Blood flow restriction does not augment low force contractions taken to or near task failure

Abstract

Low‐load exercise performed to or near task failure appears to result in similar skeletal muscle adaptations as low‐load exercise with the addition of blood flow restriction (BFR). However, there may be a point where the training load becomes too low to stimulate an anabolic response without BFR. This study examined skeletal muscle adaptions to very low‐load resistance exercise with and without BFR. Changes in muscle thickness (MTH), strength, and endurance were examined following 8‐weeks of training with a traditional high‐load [70% 1RM,(7000)], low‐load [15% 1RM,(1500)], low‐load with moderate BFR [15%1RM + 40%BFR(1540)], or low‐load with greater BFR [15% 1RM + 80%BFR(1580)]. 1RM strength changes were greater in the 7000 condition [2.09 (95% CI = 1.35–2.83) kg] compared to all low‐load conditions. For isometric and isokinetic strength, there were no changes. For endurance, there was a main effect for time [mean pre to post change = 7.9 (4.3–11.6) repetitions]. At the 50% site, the mean change in MTH in the 7000 condition [0.16 (0.10–0.22) cm] was greater than all low‐load conditions. For the 60% site, the mean change in MTH [0.15 (0.08–0.22)] was greater than all low‐load conditions. For the 70% site there was a main effect for time [mean pre to post change = 0.09 (0.05–0.14 cm]. All groups increased muscle size; however, this response was less in all very low training conditions compared to high‐load training. 1RM strength increased in the 7000 condition only, with no other changes in strength observed.