Acute Physiological Responses To Low-intensity Cycling With Different Levels Of Blood Flow Restriction

Purpose:Blood flow restriction training has attracted widespread attention because of its low intensity,which produces effects similar to high-intensity training.External pressure is a key factor in blood flow restriction training.Previous studies have used a limited range of occlusion pressures to compare the acute physiological responses mainly during small-muscle exercise.The aim of this study was to compare:i)the physiological responses of low-load exercise[(low intensity exercise(LI)]with different levels of blood flow restriction,and ii)LI with blood flow restriction on the bike with high intensity(HI)exercise without blood flow restriction.Methods:Twenty-one healthy and moderately-trained males volunteered to perform one maximal graded exercise test on the bike and seven 5-min constant intensity exercise bouts.Six bouts were constant intensity training at LI[40%peak power(Ppeak)],one without blood flow restriction and five with different levels of blood flow restriction(40%,50%,60%,70%,80%of arterial occlusion pressure,LI-BFR40/50/60/70/80).Another bout was HI without blood flow restriction(70%Ppeak).Oxygen uptake(VO2),heart rate(HR),rate of perceived exertion(RPE),and tissue oxygen saturation(TSI)were recorded during exercise,and blood lactate(BLa)was recorded before and after exercise.Results:Regardless of pressure,HR,BLa and RPE during LI-BFR were higher compared to LI(p<0.05,Effect size(ES):moderate to very large),and TSI reduction was greater in LI-BFR(LI-BFR40/50/60/70/80:-10.6±3.1%,-10.2±4.0%,-10.1±5.1%,-10.0±4.2%,-11.3±4.9%,respectively)than LI(-6.0±4.2%,p<0.05,ES:moderate to large).The responses of VO2,HR,BLa,RPE and TSI induced by the different levels of blood flow restriction in LI-BFR were similar.Regardless of pressure,the responses of VO2,HR,BLa and RPE induced by LI-BFR was lower than HI(p<0.05),except for TSI.TSI change was similar between LI-BFR40/50/60/70/80 and HI(LI-BFR40/50/60/70/80 range:-10.0±4.2%to-11.3±4.9%,HI:-11.5±4.5%).Regardless of the pressure,?O2Hb in LI-BFR were similar,and there was no significant difference between LI and HI.?HHb and ?tHb caused by all LI-BFR were similar,and these two indicators were not significantly different from HI,but the two indicators of LI-BFR and HI were significantly greater than LI(p<0.05).Conclusion:1)1)Regardless of the level of blood flow restriction,blood flow restriction combined with low-intensity aerobic training could induce greater acute physiological responses(except oxygen uptake)than low-intensity aerobic training without blood flow restriction,and blood flow restriction can be used as a method to help increase aerobic training stimulation;2)Although Low-intensity aerobic training with blood flow restriction induced less oxygen uptake,heart rate,blood lactate and rating of perceived exertion than high-intensity aerobic exercise,the application of blood flow restriction could produce similar local muscle hypoxia;3)The acute physiological responses induced by low-intensity aerobic training at different levels of blood flow restriction were similar,when performing low-intensity aerobic exercise with blood flow restriction,higher pressure couldn't improve the acute physiological responses.