Regular aerobic exercise during pregnancy is associated with improvement, or maintenance, of physical fitness (1). Overall cardiovascular function is improved, resulting in lower resting heart rate, increased heart rate variability and increased cardiac output (2). Aerobic capacity can be increased in both normal and overweight pregnant women (3), and this is associated with improved maternal health after delivery, decreased complications during labour & delivery, and quicker maternal recovery. In a cohort of female runners who continued to run recreationally during pregnancy, there was no significant difference in either gestational age at delivery or birthweight, irrespective of distance run per week or trimester of pregnancy (4).
Cardiovascular responses to resistance training during pregnancy are similar to that in non-pregnant women, and no adverse effects have been reports on pregnancy outcome or type of delivery (2). There is also strong evidence that combined aerobic and resistance exercise benefits maternal cardiorespiratory fitness. Systematic review of combined exercise interventions (25-30min of aerobic exercise & 10-15min of strength and balance exercise, 2-5x/week) reported that 3 out of 4 RCTs showed benefit with exercise interventions lasting 12 to 24 weeks (5).
Quality of evidence
High
Strength of recommendation
Strong
Conclusion
Combined aerobic and resistance exercise interventions during pregnancy can maintain, or improve, cardiovascular fitness without adverse effects.
References
1. Kramer MS, McDonald SW. Aerobic exercise for women during pregnancy Cochrane Database Syst Rev 2006 Jul 19;(3):CD000180
2. May LE et al. Fetal and maternal cardiac responses to physical activity and exercise during pregnancy Early Hum Dev. 2016 Mar;94:49-52
3. ACOG Committee Opinion No. 650: Physical Activity and Exercise During Pregnancy and the Postpartum Period Obstet Gynecol. 2015 Dec;126(6):e135-42
4. Kuhrt K, Harmon M, Hezelgrave NL et al. Is recreational running associated with earlier delivery and lower birth weight in women who continue to run during pregnancy? An international retrospective cohort study of running habits of 1293 female runners during pregnancy BMI Open Sport & Exercise Medicine 2018;4:e000296
5. Perales M et al. Benefits of aerobic or resistance training during pregnancy on maternal health and perinatal outcomes: A systematic review Early Human Dev. 2016Mar;94:43-8