The Power of Belief: Investigating the Placebo Effect in Post-Exercise Recovery Strategies for Football Players

Objectives: The objective is assessing whether the placebo effect can influence the time course of recovery following a football match. Methods: Using a randomized crossover design, eighteen youth male players (age: 15.3 ± 0.5 years, stature: 178.7 ± 6.4 cm, body mass: 65.3 ± 7.6 kg, playing experience: 8.6 ± 1.5 years) completed two friendly matches, followed by placebo (PLA; sham vagus nerve stimulation) or passive rest (CON). To assess the impact of PLA, countermovement jump height (CMJ), 10 and 20 m sprint times, heart rate variability (Ln-rMSSD), static and dynamic muscle soreness, and perceived fatigue were measured at pre-match, post-match, post-recovery, and 24 h post-match. Results: Our findings indicate that match play induced substantial fatigue, with significant deteriorations [p ≤ 0.002, small-to-large effect sizes (ES)] in CMJ, 10 and 20 m sprint performance, Ln-rMSSD, muscle soreness, and perceived fatigue at post-match and post-recovery compared to pre-match (except Ln-rMSSD between pre-match and post-recovery: p = 0.151, small ES). Although no significant between-intervention differences were found for any variable at any time point (p > 0.05), effect size analysis showed moderately lower perceived fatigue (r = 0.40) and dynamic soreness (r = 0.32) in PLA compared to CON at post-recovery. Conclusions: These findings suggest that while placebo stimulation did not affect performance or heart rate variability, it may support perceptual recovery. This holds relevance for both research and practice, as including placebo conditions can help isolate psychological effects from true treatment responses, while promoting positive expectations may enhance the perceived effectiveness of recovery strategies.