Ischemic preconditioning enhances autonomic nervous system modulation during frequency speed of kick test in taekwondo athletes: a randomized crossover study

Ischemic preconditioning (IPC) may protect against prolonged ischemic damage by improving autonomic nervous system (ANS) function. While IPC has been studied for enhancing athletic performance and recovery, its impact on ANS function and competitive status around exercise remains unclear. This study examined IPC’s effects on ANS function before and after taekwondo-specific tests. This study employed a single-blind, randomized crossover design (IPC vs. Sham). Fifteen taekwondo athletes completed the frequency speed of kick test (FSKT) after each intervention, delivering repeated kicks to an electronic gear within a set time to assess specific anaerobic capacity. Heart rate recovery (HRR) and heart rate variability (HRV) were continuously monitored, while lactate and oxygen saturation (SpO₂) were measured. The data were analyzed using repeated-measures ANOVA or generalized linear mixed models. HRV analysis revealed a trend toward significance for the main effect of trial for LF (F = 3.18, p = 0.085, partial η²=0.102) and HF (F = 3.211, p = 0.084, partial η²=0.102). The DFA α1 during warm-up was significantly greater in the IPC (1.29 ± 0.15 vs. 1.15 ± 0.21, p = 0.049, d = 0.74), with a marginal main effect (F = 4.163, p = 0.051, partial η²=0.129). Post-test sample entropy was lower in the IPC (β=-0.149, SE = 0.052, t=-2.862, p = 0.0125, d = 0.74). HRR at 60 s post-exercise had a significant main effect (F = 6.038, p = 0.02, partial η²=0.177), with higher values in the IPC after the second (22.47 ± 6.83 bpm vs. 17.53 ± 5.34 bpm, p = 0.036, d = 0.79) and third tests (31.2 ± 8.78 bpm vs. 25.13 ± 6.05 bpm, p = 0.036, d = 0.78). The 5-minute HRR post-test also improved with IPC (72.33 ± 8.71 bpm vs. 66.33 ± 12.85 bpm, p = 0.041, d = 0.53). Compared to SHAM, the total quantity of each set of FSKTs in the IPC was greater (98.67 ± 6.48 vs. 93.8 ± 5.00, p = 0.029, d = 0.83; 94.67 ± 7.05 vs. 89.13 ± 5.85, p = 0.027, d = 0.85; 94.00 ± 7.29 vs. 87.47 ± 6.27, p = 0.014, d = 0.96), and the first-round scores increased in the third test (19.93 ± 1.44 vs. 18.73 ± 1.53, p = 0.035, d = 0.81). Lactate clearance rate was greater in IPC (13.20 ± 4.84% vs. 9.22 ± 6.71%, p = 0.047, d = 0.66). IPC attenuated oxygen desaturation during peak exertion (post-test: +2.09%, 95% CI 1.18–3.00; p < 0.001), reducing the cumulative SpO₂ decline by 56% compared. IPC can optimize taekwondo athletes’ ANS function, improve their physiological state during warm-up, and accelerate post-exercise sympathetic/vagal balance and metabolic adaptation, potentially improving competitive performance. ClinicalTrials.gov ID: NCT07146399 (Retrospectively registered), 22/08/2025.