Effect of maternal exercise on fetal and placental glycogen storage in the mature rat

The purpose was to determine the effects of exercise on fetal and placental glycogen storage patterns at 20 days gestation (term 21 days) in mature (approximately 12 months of age) Sprague-Dawley rats. The exercise protocol consisted of treadmill running at 30 m min(-1), on a 10 incline for 60 min, 5 days per week, for 4 weeks prior to conception, which continued until day 19 of pregnancy. Exercise produced a significant reduction in fetal body weight, placental weight, and fetal organ weights (heart, kidney, brain, and liver) compared to sedentary control animals (p < .05). However, when fetal body size was taken into account, these differences disappeared, except for the fetal brain:body weight ratio, which was larger in the exercised animals compared to controls (p < .05). Fetal liver glycogen concentrations were significantly lower in exercised animals compared to nonrunning control animals (p < .05). These results demonstrate that exercise of mature rats may compromise fetal development and hepatic glycogen storage in the fetus.