The influence of exercise load with and without different levels of blood flow restriction on acute changes in muscle thickness and lactate

The aim of this study was to compare exercise with and without different degrees of blood flow restriction (BFR) on acute changes in muscle thickness (MTH) and whole blood lactate (WBL). Forty participants were assigned to Experiment 1, 2 or 3. Each experiment completed protocols differing by pressure, load and/or volume. MTH and WBL were measured pre and postexercise. The acute changes in MTH appear be maximized at 30% one repetition maximum (1RM) with BFR, although the difference between 20% 1RM and 30% 1RM at the lateral site was small (0.1 versus 0.2 cm, P = 0.09). Increasing the exercise load from 20% to 30% 1RM with BFR produces clear changes in WBL (3.7 versus 5.5 mmol l(-1), P<0.001). The acute changes in MTH and WBL for 30% 1RM in combination with BFR were similar to that observed with 70% 1RM and 20 and 30% to failure, albeit at a lower exercise volume. These findings may have implications for designing future studies as it suggest that exercise load (to a point) may have a greater influence on acute changes in MTH and metabolic accumulation than the applied relative pressure.