Validity of the 6-Minute Walk Test and YMCA Submaximal Cycle Test during Mid-Pregnancy

• Published in: Journal of strength and conditioning research 2021-11, Vol.35 (11), p.3236-3242
• Main Authors: Tinius, Rachel A., Blankenship, Maire, Maples, Jill M., Pitts, Bailey C., Furgal, Karen, Norris, Elizabeth S., Hoover, Donald L., Olenick, Alyssa, Lambert, Joshua, Cade, W. Todd
• Format: Article
• Language: English
• ISSN: 1064-8011; 1533-4287
• DOI: 10.1519/JSC.0000000000003263

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 VO 2max in physically active women during mid-pregnancy. Thirty-seven (n=37) pregnant women (22.1 ±1.4 weeks gestation) and ten (n=10) non-pregnant women participated in the study. Participants completed a graded maximal treadmill test at one visit to measure maximal oxygen consumption (VO 2max ) , then participants completed the 6MWT and YMCAT in randomized order during a separate visit. The predicted VO 2max from each submaximal test were compared to the measured VO 2max from the treadmill test to assess the validity of these tests during pregnancy. Among pregnant women, predicted VO 2max from the YMCAT was not correlated to the measured VO 2max (r=0.14, p=0.42), and the predicted VO 2max from the 6MWT was only moderately correlated (r=0.40, p=0.016) to the measured VO 2max . Among non-pregnant women, the predicted VO 2max values from both the YMCAT and the 6MWT had strong correlations with the measured VO 2max 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 VO 2max during mid-pregnancy (likely due to physiological changes in heart rate 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 heart rate responses to exercise. However, if a precise measure of fitness is needed, then neither test appears to have strong validity for use during mid-pregnancy.