A comparison of walking versus stretching exercises to reduce the incidence of preeclampsia: a randomized clinical trial.

OBJECTIVES To compare a walking exercise to a stretching exercise during pregnancy in high-risk women who were sedentary and had previously experienced preeclampsia. METHODS A randomized clinical trial of the effects of the two types of physical exercises was conducted between November 2001 and July 2006 in Washtenaw County, Michigan. Both groups engaged in the assigned exercise five times a week until the end of pregnancy. RESULTS Women were randomized to either the walking group (n = 41) or the stretching group (n = 38). The walkers exercised an average of 36 (SD, 6) minutes at 18 weeks gestation, 34 (SD, 7) minutes at 28 weeks gestation, and 31 (SD, 12) minutes at the last week of the intervention. On average, they exercised within target heart rate ranges 35% (SD, 32%) at 18 weeks gestation, 22% (SD, 25%) at 28 weeks gestation, and 17% (SD, 25%) at the last week of the intervention. The stretching group engaged in stretching exercises following a 40-minutes videotape. On average, the walking group exercised 4 (SD, 1) times a week at 18 weeks gestation, 4 (SD, 1) time a week at 28 weeks gestation, and 3 (SD, 1) times a week at the last week of the intervention. Equally on average, the stretching group exercised 4 (SD, 2) times a week at 18 weeks gestation, 5 (SD, 1) times a week at 28 weeks gestation, and 3 (SD, 1) times a week at the last week of the intervention. No difference between groups was observed, but both exercised significantly less frequently over the time (p 0.0001). Together, participants reported average 7,040 (SD, 2,612) steps at the beginning and 5,711 (SD, 2,739) steps at the end of the study. The walkers tracked an average 8,501 (SE, 778) steps a day at 20 weeks gestation and 7,418 (SE, 788) steps at 34 weeks gestation (n.s.). The stretchers tracked an average 6,189 (SE, 704) steps at 20 weeks gestation and 4,848 (SE, 452) steps at 34 weeks gestation (p 0.05). The incidence of preeclampsia was 14.6% (95% CI, 5.6 to 29.2) among the walkers and 2.6% (95% CI; 0.07 to 13.8) among the stretchers. The incidence of gestational hypertension was 22 % (95% C.I., 8.7 to 35.2) for the walkers and 40% (95% CI, 23.2 to 55.8) for the stretchers. The mean transferrin level, an antioxidant marker, was significantly higher in the stretching group mean (412 mg/dL, 95%CI, 389 to 435) than the walkers at the time of labor (mean = 368 mg/dL, 95%CI, 346 to 391) (p 0.05). No significant group differences were observed in birth outcomes. CONCLUSION Regular stretching exercises may promote endogenous antioxidants among women at risk for preeclampsia.