Transcutaneous Auricular Vagus Nerve Stimulation in Powerlifters: An Exploratory Pilot Study on Psychological, Sleep, and Performance Outcomes

Objective. The main objective of this study was to examine the effects of transcutaneous auricular vagus nerve stimulation (taVNS) on psychological, sleep, and performance outcomes in powerlifters. Previous research has primarily focused on taVNS in clinical or healthy samples and showed improvements in psychological functioning, recovery, and sleep. Evidence for beneficial effects of taVNS in healthy athletes, however, is missing so far. Methods. Over the course of 4 weeks, 10 healthy adult powerlifters self-administered taVNS five times a week for 30 min after strength training or before bedtime, in an uncontrolled, single-arm pilot design without a sham or control condition. Measurements were taken at three time points: before the intervention phase (pre), immediately after the 4-week intervention phase (post) and 1 month after the post-assessment (follow-up). Pre, post, and follow-up measurements included various subjective psychological domains (recovery, stress, perceived stress, affect, memory, attention, anxiety, and well-being), objective sleep domains (nocturnal HRV, sleep score, sleep duration, and subjective sleep quality), and submaximal strength performance outcomes in squat, bench press, and deadlift. The small sample size required non-parametric testing. Additionally, a responder analysis was conducted to explore individual differences in outcome-specific responses. Results. Results showed nominally significant pre-post improvements (uncorrected for multiple comparisons) in positive affect and self-reported attentional difficulties, both revealing large effect sizes; however, given the absence of a control group and the lack of correction for multiple comparisons across multiple outcomes tested, these findings should be interpreted as exploratory and hypothesis-generating rather than confirmatory. The remaining psychological domains and sleep outcomes did not show meaningful changes. Regarding performance, only two of the ten participants provided complete baseline training data, so no reliable conclusions about a beneficial effect of taVNS on strength performance could be drawn. The responder analysis was consistent with the two nominally significant findings but did not reveal a clear overall pattern of taVNS effectiveness. Conclusions. The current study is the first to implement a 4-week taVNS intervention in strength training and demonstrate differences in domain-specific responsiveness to taVNS in athletes for psychological health and self-reported cognitive performance. These findings offer important insights into the feasibility and practical application of taVNS in sports settings. Further studies with larger, sham-controlled samples, a pre-registered primary outcome and a longer intervention period are needed to determine whether these preliminary, hypothesis-generating findings reflect genuine effects of taVNS.