Development of nonexercise prediction models of maximal oxygen uptake in healthy Japanese young men

The present study developed nonexercise models for predicting maximal oxygen uptake \(({\dot{{V}}}\hbox{O}_{\rm{2max}})\) using skeletal muscle (SM) mass and cardiac dimensions and to investigate the validity of these equations in healthy Japanese young men. Sixty healthy Japanese men were randomly separated into two groups: 40 in the development group and 20 in the validation group. \({\dot{{V}}}\hbox{O}_{\rm{2max}}\) during treadmill running was measured using an automated breath-by-breath mass spectrometry system. Left ventricular internal dimensions at end-diastole (LVIDD) and at end-systole (LVIDS) were measured using M-mode ultrasound with a 2.5 MHz transducer. Stroke volume (SV) was calculated based on the Pombo rule. SM mass was predicted by B-mode ultrasound muscle thickness. Correlations were observed between \({\dot{{V}}}\hbox{O}_{\rm{2max}}\) and predicted thigh (r = 0.74, P < 0.001) and lower leg SM mass (r = 0.55, P < 0.001). Furthermore, there were correlations between \({\dot{{V}}}\hbox{O}_{\rm{2max}}\) and LVIDD (r = 0.74, P < 0.001) and SV (r = 0.72, P < 0.001). Stepwise regression analysis was applied to thigh SM mass and SV for prediction of \({\dot{{V}}}\hbox{O}_{\rm{2max}}\) in the development group, and these parameters were closely correlated with absolute measured \({\dot{{V}}}\hbox{O}_{\rm{2max}}\ ({R}^{2}=0.72, P < 0.001)\) by multiple regression analysis. When the \({\dot{{V}}}\hbox{O}_{\rm{2max}}\) prediction equations were applied to the validation group, significant correlations were also observed between the measured and predicted \({\dot{{V}}}\hbox{O}_{\rm{2max}}\ ({R}^{2}=0.83, P < 0.001).\) These results suggested that nonexercise prediction of \({\dot{{V}}}\hbox{O}_{\rm{2max}}\) using thigh SM mass and cardiac dimension is a valid method to predict \({\dot{{V}}}\hbox{O}_{\rm{2max}}\) in young Japanese adults.