South Florida, Tampa, FL.

BACKGROUND: Blood flow restriction (BFR) has never been examined in combination with a low repetition, high load training protocol. The purpose of the present study is to examine if BFR prior to a low repetition high load training protocol could enhance adaptations in muscle size, strength, or local muscular endurance and compare these adaptations to traditional high load resistance training. METHODS: 40 untrained individuals completed 8-weeks of unilateral elbow flexion resistance training on 2 days/week. Participants had each arm randomized to 1 of 3 unilateral training conditions: 1) traditional high load resistance training (TRAD); 2) low repetition high load training with pre-exercise BFR (preBFR); 3) low repetition high load resistance training (LRTRAD). The TRAD condition performed 4 sets to muscular failure at 70% 1RM with 60s rest periods. The preBFR condition performed 4 sets of 3 repetitions at 70% 1RM with 60s rest periods and BFR applied 3min prior to and during exercise. The LRTRAD condition performed 4 sets of 3 repetitions at 70% 1RM with 60s rest periods. Measures of muscle thickness (MT), 1RM strength, and endurance were taken prior to and following the training period. Data are presented as means (95%CI). RESULTS: For the 50% site, the change in MT was greater in the TRAD condition [0.21(0.13-0.28)] compared to LRTRAD [0.06 (-0.001-0.12)cm, p = 0.003] but not different compared to preBFR [0.11(0.03-0.20)cm, p = 0.09]. For the 60% site, the change in MT was greater in the TRAD condition [0.23(0.16-0.30)] compared to preBFR [0.09(0.03-0.16)cm, p = 0.004] and LRTRAD [0.08 (0.004-0.15)cm, p = 0.003], with no difference when comparing preBFR to LRTRAD (p = 0.27). For the 70% site, the change in MT was greater in the TRAD condition [0.31(0.24-0.37)cm] compared preBFR [0.10(0.03-0.17)cm, p < 0.001] and LRTRAD [0.06 (-0.002-0.13)cm, p < 0.001], with no difference when comparing preBFR to LRTRAD (p = 0.38). For 1RM strength, there were no differences (p > 0.05) in change scores between TRAD [2.15(1.6-2.6)kg], preBFR [2.19(1.8-2.5)kg], and LRTRAD [1.9(1.4-2.3)kg]. For endurance, there were no differences (p > 0.05) in change scores between TRAD [7(5-9)reps], preBFR [7(5-9)reps] and LRTRAD [6(4-7)reps].CONCLUSIONS: BFR does not enhance the hypertrophic effects of LRTRAD training. 1RM and endurance adaptations were not different despite differences in exercise volume and proximity to failure.

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