Is There a Relationship Between Limb and Trunk Muscle Hypertrophy After High-Intensity and Low-Intensity-BFR Training

Abstract

It has been reported that high-intensity resistance training or low-intensity resistance training combined with blood flow restriction (BFR) results in significant increases in limb muscle size and improved muscle function. However, it is unknown whether there is a significant correlation between limb and trunk muscle hypertrophy following the two types of resistance training programs. PURPOSE: To investigate the relationship between training-induced limb and trunk muscle hypertrophy in the high-intensity resistance training and low-intensity BFR training groups. METHODS: Twenty untrained young men (24.4±2.4 years; BMI = 21.5±2.4 kg/m2) were divided into two training groups: high-intensity resistance training group (HIT, 75% of one repetition maximum [1RM] and total 30 reps [10 reps × 3 sets], n=10) or low-intensity BFR resistance training group (LI-BFR, 30% of 1RM and total 75 reps [30, 15, 15, 15 reps], n=10). Both training groups performed free weight bench press training, 3 days/week for 6 weeks. During LI-BFR exercise sessions, subjects wore pressure cuffs (3-cm width) on both arms that were inflated to 100-160 mmHg. MRI-measured triceps brachii (TB) and pectoralis major (PM) muscle cross-sectional areas (CSA) and maximal dynamic (1RM) bench press strength were measured before and 3 days after the final training session. RESULTS: Total training volumes (lifting weight x repetition) for all of the sessions were similar between HIT [19063 (SD 3398) kg] and LI-BFR [19994 (SD 3546) kg] groups. The training led to an increase in 1RM bench press strength in both groups. TB and PM muscle CSA increased 8.8% and 15.8% (P <.01), respectively, in the HIT group and 4.9% (P <.05) and 8.3% (P <.01), respectively, in the LI-BFR group. The relative increase in PM muscle CSA was greater (P <.05) than that of TB muscle CSA in the HIT group, but not in the LI-BFR group. There was significant correlation (r = 0.70, P <.05) between increases in PM and TB muscle CSA in the HIT group. However, a significant correlation was not found in the LI-BFR group (r = 0.54, P = 0.11). CONCLUSIONS: Our results suggest that limb and trunk muscle hypertrophy occurs simultaneously during HIT training but not during low-intensity BFR training, possibly due to individual differences in muscle activation of the arm and chest muscles during the training sessions.