Key result
Caffeine intake shows no effect on post-exercise HRV indices compared to placebo.
Why the study?
The study was conducted to evaluate the influence of caffeine intake strategies, including form, timing, and dosage, on heart rate variability indices during post-exercise recovery.
Does caffeine supplementation impact heart rate variability indices during post-exercise recovery in active adults?
Meta-Analysis
Does caffeine supplementation impact heart rate variability indices during post-exercise recovery in active adults?
Caffeine intake prior to exercise does not significantly alter vagal modulation or heart rate variability recovery post-exercise in active adults.
Caffeine intake strategies do not impair post-exercise HRV recovery; supports safe use across forms, timings, and doses while extending null findings on vagal modulation.
OBJECTIVES: The objective of this systematic review and meta-analysis is to evaluate the influence of caffeine (CAF) intake strategies, taking into account their form, timing, and dosage, on heart rate variability (HRV) indices in the post-exercise recovery period. METHODS: The meta-analysis adhered to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines and is registered in the PROSPERO database (CRD42023425885). A comprehensive literature search was carried out across MEDLINE, Web of Science, LILACS, and SCOPUS, concluding in May 2023. We concentrated on randomized clinical trials comparing CAF supplementation effects to placebo on HRV indices post-exercise in active adults aged 18 and above. The primary endpoint was the assessment of HRV indices, measured both prior to and following exercise. RESULTS: Of the 10 studies included, 7 were used for the meta-analysis, and all contributed to the systematic review. The research explored a variety of CAF strategies, spanning different forms (capsule, drink, gum), times (10, 45, 60 min) and doses (2.1 to 6.0 mg/kg). The outcomes revealed no substantial variations between the placebo and CAF conditions in terms of both the square root of the average of successive squared differences between adjacent RR intervals (RMSSD) (standardized mean difference (SMD) -0.03, 95% CI -0.265 to 0.197, p=0.77) and high frequency (HF) index (SMD -0.061, 95% CI -0.272 to 0.150, p=0.57). Furthermore, metaregression analysis, employing a fixed-effects model and accounting for the administered CAF doses, revealed no significant correlation between caffeine doses and HRV indices (p>0.05). CONCLUSION: In conclusion, there is moderate-certainty evidence suggesting that different CAF intake strategies, encompassing aspects such as form, time, and dose, do not have a significant impact on HRV indices recovery post-exercise (i.e., vagal modulation).
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Almeida et al. (2024) conducted a meta-analysis in Post-exercise recovery. Caffeine vs. Placebo was evaluated on Heart rate variability indices (RMSSD) (SMD -0.03, 95% CI -0.265 to 0.197, p=0.77). Caffeine intake strategies did not significantly impact post-exercise heart rate variability indices such as RMSSD (SMD -0.03; 95% CI -0.265 to 0.197; p=0.77) compared to placebo.
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