Physiological and Performance Effects of Caffeine Gum Consumed During a Simulated Half-Time by Professional Academy Rugby Union Players.

Russell, M, Reynolds, NA, Crewther, BT, Cook, CJ, and Kilduff, L. Physiological and performance effects of caffeine gum consumed during a simulated half-time by professional academy rugby union players. J Strength Cond Res 34(1): 145-151, 2020-Despite the prevalence of caffeine (CAF) as an ergogenic aid, few studies have examined the use of caffeinated gums, especially during half-time in team sports. The physiological (blood lactate and salivary hormone concentrations) and performance (repeated sprints and cognitive function) effects of consuming CAF gum during a simulated half-time were examined. Professional academy rugby union players (n = 14) completed this double-blind, randomized, counterbalanced study. After pre-exercise measurements, players chewed a placebo (PLC) gum for 5 minutes before a standardized warm-up and completing repeated sprint testing (RSSA1). Thereafter, during a 15-minute simulated half-time period, players chewed either CAF (400 mg; 4.1 ± 0.5 mg·kg) or PLC gum for 5 minutes before completing a second repeated sprint test (RSSA2). Blood lactate, salivary testosterone and cortisol concentrations, and indices of cognitive function (i.e., reaction time and Stroop test) were measured at baseline, pre-RSSA1, post-RSSA1, pre-RSSA2, and post-RSSA2. Sprint performance was not affected by CAF (p = 0.995) despite slower sprint times after the first sprint of both RSSA tests (all p < 0.002). After half-time, salivary testosterone increased by 70% (+97 ± 58 pg·ml) in CAF vs. PLC (p < 0.001), whereas salivary cortisol remained unchanged (p = 0.307). Cognitive performance was unaffected by time and trial (all p > 0.05). Although performance effects were absent, chewing CAF gum increased the salivary testosterone concentrations of professional rugby union players over a simulated half-time. Practitioners may, therefore, choose to recommend CAF gum between successive exercise bouts because of the increases in salivary testosterone observed; a variable associated with increased motivation and high-intensity exercise performance.

Construct validity of the Heart Failure Screening Tool (Heart-FaST) to identify heart failure patients at risk of poor self-care: Rasch analysis.

AIM: The aim of this study was to psychometrically evaluate the Heart Failure Screening Tool (Heart-FaST) via: (1) examination of internal construct validity; (2) testing of scale function in accordance with design; and (3) recommendation for change/s, if items are not well adjusted, to improve psychometric credential. BACKGROUND: Self-care is vital to the management of heart failure. The Heart-FaST may provide a prospective assessment of risk, regarding the likelihood that patients with heart failure will engage in self-care. DESIGN: Psychometric validation of the Heart-FaST using Rasch analysis. METHOD: The Heart-FaST was administered to 135 patients (median age = 68, IQR = 59-78 years; 105 males) enrolled in a multidisciplinary heart failure management program. The Heart-FaST is a nurse-administered tool for screening patients with HF at risk of poor self-care. A Rasch analysis of responses was conducted which tested data against Rasch model expectations, including whether items serve as unbiased, non-redundant indicators of risk and measure a single construct and that rating scales operate as intended. RESULTS: The results showed that data met Rasch model expectations after rescoring or deleting items due to poor discrimination, disordered thresholds, differential item functioning, or response dependence. There was no evidence of multidimensionality which supports the use of total scores from Heart-FaST as indicators of risk. CONCLUSION: Aggregate scores from this modified screening tool rank heart failure patients according to their "risk of poor self-care" demonstrating that the Heart-FaST items constitute a meaningful scale to identify heart failure patients at risk of poor engagement in heart failure self-care.