The effect of caffeine on subsequent sleep: A systematic review and meta-analysis.

The consumption of caffeine in response to insufficient sleep may impair the onset and maintenance of subsequent sleep. This systematic review and meta-analysis investigated the effect of caffeine on the characteristics of night-time sleep, with the intent to identify the time after which caffeine should not be consumed prior to bedtime. A systematic search of the literature was undertaken with 24 studies included in the analysis. Caffeine consumption reduced total sleep time by 45 min and sleep efficiency by 7%, with an increase in sleep onset latency of 9 min and wake after sleep onset of 12 min. Duration (+6.1 min) and proportion (+1.7%) of light sleep (N1) increased with caffeine intake and the duration (-11.4 min) and proportion (-1.4%) of deep sleep (N3 and N4) decreased with caffeine intake. To avoid reductions in total sleep time, coffee (107 mg per 250 mL) should be consumed at least 8.8 h prior to bedtime and a standard serve of pre-workout supplement (217.5 mg) should be consumed at least 13.2 h prior to bedtime. The results of the present study provide evidence-based guidance for the appropriate consumption of caffeine to mitigate the deleterious effects on sleep.

Optimisation and Validation of a Nutritional Intervention to Enhance Sleep Quality and Quantity.

BACKGROUND: Disturbed sleep may negatively influence physical health, cognitive performance, metabolism, and general wellbeing. Nutritional interventions represent a potential non-pharmacological means to increase sleep quality and quantity. OBJECTIVE: (1) Identify an optimal suite of nutritional ingredients and (2) validate the effects of this suite utilising polysomnography, and cognitive and balance tests. METHODS: The optimal and least optimal combinations of six ingredients were identified utilising 55 male participants and a Box-Behnken predictive model. To validate the model, 18 healthy, male, normal sleepers underwent three trials in a randomised, counterbalanced design: (1) optimal drink, (2) least optimal drink, or (3) placebo were provided before bed in a double-blinded manner. Polysomnography was utilised to measure sleep architecture. Cognitive performance, postural sway, and subjective sleep quality, were assessed 30 min after waking. RESULTS: The optimal drink resulted in a significantly shorter sleep onset latency (9.9 ± 12.3 min) when compared to both the least optimal drink (26.1 ± 37.4 min) and the placebo drink (19.6 ± 32.0 min). No other measures of sleep, cognitive performance, postural sway, and subjective sleep quality were different between trials. CONCLUSION: A combination of ingredients, optimised to enhance sleep, significantly reduced sleep onset latency. No detrimental effects on sleep architecture, subjective sleep quality or next day performance were observed.

International Association of Athletics Federations Consensus Statement 2019: Nutrition for Athletics.

The International Association of Athletics Federations recognizes the importance of nutritional practices in optimizing an Athlete's well-being and performance. Although Athletics encompasses a diverse range of track-and-field events with different performance determinants, there are common goals around nutritional support for adaptation to training, optimal performance for key events, and reducing the risk of injury and illness. Periodized guidelines can be provided for the appropriate type, amount, and timing of intake of food and fluids to promote optimal health and performance across different scenarios of training and competition. Some Athletes are at risk of relative energy deficiency in sport arising from a mismatch between energy intake and exercise energy expenditure. Competition nutrition strategies may involve pre-event, within-event, and between-event eating to address requirements for carbohydrate and fluid replacement. Although a "food first" policy should underpin an Athlete's nutrition plan, there may be occasions for the judicious use of medical supplements to address nutrient deficiencies or sports foods that help the athlete to meet nutritional goals when it is impractical to eat food. Evidence-based supplements include caffeine, bicarbonate, beta-alanine, nitrate, and creatine; however, their value is specific to the characteristics of the event. Special considerations are needed for travel, challenging environments (e.g., heat and altitude); special populations (e.g., females, young and masters athletes); and restricted dietary choice (e.g., vegetarian). Ideally, each Athlete should develop a personalized, periodized, and practical nutrition plan via collaboration with their coach and accredited sports nutrition experts, to optimize their performance.

Influence of body composition on physiological responses to post-exercise hydrotherapy.

This study examined the influence of body composition on temperature and blood flow responses to post-exercise cold water immersion (CWI), hot water immersion (HWI) and control (CON). Twenty-seven male participants were stratified into three groups: 1) low mass and low fat (LM-LF); 2) high mass and low fat (HM-LF); or 3) high mass and high fat (HM-HF). Experimental trials involved a standardised bout of cycling, maintained until core temperature reached 38.5°C. Participants subsequently completed one of three 15-min recovery interventions (CWI, HWI, or CON). Core, skin and muscle temperatures, and limb blood flow were recorded at baseline, post-exercise, and every 30 min following recovery for 240 min. During CON and HWI there were no differences in core or muscle temperature between body composition groups. The rate of fall in core temperature following CWI was greater in the LM-LF (0.03 ± 0.01°C/min) group compared to the HM-HF (0.01 ± 0.001°C/min) group (P = 0.002). Muscle temperature decreased to a greater extent during CWI in the LM-LF and HM-LF groups (8.6 ± 3.0°C) compared with HM-HF (5.1 ± 2.0°C, P < 0.05). Blood flow responses did not differ between groups. Differences in body composition alter the thermal response to post-exercise CWI, which may explain some of the variance in the responses to CWI recovery.

The Effects of the Removal of Electronic Devices for 48 Hours on Sleep in Elite Judo Athletes.

This study examined the effects of evening use of electronic devices (i.e., smartphones, etc.) on sleep quality and next-day athletic and cognitive performance in elite judo athletes. Over 6 consecutive days and nights, 23 elite Australian judo athletes were monitored while attending a camp at the Australian Institute of Sport (AIS). In 14 athletes, all electronic devices were removed on days 3 and 4 (i.e., for 48 hours: the "device-restricted group"), whereas 9 were permitted to use their devices throughout the camp (the "control group"). All athletes wore an activity monitor (Readiband) continuously to provide measures of sleep quantity and quality. Other self-reported (diary) measures included time in bed, electronic device use, and rate of perceived exertion during training periods. Cognitive performance (Cogstate) and physical performance (single leg triple hop test) were also measured. When considering night 2 as a "baseline" for each group, removal of electronic devices on nights 3 and 4 (device-restricted group) resulted in no significant differences in any sleep-related measure between the groups. When comparing actigraphy-based measures of sleep to subjective measures, all athletes significantly overestimated sleep duration by 58 ± 85 minutes (p = 0.001) per night and underestimated time of sleep onset by 37 ± 72 minutes (p = 0.001) per night. No differences in physical or cognitive function were observed between the groups. CONCLUSION: This study has shown that the removal of electronic devices for a period of two nights (48 hours) during a judo camp does not affect sleep quality or quantity or influence athletic or cognitive performance.

Physical Activity Performed in the Evening Increases the Overnight Muscle Protein Synthetic Response to Presleep Protein Ingestion in Older Men.

BACKGROUND: The age-related decline in skeletal muscle mass is partly attributed to anabolic resistance to food intake. Dietary protein ingestion before sleep could be used as a nutritional strategy to compensate for anabolic resistance. OBJECTIVE: The present study assessed whether physical activity performed in the evening can augment the overnight muscle protein synthetic response to presleep protein ingestion in older men. METHODS: In a parallel group design, 23 healthy older men (mean ± SEM age: 71 ± 1 y) were randomly assigned to ingest 40 g protein intrinsically labeled with l-[1-(13)C]-phenylalanine and l-[1-(13)C]-leucine before going to sleep with (PRO+EX) or without (PRO) performing physical activity earlier in the evening. Overnight protein digestion and absorption kinetics and myofibrillar protein synthesis rates were assessed by combining primed, continuous infusions of l-[ring-(2)H5]-phenylalanine, l-[1-(13)C]-leucine, and l-[ring-(2)H2]-tyrosine with the ingestion of intrinsically labeled casein protein. Muscle and blood samples were collected throughout overnight sleep. RESULTS: Protein ingested before sleep was normally digested and absorbed, with 54% ± 2% of the protein-derived amino acids appearing in the circulation throughout overnight sleep. Overnight myofibrillar protein synthesis rates were 31% (0.058% ± 0.002%/h compared with 0.044% ± 0.003%/h; P < 0.01; based on l-[ring-(2)H5]-phenylalanine) and 27% (0.074% ± 0.004%/h compared with 0.058% ± 0.003%/h; P < 0.01; based on l-[1-(13)C]-leucine) higher in the PRO+EX than in the PRO treatment. More dietary protein-derived amino acids were incorporated into de novo myofibrillar protein during overnight sleep in PRO+EX than in PRO treatment (0.042 ± 0.002 compared with 0.033 ± 0.002 mole percent excess; P < 0.05). CONCLUSIONS: Physical activity performed in the evening augments the overnight muscle protein synthetic response to presleep protein ingestion and allows more of the ingested protein-derived amino acids to be used for de novo muscle protein synthesis during overnight sleep in older men. This trial was registered at Nederlands Trial Register as NTR3885.

Nitrate supplementation and high-intensity performance in competitive cyclists.

Consumption of inorganic nitrate (NO3(-)) is known to enhance endurance exercise performance in recreationally trained subjects. Here we report the effect on a high-intensity performance task in national-level cyclists. The performance test consisted of 2 cycle ergometer time trials of 4 min duration with 75 min between trials. In a randomized crossover design, 26 cyclists performed the test under the following 4 conditions (each separated by a 6-day washout): consumption of 70 mL of nitrate-rich beetroot juice at 150 min or 75 min before the first time trial, addition of a 35 mL "top-up dose" following the first time trial in the 150 min condition, and consumption of a placebo. A linear mixed model with adjustments for learning effects and athlete fitness (peak incremental power) was used to estimate effects on mean power, with probabilistic inferences based on a smallest important effect of 1.0%. Peak plasma nitrite (NO2(-)) concentration was greatest when nitrate was taken 75 min before the first time trial. Relative to placebo, the mean effect of all 3 nitrate treatments was unclear in the first time trial (1.3%, 90% confidence limits: ±1.7%), but possibly harmful in the second time trial (-0.3%, ±1.6%). Differences between nitrate treatments were unclear, as was the estimate of any consistent individual response to the treatments. Allowing for sampling uncertainty, the effect of nitrate on performance was less than previous studies. Under the conditions of our experiment, nitrate supplementation may be ineffective in facilitating high-intensity exercise in competitive athletes.

Influence of contrast shower and water immersion on recovery in elite netballers.

Contrast water therapy is a popular recovery modality in sport; however, appropriate facilities can often be difficult to access. Therefore, the present study examined the use of contrast showers as an alternative to contrast water therapy for team sport recovery. In a randomized, crossover design, 10 elite female netball athletes (mean ± SD: age, 20 ± 0.6 years; height, 1.82 ± 0.05 m; body mass, 77.0 ± 9.3 kg) completed 3 experimental trials of a netball specific circuit followed by one of the following 14-minute recovery interventions: (a) contrast water therapy (alternating 1 minute 38° C and 1 minute 15° C water immersion), (b) contrast showers (alternating 1 minute 38° C and 1 minute 18° C showers), or (c) passive recovery (seated rest in 20° C). Repeated agility, skin and core temperature, and perception scales were measured before, immediately after, 5 and 24 hours postexercise. No significant differences in repeated agility were evident between conditions at any time point. No significant differences in core temperature were observed between conditions; however, skin temperature was significantly lower immediately after contrast water therapy and contrast showers compared with the passive condition. Overall perceptions of recovery were superior after contrast water therapy and contrast showers compared with passive recovery. The findings indicate contrast water therapy and contrast showers did not accelerate physical recovery in elite netballers after a netball specific circuit; however, the psychological benefit from both interventions should be considered when determining the suitability of these recovery interventions in team sport.

Does hydrotherapy help or hinder adaptation to training in competitive cyclists?

PURPOSE: Cold water immersion (CWI) may be beneficial for acute recovery from exercise, but it may impair long-term performance by attenuating the stimuli responsible for adaptation to training. We compared effects of CWI and passive rest on cycling performance during a simulated cycling grand tour. METHODS: Thirty-four male endurance-trained competitive cyclists were randomized to CWI for four times per week for 15 min at 15°C or control (passive recovery) groups for 7 d of baseline training, 21 d of intensified training, and an 11-d taper. Criteria for completion of training and testing were satisfied by 10 cyclists in the CWI group (maximal aerobic power, 5.13 ± 0.21 W·kg; mean ± SD) and 11 in the control group (5.01 ± 0.41 W·kg). Each week, cyclists completed a high-intensity interval cycling test and two 4-min bouts separated by 30 min. CWI was performed four times per week for 15 min at 15°C. RESULTS: Between baseline and taper, cyclists in the CWI group had an unclear change in overall 4-min power relative to control (2.7% ± 5.7%), although mean power in the second effort relative to the first was likely higher for the CWI group relative to control (3.0% ± 3.8%). The change in 1-s maximum mean sprint power in the CWI group was likely beneficial compared with control (4.4% ± 4.2%). Differences between groups for the 10-min time trial were unclear (-0.4% ± 4.3%). CONCLUSION: Although some effects of CWI on performance were unclear, data from this study do not support recent speculation that CWI is detrimental to performance after increased training load in competitive cyclists.

Effect of contrast water therapy duration on recovery of running performance.

PURPOSE: To investigate whether contrast water therapy (CWT) assists acute recovery from high-intensity running and whether a dose-response relationship exists. METHODS: Ten trained male runners completed 4 trials, each commencing with a 3000-m time trial, followed by 8 × 400-m intervals with 1 min of recovery. Ten minutes postexercise, participants performed 1 of 4 recovery protocols: CWT, by alternating 1 min hot (38°C) and 1 min cold (15°C) for 6 (CWT6), 12 (CWT12), or 18 min (CWT18), or a seated rest control trial. The 3000-m time trial was repeated 2 h later. RESULTS: 3000-m performance slowed from 632 ± 4 to 647 ± 4 s in control, 631 ± 4 to 642 ± 4 s in CWT6, 633 ± 4 to 648 ± 4 s in CWT12, and 631 ± 4 to 647 ± 4 s in CWT18. Following CWT6, performance (smallest worthwhile change of 0.3%) was substantially faster than control (87% probability, 0.8 ± 0.8% mean ± 90% confidence limit), however, there was no effect for CWT12 (34%, 0.0 ± 1.0%) or CWT18 (34%, -0.1 ± 0.8%). There were no substantial differences between conditions in exercise heart rates, or postexercise calf and thigh girths. Algometer thigh pain threshold during CWT12 was higher at all time points compared with control. Subjective measures of thermal sensation and muscle soreness were lower in all CWT conditions at some post-water-immersion time points compared with control; however, there were no consistent differences in whole body fatigue following CWT. CONCLUSIONS: Contrast water therapy for 6 min assisted acute recovery from high-intensity running; however, CWT duration did not have a dose-response effect on recovery of running performance.

Does the time frame between exercise influence the effectiveness of hydrotherapy for recovery?

An increase in research investigating recovery strategies has occurred alongside the increase in usage of recovery by elite athletes. Because there is inconsistent evidence regarding the benefits of recovery on performance, it is necessary to examine research design to identify possible strategies that enhance performance in different athlete settings. The purpose of this review is to examine available recovery literature specifically related to the time frame between performance assessments to identify considerations for both research design and practical use of recovery techniques.

Effects of carbohydrate supplementation on performance and carbohydrate oxidation after intensified cycling training.

To study the effects of carbohydrate (CHO) supplementation on performance changes and symptoms of overreaching, six male endurance cyclists completed 1 wk of normal (N), 8 days of intensified (ITP), and 2 wk of recovery training (R) on two occasions in a randomized crossover design. Subjects completed one trial with a 6% CHO solution provided before and during training and a 20% solution in the 1 h postexercise (H-CHO trial). On the other occasion, subjects consumed a 2% CHO solution at the same time points (L-CHO). A significant decline in time to fatigue at approximately 63% maximal power output (H-CHO: 17 +/- 3%; L-CHO: 26 +/- 7%) and a significant increase in mood disturbance occurred in both trials after ITP. The decline in performance was significantly greater in the L-CHO trial. After ITP, a significant decrease in estimated muscle glycogen oxidation (H-CHO: N 49.3 +/- 2.9 kcal/30 min, ITP 32.6 +/- 3.4 kcal/30 min; L-CHO: N 49.1 +/- 30 kcal/30 min, ITP 39.0 +/- 5.6 kcal/30 min) and increase in fat oxidation (H-CHO: N 16.3 +/- 2.4 kcal/30 min, ITP 27.8 +/- 2.3 kcal/30 min; L-CHO: N 16.9 +/- 2.6 kcal/30 min, ITP: 25.4 +/- 3.5 kcal/30 min) occurred alongside significant increases in glycerol and free fatty acids and decreases in free triglycerides in both trials. An interaction effect was observed for submaximal plasma concentrations of cortisol and epinephrine, with significantly greater reductions in these stress hormones in L-CHO compared with H-CHO after ITP. These findings suggest that CHO supplementation can reduce the symptoms of overreaching but cannot prevent its development. Decreased endocrine responsiveness to exercise may be implicated in the decreased performance and increased mood disturbance characteristic of overreaching.