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Zusammenfassung Wearable Devices versprechen durch ihre motivierende Wirkung einen wichtigen Beitrag zur Bindung des Individuums an körperlich-sportliche Aktivitäten und somit zum Aufbau und Erhalt von Gesundheit und Leistungsfähigkeit in Zeiten des digitalen gesellschaftlichen Wandels. Übergeordnetes Ziel der vorliegenden Untersuchung war die Beurteilung der Testgüte von Wearable Devices anhand eines marktrelevanten Gerätes, der Garmin fēnix® 5. Als Forschungsdesiderat wurde der Reliabilitätsaspekt der Methodenkonkordanz identifiziert. Zur Überprüfung der Methodenkonkordanz wurden das Stresslevel bei kognitiver Stressinduktion, der Kalorienverbrauch bei moderater Ausdauerlaufbelastung sowie die maximale Sauerstoffaufnahme bei Laufausbelastung von 30 männlichen Probanden (Alter: 23,13 ± 2,5 Jahre; BMI: 24,95 ± 2,45 kg/m2) mit der Garmin fēnix® 5 bestimmt und die Ergebnisse mit denen im Feld gängigen Referenzmethoden Elektrokardiographie, Indirekte Kalorimetrie bzw. Spiroergometrie verglichen. Zur rechnerischen Überprüfung der Methodenkonkordanz diente Lin’s Konkordanzkorrelationskoeffizient (CCCLin). Die Ergebnisse zeigen eine hohe Präzision der Garmin fēnix® 5 im Vergleich mit der Referenzmethode Elektrokardiographie hinsichtlich der Messung des notwendigerweise z-standardisierten Stressparameters (p = 0,89) sowie eine gerade mittlere exakte intrainidividuelle Konkordanz mit der Referenzmethode Indirekte Kalorimetrie bzw. Spiroergometrie hinsichtlich der Messung des Parameters Kalorienverbrauch (CCCLin = 0,43 [p = 0,52, Cb = 0,82]) bzw. maximale Sauerstoffaufnahme (CCCLin = 0,50 [p = 0,77, Cb = 0,66]). Die Garmin fēnix® 5 kann somit zumindest bei erstmaliger Verwendung nicht als hinreichend konkordante Alternative zu den gängigen aktivitäts- und leistungsbezogenen Referenzmethoden empfohlen werden.

Background In current sports science, the important role of sleep quality for health and peak performance is well acknowledged. More precisely, it is evident that the negative combination of stressful factors, low resources, and bad sleep habits causes short-term performance losses as well as long-term health consequences. As the maximization of human performance consisting of multiple fixed workloads is the main motivation in CrossFit® (CF), the aim of the present study was to investigate the influence of high sleep quality on performance in CrossFit® athletes (CFA) and the different training categories that are addressed in CF. Methods In total, 149 CFA (81 females, 68 males; 32.01 ± 7.49 years old, 2.56 ± 1.77 active years in CF) filled in the online survey comprising the Pittsburgh Sleep Quality Index (PSQI) and CF performance-specific questions. Results It was found that CFA with high sleep quality reported higher values in all performance-related outcomes. Especially in Hero-/Girl-Workouts (χ2 = (1, n = 83) = 9.92, p = .002, φ = 0.37) and Gymnastics (χ2 = (1, n = 129) = 8.74, p = .003, φ = 0.28), performance differed significantly between good and poor sleeping CFA. Since those CF categories are highly technical- and cognitive-demanding high sleep quality seems to play a fundamental role in complex motor skill learning and performance development. Conclusions These results reveal for the first time the positive effects of high sleep quality for performance in CFA and could be used as basis for future studies. Future research should also develop and empirically test suitable interventions to foster high sleep quality in CFA. Trial Registration: The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Ethics Committee of University of the Federal Armed Forces Munich, Germany (06/04/2018).

Nowadays, self-tracking and optimization are widely spread. As sleep is essential for well-being, health, and peak performance, the number of available consumer technologies to assess individual sleep behavior is increasing rapidly. However, little is known about the consumer wearables’ usability and reliability for sleep tracking. Therefore, the aim of the present study was to compare the sleep measures of wearable devices with a standardized sleep diary in young healthy adults in free-living conditions. We tracked night sleep from 30 participants (19 females, 11 males; 24.3 ± 4.2 years old). Each wore three wearables and simultaneously assessed individual sleep patterns for four consecutive nights. Wearables and diaries correlated substantially regarding time in bed (Range CCCLin: 0.74–0.84) and total sleep time (Range CCCLin: 0.76–0.85). There was no sufficient agreement regarding the measures of sleep efficiency (Range CCCLin: 0.05–0.34) and sleep interruptions (Range CCCLin: −0.02–0.10). Finally, these results show wearables to be an easy-to-handle, time- and cost-efficient alternative to tracking sleep in healthy populations. Future research should develop and empirically test the usability of such consumer sleep technologies.

Background Following and posting sport-related content on social media is wide-spread among young people. To date, little is known about the interdependence between sport-related social media use and the thereby perceived personal body image. Methods We conducted an online survey (N = 285) to examine how social media influences the sport-related body image. Results In general, social media are frequently used for sport (n = 136, 47.7%). Resistance training correlated significantly with several motives of sport-related use of social media, and thus, represents the strong online presence of athletic sports. Less correlations could be found in team or other sports. Regarding the perception of body image, it was found that the group of rejecting (negative) body image significantly correlated with the emulation of social media mediated sport-related beauty and body ideals (r = 0.63, p = 0.001), as well as with increased body dissatisfaction when viewing sport-related posts on social media (r = 0.590, p = 0.001). Perceived social pressure and comparison were found to be mediators of the prevailing influence of social media usage. Conclusions These results reveal the importance of taking a closer look at socially shaped beauty and body ideals, especially in sport-related contents, striving for more educational campaigns such as Body Positivity and, above all, filtering information. Finally, future research is needed to gain deeper insight into young persons’ usage behavior of social media and its impact on the individual’s body image. Trial Registration The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Ethics Committee of University of the Federal Armed Forces Munich, Germany (01/24/2022).