Blood Flow Restricted Resistance Exercise Increases Hypertrophy in National Level Powerlifters

Abstract

Blood flow restricted resistance exercise (BFRE) has been shown to induce muscle mass gains in untrained subjects, elderly, patients recovering from knee surgery, and athletes. However, the effects of BFRE in highly trained strength athletes are largely unknown. PURPOSE: The aim of the present study was to investigate the effects of including two blocks of frequent BFRE during six weeks of periodized strength training on muscle growth and strength in powerlifters. METHODS: 17 national level powerlifters (25±6 years (mean±SD); 15 men, and 2 women) volunteered for the study. The powerlifters were randomized in to two groups: a BFRE group (BFR; n=9) that performed two blocks (week 1 and week 3) of five BFRE front squat sessions during the 6-week strength training period, and a control group (CON; n=8) performing normal front squats (∼70% of 1RM). The BFRE protocol consisted of four sets to voluntary failure (30 s rest between sets) at 25-30% of one repetition maximum (1RM). Elastic knee bands were wrapped around the upper thighs to apply a pressure of ∼120 mmHg (verified with an underlying pressure cuff in the first session). Muscle growth was assessed as changes in thickness and cross sectional area (CSA) of m. vastus lateralis and m. rectus femoris, as well as thickness of m. vastus medialis, using ultrasound imaging. Strength was measured as 1RM in front squat and isokinetic peak torque (60 degrees per second) in leg extension. RESULTS: The BFR group showed a significantly larger increase in thickness of m. vastus lateralis (mean±SD, BFR: 4.7±3.3% vs. CON: -0.8±5.0%; p=0.02), m. rectus femoris (BFR: 5.0±2.8% vs. CON: -1.3±5.9%; p=0.01) and m. vastus medialis (BFR: 1.9±2.2% vs. CON: -2.7±4.9%; p=0.02), compared to CON group. Similarly, CSA of m. vastus lateralis increased more in the BFR group (7.7±6.5% vs. 0.5±4.3%, p=0.04). In CSA changes of m. rectus femoris, a tendency towards higher increases was observed in favor of the BFR group (BFR: 6.8±7.5% vs. CON: 1.4±3.9%; p=0.09). Changes in 1RM in front squat, as well as for isokinetic peak torque in leg extension, did not differ significantly between groups. CONCLUSION: The inclusion of ten BFR sessions produced significantly larger gains in muscle thickness and CSA than normal training during 6 weeks of strength training. However, no differences were observed in strength.