Abstract
Objectives:
BFR is a training method that partially restricts arterial inflow and fully restricts venous outflow to selected muscle groups during exercise. A decrease in oxygen levels creates anaerobic fatigue that stimulates protein synthesis for muscular repair and strengthening. Low-load BFR training was recently demonstrated in a randomized controlled trial to increase lower extremity muscle strength (proximal, distal, and contralateral) based on isokinetic testing, dynamometer measurements, and single-leg heel raises. BFR is a training method that partially restricts arterial inflow and fully restricts venous outflow to selected muscle groups during exercise. A decrease in oxygen levels creates anaerobic fatigue that stimulates protein synthesis for muscular repair and strengthening. The primary objective of this study is to determine the effects of low-load blood flow restriction (BFR) training compared to a conventional strengthening program using dynamic force plate and isometric force frame analyses in healthy subjects.
Methods:
This was a randomized controlled trial of healthy participants completing a standardized 16-week course of BFR training. Patients were randomized to BFR training on 1 extremity or to a control group. Low-load training, with or without BFR, was done 3x per week. For subjects randomized to BFR training, the tourniquet was placed on the non-dominant limb. Data was collected at baseline, 4 weeks, 6 weeks, 8 weeks, 12 weeks, and 16 weeks. At each data collection time point, quantitative strength measurement using ForceFrames and ForceDecks were obtained.
Results:
There was no difference in change in average force between the BFR group and the control group from baseline testing to final 16 week testing. Additionally, there was no difference between BFR limb and non-BFR limb within the experimental group from baseline testing to final 16 week testing.
Conclusions:
In conclusion, low load BFR testing did not improve effects of strength training in terms of force testing when compared to conventional training in healthy subjects. The use of healthy subjects rather than subjects in pathologic and post-surgical states may explain why low-load BFR did not confer additional benefit. A low-load BFR regimen may not provide enough stimulus to produce muscle hypertrophy compared to a higher load regimen when applied to healthy subjects. Ultimately, further study into the optimal duration of BFR training is required.
