Effects of simulated domestic and international air travel on sleep, performance, and recovery for team sports

© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. The present study examined effects of simulated air travel on physical performance. In a randomized crossover design, 10 physically active males completed a simulated 5-h domestic flight (DOM), 24-h simulated international travel (INT), and a control trial (CON). The mild hypoxia, seating arrangements, and activity levels typically encountered during air travel were simulated in a normobaric, hypoxic altitude room. Physical performance was assessed in the afternoon of the day before (D-1 PM) and in the morning (D+1 AM) and afternoon (D+1 PM) of the day following each trial. Mood states and physiological and perceptual responses to exercise were also examined at these time points, while sleep quantity and quality were monitored throughout each condition. Sleep quantity and quality were significantly reduced during INT compared with CON and DOM (P0.05). Compared with baseline, physiological and perceptual responses to exercise, and mood states were exacerbated following the INT trial (P<0.05). Attenuated intermittent-sprint performance following simulated international air travel may be due to sleep disruption during travel and the subsequent exacerbated physiological and perceptual markers of fatigue

Bounds and comparisons of the loss ratio in queues driven by an M/M/∞ source.

We obtain upper bounds for the loss probability in a queue driven by an M/M/∞ source. The bound is compared with exact numerical results, and with bounds for two related arrivals models: superposed two state Markov fluids, and the Ornstein—Uhlenbeck process. The bounds are shown to behave continuously through approximation procedures relating the models

Desperate Prawns: Drivers of Behavioural Innovation Vary across Social Contexts in Rock Pool Crustaceans

Innovative behaviour may allow animals to cope with changes in their environment. Innovative propensities are known to vary widely both between and within species, and a growing body of research has begun to examine the factors that drive individuals to innovate. Evidence suggests that individuals are commonly driven to innovate by necessity; for instance by hunger or because they are physically unable to outcompete others for access to resources. However, it is not known whether the factors that drive individuals to innovate are stable across contexts. We examined contextual variation in the drivers of innovation in rock pool prawns (Palaemon spp), invertebrates that face widely fluctuating environments and may, through the actions of tides and waves, find themselves isolated or in groups. Using two novel foraging tasks, we examined the effects of body size and hunger in prawns tested in solitary and group contexts. When tested alone, small prawns were significantly more likely to succeed in a spatial task, and faster to reach the food in a manipulation task, while hunger state had no effect. In contrast, size had no effect when prawns were tested in groups, but food-deprived individuals were disproportionately likely to innovate in both tasks. We suggest that contextual variation in the drivers of innovation is likely to be common in animals living in variable environments, and may best be understood by considering variation in the perception of relative risks and rewards under different conditions.Biotechnology and Biological Sciences Research Council (BBSRC) - David Phillips Fellowshi

Prenatal programming of postnatal obesity: fetal nutrition and the regulation of leptin synthesis and secretion before birth

Exposure to either an increased or decreased level of intrauterine nutrition can result in an increase in adiposity and in circulating leptin concentrations in later life. In animals such as the sheep and pig in which fat is deposited before birth, leptin is synthesised in fetal adipose tissue and is present in the fetal circulation throughout late gestation. In the sheep a moderate increase or decrease in the level of maternal nutrition does not alter fetal plasma leptin concentrations, but there is evidence that chronic fetal hyperglycaemia and hyperinsulinaemia increase fetal fat mass and leptin synthesis within fetal fat depots. Importantly, there is a positive relationship between the relative mass of the ‘unilocular’ component of fetal perirenal and interscapular adipose tissue and circulating fetal leptin concentrations in the sheep. Thus, as in the neonate and adult, circulating leptin concentrations may be a signal of fat mass in fetal life. There is also evidence that leptin can act to regulate the lipid storage, leptin synthetic capacity and potential thermogenic functions of fat before birth. Thus, leptin may act as a signal of energy supply and have a ‘lipostatic’ role before birth. Future studies are clearly required to determine whether the intrauterine and early postnatal nutrient environment programme the endocrine feedback loop between adipose tissue and the central and peripheral neuroendocrine systems that regulate energy balance, resulting in an enhanced risk of obesity in adult life.I. C. McMillen, B. S. Muhlhausler, J. A. Duffield and B. S. J. Yue

Effect of Training/Competition Load and Scheduling on Sleep Characteristics in Professional Rugby League Athletes.

AbstractConlan, G, McLean, B, Kemp, J, and Duffield, R. Effect of training/competition load and scheduling on sleep characteristics in professional rugby league athletes. J Strength Cond Res XX(X): 000-000, 2021-This study examined the effect of training/competition load, scheduling, and associated factors on sleep behavior in professional rugby league athletes. Sleep characteristics were assessed in 26 professional rugby league athletes using wrist-mounted actigraphy and nightly sleep diaries. Sleep actigraphy assessed the time into and out of bed, the duration in bed, sleep duration, efficiency, latency, wake after sleep onset, number of awakenings, and the awakening length. Sleep was measured during 3 different weeks: (a) preseason low training load (TL) (2,356 ± 322 AU), (b) preseason high TL (3,542 ± 445 AU), and (c) in-season match week (1,526 ± 409 AU). The influences of internal TL (session rating of perceived exertion load), training schedule, age, and training location on sleep behavior were analyzed. Repeated-measures 2-way analysis of variance and effect size analyses (d) compared sleep variables between training weeks. The mean weekly sleep duration was significantly lower during high TL week (5 hours 53minutes ± 14 min/night; p = 0.015, d = 0.59) compared with the low TL (6 hours 25minutes ± 8 min·night-1) or match weeks (6 hours 26minutes ± 10 min·night-1; p = 0.02, d = 2.04). Reduced sleep duration in the high TL week occurred alongside earlier out-of-bed times compared with the low TL (p = 0.003, d = 1.46) and match weeks (p = 0.001, d = 5.99). Regardless, the lowest sleep duration was on match night (p = 0.0001, d = 1.22). Earlier training start times resulted in earlier wake times (p = 0.003, d = 4.84), shorter in-bed durations (p = 0.0001, d = 0.62), and shorter sleep durations (p = 0.002, d = 0.32). Younger athletes slept for longer durations (p = 0.029, d = 1.70) and perceived their sleep quality to be superior (p = 0.006, d = 14.94) compared with older athletes. Sleep attained by rugby league athletes is influenced by training and competition schedules, with early training start times and late-night matches being primary drivers of sleep behavior. Coaching staff should have awareness surrounding the implications of training and playing schedules on athlete sleeping patterns