Comparison of Factors and Effects of Repeated vs. Acute Ischemic Preconditioning on Enhancing Athletic Performance: A Systematic Review and Meta-Analysis

Background Repeated ischemic preconditioning (RIPC) has been shown to significantly improve endothelial function, but its effect on enhancing athletic performance remains highly controversial. On the other hand, acute ischemic preconditioning (AIPC) has already been proven to enhance athletic performance. Similar to AIPC, factors such as exercise modality, dosage, training status, and timing of testing are crucial influences on the final effects of RIPC, yet related studies exhibit considerable disagreement. Moreover, the comparison between the effects of repeated ischemic preconditioning and acute ischemic preconditioning has yet to be further clarified. Objective The primary aim of this meta-analysis is to investigate whether RIPC truly enhances athletic performance while considering exercise modality, dosage, the training status of the tested population, and the timing of observation. It also seeks to compare the effects of RIPC and AIPC on enhancing athletic performance. Methods A literature search was conducted in five databases. For each outcome, standard error and mean difference or standardized mean difference were calculated. A random-effects model (SMD) with a 95% confidence interval (CI) was used, and analysis was performed using the inverse variance statistical method. The risk of bias was assessed using ROB2 and considerations for randomized controlled trials. Results RIPC had a small beneficial effect on athletic performance (p = 0.02; SMD = 0.33; 95% CI 0.06–0.60). Regarding exercise modality, RIPC had a small beneficial effect on anaerobic exercise (p = 0.05; SMD = 0.48; 95% CI 0.00–0.97), but no improvement for aerobic exercise (p = 0.12; SMD = 0.26; 95% CI -0.07–0.59). A dosage of RIPC lasting one week or longer was effective (p = 0.006; SMD = 0.37; 95% CI 0.01–0.75). The time interval between RIPC and the start of exercise did not affect the benefit (p > 0.05). RIPC had a greater impact on enhancing athletic performance in the general population (p = 0.06; SMD = 0.36; 95% CI -0.01–0.73; p = 0.001; SMD = 1.03; 95% CI 0.41–1.65) compared to athletes (p > 0.05). The benefit of RIPC compared to AIPC remains unclear (p = 0.1; SMD = 0.22; 95% CI -0.05–0.49). Conclusion RIPC can effectively improve anaerobic exercise performance and is influenced by RIPC dosage and the training level of the subjects. RIPC dosage lasting one week or longer is most effective in untrained populations and can be observed at any time. However, there are certain limitations in current research, such as the small number of studies available for analysis, and there is insufficient evidence to determine whether repeated or acute IPC application is more effective. Further research is needed to supplement these findings. PROSPERO registration number CRD42024579390