Validity of a modified aerobic fitness test for adults with mental retardation

The purpose of this study was to determine whether further modifications to the Rockport Fitness Walking Test (RFWT) protocol produces similar results to the previously modified protocol (Rintala et al., 1992) used for adults with mental retardation (MR). A second purpose of this study was to evaluate prediction equations developed to estimate aerobic capacity from the 1:5RFWT. In an effort to make the RFWT more efficient for testing adults with MR the one pacer to one walker protocol (1:1RFWT) was further modified to one pacer to five walkers (1:5RFWT). Ten healthy men and 13 women (21.7 +/- 2.6 yr) with MR (IQ = 42-68) performed graded maximal treadmill tests, one 1:1RFWT and two 1:5RFWT. The end times (P = 0.326) and end heart rates (P = 0.457) did not significantly differ between the 1:1RFWT, the first 1:5RFWT, and the second 1:5RFWT. Separate Bland and Altman plots indicated that both end time and end heart rate had good agreement between protocols and also had good repeatability between the two 1:5RFWT. The main predictor variable, end time, from the 1:1RFWT and the 1:5RFWT was highly (and similarly) associated with the measured aerobic capacity (VO2peak), indicating a high predictive value for the 1:5RFWT end time. Bland and Altman plots of predicted and measured VO2peak for the prediction equations of Kline et al. (1987) and Rintala et al. (1987) indicated a general overestimation of measured values. The 1:5RFWT provides similar end times and end heart rates as the 1:1RFWT along with similar associations of end times to measured VO2peak. The 1:5RFWT could be used to predict aerobic capacity; unfortunately, the present prediction equations overpredict VO2peak for adults with MR and need to be revised.