Fig. 5. Metabolic rate was predicted well by the cyclic force hypothesis. (A) Metabolic rate, , increased (P<0.05), approximately with frequency f raised to the 2.5 power, as in Eqn 7 (R²=0.95). The same prediction, extrapolated to the low-amplitude trial performed at 0.67 Hz (broken line), also agrees reasonably well with the independently measured data (open symbol). (B) Metabolic rate also increased approximately linearly with the empirically measured rate of force/time as in Eqn 8 (R²=0.95).