Does creatine supplementation affect recovery speed of impulse above critical torque?

We previously reported that creatine supplementation improved intermittent isometric exercise performance by augmenting the total impulse performed above end-test torque (total IET '). However, our previous analyses did not enable mechanistic assessments. The objective of this study was to determine if creatine supplementation affected the IET ' speed of recovery. To achieve this objective, we retrospectively analyzed our data using the IET ' balance model to determine the time constant for the recovery of IET ' (tau IET '). Sixteen men were randomly allocated into creatine (N = 8) or placebo (N = 8) groups. Prior to supplementation, participants performed quadriceps all-out exercise to determine end-test torque (ET) and IETMODIFIER LETTER PRIME. Participants then performed quadriceps exercise at ET + 10% until task-failure before supplementation (Baseline), until task-failure after supplementation (Creatine or Placebo), and until the Baseline time after supplementation (Creatine- or Placebo-Isotime). tau IET ' was faster than Baseline for Creatine (669 +/- 98 vs 470 +/- 66 s), but not Placebo (792 +/- 166 vs 786 +/- 161 s). The creatine-induced change in tau IET ' was inversely correlated with the creatine-induced changes in both the rate of peripheral fatigue development and time to task-failure. tau IET ' was inversely correlated with total IET ' and ET in all conditions, but creatine supplementation shifted this relationship such that tau IET ' was faster for a given ET. Creatine supplementation, therefore, sped the recovery of IET ' during intermittent isometric exercise, which was inversely related to the improvement in exercise performance. These findings support that the improvement in exercise performance after creatine supplementation was, at least in part, specific to effects on the physiological mechanisms that determine the IET ' speed of recovery.

Automated summary

The study aimed to investigate whether creatine supplementation affected the speed of recovery in intermittent isometric exercise. The findings showed that creatine supplementation accelerated the recovery of intermittent exercise, with a significant inverse correlation between the creatine-induced change in recovery speed and the rate of peripheral fatigue development as well as time to task-failure. This suggests that the improvement in exercise performance after creatine supplementation is related to the physiological mechanisms of recovery speed.