Abstract des Autors

Previous work with pregnant ewes has shown that acute bouts of exercise may cause changes in plasma hormone concentrations, blood flow distribution, and maternal and fetal temperatures. However, most of these studies do not quantify the chosen exercise intensity through measurement of oxygen consumption (VO2). Therefore the purpose of this study was to statistically model in VO2 response of pregnant sheep to treadmill (TM) exercise to determine the exercise intensities (% maximal VO2) of previous studies. Ewes with either single (n = 9) or twin (n = 5) fetuses were studied from100 to 130 days of gestation. After 1-2 wk of TM habituation, maximal VO2 (VO2max) was etemrined by measurements of VO2 (open flow-through method) and blood lactate concentration. VO2 was measured as a function of TM incline (0, 3, 5, and 7 degrees) and speed (0.8-3.4 m/s). VO2max averaged 57 +/- 7 (SD) ml/min/kg, and peak lactate concentration during exercise averaged 22 +/- 2 mmol/l. The relationship between VO2 (ml/min/kg) and incline (INC) and speed (SP) (VO2 = 0.70(INC) + 13.95(SP) + 1.07(INC x SP) - 1.18) was linear (r**2 = 0.94). Our findings suggest that most previous research used exercise intensities <60% VO2max and indicate the need for further research that examines the effect of exercise during pregnancy at levels >60% VO2max. Verf.-Referat