The Influence Of Cuff Width On Regional Muscle Growth

Abstract

A variety of protocols with different cuff widths have been used with blood flow restriction training (BFR). However, little is known about the influence of cuff width on muscle adaptations. PURPOSE: To determine if the cuff width differentially affects regional muscle growth and strength with BFR. METHODS: Eleven active males (mean ± SD: age 25.2 ± 6.1 years, height 1.70 ± 0.1 m, body mass 74.9 ± 9.5 kg) volunteered for the study. Subjects had their legs randomly divided into two conditions: low-load blood flow restriction exercise with a narrow cuff (NBFR - 7 cm) and low-load blood flow restriction exercise with a wide cuff (WBFR - 17.5 cm). Both cuffs were placed on the proximal portion of the thigh and inflated to 80% of the resting arterial occlusion pressure for each cuff. All subjects performed unilateral knee extension 2x/week, 3 sets to volitional failure, 60s rest interval, at 20% 1RM, for 12 weeks. The cuffs remained inflated throughout each exercise session and deflated at the end of exercise. Knee extension strength (1RM), cross-sectional area (CSA) of different quadriceps regions (proximal, middle and distal), exercise volume and femoral blood flow were assessed for both cuff sizes. A repeated measures ANOVA was performed for each dependent variable, and statistical significance was set at p≤ 0.05. RESULTS: Knee extension 1RM increased in both conditions (NBFR=6% vs WBFR=9.5%, p<0.001). The CSA of the proximal region did not change following either condition (p>0.05), however, more than half of subjects from WBFR had their CSA reduced. There were increases in CSA of the middle and distal regions in the NBFR (6.2% and 5.6%) and WBFR (3% and 5.4%), respectively. The NBFR condition completed greater exercise volume compared to the WBFR (1026 kg vs 750 kg). The femoral blood flow was similarly reduced in both conditions (NBFR = 58.1% vs WBFR = 70%). CONCLUSIONS: There were no changes in skeletal muscle CSA of the proximal region with either the wide or narrow cuff. Further, and although not significant, individual response data suggested that the proximal and middle regions may have also been attenuated and/or reduced by the wide cuff in some participants. These preliminary findings appear to suggest that cuff width may exert differential responses despite being inflated to the same relative pressure.