Trent A. Hargens, FACSM, Tara L. Thompson, Nicki Stallings, Nicholas D. Luden. James Madison University, Harrisonburg, VA.

Sleep is a vital component of health and wellness. Poor sleep has been shown to significantly impact athletic performance. Most research, however, has focused on several days or more of sleep deprivation. Sleep fragmentation is defined as multiple arousals during the night, which may impact an athlete before an important event due to pre-competition anxiety. PURPOSE: To examine the effect of one night of sleep fragmentation (SF) on cycle time trial (TT) performance compared to a night of normal sleep (NS). METHODS: Eight active individuals [age = 20.4 ± 1.7 yr.; body mass index (BMI) = 22.0 ± 2.1; VO2max = 41.1 ± 9.8 mL.kg-1.min-1] completed 3 performance trials (1 familiarization and 2 experimental) consisting of a 3-kilometer time trial (TT) on a cycle ergometer. Trials were performed after NS (6-8 hours) or SF. The SF condition consisted of being awakened at least one time per hour of sleep for 8 hours. The trials were performed at the same time of day (8:00 - 10:00 am), with randomly counter-balances sleep conditions. Diet was replicated prior to each trial and physical activity was monitored for 48 hours prior to each trial with accelerometer. Sleep was monitored via accelerometry the night of the experimental trials to confirm sleep duration. Data are presented as means ± SD. RESULTS: There was no difference in peak power (294 ± 107 vs. 306 ± 123 Watts for SF and NS, respectively; P = 0.7), average heart rate (162 ± 16 vs. 168 beats.min-1 ± 12; P = 0.5), or TT finish time (5.6 ± 1.0 vs. 5.5 ± 1.0 minutes; P = 0.1) between the experimental trials. Average TT power trended towards significance (211 ± 83 vs. 228 ± 100 Watts for SF and NS, respectively; P = 0.08). Peak TT oxygen consumption was lower during the SF trial (43.6 ± 12.3 mL.kg-1.min-1) compared to the NS trial (47.9 ± 11.5 mL.kg-1.min-1; P = 0.017), while average oxygen consumption trended lower during the SF trial (37.0 ± 11.5 mL.kg-1.min-1) compared to NS (44.6 ± 14.2 mL.kg-1.min-1, P = 0.07). CONCLUSION: Results showed that SF may impact subsequent 3-km TT performance, reflected by a lower peak VO2 and a trend towards lower average power output and oxygen consumption, although there were no differences in TT finish time. Further research with a larger sample size is needed to make more definitive conclusions about the potential consequences of SF.

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