A strong foundation in physical conditioning and sport-specific experience, in addition to a bespoke and periodized training and nutrition program, are essential for athlete development. Once these underpinning factors are accounted for, and the athlete reaches a training maturity and competition level where marginal gains determine success, a role may exist for the use of evidence-based performance supplements. However, it is important that any decisions surrounding performance supplements are made in consideration of robust information that suggests the use of a product is safe, legal, and effective. The following review focuses on the current evidence-base for a number of common (and emerging) performance supplements used in sport. The supplements discussed here are separated into three categories based on the level of evidence supporting their use for enhancing sports performance: (1) established (caffeine, creatine, nitrate, beta-alanine, bicarbonate); (2) equivocal (citrate, phosphate, carnitine); and (3) developing. Within each section, the relevant performance type, the potential mechanisms of action, and the most common protocols used in the supplement dosing schedule are summarized.

Sand surfaces can offer a higher energy cost (EC) and lower impact training stimulus compared with firmer and more traditional team sport training venues such as grass. This review aims to summarise the existing research on sand training, with a specific focus on its application as a team sports training venue. Compared with grass, significant physiological and biomechanical differences are associated with sand exercise. However, evidence also exists to suggest that training adaptations unique to sand can positively influence firm-ground performance. Furthermore, the lower impact forces experienced on sand can limit muscle damage, muscle soreness, and decrements in performance capacity relative to exercise intensity. Therefore, using a sand training surface in team sports may allow greater training adaptations to be achieved, while reducing performance decrements and injuries that may arise from heavy training. Nevertheless, further research should investigate the effect of sand surfaces over a greater range of training types and performance outcomes, to increase the application of sand training for team sports.

This study compared the use of sand and grass training surfaces throughout an 8-week conditioning programme in well-trained female team sport athletes (n = 24). Performance testing was conducted pre- and post-training and included measures of leg strength and balance, vertical jump, agility, 20 m speed, repeat speed (8 × 20 m every 20 s), as well as running economy and maximal oxygen consumption (VO_2max). Heart rate (HR), training load (rating of perceived exertion (RPE) × duration), movement patterns and perceptual measures were monitored throughout each training session. Participants completed 2 × 1 h conditioning sessions per week on sand (SAND) or grass (GRASS) surfaces, incorporating interval training, sprint and agility drills, and small-sided games. Results showed a significantly higher (P < 0.05) HR and training load in the SAND versus GRASS group throughout each week of training, plus some moderate effect sizes to suggest lower perceptual ratings of soreness and fatigue on SAND. Significantly greater (P < 0.05) improvements in VO_2max were measured for SAND compared to GRASS. These results suggest that substituting sand for grass training surfaces throughout an 8-week conditioning programme can significantly increase the relative exercise intensity and training load, subsequently leading to superior improvements in aerobic fitness.

Purpose: To determine the effect of limb selection (upper/lower), cuff width (small (6 cm)/medium (13 cm) upper; medium/large (18 cm) lower) and anthropometry on arterial occlusion pressure (AOP) in ischemic preconditioning (IPC). Methods: Twenty athletes (10 females and 10 males) had surface anthropometry and dual x‐ray absorptiometry (DXA) assessments before using Doppler ultrasound to confirm AOP for each limb. Subsequently, 5 min of occlusion occurred, with near‐infrared spectroscopy (NIRS) measuring muscle oxygenation changes. Resultant AOP was compared between sexes, limbs and cuff sizes using linear regression models. Results: Mean AOP was higher in the lower limbs than the upper limbs (161 ± 18 vs. 133 ± 12 mm Hg; p < .001), and with smaller cuffs in upper (161 ± 16 vs. 133 ± 12 mm Hg; p < .001), but not lower limbs (161 ± 16 vs. 170 ± 26 mm Hg; p = .222). Sex and resting systolic blood pressure (SBP) accounted for 77% (small cuff) to 83% (medium cuff) of variance in AOP for upper limbs, and 61% (medium cuff) to 63% (large cuff) in lower limbs. Including anthropometry accounted for 82% (small cuff) to 89% (medium cuff) and 78% (medium cuff) to 79% (large cuff) of variance for upper and lower limbs, respectively. Adding DXA variables improved the explained variance up to 83% (small cuff) to 91% (medium cuff) and 79% (medium cuff) to 87% (large cuff) for upper and lower limbs, respectively. NIRS data showed significantly greater tissue oxygenation changes in upper versus lower limbs. Conclusions: The AOP in athletes is dependent on limb occluded, sex, SBP, limb and cuff size, and body composition.

This study compared the effect of sand and grass training surfaces during a common preseason interval training session in well-trained team sport athletes (n = 10). The participants initially completed a preliminary testing session to gather baseline (BASE) performance data for vertical jump, repeated sprint ability, and a 3-km running time trial (RTT). Three days subsequent to BASE, all the athletes completed the first interval training session, which was followed by a repeat of the BASE performance tests the following day (24 hours postexercise). Seven days later, the same interval training session was completed on the opposing surface and was again followed 24 hours later by the BASE performance tests. During each session, blood lactate (BLa), ratings of perceived exertion, and heart rate (HR) were recorded. Additionally, venous blood was collected preexercise, postexercise, and 24 hours postexercise and analyzed for serum concentrations of myoglobin, creatine kinase, haptoglobin, and C-reactive protein. Results showed significantly higher BLa and HR responses experienced during the SAND session (p < 0.05), with no differences observed between surfaces for the blood markers of muscle damage, inflammation, and hemolysis (p > 0.05). Twenty-four hours later, the RTT was performed significantly faster after the SAND session compared with GRASS (p = 0.001). These results suggest that performing interval training on a sand (vs. grass) surface can result in a greater physiological response, without any additional detriment to next day endurance performance.

This study assessed the associations between gender, anthropometry, predominant training environment and Vitamin D status in 72 elite athletes. Additionally, any links between Vitamin D status and recent injury/health status, or sun protection practices were investigated. Athletes underwent an anthropometric assessment and provided venous blood samples for the determination of 25-hydroxyvitamin D (25(OH)D), the accepted biological marker of Vitamin D status. Finally, athletes completed a questionnaire relating to their recent training and injury history, and their sun protection practices. The athlete cohort were divided by predominant training environment as either indoor, outdoor, or mixed training environment athletes. The average (±SD) 25(OH)D levels of the group were 111±37 nmol/L, with the indoor training group (90±28 nmol/L) significantly lower than the outdoor (131±35 nmol/L), and mixed (133±29 nmol/L) training groups (p=0.0001). Anthropometrical measures were positively associated with 25(OH)D levels; however, recent injury status or sun protection practice showed no association. Given the significant differences in 25(OH)D levels between the outdoor and indoor predominant training environments, coaches of indoor athletes may wish to monitor their athletes’ Vitamin D levels throughout the year, in order to avoid any possibilities of a deficiency occurring.