A short duration of physical training benefits cardiovascular performance.

The present study explored the possibility of short duration of supervised physical training on cardiovascular performance and attempted to look into the changes in the autonomic tone as assessed by heart rate variability (HRV), if any. The study was conducted on 25 healthy adult male subjects (mean age: 32.08+/-8.32 years) who underwent 15 days of moderate physical training on bicycle ergometer. Heart rate and blood pressure response to exercise and during recovery was monitored as well as autonomic activity (tone) was assessed by heart rate variability in resting condition and all the parameters were compared before and after physical training of 15 days. Heart rate response to graded exercise on bicycle ergometer showed a significant decrease at 2nd minute, 3rd minute, 5th minute and 6th minute during exercise after physical training, and systolic blood pressure response also showed a significant decrease at 4th minute, 5th minute and 6th minute during exercise after physical training. Physical training resulted in quick recovery during the 1st minute after cessation of exercise (percentage drop 21.03+/-7.93 vs. 23.50+/-6.97, P<0.05). Although there was no significant change in the HRV parameters, there was a trend reflecting an increase in parasympathetic tone and a decrease in sympathetic tone after physical training. We conclude from the present study that even a short duration of physical training results in favorable cardiovascular performance and it may be ascribed to autonomic modulation.

Short-term physical training alters cardiovascular autonomic response amplitude and latencies.

This study reports the results of 15 days of exercise training in 25 adult males on cardiovascular autonomic response amplitude and latencies. A standard battery of autonomic function tests including both activity (tone) and reactivity was used. Parasympathetic activity as evaluated from Heart rate variability (HRV) showed no statistically significant change in both time and frequency domain measures, similarly Sympathetic activity as measured by QT/QS2 ratio showed no statistically significant change, but there was a trend of a decrease in sympathetic activity and an increase in parasympathetic activity. There were no changes in the parameters measuring parasympathetic reactivity. Sympathetic reactivity as evaluated by diastolic blood pressure responses to hand grip test (HGT) and cold pressor test (CPT) showed significant decreases. Time domain assessment of autonomic responses was done by measuring tachycardia and bradycardia latencies during Valsalva maneuver (VM) and lying to standing test (LST). Physical training resulted in a decrease in tachycardia latency during LST and a decrease in bradycardia latency during VM. We conclude from the present study that 15 days of physical training is not enough to alter autonomic activity and PNS reactivity but can result in changes in SNS reactivity and latency parameters. We hypothesize that a decrease in bradycardia latency during VM signifies a faster recovery of heart rate during VM and a decrease in tachycardia latency during LST denotes a delayed activation of the system both of which are favorable cardiovascular responses.