Strength Training and Vigorous Exercise Beneficial in Pregnancy

Exercise, an important component to overall general health, is a useful tool in pregnancy to decrease the risk of gestational diabetes and to moderate or limit weight gain.¹ According to new proposed guidelines for exercise during pregnancy, increasing weekly physical-activity expenditure while incorporating vigorous exercise provides optimal health outcomes for pregnant women and their fetuses. In addition, light strength training during the second and third trimesters does not negatively affect newborn body size and overall health.

Research shows that to reduce the risk of gestational diabetes, exercise intensity should reach at least 60% of the heart rate reserve during pregnancy while gradually increasing physical-activity energy expenditure.¹ Essentially, the more vigorous the exercise, the less total exercise time is required. A regular exercise routine during pregnancy can also help minimize excess weight gain, which if not lost after the delivery can lead to obesity-associated comorbidities. However, some pregnant women should avoid exercise, and all pregnant women who do exercise should be made aware of warning signs to discontinue their activity (Table).

Strength training for pregnant women aged 18 to 45 years can be performed once or twice per week on nonconsecutive days, with 8 to 10 strength exercises per session.² Because pregnancy-related hormones can loosen or weaken connective tissue, pregnant women should use lighter weights with more repetitions to better protect joints. To minimize risk of injury to connective tissue in the pelvic area, walking lunges should be avoided. Resistance bands are a better choice than free weights, because there is less risk of a force injury to the abdomen (eg, a weight falling and hitting the abdomen). Lying flat on the back can disrupt fetal blood flow in the second and third trimesters, so all exercises should be performed standing, sitting, or on an inclined bench. Pregnant women should also try to prevent the often-reflexive valsalva maneuver; a focus on breathing during exercise and using lighter weights can often minimize this action. Most importantly, however, pregnant women should listen to their bodies, modifying their routine when strain or fatigue occurs.

References:

Reference
1. Zavorsky GS, Longo LD. Exercise guidelines in pregnancy: new perspectives. Sports Med. 2011;41:345-360.
2. Zavorsky GS, Longo LD. Adding strength training, exercise intensity, and caloric expenditure to exercise guidelines in pregnancy. AJOG. 2011;117:1399-1402