Purpose: Repeated bouts of ischemia followed by reperfusion (i.e., ischemic preconditioning (IPC)) protect against damage after a myocardial infarction. Recent observational data indicate that IPC improves exercise performance. However, no previous study has examined potential underlying mechanisms for this effect of IPC. Therefore, we examined the potential of IPC to improve 5-km running time trial performance and reduce lactate accumulation during an incremental exercise test.
Methods: In a randomized, crossover study, 13 healthy men performed running exercise, which was preceded by IPC (4 × 5-min 220 mm Hg bilateral leg occlusion) or a control intervention (C) (4 × 5-min 20 mm Hg bilateral leg occlusion). Participants performed a graded maximal treadmill running test, starting with five 3-min submaximal stages (10-14 km·h), followed by increments of 1 km·h every 2 min to 16 km·h, followed by an incline of the treadmill of 2% every 2 min. Blood lactate was examined at each 3-min stage. After 45 min of rest in the supine position, subjects then performed a 5-km running time trial.
Results: We found similar submaximal gas parameters during running exercise with both interventions. The overall increase in blood lactate during the submaximal stages was 1.07 ± 0.11 mmol·L lower when exercise was preceded with IPC versus C (P = 0.023). The 5-km running time trial was completed in a time that was 34 s faster after IPC versus C (95% confidence interval, 5-64 s; P = 0.027).
Conclusion: IPC improves 5-km time trial performance in healthy male individuals. Moreover, we found that IPC is associated with an attenuated rise in blood lactate concentration at submaximal level during an incremental running test. This could indicate that IPC allows for higher work rates and thus improves time trial performance.