The effects of a walking program on aerobic fitness, riboflavin and thiamin status, and birth outcome in pregnant women taking vitamin-mineral supplements

Abstract

The effects of an aerobic walking program, from 22 to 30 wk gestation, on aerobic fitness, riboflavin and thiamin status, and birth outcome were studied in 28 healthy, pregnant women, 24-36 yr of age, receiving vitamin-mineral supplements. Aerobic capacity was evaluated by measurements of heart rate (HR) and relative oxygen consumption (VO₂, ml/kg/min) during two submaximal treadmill walking tests (22 and 30 wk). HR responses were significantly lower for walking subjects (W; n=l8) compared to nonwalking (NW; n=l0) at two (~2.9 METS) and four (~3.8 METS) min, and near significant at six (~4.6 METS) min of the 30 wk tests. HR at two min of exercise for NW subjects increased significantly from 22 to 30 wk. Oxygen consumption for W decreased significantly from 22 to 30 wk at two, four, and six min of exercise. Comparison of VO₂ changes (22 to 30 wk) between W and NW indicated a significant difference at six min and near significance at four min. Riboflavin and thiamin status, as determined by erythrocyte glutathione and transketolase activity coefficients, was adequate for 86% of the subjects with respect to riboflavin and 96% for thiamin. There was a significant correlation (r = 0.58) between aerobic activity scores and ETKAC values (W group). Participation in a walking program slightly improved aerobic capacity without affecting birth outcome or riboflavin and thiamin status in pregnant women taking vitamin-mineral supplements.