Effect of slow and fast pranayams on reaction time and cardiorespiratory variables.

We planned to undertake a comparative study of the effect of short term (three weeks) training in savitri (slow breathing) and bhastrika (fast breathing) pranayams on respiratory pressures and endurance, reaction time, blood pressure, heart rate, rate-pressure product and double product. Thirty student volunteers were divided into two groups of fifteen each. Group I was given training in savitri pranayam that involves slow, rhythmic, and deep breathing. Group II was given training in bhastrika pranayam, which is bellows-type rapid and deep breathing. Parameters were measured before and after three week training period. Savitri pranayam produced a significant increase in respiratory pressures and respiratory endurance. In both the groups, there was an appreciable but statistically insignificant shortening of reaction time. Heart rate, rate-pressure product and double product decreased in savitri pranayam group but increased significantly in bhastrika group. It is concluded that different types of pranayams produce different physiological responses in normal young volunteers.

Correlation between short-term heart rate variability indices and heart rate, blood pressure indices, pressor reactivity to isometric handgrip in healthy young male subjects.

The purpose of the present study was to determine whether readily measured blood pressure (BP) indices and, responses to autonomic reflex tests could be used as surrogates of short-term heart rate variability (HRV), which is an established marker of autonomic regulation of SA node. Therefore, we examined the correlation between short-term HRV and heart rate (HR), BP indices viz. systolic pressure, diastolic pressure, pulse pressure (PP), and rate-pressure product (RPP), during supine rest and head-up tilt in 17 young healthy normotensive subjects, aged 19.8 +/- 1 yr (mean +/- SD). Three classic autonomic indices viz. Valsalva ratio, HR response to deep breathing and pressor response to isometric handgrip were also determined. We noted two interesting and statistically significant (P < 0.05 in both cases) correlations viz. i) a positive correlation (r = 0.6) between change in RPP during tilt and change in low frequency (LF) RR spectral power expressed in normalized units (LF nu) during tilt, and ii) a negative correlation (r = -0.6) between change in PP during isometric handgrip and LF nu during tilt. The possible physiologic significance of these and other correlations is discussed in this paper. In conclusion, the presence of a statistically significant correlation between RPP, PP and spectral measures of short-term HRV supports a simplistic approach to autonomic assessment, in that, easily measurable BP indices could be used as surrogates of HRV when it is not feasible to determine HRV indices directly. However, the same have to be tested in healthy subjects belonging to various age groups and in patients with conditions known to be associated with autonomic dysregulation.

Modulation of stress induced by isometric handgrip test in hypertensive patients following yogic relaxation training.

13 essential hypertensive patients aged 41 to 60 years were given yoga training for 60 min daily, Monday through Saturday, for a total duration of 4 weeks. Blood pressure and heart rate (HR) were measured with non-invasive semi-automatic blood pressure monitor. Measurements were recorded before the training and at weekly intervals during the 4 week training period. Results of our study show a significant (P<0.001) reduction in resting HR and rate-pressure-product (RPP) after 2 weeks of yoga training. Systolic pressure (SP), diastolic pressure (DP) (P<0.001) and mean pressure (MP) (P<0.05) showed a significant reduction at 3 weeks of training period. After 4 weeks of training, there was further fall in SP, DP, pulse pressure (PP) (P<0.05), MP (P<0.001), HR and RPP. Isometric handgrip test before yoga training produced a significant rise in SP and MP and insignificant rise in DP, HR and RPP. After yoga training, there was a significant rise in all these parameters. Our results show that yoga training optimises the sympathetic response to stressful stimuli like isometric handgrip test and restores the autonomic regulatory reflex mechanisms in hypertensive patients.