To develop a data-driven model that allows oxygen consumption (and thus metabolism) to scale with polar bear speed and mass, we extracted original data from the three published studies that reported measurements of oxygen consumption (V˙O2; in millilitres of O2 per gram per hour) as a function of walking speed for polar bears that weighed 125, 155, 190 and 235 kg. The 125 and 155 kg animals were subadult males (as defined by Watts et al., 1991), the 190 kg animal was a 4-year-old female (Hurst et al., 1982a) and the 235 kg animal was a ~4-year-old male (Øritsland et al., 1976). We used the means of the multiple trials of each bear at each speed as the best estimates of O2 consumption for each mass and speed. Both linear (Øritsland, 1970; Hurst et al., 1982a) and double exponential regression models (Hurst et al., 1982a) have previously been used to describe how oxygen consumption changes with speed for bears of different sizes. Here, we first considered three potential models to describe the general shape of the relationship between polar bear speed [S; we use this term rather than velocity (V) as used by Hurst et al., 1982a] and oxygen consumption (V˙O2) using data from Øritsland et al. (1976), Hurst et al. (1982a) and Watts et al. (1991). Our initial model set included the following: