Type 1 Muscle Fiber Hypertrophy after Blood Flow–restricted Training in Powerlifters

Purpose To investigate the effects of blood flow–restricted resistance exercise (BFRRE) on myofiber areas (MFA), number of myonuclei and satellite cells (SC), muscle size and strength in powerlifters. Methods Seventeen national level powerlifters (25 ± 6 yr [mean ± SD], 15 men) were randomly assigned to either a BFRRE group (n = 9) performing two blocks (weeks 1 and 3) of five BFRRE front squat sessions within a 6.5-wk training period, or a conventional training group (Con; n = 8) performing front squats at 60%–85% of one-repetition maximum (1RM). The BFRRE consisted of four sets (first and last set to voluntary failure) at ~30% of 1RM. Muscle biopsies were obtained from m. vastus lateralis (VL) and analyzed for MFA, myonuclei, SC and capillaries. Cross-sectional areas (CSA) of VL and m. rectus femoris were measured by ultrasonography. Strength was evaluated by maximal voluntary isokinetic torque (MVIT) in knee extension and 1RM in front squat. Results BFRRE induced selective increases in type I MFA (BFRRE: 12% vs Con: 0%, P

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