The present study determined the relationship between maximum leg force (MLF) and various measures of leg composition to maxV̇o2 measured on a treadmill (TM) and bicycle ergometer (BE). MLF was measured for N = 50 during pedaling at 60 rpm in the exact cycling pattern of a BE maxV̇o2 test by coupling an isokinetic dynamometer directly with a Monark (Sweden) BE. Significant correlations (P < .01) were found between MLF vs maxV̇o2 on the TM (r = .46) and BE (r = .40), body weight (r = .59), leg weight (r = .45), leg volume (r = .47) and lean body weight (r = .62). Although a low but significant r = .33 (P < .05) was obtained between MLF and TM and BE maxV̇o2 differences, this correlation was not in the expected direction of a negative relationship (i.e., subjects able to exert more force with the legs have a smaller difference between TM and BE maxV̇o2). This correlation was reduced to r = .03 when heterogeneity in body size was statistically controlled by use of partial correlations. These partial correlations indicate that MLF and MLF relative to body weight, leg weight, leg volume, body composition and absolute maxV̇o2 values accounts for less than two percent of the variability in TM and BE maxV̇o2, or the difference between TM and BE maxV̇o2, when these differences are expressed in either absolute (l/min) or percentage terms. Apparently, factors other than MLF or leg composition are associated with the 12.4% higher values of maxV̇o2 on the TM (3.93 l/min; 54.8 ml/kg · min) compared with the BE (3.44 l/min; 48.1 ml/kg · min).