RESTING AUTONOMIC FUNCTION IN AEROBICALLY TRAINED AND UNTRAINED POSTMENOPAUSAL WOMEN

The relationship between aging, physical activity, and vagal influence on the heart was assessed by measuring resting heart period variabili ty in postmenopausal women. Participants were 14 aerobically trained w omen (mean age 55 +/- 1.0 years) and 20 untrained women (mean age 59 /- 1.1 years). Participants lay for 25 min while heart period variabil ity was assessed during spontaneous and paced breathing (7.5 breaths . min(-1)). Heart period variability was assessed through time series a nalysis (HPVts) of the interbeat interval. Results indicated that the trained women had significantly (p <.05) lower supine resting heart ra te than the untrained group. HPVts at high frequencies during spontane ous and paced breathing was greater for trained compared to untrained participants. Similarly, HPVts at medium frequencies during spontaneou s and paced breathing was greater for trained compared to untrained pa rticipants. Also, rate pressure product of the trained group was signi ficantly lower than for the untrained. These results extend prior rese arch by showing that aerobically trained postmenopausal women possesse d significantly elevated resting vagal influence on the heart compared to their untrained counterparts.