Fig. 5. Rate of energy expenditure of ruff sandpipers at rest (speed 0) and during running at various speeds. Line indicated was fitted by linear regression for exercise values only (y=0.02x+2.19). The cost of transport of running ruffs (=slope of line) is 1.29 J m^–1. Values are means ± S.E.M. (sample sizes as in Fig. 3). ^*Significant difference from control value at speed 0 (P<0.005).