Non-technical summary This is the first study, to our knowledge, to use cardiac MRI before and after intensive and closely supervised resistance and endurance exercise training in humans. There is a long held belief that these different forms of training induce 'concentric' and 'eccentric' adaptation of the heart, but this concept is based on echocardiographic assessments and cross-sectional comparison of different types of elite athletes. Our findings, using highly sensitive MRI methodology, suggest that concept may need to be reconsidered. This study is of fundamental importance to the understanding of the impact of exercise on human cardiac morphology and physiology.Abstract The principle that 'concentric' cardiac hypertrophy occurs in response to strength training, whilst 'eccentric' hypertrophy results from endurance exercise has been a fundamental tenet of exercise science. This notion is largely based on cross-sectional comparisons of athletes using echocardiography. In this study, young (27.4 ± 1.1 years) untrained subjects were randomly assigned to supervised, intensive, endurance (END, n = 10) or resistance (RES, n = 13) exercise and cardiac MRI scans and myocardial speckle tracking echocardiography were performed at baseline, after 6 months of training and after a subsequent 6 weeks of detraining. Aerobic fitness increased significantly in END (3.5 to 3.8 l min −1 , P < 0.05) but was unchanged in RES. Muscular strength significantly improved compared to baseline in both RES and END ( = 53.0 ± 1.1 versus 36.4 ± 4.5 kg, both P < 0.001) as did lean body mass (2.3 ± 0.4 kg, P < 0.001 versus 1.4 ± 0.6 kg P < 0.05). MRI derived left ventricular (LV) mass increased significantly following END (112.5 ± 7.3 to 121.8 ± 6.6 g, P < 0.01) but not RES, whilst training increased end-diastolic volume ( LVEDV, END: +9.0 ± 5.0 versus RES +3.1 ± 3.6 ml, P = 0.05). Interventricular wall thickness significantly increased with training in END (1.06 ± 0.0 to 1.14 ± 0.06, P < 0.05) but not RES. Longitudinal strain and strain rates did not change following exercise training. Detraining reduced aerobic fitness, LV mass and wall thickness in END (P < 0.05), whereas LVEDV remained elevated. This study is the first to use MRI to compare LV adaptation in response to intensive supervised endurance and resistance training. Our findings provide some support for the 'Morganroth hypothesis' , as it pertains to LV remodelling in response to endurance training, but cast some doubt over the proposal that remodelling occurs in response to resistance training.

SP improved RSA in team-sport, female athletes when fresh (set 1) and during the later sets of a STGC (sets 2 and 3). Specifically, total and best sprint times were faster after SP compared with placebo and BJ.

Legal nutritional ergogenic aids can offer athletes an additional avenue to enhance their performance beyond what they can achieve through training. Consequently, the investigation of new nutritional ergogenic aids is constantly being undertaken. One emerging nutritional supplement that has shown some positive benefits for sporting performance is sodium phosphate. For ergogenic purposes, sodium phosphate is supplemented orally in capsule form, at a dose of 3-5 g/day for a period of between 3 and 6 days. A number of exercise performance-enhancing alterations have been reported to occur with sodium phosphate supplementation, which include an increased aerobic capacity, increased peak power output, increased anaerobic threshold and improved myocardial and cardiovascular responses to exercise. A range of mechanisms have been posited to account for these ergogenic effects. These include enhancements in 2,3-Diphosphoglycerate (2,3-DPG) concentrations, myocardial efficiency, buffering capacity and adenosine triphosphate/phosphocreatine synthesis. Whilst there is evidence to support the ergogenic benefits of sodium phosphate, many studies researching this substance differ in terms of the administered dose and dosing protocol, the washout period employed and the fitness level of the participants recruited. Additionally, the effect of gender has received very little attention in the literature. Therefore, the purpose of this review is to critically examine the use of sodium phosphate as an ergogenic aid, with a focus on identifying relevant further research.

The effects of sodium phosphate and caffeine supplementation were assessed on repeated-sprint ability. Using a randomised, double-blind, Latin-square design, 12 female, team-sport players participated in four trials: (1) sodium phosphate and caffeine, (2) sodium phosphate and placebo (for caffeine), (3) caffeine and placebo (for sodium phosphate) and (4) placebo (for sodium phosphate and caffeine), with ~21 days separating each trial. After each trial, participants performed a simulated team-game circuit (4 × 15 min quarters) with 6 × 20-m repeated-sprints performed once before (Set 1), at half-time (Set 2), and after end (Set 3). Total sprint times were faster after sodium phosphate and caffeine supplementation compared with placebo (Set 1: P = 0.003; Set 2: d = -0.51; Set 3: P < 0.001; overall: P = 0.020), caffeine (Set 3: P = 0.004; overall: P = 0.033) and sodium phosphate (Set 3: d = -0.67). Furthermore, total sprint times were faster after sodium phosphate supplementation compared with placebo (Set 1: d = -0.52; Set 3: d = -0.58). Best sprint results were faster after sodium phosphate and caffeine supplementation compared with placebo (Set 3: P = 0.007, d = -0.90) and caffeine (Set 3: P = 0.024, d = -0.73). Best sprint times were also faster after sodium phosphate supplementation compared with placebo (d = -0.54 to -0.61 for all sets). Sodium phosphate and combined sodium phosphate and caffeine loading improved repeated-sprint ability.

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