Cardiac autonomic recovery after a single session of resistance exercise with and without vascular occlusion

The aim of this study was to investigate the heart rate variability (HRV) after resistance training with and without vascular occlusion. It was hypothesized that low intensity (LI) with vascular occlusion (LIO) would elicit comparable postexercise HRV responses with that of high intensity (HI) without vascular occlusion. Nine subjects undertook 4 experimental sessions of leg press exercise on different days: (a) 1 repetition maximum (1RM) test, (b) 4 sets of 8 repetitions + 1 set until exhaustion at 80% of 1RM without vascular occlusion (HI), (c) 4 sets of 16 repetitions + 1 set until exhaustion at 40% of 1RM with vascular occlusion (LIO), and (d) 4 sets of 16 repetitions + 1 set with the number of repetitions equal to the last set of LIO but at 40% of 1RM without vascular occlusion (LI). Heart rate variability was analyzed 10 minutes, 20 minutes, 30 minutes, 1 hour, 5 hours, and 24 hours after the HI, LIO, and LI sessions. The HI session increased the heart rate (HR) and reduced the root mean square of the successive difference of R-R intervals (RMSSD) and log-transformed high-frequency (lnHF) power during prolonged recovery (HR = 5 hours; RMSSD = 30 minutes; lnHF = 1 hour) at a greater magnitude when compared with LIO and LI. Despite the same intensity of exercise for LIO and LI, the occlusion delayed the recovery of HR and HRV variables. Postexercise blood lactate concentration was moderate to strongly correlated with peak HR (r = 0.87), RMSSD (r = -0.64), and lnHF (r = -0.68). This study has demonstrated that LIO was able to reduce cardiac autonomic stress when compared with HI.