Validation of the Rockport Fitness Walking Test for adults with mild to moderate mental retardation
Kittredge, Jennifer M.
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The purpose of this study was to determine if the generalized equations created by the original investigators of the Rockport Fitness Walking Test (RFWT) were a valid and reliable estimation of cardiorespiratory fitness for adults with mental retardation (MR). Subjects included 25 males and fenales (X̄ age = 33.3 ± 7.4 years) with mild to moderate mental retardation (MR) (X̄ IQ = 55.6 ± 9.7). Each subject performed 2-3 trials of the RFWT until two RFWT times were within 40-seconds of each other. Test-retest intraclass reliability for the two walks (R̲ =.97) and peak HRs (R̲ =.80) was high. A maximal treadmill (TM) test was administered to the subjects using a modified Balke protocol (X̄ VO[sub 2peak] = 29.5 ± 7.2 ml·kg^(-1)·min^(-1); 2.2 ± .62 L·min^(-1)). Subjects' age, weight, sex, walk time, and immediate post HR were used in the generalized equations for predicting VO[sub 2peak] (X̄ VO[sub 2peak] = 36.5 ± 7.6 ml·kg^(-1)·min^(-1) and 2.7 ± .66 L·min^(-1)). Significant correlations (p̲ < .01) were obtained between the measured and predicted peak VO[sub 2] levels (r̲ =.81 for ml·kg^(-1)·min^(-1); r̲ =.87 for L·min^(-1)). However, significant and consistent differences were also observed between the measured and predicted VO[sub 2] values (p̲ < .02). To evaluate these differences, the standard error of estimate (.30 L·min^(-1), 4.25 ml·kg^(-1)·min^(-1)) and Total Error (.65 L·min^(-1), 8.41 ml·kg^(-1)·min^(-1)) were calculated to describe the prediction error for the generalized equations. Only 28% (L·min^(-1)) and 36% (ml·kg^(-1)·min^(-1)) of the subjects' measured VO[sub 2] fell within the pre-specified value of the predicted VO[sub 2peak] thus the prediction equations overestimated the VO[sub 2peak] fitness levels of adults with MR.