HEIL, D. P., P. S. FREEDSON, L. E. AHLQUIST, J. PRICE, and J. M. RIPPE. Nonexercise regression models to estimate peak oxygen consumption.Med. Sci. Sports Exerc., Vol. 27, No. 4, pp. 599–606, 1995. The purpose of this study was to develop a VO2peakprediction model derived from nonexercise (N-EX) based predictors. VO2peakwas measured using a walking treadmill protocol with 229 females and 210 males between 20 and 79 yr of age (mean ± SD: 38.62 ± 10.36 ml·kg-1·min-1). Subjects were randomly divided into validation (V) (85% of total;N= 374) and cross-validation (CV) (15% of total;N= 65) groups. The V group was used to validate generalized and gender-specific models using stepwise multiple regression procedures with gender, age and age, percent body fat, and a physical activity code (AC). The generalized ml·kg-1·min-1(R2= 0.77, SEE = 4.90 ml·kg-1·min-1, SEE% = 12.7%) and gender-specific (females: R2= 0.72, SEE = 4.64 ml·kg-1·min-1males: R2= 0.72, SEE = 5.02 ml·kg-1·min-1) models were highly accurate relative to N-EX and exercise based models in the literature. Cross-validation procedures were used to evaluate model stability. The generalized model was stable across the total CV group and various CV subsamples (by gender, decade-wide age groups, and AC groups), but not across groups similar in VO2peak. These results suggest that N-EX models can be valid predictors of VO2peakfor heterogenous samples.