Strengthening recovery, enduring sleep. An ecologically valid assessment of sleep quantity and quality in hybrid athletes: does training mode matter?

Purpose This study assessed sleep characteristics in a sample of experienced “hybrid” athletes (i.e., athletes who participateand train for competitions that combine endurance and resistance tasks, e.g., Hyrox, Cross-Fit) to investigate the influence oftraining mode (i.e., resistance training and endurance training) on sleep quality, quantity, and architecture.Methods Eight male “Hyrox” athletes (23–32 years) wore a validated, non-invasive, ambulatory sleep monitoring deviceafter completing either a primarily resistance or endurance training bout, performed within a two-week period, consistingof a total two resistance and two endurance post-training nights evaluated. Objectively-measured sleep parameters analysedincluded: total sleep time (TST), sleep onset latency (SOL), wake after sleep onset (WASO), sleep architecture (sleep stagesproportion), and the number and duration of cardiac arousals occurring before and after sleep onset.Results Despite reporting ‘good’ overall sleep quality, hybrid athletes experienced shorter TST (~ 6.6 h) and spent ~ 5% lesstime in REM compared to reference non-athletes, but in-line with other sport populations. Compared to endurance training,resistance training was associated with longer SOL (29 vs. 10 min, p = 0.003) and shorter WASO (31 vs. 48 min, p = 0.008),with corresponding differences in cardiac arousals before and after sleep onset (13 vs. 5 events before SO, 81 vs. 99 eventsafter SO, respectively, p = 0.006 and p = 0.010).Conclusion Hybrid athletes presented sleep characteristics that differed depending on the training mode of their exercisebout. In particular, sleep latency and WASO time were positively associated with cardiac autonomic responses before andafter sleep onset.