Effects of recovery interval duration on the parameters of the critical power model for incremental exercise

Introduction We tested the linear critical power ( w ˙ cr ) model for discrete incremental ramp exercise implying recovery intervals at the end of each step. Methods Seven subjects performed incremental (power increment 25 W) stepwise ramps to subject’s exhaustion, with recovery intervals at the end of each step. Ramps’ slopes ( S ) were 0.83, 0.42, 0.28, 0.21, and 0.08 W s −1 ; recovery durations ( t r ) were 0 (continuous stepwise ramps), 60, and 180 s (discontinuous stepwise ramps). We determined the energy store component ( W′ ), the peak power ( w ˙ peak ), and w ˙ cr . Results When t r = 0 s, w ˙ cr and W′ were 187 ± 26 W and 14.5 ± 5.8 kJ, respectively. When t r = 60 or 180 s, the model for ramp exercise provided inconsistent w ˙ cr values. A more general model, implying a quadratic w ˙ peak versus S relationship, was developed. This model yielded, for t r = 60 s, w ˙ cr = 189 ± 48 W and W′ = 18.6 ± 17.8 kJ, and for t r = 180 s, w ˙ cr = 190 ± 34 W, and W′ = 16.4 ± 16.7 kJ. These w ˙ cr and W′ did not differ from the corresponding values for t r = 0 s. Nevertheless, the overall amount of energy sustaining work above w ˙ cr , due to energy store reconstitution during recovery intervals, was higher the longer t r, whence higher w ˙ peak values. Conclusions The linear w ˙ cr model for ramp exercise represents a particular case (for t r = 0 s) of a more general model, accounting for energy resynthesis following oxygen deficit payment during recovery.