Influence of exercise-induced maternal stress on fetal outcome in Wistar rats: Inter-generational effects

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Abstract
The effects of physical activity during pregnancy and lactation on the fetal outcome and the growth of pups was studied in Wistar rats (n144). Rats were trained to swim for 2 h every day, 6 dsweek through pre-pregnancy, pregnancy and lactation. Maternal exercise during pregnancy, despite the dams havingad lib. access to food, resulted in low-birth-weight pups (5·6 (SD 0·7) g;n178 in exercised damsv. 6·2(SD 0·8)g;n238 in sedentary dams). Maternal exercise continued through lactation exaggerated further the growth retardation of these pups (30·0 (SD 4·7) g;n78 in exercised damsv. 36·0 (SD 6·9) g;n126 in sedentary dams). The effects of maternal exercise during pregnancy and lactation studied over two successive generations revealed a reduction in the growth rates of the second generation progeny of both exercised (5·3 (SD 0·9) g;n125 at birth and 25·1 (SD 6·8) g;n54 at weaning) and sedentary rats (6·0 (SD 0·2) g;n110 at birth and 31·3 (SD 4·3) g at weaning) born to first-generation exercised rats. While slower growth in the former indicates a cumulative effect of exercise stress over two generations, that of the latter indicates that the generational effects are manifest even though the dams of the F1generation were not exposed to exercise stress during pregnancy and lactation. These findings suggest that the adverse effect of maternal exercise during pregnancy and lactation on fetal outcome in one generation is transferred to the subsequent generation.