Purpose: Applying blood flow restriction during low-load resistance training has been shown to augment muscle hypertrophy which has been attributed to metabolic accumulation. It remains unknown, however, whether metabolites can augment muscle growth when maintained post-exercise.
Methods: Thirteen untrained individuals (6 males and 7 females) performed 24 training sessions. The control arm performed one set of elbow flexion (70 % 1RM) to volitional fatigue, while the experimental arm performed the same protocol immediately followed by 3 min of blood flow restriction (70 % arterial occlusion). Muscle growth (ultrasound) was measured at 50, 60, and 70 % of the distance between the lateral epicondyle and acromion process.
Results: Both conditions completed the same exercise volume [3678 (95 % CI 2962, 4393) vs. 3638 kg (95 % CI 2854, 4423)]. There was a condition by time interaction (p = 0.031) demonstrating an attenuation of muscle growth at the 60 % site in the experimental [pre 3.1 (95 % CI 2.8, 3.5), post 3.1 (95 % CI 2.7, 3.5) cm] vs. control [pre 3.1 (95 % CI 2.6, 3.6), post 3.3 (95 % CI 2.8, 3.7) cm] condition. Muscle growth at the 50 % and 70 % sites was similar at the group level, although there were attenuations at the individual level. Exploratory analyses of pre-post mean (95 % CI) changes in muscle thickness suggested that this attenuation in the experimental condition occurred only in females [50 % site 0.0 (-0.2, 0.0) cm; 60 % site -0.1 (-0.3, 0.0) cm; 70 % site 0.0 (-0.1, 0.1) cm].
Conclusions: The application of blood flow restriction post high-load training did not augment muscle growth for either sex, and appeared to attenuate muscle growth among females.
Keywords: Elbow flexion; KAATSU; Occlusion training; Oxidative stress; Resistance exercise; Strength.