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Journal: Sports medicine - open


Cannabidiol (CBD) is a non-intoxicating cannabinoid derived from Cannabis sativa. CBD initially drew scientific interest due to its anticonvulsant properties but increasing evidence of other therapeutic effects has attracted the attention of additional clinical and non-clinical populations, including athletes. Unlike the intoxicating cannabinoid, Δ9-tetrahydrocannabinol (Δ9-THC), CBD is no longer prohibited by the World Anti-Doping Agency and appears to be safe and well-tolerated in humans. It has also become readily available in many countries with the introduction of over-the-counter “nutraceutical” products. The aim of this narrative review was to explore various physiological and psychological effects of CBD that may be relevant to the sport and/or exercise context and to identify key areas for future research. As direct studies of CBD and sports performance are is currently lacking, evidence for this narrative review was sourced from preclinical studies and a limited number of clinical trials in non-athlete populations. Preclinical studies have observed robust anti-inflammatory, neuroprotective and analgesic effects of CBD in animal models. Preliminary preclinical evidence also suggests that CBD may protect against gastrointestinal damage associated with inflammation and promote healing of traumatic skeletal injuries. However, further research is required to confirm these observations. Early stage clinical studies suggest that CBD may be anxiolytic in “stress-inducing” situations and in individuals with anxiety disorders. While some case reports indicate that CBD improves sleep, robust evidence is currently lacking. Cognitive function and thermoregulation appear to be unaffected by CBD while effects on food intake, metabolic function, cardiovascular function, and infection require further study. CBD may exert a number of physiological, biochemical, and psychological effects with the potential to benefit athletes. However, well controlled, studies in athlete populations are required before definitive conclusions can be reached regarding the utility of CBD in supporting athletic performance.


Recent interest in barefoot running has led to the development of minimalist running shoes that are popular in distance runners. A careful transition to these shoes has been suggested and examined in the literature. However, no guidelines based on systematic evidence have been presented. The purpose of this review is to systematically examine the methods employed in the literature to transition to minimal footwear (MFW), as well as the outcomes to these studies in distance runners. In addition, MFW transition guidelines for future clinical practice will be presented based on observations from this review.

Concepts: Running


The test-retest reliability of the one-repetition maximum (1RM) test varies across different studies. Given the inconsistent findings, it is unclear what the true reliability of the 1RM test is, and to what extent it is affected by measurement-related factors, such as exercise selection for the test, the number of familiarization trials and resistance training experience.


Performance tests are used for multiple purposes in exercise and sport science. Ensuring that a test displays an appropriate level of measurement properties for use within a population is important to ensure confidence in test findings. The aim of this study was to obtain subject matter expert consensus on the measurement and feasibility properties that should be considered for performance tests used in the exercise and sport sciences and how these should be defined. This information was used to develop a checklist for broader dissemination.

Concepts: Scientific method, Measurement, Science, Test method, Theory, Subject matter, Sports science



Endurance athletes perform periodized training in order to prepare for main competitions and maximize performance. However, the coupling between alterations of total energy expenditure (TEE), energy intake, and body composition during different seasonal training phases is unclear. So far, no systematic review has assessed fluctuations in TEE, energy intake, and/or body composition in endurance athletes across the training season. The purpose of this study was to (1) systematically analyze TEE, energy intake, and body composition in highly trained athletes of various endurance disciplines and of both sexes and (2) analyze fluctuations in these parameters across the training season.

Concepts: Energy, Thermodynamics, Kinetic energy, Training, Performance, Season, Classical mechanics


Talent identification (TI) is a popular and hugely important topic within sports performance, with an ever-increasing amount of resources dedicated to unveiling the next sporting star. However, at present, most TI processes appear to select high-performing individuals at the present point in time, as opposed to identifying those individuals with the greatest capacity to improve. This represents a potential inefficiency within the TI process, reducing its effectiveness. In this article, we discuss whether the ability to adapt favorably, and with a large magnitude, to physical training can be considered a talent, testing it against proposed criteria. We also discuss whether, if such an ability can be considered a talent, being able to test for it as part of the TI process would be advantageous. Given that such a capacity is partially heritable, driven by genetic variation between individuals that mediate the adaptive response, we also explore whether the information gained from genetic profiling can be used to identify those with the greatest capacity to improve. Although there are some ethical hurdles which must be considered, the use of genetic information to identify those individuals with the greatest capacity appears to hold promise and may improve both the efficiency and effectiveness of contemporary TI programmes.

Concepts: DNA, Present, Time, Genetics, Contemporary history, Identification


While the words “fit” and “healthy” are often used synonymously in everyday language, the terms have entirely separate meanings. Fitness describes the ability to perform a given exercise task, and health explains a person’s state of well-being, where physiological systems work in harmony. Although we typically view athletes as fit and healthy, they often are not. The global term we place on unhealthy athletes is the overtraining syndrome. In this current opinion, we propose that two primary drivers may contribute to the development of the overtraining syndrome, namely high training intensity and the modern-day highly processed, high glycemic diet. Both factors elicit a sympathetic response through the hypothalamic-pituitary-adrenal axis, in turn driving systemic reactive oxygen species production, inflammation, and a metabolic substrate imbalance towards carbohydrate and away from fat oxidation, manifesting in an array of symptoms often labeled as the overtraining syndrome. Ultimately, these symptoms reveal an unhealthy athlete. We argue that practitioners, scientists, and athletes may work towards health and alleviate overtraining syndrome by lowering training intensity and removing processed and/or high glycemic foods from the diet, which together enhance fat oxidation rates. Athletes should be fit and healthy.

Concepts: Health care, Oxygen, Health, Human, Nutrition, Oxidative phosphorylation, Hydrogen peroxide, Glycemic index


Rapid restoration of muscle glycogen stores is imperative for athletes undertaking consecutive strenuous exercise sessions with limited recovery time (e.g. ≤ 8 h). Strategies to optimise muscle glycogen re-synthesis in this situation are essential. This two-part systematic review and meta-analysis investigated the effect of consuming carbohydrate (CHO) with and without protein (PRO) on the rate of muscle glycogen re-synthesis during short-term post-exercise recovery (≤ 8 h).


Non-steroidal anti-inflammatory drugs (NSAIDs) are medications that are frequently used by athletes. There may also be some abuse of these substances, although it is unclear whether NSAIDs in fact enhance performance. We performed a systematic review and meta-analysis to evaluate the effect of NSAIDs on sport performance indices.