{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,31]],"date-time":"2026-10-31T07:28:50Z","timestamp":1793431730584,"version":"4.5.0"},"reference-count":57,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2025,1,17]],"date-time":"2025-01-17T00:00:00Z","timestamp":1737072000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Polar Electro Oy (HR monitors and partial funding for the study)"},{"name":"The Foundation of Sports Institute"},{"name":"The Finnish Sports Research Foundation"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Previous studies on the effects of intensified training on sleep quality\/quantity have been somewhat contradictory. Moreover, recreational athletes often track various sleep metrics, and those metrics\u2019 actual connections to training adaptations are unknown. This study explored the effects of intensified training on sleep and nightly recovery along with their associations with training adaptations. A total of 24 participants (10 females) performed a 3-week baseline training period (BL), a 2-week overload period (OL), and a 1-week recovery period (REC), which were followed by test days (T1\u2013T3). The endurance performance was assessed with a 3000 m running test. Throughout all of the periods, the nightly recovery information was monitored with a wrist-worn wearable, including sleep quantity and quality, heart rate (HR) and HR variability (HRV), and proprietary parameters combining several parameters and scaling the results individually. In addition, the perceived strain and muscle soreness were evaluated daily. The 3000 m running performance improved from T1 to T2 (\u22121.2 \u00b1 1.7%, p = 0.006) and from T1 to T3 (\u22121.7 \u00b1 1.2%, p = 0.002). The perceived strain and muscle soreness increased (p &lt; 0.001) from the final week of the BL to the final week of the OL, but the subjective sleep quality and nightly recovery metrics remained unchanged. The OL average of the proprietary parameter, autonomic nervous system charge (\u201cANS charge\u201d, combining the HR, HRV, and breathing rate), as well as the change in the sleep HR and HRV from the BL to the OL, were associated (p &lt; 0.05) with a change in the 3000 m running time. In conclusion, the subjective recovery metrics were impaired by intensified training, while the sleep and nightly recovery metrics showed no consistent changes. However, there were substantial interindividual differences in nightly recovery, which were also associated with the training adaptations. Therefore, monitoring nightly recovery can help in recognizing individual responses to training and assist in optimizing training prescriptions.<\/jats:p>","DOI":"10.3390\/s25020533","type":"journal-article","created":{"date-parts":[[2025,1,17]],"date-time":"2025-01-17T11:24:56Z","timestamp":1737113096000},"page":"533","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Monitoring Sleep and Nightly Recovery with Wrist-Worn Wearables: Links to Training Load and Performance Adaptations"],"prefix":"10.3390","volume":"25","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4819-0619","authenticated-orcid":false,"given":"Olli-Pekka","family":"Nuuttila","sequence":"first","affiliation":[{"name":"Faculty of Sport and Health Sciences, University of Jyv\u00e4skyl\u00e4, 40014 Jyv\u00e4skyl\u00e4, Finland"},{"name":"UKK Institute for Health Promotion Research, 33500 Tampere, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Daniela","family":"Sch\u00e4fer Olstad","sequence":"additional","affiliation":[{"name":"Polar Electro Oy, 90440 Kempele, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kaisu","family":"Martinm\u00e4ki","sequence":"additional","affiliation":[{"name":"Polar Electro Oy, 90440 Kempele, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5177-0273","authenticated-orcid":false,"given":"Arja","family":"Uusitalo","sequence":"additional","affiliation":[{"name":"Department of Sports and Exercise Medicine, Clinicum, University of Helsinki, 00014 Helsinki, Finland"},{"name":"Helsinki Clinic for Sports and Exercise Medicine, Foundation for Sports and Exercise Medicine, 00550 Helsinki, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3822-1733","authenticated-orcid":false,"given":"Heikki","family":"Kyr\u00f6l\u00e4inen","sequence":"additional","affiliation":[{"name":"Faculty of Sport and Health Sciences, University of Jyv\u00e4skyl\u00e4, 40014 Jyv\u00e4skyl\u00e4, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,1,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1249\/FIT.0000000000000933","article-title":"2024 ACSM Worldwide Fitness Trends: Future Directions of the Health and Fitness Industry","volume":"28","author":"Newsome","year":"2024","journal-title":"ACSM\u2019s Health Fit. 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