EFFECT OF MATERNAL WEIGHT-GAIN DURING PREGNANCY ON EXERCISE PERFORMANCE

We examined the effect of maternal weight gain during pregnancy on exercise performance. Ten women performed submaximal cycle (up to 60 W) and treadmill (4 km/h, up to 10% grade) exercise tests at 34 ± 1.5 (SD) wk gestation and 7.6 ± 1.7 wk postpartum. Postpartum subjects wearing weighted belts designed to equal their body weight during the antepartum test performed two additional treadmill tests. Absolute O2 uptake (V̇O2) at the same work load was higher during pregnancy than postpartum during cycle (1.04 ± 0.08 vs. 0.95 ± 0.09 l/min, P = 0.014), treadmill (1.45 ± 0.010 vs. 1.27 ± 0.20 l/min, P = 0.0002), and weighted treadmill (1.45 ± 0.19 vs. 1.36 ± 0.20 l/min, P = 0.04) exercise. None of these differences remained, however, when V̇O2 was expressed per kilogram of body weight. Maximal V̇O2 (V̇O(2 max)) estimated from the individual heart rate-V̇O2 curves was the same during and after pregnancy during cycling (1.96 ± 0.37 to 1.98 ± 0.39 l/min), whereas estimated V̇O(2 max) increased postpartum during treadmill (2.04 ± 0.38 to 2.21 ± 0.36 l/min, P = 0.03) and weighted treadmill (2.04 ± 0.38 to 2.19 ± 0.38 l/min, P = 0.03) exercise. We conclude that increased body weight during pregnancy compared with the postpartum period accounts for 75% of the increased V̇O2 during submaximal weight-bearing exertion in pregnancy and contributes to reduced exercise capacity. The postpartum increase in estimated V̇O(2 max) during weight-bearing exercise is the result of consistently higher antepartum heart rates during all submaximal work loads.