Cardiovascular Responses To Resistance Exercise Training With Upper Limb Blood Flow Restriction

Objective:Acute blood flow restricted (BFR) resistance exercise does not appear to negatively affect the local vasculature and cardiovascular responses, however, the effects of long-term cardiovascular of BFR resistance have remained unknown. This investigation measured local vascular and cardiovascular response of 30% 1RM flexion of elbow resistance exercise training combined with or without BFR after 8 weeks.Methods:Twenty-four participants (men 20.44±1.24 yr) were randomly assigned to three groups:resistance exercise without occlusion cuff (CON), resistance exercise with occlusion cuff pressure set at 65% resting systolic blood pressure (BFR-L) and resistance exercise with occlusion cuff pressure set at 130% resting systolic blood pressure (BFR-H). Each subject underwent five bouts of 1-minute 30% 1RM flexor elbow resistance exercise with 1-min interval either with or without tourniquet cuffs inflated on left arms of 5 times a week for 8 weeks. Cardiovascular and brachial artery vascular responses were evaluated before, immediately after, and for 8 weeks rest and post-exercise. Aortic root dimension (AOD), left atrial diameter (LAD), left ventricular diastolic diameter (LVDd), left ventricular systolic diameter (LVDs), stroke volume (SV), left ventricular posterior wall thickness (LVPW), left ventricular fractional shortening (FS), left ventricular ejection fraction (EF), brachial artery diameter, velocity, stroke volume (SV) and resistance index (RI) were measured using Doppler ultrasound.Results:1. Cardiovascular index did not change significantly (P>0.05) at rest before and after 8 weeks among the three groups except LAD decreased significantly (P<0.05) in CON group. However, brachial artery diameter of CON group increased significantly (P<0.05) and systolic blood pressure decreased significantly (P<0.05).2. Some index changed significantly in the last exercise after 8 weeks than the first exercise before 8 weeks. LAD in the CON group decreased (P<0.05). EF and FS in the BFR-H group increased (P<0.05), and the BFR-H group increased more obviously than the CON group (P<0.05). Brachial artery systolic peak velocity of BFR-H had increased significantly (P<0.05) and RI of BFR-H was the highest (P<0.05). There was no change of SBP. DBP was lower in the CON group (P?0.05).Conclusion:1. Long-term low intensity resistance training, which makes the systolic blood pressure decrease, and the diastolic blood pressure decreased after exercise immediately. It indicates that long-term low intensity resistance training has a positive effect on the decrease of blood pressure.2. Left atrial diameter decreased in long-term low intensity resistance training, suggesting that it can improve the left ventricular diastolic function, and has a protective effect on the heart function.3. Long-term BFR resistance training will increase FS and EF, which suggests that the improvement of myocardial contractile abnormalities.4. Long-term low intensity BFR resistance training will not cause damage and adverse effects on the heart vessels and peripheral vessels, which indicates that the training method is safe in the long term.