EFFECTS OF AEROBIC EXERCISE TRAINING AND YOGA ON THE BAROREFLEX IN HEALTHY ELDERLY PERSONS

It is unclear whether the age-associated reduction in baroreflex sensi tivity is modifiable by exercise training. The effects of aerobic exer cise training and yoga, a non-aerobic control intervention, on the bar oreflex of elderly persons was determined. Baroreflex sensitivity was quantified by the alpha-index, at high frequency (HF; 0.15-0.35 Hz, re flecting parasympathetic activity) and mid-frequency (MF; 0.05-0.15 Hz , reflecting sympathetic activity as well), derived from spectral and cross-spectral analysis of spontaneous fluctuations in heart rate and blood pressure. Twenty-six (10 women) sedentary, healthy, normotensive elderly (mean 68 years, range 62-81 years) subjects were studied. Fou rteen (4 women) of the sedentary elderly subjects completed 6 weeks of aerobic training, while the other 12 (6 women) subjects completed 6 w eeks of yoga. Heart rate decreased following yoga (69 +/- 8 vs. 61 +/- 7 min(-1), P < 0.05) but not aerobic training (66 +/- 8 vs. 63 +/- 9 min(-1), P = 0.29). VO2 max increased by 11% following yoga (P < 0.01) and by 24% following aerobic training (P < 0.01). No significant chan ge in alpha(MF) (6.5 +/- 3.5 vs. 6.2 +/- 3.0 ms mmHg(-1), P = 0.69) or alpha(HF) (6.5 +/- 4.7 vs. 8.9 +/- 3.5 ms mmHg(-1), P = 0.65) occurre d after aerobic training. Following yoga, alpha(HF) (8.0 +/- 3.6 vs. 1 1.5 +/- 5.2 ms mmHg(-1), P < 0.01) but not alpha(MF) (6.5 +/- 3.0 vs. 7.6 +/- 2.8 ms mmHg(-1), P = 0.29) increased. Short-duration aerobic t raining does not modify the alpha-index at alpha(MF) or alpha(HF) in h ealthy normotensive elderly subjects. alpha(HF) but not alpha(MF) incr eased following yoga, suggesting that these parameters are measuring d istinct aspects of the baroreflex that are separetly modifable.