Physical activity and gestational weight gain predict physiological and perceptual responses to exercise during pregnancy.

BACKGROUND: Exercise is known to improve the health of the pregnant woman and her child. Studies that have evaluated physiological parameters during prenatal exercise have conflicting results. Better understanding of these physiological responses can modify exercise prescriptions, safety, and monitoring strategies. We examined the association between age, prepregnancy body mass index (BMI), gestational weight gain (GWG), and physical activity (PA) levels, factors that may influence a change in physiological (HR, VO2 responses) and perceptual (RPE) responses to acute exercise throughout pregnancy. METHODS: Twenty-two healthy pregnant women (31.4 ± 3.7 years) performed a Submaximal incremental Walking Exercise Test (SWET). Early- (13-18 weeks), mid- (24-28 weeks), and late-pregnancy (34-37 weeks) were compared. VO2 (L/min; ml/kg/min), HR (bpm), and RPE were collected at the end of each test stage. PA was determined by accelerometry. We associated PA levels, GWG, prepregnancy BMI, and age with HR, RPE, and VO2 responses. RESULTS: HR, RPE, and absolute VO2 were higher in late-pregnancy compared to earlier time points (p < .05; η2 = 0.299-0.525). Regression models were built for HR (all time points), RPE (early- and late-pregnancy), and VO2 (L/min; late-pregnancy). HR (late-pregnancy) was predicted by time in vigorous PA, GWG, age, and prepregnancy BMI (r2 = 0.645; SEE = 5.84). RPE (late-pregnancy) was predicted by sedentary time, GWG, prepregnancy BMI, and age (r2 = 0.662; SEE = 1.21). CONCLUSION: Physiological/perceptual responses were higher in late-pregnancy compared to other time points and associated with combined PA, GWG, prepregnancy BMI, and age. These findings can be used to modify exercise prescriptions and designs for future PA interventions in pregnant women.