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Melissa Skein, Rob Duffield, Geoffrey M. Minett, Alanna Snape and Alistair Murphy

Purpose:

This study examined the effects of overnight sleep deprivation on recovery after competitive rugby league matches.

Methods:

Eleven male amateur rugby league players played 2 competitive matches, followed by either a normal night’s sleep (~8 h; CONT) or a sleep-deprived night (~0 h; SDEP) in a randomized fashion. Testing was conducted the morning of the match, immediately postmatch, 2 h postmatch, and the next morning (16 h postmatch). Measures included countermovement-jump (CMJ) distance, knee-extensor maximal voluntary contraction (MVC) and voluntary activation (VA), venous-blood creatine kinase (CK) and C-reactive protein (CRP), perceived muscle soreness, and a word–color recognition cognitive-function test. Percent change between postmatch and 16-h postmatch was reported to determine the effect of the intervention the next morning.

Results:

Large effects indicated a greater postmatch to 16-h-postmatch percentage decline in CMJ distance after SDEP than in CONT (P = .10–.16, d = 0.95–1.05). Similarly, the percentage decline in incongruent word–color reaction times was increased in SDEP trials (P = .007, d = 1.75). Measures of MVC did not differ between conditions (P = .40–.75, d = 0.13–0.33), although trends for larger percentage decline in VA were detected in SDEP (P = .19, d = 0.84). Furthermore, large effects indicated higher CK and CRP responses 16 h postmatch in SDEP than in CONT (P = .11–.87, d = 0.80–0.88).

Conclusions:

Sleep deprivation negatively affected recovery after a rugby league match, specifically impairing CMJ distance and cognitive function. Practitioners should promote adequate postmatch sleep patterns or adjust training demands the next day to accommodate the altered physical and cognitive state after sleep deprivation.

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Christian Cook, C. Martyn Beaven, Liam P. Kilduff and Scott Drawer

Introduction:

This study aimed to determine whether caffeine ingestion would increase the workload voluntarily chosen by athletes in a limited-sleep state.

Methods:

In a double-blind, crossover study, 16 professional rugby players ingested either a placebo or 4 mg/kg caffeine 1 hr before exercise. Athletes classified themselves into nondeprived (8 hr+) or sleep-deprived states (6 hr or less). Exercise comprised 4 sets of bench press, squats, and bent rows at 85% 1-repetition maximum. Athletes were asked to perform as many repetitions on each set as possible without failure. Saliva was collected before administration of placebo or caffeine and again before and immediately after exercise and assayed for testosterone and cortisol.

Results:

Sleep deprivation produced a very large decrease in total load (p = 1.98 × 10−7). Caffeine ingestion in the nondeprived state resulted in a moderate increase in total load, with a larger effect in the sleep-deprived state, resulting in total load similar to those observed in the nondeprived placebo condition. Eight of the 16 athletes were identified as caffeine responders. Baseline testosterone was higher (p < .05) and cortisol trended lower in non-sleep-deprived athletes. Changes in hormones from predose to preexercise correlated to individual workload responses to caffeine. Testosterone response to exercise increased with caffeine compared with placebo, as did cortisol response.

Conclusions:

Caffeine increased voluntary workload in professional athletes, even more so under conditions of self-reported limited sleep. Caffeine may prove worthwhile when athletes are tired, especially in those identified as responders.

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Kazuto Omiya, Yoshihiro J Akashi, Kihei Yoneyama, Naohiko Osada, Kazuhiko Tanabe and Fumihiko Miyake

The aim of this study was to clarify the mechanism of impaired exercise tolerance in chronic sleep-restricted conditions by investigating variables related to heart-rate (HR) response to sympathetic nervous stimulation. Sixteen healthy men (mean age 21.5 years) were tested in a control state, acute sleep-loss state, and chronic sleeprestricted state. Participants underwent cardiopulmonary exercise testing in each state. Their norepinephrine (NE) concentration was measured before and immediately after exercise. Intracellular magnesium (Mg) concentration was measured in a resting state. Exercise duration was shorter and the ratio of HR response to the percentage increase in NE was higher in the chronic sleep-restricted state than in the control state. Intracellular Mg gradually decreased from control to chronic sleep restriction. There was a negative correlation between peak exercise duration and the ratios of HR response to the rate of increase in NE. Intracellular Mg was positively correlated with the ratios of HR response to the increase in NE both in control and in acute sleep loss. The authors conclude that the impaired exercise tolerance in a chronic sleep-restricted state is caused by hypersensitivity of the HR response to sympathetic nervous stimulation, which showed a compensation for decreased intracellular Mg concentration.

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Francis Degache, Jean-Benoît Morin, Lukas Oehen, Kenny Guex, Guido Giardini, Federico Schena, Guillaume Y. Millet and Grégoire P. Millet

The aim of study was to examine the effects of the world’s most challenging mountain ultramarathon (Tor des Géants [TdG]) on running mechanics. Mechanical measurements were undertaken in male runners (n = 16) and a control group (n = 8) before (PRE), during (MID), and after (POST) the TdG. Contact (t c) and aerial (t a) times, step frequency (f), and running velocity (v) were sampled. Spring-mass parameters of peak vertical ground-reaction force (F max), vertical downward displacement of the center of mass (Δz), leg-length change (ΔL), and vertical (k vert) and leg (k leg) stiffness were computed. Significant decreases were observed in runners between PRE and MID for t a (P < .001), F max (P < .001), Δz (P < .05), and k leg (P < .01). In contrast, f significantly increased (P < .05) between PRE and MID-TdG. No further changes were observed at POST for any of those variables, with the exception of k leg, which went back to PRE. During the TdG, experienced runners modified their running pattern and spring-mass behavior mainly during the first half. The current results suggest that these mechanical changes aim at minimizing the pain occurring in lower limbs mainly during the eccentric phases. One cannot rule out that this switch to a “safer” technique may also aim to anticipate further damages.

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Giovanna Ghiani, Sara Magnani, Azzurra Doneddu, Gianmarco Sainas, Virginia Pinna, Marco Caboi, Girolamo Palazzolo, Filippo Tocco and Antonio Crisafulli

involve circumnavigation of the globe and can last more than 100 days. During Solo races, the sailor is exposed to many consecutive bouts of high-intensity physical activity ( Myers et al., 2008 ). The level of physiological stress depends on many factors, such as weather conditions, craft model, sleep

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Lara A. Carlson, Kaylee M. Pobocik, Michael A. Lawrence, Daniel A. Brazeau and Alexander J. Koch

Adequate sleep is an important element for both health and performance, especially among elite athletes. According to the National Sleep Foundation, there have been consistent findings of exercise improving total sleep time and quality of sleep. 1 Sleep deprivation alters cognition, pain, mood

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Alice K. Lindeman

Meeting the energy demands of ultraendurance cycling requires careful planning and monitoring of food and fluid intake. This case study presents the nutrient intake of a cyclist while training for and competing in the Race Across AMerica (RAAM). Carbohydrate accounted for 65% of the calories consumed during training (4,743 kcal), 75% during 24-hr races (10,343 kcal), and 78% during RAAM (8,429 kcal). Gastrointestinal complaints during RAAM included nausea, feeling of fullness, and abdominal distension. Although probably exacerbated by sleep deprivation, these problems were all diet related. Based on this experience, it appears that by controlling the carbohydrate concentration of beverages, limiting dietary fiber, and relying on carbohydrate as the primary energy source, one could both control gastrointestinal symptoms and promote optimal performance in training and in ultramarathon cycling.

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Emma L. Sweeney, Daniel J. Peart, Irene Kyza, Thomas Harkes, Jason G. Ellis and Ian H. Walshe

appears to be a promising intervention to alleviate the impairment in insulin sensitivity following total sleep deprivation. Two weeks of high-intensity exercise training has been shown to attenuate the insulin response to an oral glucose tolerance test after one night of total sleep deprivation ( de

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Anis Kamoun, Omar Hammouda, Abdelmoneem Yahia, Oussema Dhari, Houcem Ksentini, Tarak Driss, Nizar Souissi and Mohamed Habib Elleuch

, Cheng, & Kerr, 2012 ). Obviously, sleep deprivation could affect postural control leading to increased fall risk ( Patel et al., 2008 ). Particularly, it has been shown that the effect of sleep deprivation on postural control is more clear in the elderly than in the young ( Robillard, Prince, Filipini

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Sigridur L. Gudmundsdottir

after a continuous sleep deprivation for up to 50 hours ( 22 ) or partial sleep deprivation for up to 4 nights ( 33 ). In summary, the authors found that reducing athletes’ sleep for a few nights did not affect their ability to sustain maximal exercise intensity during cycling and running tests. On the