Background
Use of Global positioning system (GPS) technology in team sport permits measurement of player position, velocity, and movement patterns. GPS provides scope for better understanding of the specific and positional physiological demands of team sport and can be used to design training programs that adequately prepare athletes for competition with the aim of optimizing on-field performance.

Global Positioning Systems (GPS) and Microtechnology Sensors in Team Sports: A Systematic Review

Short-duration sprints (<10 seconds), interspersed with brief recoveries (<60 seconds), are common during most team and racket sports. Therefore, the ability to recover and to reproduce performance in subsequent sprints is probably an important fitness requirement of athletes engaged in these disciplines, and has been termed repeated-sprint ability (RSA). This review (Part I) examines how fatigue manifests during repeated-sprint exercise (RSE), and discusses the potential underpinning muscular and neural mechanisms. A subsequent companion review to this article will explain a better understanding of the training interventions that could eventually improve RSA. Using laboratory and field-based protocols, performance analyses have consistently shown that fatigue during RSE typically manifests as a decline in maximal/mean sprint speed (i.e. running) or a decrease in peak power or total work (i.e. cycling) over sprint repetitions. A consistent result among these studies is that performance decrements (i.e. fatigue) during successive bouts are inversely correlated to initial sprint performance. To date, there is no doubt that the details of the task (e.g. changes in the nature of the work/recovery bouts) alter the time course/magnitude of fatigue development during RSE (i.e. task dependency) and potentially the contribution of the underlying mechanisms. At the muscle level, limitations in energy supply, which include energy available from phosphocreatine hydrolysis, anaerobic glycolysis and oxidative metabolism, and the intramuscular accumulation of metabolic by-products, such as hydrogen ions, emerge as key factors responsible for fatigue. Although not as extensively studied, the use of surface electromyography techniques has revealed that failure to fully activate the contracting musculature and/or changes in inter-muscle recruitment strategies (i.e. neural factors) are also associated with fatigue outcomes. Pending confirmatory research, other factors such as stiffness regulation, hypoglycaemia, muscle damage and hostile environments (e.g. heat, hypoxia) are also likely to compromise fatigue resistance during repeated-sprint protocols.

Repeated-Sprint Ability – Part I: Factors Contributing to Fatigue

Although its true function remains unclear, sleep is considered critical to human physiological and cognitive function. Equally, since sleep loss is a common occurrence prior to competition in athletes, this could significantly impact upon their athletic performance. Much of the previous research has reported that exercise performance is negatively affected following sleep loss; however, conflicting findings mean that the extent, influence, and mechanisms of sleep loss affecting exercise performance remain uncertain. For instance, research indicates some maximal physical efforts and gross motor performances can be maintained. In comparison, the few published studies investigating the effect of sleep loss on performance in athletes report a reduction in sport-specific performance. The effects of sleep loss on physiological responses to exercise also remain equivocal; however, it appears a reduction in sleep quality and quantity could result in an autonomic nervous system imbalance, simulating symptoms of the overtraining syndrome. Additionally, increases in pro-inflammatory cytokines following sleep loss could promote immune system dysfunction. Of further concern, numerous studies investigating the effects of sleep loss on cognitive function report slower and less accurate cognitive performance. Based on this context, this review aims to evaluate the importance and prevalence of sleep in athletes and summarises the effects of sleep loss (restriction and deprivation) on exercise performance, and physiological and cognitive responses to exercise. Given the equivocal understanding of sleep and athletic performance outcomes, further research and consideration is required to obtain a greater knowledge of the interaction between sleep and performance.

Sleep and athletic performance: the effects of sleep loss on exercise performance, and physiological and cognitive responses to exercise.

Sleep and exercise: a reciprocal issue?

Sleep has numerous important physiological and cognitive functions that may be particularly important to elite athletes. Recent evidence, as well as anecdotal information, suggests that athletes may experience a reduced quality and/or quantity of sleep. Sleep deprivation can have significant effects on athletic performance, especially submaximal, prolonged exercise. Compromised sleep may also influence learning, memory, cognition, pain perception, immunity and inflammation. Furthermore, changes in glucose metabolism and neuroendocrine function as a result of chronic, partial sleep deprivation may result in alterations in carbohydrate metabolism, appetite, food intake and protein synthesis. These factors can ultimately have a negative influence on an athlete’s nutritional, metabolic and endocrine status and hence potentially reduce athletic performance. Research has identified a number of neurotransmitters associated with the sleep–wake cycle. These include serotonin, gamma-aminobutyric acid, orexin, melanin-concentrating hormone, cholinergic, galanin, noradrenaline, and histamine. Therefore, nutritional interventions that may act on these neurotransmitters in the brain may also influence sleep. Carbohydrate, tryptophan, valerian, melatonin and other nutritional interventions have been investigated as possible sleep inducers and represent promising potential interventions. In this review, the factors influencing sleep quality and quantity in athletic populations are examined and the potential impact of nutritional interventions is considered. While there is some research investigating the effects of nutritional interventions on sleep, future research may highlight the importance of nutritional and dietary interventions to enhance sleep.

/pdf/sleep-in-elite-athletes-and-nutritional-interventions-to-3mddqtxhst.pdf

Sleep in elite athletes and nutritional interventions to enhance sleep.

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
To assess the effects of heat acclimation interventions aimed at protecting health and performance from exertional heat stress.

Heat acclimation for protection from exertional heat stress (Protocol)

A Comparison of Acute High- and Moderate-Intensity Exercise on Cardio- Metabolic Function and Sleep Among Shift Workers

Whilst non-motor experiences of daily living (NMeDL) reduce quality of life (QoL) in people with Parkinson's Disease (PD), research dedicated to NMeDL is lacking compared to motor symptoms. The aim of this Network Meta-Analysis (NMA) was to compare and determine the effects of exercise and dual-task training interventions on NMeDL for people with early-to-mid stage PD.Eight electronic databases were systematically searched, identifying randomised control trials (RCTs) that assessed the effect of interventions on the Movement Disease Society - Unified Parkinson's Disease Rating Scale (MDS-UPDRS); Part I scores. A fixed-effect pairwise and NMA were completed and confidence in estimates were assessed using the Confidence in Network Meta-Analysis (CINeMA) framework.Five RCTs involving exercise were identified, involving 218 participants. No dual-tasking studies were suitable. Pairwise comparisons favoured tango and mixed-treadmill training (TT) when compared to control, however 95% Confidence Intervals (CI) crossed the line of no effect (MD = 0). Indirect comparisons revealed tango had clinically meaningful reductions in Part I scores compared to speed-TT and body-weight resistance training, (MD -4.47; 95% CI -8.50 to -0.44 and MD -4.38; 95% CI -7.86 to -0.90), indicating improved NMeDL. Compared to control, low confidence evidence suggests tango and mixed-TT improves NMeDL.Tango and mixed-TT are the most effective exercise interventions for improving NMeDL. Adoption of an exercise program in the early stages of PD, irrespective of modality, may be effective and holds potential clinical importance immediately following a diagnosis of PD.Other: Prospero Registration Number; CRD42022322470. 

https://doi.org/10.1016/j.prdoa.2023.100203

Melissa Skein

Papers

Heat acclimation for protection from exertional heat stress (Protocol)

A Comparison of Acute High- and Moderate-Intensity Exercise on Cardio- Metabolic Function and Sleep Among Shift Workers

The effects of exercise on non-motor experiences of daily living experienced in Parkinson’s Disease: A systematic review and network meta-analysis