Pregnancy-Related Changes in Physical Activity, Fitness, and Strength


Medicine & Science in Sports & Exercise:
Applied Sciences: Physical Fitness and Performance

Purpose: The objective was to examine the pregnancy-related changes in physical activity, fitness, and strength in women of varying body mass indices (BMI).

Methods: Women (N = 17 low BMI, N = 34 normal BMI, and N = 12 high BMI, mean age ± SD = 30.7 ± 4.1 yr) were studied before pregnancy (0 wk) and postpartum (6 and 27 wk) for body composition and for physical activity, fitness, and strength. Physical activity was assessed by questionnaire, fitness by a maximal oxygen consumption (V̇O2) test on a cycle ergometer, and strength by the one-repetition maximum test. Data were analyzed by repeated measures ANOVA testing for time and BMI group.

Results: Total physical activity differed qualitatively, but not quantitatively, with time. Significant time effects were observed for maximal workload, heart rate, respiration rate, ventilation, V̇O2, respiratory exchange ratio, and strength. V̇O2max, adjusted for weight, dropped by ∼385 mL·min−1 from 0 to 6 wk postpartum (P < 0.0001) and by ∼234 mL·min−1 from 0 to 27 wk postpartum (P < 0.01). The high-BMI group had a lower V̇O2max (adjusted for weight or fat-free mass) than the normal-BMI group (P < 0.05). Strength decreased for the leg press by 24% (P < 0.02) and for the latissimus pull down by 8% (P < 0.01) from 0 to 6 wk postpartum, and then increased by 44 and 12%, respectively (both P < 0.05), by 27 wk postpartum.

Conclusion: Relative to prepregnancy performance, fitness and strength declined in the early postpartum period but improved by 27 wk postpartum.

Author Information

1Center for Human Nutrition, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD; and 2USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX

Address for correspondence: Margarita S. Treuth, Ph.D., Center for Human Nutrition, The Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe St., Baltimore, MD 21205; E-mail:

Submitted for publication June 2004.

Accepted for publication November 2004.

This work is a publication of the U.S. Department of Agriculture (USDA)/Agricultural Research Service (ARS) Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine and Texas Children’s Hospital, Houston, Texas. This project was funded with federal funds from the U.S. Department of the Army under grant DAMD 17-95-1-5070 and from USDA/ARS under Cooperative Agreement 58-6250-6001 (to N. F. Butte).

The contents of this publication do not necessarily reflect the views or policies of the Army or the USDA, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.

©2005The American College of Sports Medicine