This study aimed to investigate the effects of blood flow restriction (BFR) combined with electrical muscle stimulation (EMS) on skeletal muscle mass and strength during a period of limb disuse.
Thirty healthy participants (22 ± 3 yr; 23 ± 3 kg·m−2) were randomly assigned to control (CON; n = 10), BFR alone (BFR; n = 10), or BFR combined with EMS (BFR + EMS; n = 10). All participants completed unloading of a single leg for 14 d, with no treatment (CON), or while treated with either BFR or BFR + EMS (twice daily, 5 d·wk−1). BFR treatment involved arterial three cycles of 5-min occlusion using suprasystolic pressure, each separated by 5 min of reperfusion. EMS (6 s on, 15 s off; 200 μs; 60 Hz; 15% maximal voluntary contraction [MVC]) was applied continuously throughout the three BFR cycles. Quadriceps muscle mass (whole-thigh lean mass via dual-energy x-ray absorptiometry and vastus lateralis [VL] muscle thickness via ultrasound) and strength (via knee extension MVC) were assessed before and after the 14-d unloading period.
After limb unloading, whole-thigh lean mass decreased in the control group (−4% ± 1%, P < 0.001) and BFR group (−3% ± 2%, P = 0.001), but not in the BFR + EMS group (−0.3% ± 3%, P = 0.8). VL muscle thickness decreased in the control group (−4% ± 4%, P = 0.005) and was trending toward a decrease in the BFR group (−8% ± 11%, P = 0.07) and increase in the BFR + EMS group (+5% ± 10%, P = 0.07). Knee extension MVC decreased over time (P < 0.005) in the control group (−18% ± 15%), BFR group (−10% ± 13%), and BFR + EMS group (−18% ± 15%), with no difference between groups (P > 0.5).
Unlike BFR performed in isolation, BFR + EMS represents an effective interventional strategy to attenuate the loss of muscle mass during limb disuse, but it does not demonstrate preservation of strength.