Oxygen cost for cycling as related to leg mass in males and females, aged 20 to 80

In order to evaluate the determinants of the metabolic cost for cycle ergom etry, we analyzed the relationship between (V)over dot O-2 and leg mass (LM ) and total body mass (TBM) in 71 randomly-selected sedentary subjects (34 men), aged 20 to 80. Participants performed constant work rate (WR) tests a t 0, 25, and 50 W (at 60 rpm) for 6 minutes in a randomized sequence: gross (V)over dot O-2, gross efficiency, and work efficiency were related to TBM and LM as assessed by dual energy x-ray absorptiometry. We found that gros s (V)over dot O-2, and gross efficiency were more strongly related to LM th an TBM but work efficiency values were independent of both (P > 0.05), Sign ificantly higher values of (V)over dot O-2/TBM were found in subjects with large LM/TBM ratios and vice-verse; (V)over dot O-2/LM, however, did not ch ange with anthropometric characteristics. Gross (V)over dot O-2 (mL/min) wa s predicted by a LM-based equation (10.6 [WR, W] + 16.8 [LM, kg] +75) with a mean error below 5%: this equation predicted the cost more accurately tha n previous TBM-based formulations (P < 0.01). We conclude that leg mass act ually provides the preferred frame of reference for predicting the oxygen c ost for cycle ergometry at 60 rpm in sedentary subjects, independent of age or gender.