An equation was developed to estimate maximal oxygen uptake (JOURNAL/mespex/04.02/00005768-199108000-00014/ENTITY_OV0312/v/2017-07-20T222257Z/r/image-pngO2max, ml.kg−1.min−1) based on a single submaximal stage of a treadmill walking test. Subjects (67 males, 72 females) aged 20–59 yr completed 4-min stages at 0, 5, and 10% grades walking at a constant speed (2.0–4.5 mph) and then performed a JOURNAL/mespex/04.02/00005768-199108000-00014/ENTITY_OV0312/v/2017-07-20T222257Z/r/image-pngO2max test. Heart rate and respiratory gas exchange variables were measured during the test. Multiple regression analysis (N = 117) to estimate JOURNAL/mespex/04.02/00005768-199108000-00014/ENTITY_OV0312/v/2017-07-20T222257Z/r/image-pngO2max from the 4-min stage at 5% grade yielded the following model (R2 = 0.86; SEE = 4.85 ml.kg−1.min−1):
JOURNAL/mespex/04.02/00005768-199108000-00014/ENTITY_OV0312/v/2017-07-20T222257Z/r/image-pngO2max = 15.1 + 21.8*SPEED (mph)
−0.327*HEART RATE (bpm)
+0.00504*HEART RATE*AGE + 5.98*GENDER (0 = Female; 1 = Male).
The constant and all coefficients were highly significant (P < 0.01). To assess the accuracy of the model in a cross-validation group (N = 22), an estimated JOURNAL/mespex/04.02/00005768-199108000-00014/ENTITY_OV0312/v/2017-07-20T222257Z/r/image-pngO2max value was obtained using the above model. Estimated JOURNAL/mespex/04.02/00005768-199108000-00014/ENTITY_OV0312/v/2017-07-20T222257Z/r/image-pngO2max then was regressed on observed JOURNAL/mespex/04.02/00005768-199108000-00014/ENTITY_OV0312/v/2017-07-20T222257Z/r/image-pngO2max yielding the following equation (R2 = 0.92):
ESTIMATED JOURNAL/mespex/04.02/00005768-199108000-00014/ENTITY_OV0312/v/2017-07-20T222257Z/r/image-pngO2max = 0.15 + 1.03*OBSERVED JOURNAL/mespex/04.02/00005768-199108000-00014/ENTITY_OV0312/v/2017-07-20T222257Z/r/image-pngO2max.
The intercept and slope of this equation were not significantly different from 0 and 1, respectively. For 90.9% of the subjects in the cross-validation group, residual scores were within the range of ± 5 ml.kg−1 · min−1. In conclusion, this submaximal walking test based on a single stage of a treadmill protocol provides a valid and time-efficient method for estimating JOURNAL/mespex/04.02/00005768-199108000-00014/ENTITY_OV0312/v/2017-07-20T222257Z/r/image-pngO2max.