Resumen de Validity of the 6-Minute Walk Test and YMCA Submaximal Cycle Test During Midpregnancy

Rachel A. Tinius, Maire Blankenship, Jill M. Maples, Bailey C. Pitts, Karen Furgal, Elizabeth S. Norris, Donald L. Hoover, Alyssa Olenick, Joshua Lambert, William Todd Cade

• Submaximal exercise testing can be a feasible alternative to maximal testing within special populations to safely predict fitness levels; however, submaximal exercise testing has not been well-validated for use during pregnancy. The purpose of this study was to determine the concurrent validity of the 6-minute walk test (6MWT) and the YMCA submaximal cycle test (YMCAT) to predict V[Combining Dot Above]O2max in physically active women during midpregnancy. Thirty-seven (n = 37) pregnant women (22.1 +/- 1.4 weeks' gestation) and 10 (n = 10) nonpregnant women participated in the study. Subjects completed a graded maximal treadmill test at 1 visit to measure maximal oxygen consumption (V[Combining Dot Above]O2max), and then subjects completed the 6MWT and YMCAT in randomized order during a separate visit. The predicted V[Combining Dot Above]O2max from each submaximal test were compared with the measured V[Combining Dot Above]O2max from the treadmill test to assess the validity of these tests during pregnancy. Among pregnant women, predicted V[Combining Dot Above]O2max from the YMCAT was not correlated to the measured V[Combining Dot Above]O2max (r = 0.14, p = 0.42), and the predicted V[Combining Dot Above]O2max from the 6MWT was only moderately correlated (r = 0.40, p = 0.016) to the measured V[Combining Dot Above]O2max. Among nonpregnant women, the predicted V[Combining Dot Above]O2max values from both the YMCAT and the 6MWT had strong correlations with the measured V[Combining Dot Above]O2max values (YMCAT: r = 0.71, p = 0.02; 6MWT: r = 0.80, p = 0.006). Neither test demonstrated concurrent validity among the pregnant sample. The main finding is that the YMCAT is not a valid method to estimate V[Combining Dot Above]O2max during midpregnancy (likely due to physiological changes in heart rate [HR] during pregnancy). The 6MWT has potential to be used clinically for estimating fitness as actual and predicted values did positively correlate, and it is not dependent on HR responses to exercise. However, if a precise measure of fitness is needed, then neither test appears to have strong validity for use during midpregnancy.