Abstract des Autors

We have previously reported that during pregnancy the heart rate, at a given metabolic rate, is greater during aerobic dance (AD) than treadmill walking (TW). The present study aimed at determining whether the heart rate/oxygen uptake differences were related to catecholamine levels. Eight women, pregnant for 21-28 weeks, completed a 40 min low-impact aerobic dance. Maternal heart rates and oxygen uptakes (VO2) were recorded every 10 min. Blood samples were obtained at rest, 20, 30 and 40 min of exercise and analysed for adrenaline and noradrenaline using HPLC. The maternal heart rates were similar during both trials, with highest values recorded in the 30th min of exercise (AD: 142+/-4; TW: 152+/-6 beats/min). VO2 values during the TW were significantly higher than during AD, the overall difference being equal to 0.28+/-0.08 l/min; P<0.01). Resting catecholamine levels were similar before both trials. Both AD and TW elevated adrenaline (A) and noradrenaline (NA) two- to threefold (P<0.05). However, there was no significant between-trial difference. The relationship between heart rate and NA or A was strong for both modes of exercise (r=0.67 to 0.96; P<0.05). The relationship between metabolic rate and NA was not significant during aerobic dance, but strong during walking (r=0.98; P<0.01). In summary, the elevated heart rate/VO2 relationship during AD appears to be related to a greater than expected catecholamine response. Verf.-Referat