Fig. 6. The distribution of oxygen consumption (_O2) during voluntary wheel-running in 32 deer mice tested at different ambient temperatures (T_a). Data are 1 min averages, with different points from each animal separated by 3 min (see text). The same animals were tested at each T_a (variation in sample sizes reflects slight differences in the number of data points in each sample period, and in data lost due to equipment problems). All _O2 values were adjusted to the mean body mass of 22.2 g using a scaling factor of mass^0.79 (see text). Downward-pointing arrows indicate the treadmill-elicited maximum _O2 (_O2max) for a 22.2 g mouse (4.2 ml O₂ min^-1) and the associated percentage is the fraction of data exceeding _O2max. The bin size was 0.1 ml O₂ min^-1.