Fig. 2. Organismal oxygen consumption of guinea fowl at rest, running at 1.5 m s^–1 on the level, running at 1.5 m s^–1 on a 15% gradient and running at 2.28–2.39 m s^–1 on the level. Values are means ± s.e.m. (N=8). *Significant difference (P<0.05) between the level run at 1.5 m s^–1 and both the level run at 2.28–2.39 m s^–1 and incline run at 1.5 m s^–1 and 15% gradient, as measured by paired t-tests. There was no significant difference between the 1.5 m s^–1 incline run and the 2.28–2.39 m s^–1 level run.