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Article History

Received: 3 June 2026

Accepted: 9 September 2026

First Online: 20 September 2026

Declarations

Ethics approval and consent to participate: Ethical approval was not required for this study under German national regulations. In Germany, review by an ethics committee is mandatory only for defined categories of research, in particular clinical trials of medicinal products (§§ 40 and 41 Arzneimittelgesetz, in conjunction with Regulation (EU) No 536/2014), clinical investigations of medical devices (§§ 31 and 33 Medizinprodukterecht-Durchführungsgesetz, in conjunction with Regulation (EU) 2017/745) and the application of radioactive substances or ionising radiation to humans for medical research purposes (§§ 31 and 36 Strahlenschutzgesetz). The present study falls within none of these categories, and the obligation of physicians to consult an ethics committee under § 15 of the Model Professional Code for Physicians in Germany (MBO-Ä) did not apply, as no physician was involved in its conduct. Accordingly, no ethics committee approval was obtained for this study. The study was purely observational and non-interventional, involved only non-invasive measurements under routine training conditions and posed no risk beyond that of ordinary participation in the training sessions. No vulnerable populations were involved. Participation was entirely voluntary, trackers were self-applied and distributed without recording names, and participants could withdraw at any time without consequences. Consent documentation was stored separately and was not used to link data to individuals. The study was conducted in accordance with the Declaration of Helsinki and its later amendments. All participants provided written informed consent prior to participation.

Consent for publication: Not applicable.

AI-based language models: During manuscript preparation, ChatGPT and Claude (Anthropic) were used for language editing and stylistic improvements. The author confirms full responsibility for the content of the manuscript.

Competing interests: The author declares no competing interests.