Prescription of Aerobic Exercise During Pregnancy

Abstract

Available evidence supports the existence of both risks and benefits of aerobic conditioning during human pregnancy. During intensive exertion, maternal skeletal muscle and the fetus may compete for blood flow, oxygen delivery and essential fuel substrates. Hence, the most important hypothetical risks include acute fetal hypoxia, hyperthermia and malnutrition. If exercise is repeated on a chronic basis, teratogenic effects, fetal growth retardation or altered fetal development may result if maternal/fetal adaptive reserve is exceeded. A dose-response relationship for such effects has been demonstrated in laboratory animals, but specific findings may have limited applicability to voluntary exercise in pregnant women. Although further investigation is needed, the majority of published studies suggest that fitness-type conditioning does not jeopardise fetal well-being in healthy well-nourished women. Benefits of such exercise appear to include increases in maximal aerobic power (VO2max, L/min) and enhanced cardiopulmonary reserve. It has also been proposed that exercise prevents accumulation of excess body fat, promotes psychological well-being, helps to prevent gestational diabetes and low back pain and may facilitate labour. However, these benefits remain to be confirmed by objective scientific study. Due primarily to a lack of scientific data, existing medical guidelines for exercise during pregnancy are conservative and follow a common sense approach. Good agreement exists on the need for preparticipation medical screening and continuing surveillance to verify the existence of maternal/fetal adaptive reserve. Women are advised to select safe, non-ballistic exercise modalities and to avoid thermal or hyperbaric environmental stress during exercise. Exercise in the supine position is also prudent to avoid, particularly in late gestation. The usefulness of heart rate in prescribing and monitoring exercise intensity has been questioned, with use of conventional perception of exertion scales being the most logical alternative. Prediction of maximal aerobic power (VO2max) from submaximal work rate/heart rate relationships is also problematic during pregnancy. Other areas of debate include the advisability of initiating a new exercise programme during pregnancy, methods for prevention of fetal hyperthermia, the safety of weight-training/isometric exercise and optimal methods for training of pre/postnatal fitness instructors.

Practice and Pattern of Antenatal and Postnatal Exercise among Nigerian Women: A Cross-Sectional Study

“…This study found aerobic and stretching as the predominant physical exercise types in pregnancy and postpartum. This study corroborates previous findings that have found aerobic and stretching exercises as simple, easy to do and adequate in pregnancy (4,(36)(37)(38)(39). Although, cycling and swimming have quantity of support in literature as ideal exercises in pregnancy and postpartum, they were scarcely practiced among the women in this study.…”

Does exercise training during pregnancy affect gestational age? A randomised controlled trial

“…In this regard, regular sustained exercise during pregnancy has traditionally been a cause of concern as it could potentially challenge the homeostasis of the maternal–fetal unit and thus it might adversely affect the course and outcome of pregnancy, by inducing changes in visceral blood flow, body temperature, carbohydrate utilisation or shear stress 3 29 – 32. Although regular exercise and the resulting high fitness level can in fact facilitate efficient and timely labour,33 there has been concern that increases in norepinephrine and prostaglandin levels following each exercise bout during pregnancy could stimulate uterine motility and lead to premature labour and delivery 34. Particular caution should theoretically be placed on exercise performed during the last trimester of pregnancy, which is necessary for the maturation of the fetal lungs and other organs in preparation for extra-uterine life.…”

The relationship between physical activity and sleep among pregnant women

“…Although exercising during pregnancy was once thought to be deleterious to the fetus through hypothetical risks such as acute fetal hypoxia and hyperthermia (Wolfe et al, 1989), empirical evidence suggests otherwise during uncomplicated pregnancies (Zeanah & Schlosser, 1993). For example, Brenner, Wolfe, Monga, and McGrath (1999) showed that a brief progressive exercise test terminated at a maternal heart rate of 170 beats per min did not induce fetal distress during a healthy pregnancy.…”