Accuracy of exercise-based tests for estimating cardiorespiratory fitness and muscle strength in early-stage breast cancer survivors in Japan.

Abstract

We aimed to examine whether cardiorespiratory fitness and leg strength can be estimated based on their relationship with physical performance tests in Japanese breast cancer survivors. Participants were 50 sedentary women aged 20 to 59years who have received breast surgery in the past 2 to 13months after diagnosis of invasive breast cancer (stage I-IIa). Cardiorespiratory fitness and leg strength were measured by peak oxygen consumption (VO2peak), and one-repetition maximum for leg press (leg press 1RM). Physical performance tests were performed 6-min walk test, chair stand test, and grip strength. Using multiple regression analysis, we developed prediction equations for VO2peak and leg strength based on their associations with the physical performance tests. The validity of the estimation equations was assessed using Bland-Altman plots. Mean age, VO2peak, and leg press 1RM were 48 ± 6years, 25.0 ± 3.6mL/kg/min, and 95 ± 32kg, respectively. Multiple regression analysis yielded 6-min walk test distance, age, height, and body weight as predictors of VO2peak. Measured VO2peak and predicted VO2peak showed a moderate positive correlation (r = 0.463, p < 0.001). Chair stand test, grip strength, age, height, and body weight were selected as predictors of leg press 1RM. There was a strong positive correlation between predicted and measured leg press 1RM (r = 0.754, p < 0.001). The results suggest that leg strength can be predicted using physical performance tests. However, further examination may be needed to determine whether cardiorespiratory fitness can be predicted based on 6-min walk test.