A recent review article published in Jan 2022, in the Journal Frontiers in Psychology, looked at the impact of hypnosis in sport performance. The conclusions were as follow:

“There is a lot of evidence that hypnosis may be a helpful tool to address a variety of issues in sports; for example, hypnosis may help athletes improve their psychological quality, increase their self-confidence, relieve their fatigue, restore energy, help them better concentrate on the daily training and competition, and better improve their skills. However, there is little methodologically rigorous empirical research substantiating its value, and there is still a lack of extensive experimental evidence to prove its mechanism. As a result, hypnosis in sports still needs to be studied in more depth and breadth, and empirical verification is necessary and required. But it is undeniable that hypnosis is a simple and easy way to adjust physical and mental conditioning without special requirements in terms of venues or equipment.”

(2022)The Application of Hypnosis in Sports

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8820393/