Author(s): YAMASAKI, D., KANEKO, N., SAKAKIBARA, Y., MURAKAMI, T., AOKI, R., OKEGAWA, T., NAKAZAWA, K., Institution: THE UNIVERSITY OF TOKYO, Country: JAPAN, Abstract-ID: 2214

INTRODUCTION:
Yips is defined as a psycho-neuromuscular impairment that disrupts the execution of fine motor skills in sports performance [1]. Yips can cause severe deterioration in sports performance and even lead to an athlete’s career termination; however, its underlying neural mechanisms remain unclear. Among the brain regions involved, the primary motor cortex (M1) deserves particular attention due to its critical role in the output of descending motor commands. Indeed, a previous study indicated that athletes with the yips exhibit greater activation in the M1 than healthy controls during motor execution [2]. This study aimed to elucidate the causal effects of inhibitory continuous theta burst stimulation (cTBS) over the M1 on the occurrence of the yips and throwing performance in baseball players with the yips.
METHODS:
12 male baseball players (age: 22.5 ± 3.3 years; playing experience: 13.9 ± 3.6 years) with yips symptoms participated. Participants performed a throwing task toward a target located 18.44 m away at a self-selected subjective intensity at which they experienced the most pronounced yips symptoms (approximately 50–80% of maximal effort). They first performed a pre-stimulation throwing set (pre), followed by two throwing sets (post1, post2), each preceded by cTBS [3]. Each set consisted of 20 throwing trials. cTBS was applied over the forearm hotspot in the M1 contralateral to the dominant pitching hand. Throwing performance measures included ball speed, proportion of throws with self-reported yips symptoms, and absolute error of ball arrival position. The Friedman tests and Wilcoxon signed-rank tests were used to compare these measures across conditions, with statistical significance set at p < 0.05.
RESULTS:
The Friedman test revealed no significant differences in ball speed among all conditions (p > 0.05). In contrast, a Friedman test followed by post-hoc Wilcoxon signed-rank tests showed that both the post1 and post2 conditions exhibited significantly lower rates of throws with self-reported yips symptoms (pre: median [IQR]: 25.0 % [12.5–41.2 %]; post1: 15.0 % [3.8–25.0 %]; post2: 5.0 % [0–11.2 %]) and lower absolute error of ball arrival position (pre: median [IQR]: 58.6 cm [52.4–76.4 cm]; post1: 56.7 cm [42.9–74.3 cm]; post2: 52.5 cm [38.9–59.9 cm] ) compared with the pre condition (post1: p < 0.05; post2: p < 0.01).
CONCLUSION:
Our results showed that cTBS significantly reduced the rate of throws with self-reported yips symptoms and the absolute error of ball arrival position, whereas ball speed remained unchanged. These findings indicate that the observed changes cannot be attributed to differences in throwing intensity across conditions, but rather to the inhibitory effects of cTBS. These findings provide valuable insight into the neural mechanisms underlying the yips and offer a novel foundation for future intervention strategies.
REFERENCES: [1] Clarke et al., 2015 Int Rev Sport Exerc Psychol [2] Watanabe et al., 2021 SciRep [3] Huang et al., 2005 Neuron.