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The purpose of this investigation was to quantify the effects of storage temperature and duration on the assessment of urine electrolytes. Twenty-one separate human urine specimens were analyzed as baseline and with the remaining specimen separated into eight vials, two in each of the following four temperatures: 22, 7, −20, and −80 °C. Each specimen was analyzed for urine electrolytes (sodium, potassium, and chloride) after 24 and 48 hr. After 24 hr, no significant difference was detected from baseline in urine sodium, potassium, and chloride at all four storage temperatures (p > .05). Similarly, after 48 hr, urine sodium, potassium, and chloride were not significantly different from baseline in all four storage temperatures (p > .05). In conclusion, these data show that urine specimens analyzed for urine sodium, chloride, and potassium are stable up to 48 hr in temperatures ranging from deep freezing to room temperature.

This article has been retracted as of May 6, 2022, because concerns were received from a reader that the article contains inaccurate data. An independent review of the study data was conducted in coordination with the authors, and it was determined that the originally published data are inaccurate and a complete set of corrected data is not available as the authors claim a portion of the original measurements have been lost. As a result of these findings, the article is retracted.

Carbohydrate (CHO) mouth rinsing seems to improve performance in exercises lasting 30–60 min. However, its effects on intermittent exercise are unclear. It is also unknown whether serial CHO mouth rinses can promote additional ergogenic effects when compared with a single mouth rinse. The aim of this study was to evaluate the effect of single and serial CHO mouth rinses on Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1) performance in soccer players. In a randomized, crossover, double-blind, placebo-controlled design, 12 male (18.9 ± 0.5 years) soccer players performed eight serial mouth rinses under three different conditions: placebo solution only (noncaloric juice), seven placebo mouth rinses plus a single CHO mouth rinse (8% maltodextrin), or eight CHO mouth rinses (8-CHO). Following the final mouth rinse, individuals performed the Yo-Yo IR1 test to evaluate the maximal aerobic endurance performance measured via total distance covered. There were no differences in Yo-Yo IR1 performance between sessions (p = .32; single CHO mouth rinse (8% maltodextrin): 1,198 ± 289 m, eight CHO mouth rinses: 1,256 ± 253 m, placebo: 1,086 ± 284 m). In conclusion, single and serial CHO mouth rinsing did not improve performance during the Yo-Yo IR1 for soccer players. These data suggest that CHO mouth rinsing is not an effective ergogenic strategy for intermittent exercise performance irrespective of the number of rinses.

This study investigated the effects of 6 mg/day of astaxanthin supplementation on markers of oxidative stress and substrate metabolism during a graded exercise test in active young men. A double-blind, randomized, counterbalanced, cross-over design was used. Fourteen men (age = 23 ± 2 years) supplemented with 6 mg/day of astaxanthin and a placebo for 4 weeks, with a 1 week washout period between treatments. Following each supplementation period, a fasting blood sample was obtained to measure markers of oxidative stress: glutathione, hydrogen peroxide, advanced oxidation protein products, and malondialdehyde. Participants also completed a graded exercise test after each treatment to determine substrate utilization during exercise at increasing levels of intensity. Glutathione was ∼7% higher following astaxanthin compared with placebo (1,233 ± 133 vs. 1,156 ± 185 μM, respectively; p = .02, d = 0.48). Plasma hydrogen peroxide and malondialdehyde were not different between treatments (p > .05). Although not statistically significant (p = .45), advanced oxidation protein products were reduced by ∼28%. During the graded exercise test, mean fat oxidation rates were not different between treatments (p > .05); however, fat oxidation decreased from 50 to 120 W (p < .001) and from 85 to 120 W (p = .004) in both conditions. Astaxanthin supplementation of 6 mg/day for 4 weeks increased whole blood levels of the antioxidant glutathione in active young men but did not affect oxidative stress markers or substrate utilization during exercise. Astaxanthin appears to be an effective agent to increase endogenous antioxidant status.

The purpose was to investigate the effects of CYP1A2 −163C > A polymorphism on the effects of acute caffeine (CAF) supplementation on anaerobic power in trained males. Sixteen trained males (age: 21.6 ± 7.1 years; height: 179.7 ± 5.6 cm; body mass: 72.15 ± 6.8 kg) participated in a randomized, double-blind, placebo (PLA) controlled crossover design. Participants supplemented with CAF (6 mg/kg of body mass) and an isovolumetric PLA (maltodextrin) in random order and separated by 7 days, before an all-out 30-s anaerobic cycling test to determine peak, average, and minimum power output, and fatigue index. Genomic deoxyribonucleic acid was extracted to identify each participants CYP1A2 genotype. Six participants expressed AA homozygote and 10 expressed C alleles. There was a treatment by genotype interaction for peak power output (p = .041, η² = .265, observed power = 0.552) with only those expressing AA genotype showing improvement following CAF supplementation compared with PLA (CAF: 693 ± 108 watts vs. PLA: 655 ± 97 watts; p = .039), while no difference between treatments was noted in those expressing C alleles (CAF: 614 ± 92 watts vs. PLA: 659 ± 144 watts; p = .135). There were no other interaction or main effects for average or minimum power output, or fatigue index (p > .05). In conclusion, the ingestion of 6 mg/kg of CAF improved peak power output only in participants with the AA genotype compared with PLA; however, expression of the CYP1A2 did not influence average or minimum power output or fatigue index.

People with spinal cord injury (SCI) tend to be more sedentary and increase fat accumulation, which could have a negative influence on metabolic flexibility. The aim of this study was to investigate the capacity to oxidize fat in a homogenous sample of men with thoracic SCI compared with healthy noninjured men during an arm cycling incremental test. Forty-one men, 21 with SCI and 20 noninjured controls, performed an incremental arm cycling test to determine peak fat oxidation (PFO) and the intensity of exercise that elicits PFO (Fat_max). PFO was expressed in absolute values (g/min) and relative to whole-body and upper-body lean mass ([mg·min⁻¹]·kg⁻¹) through three different models (adjusting by cardiorespiratory fitness and fat mass). Gross mechanical efficiency was also calculated. PFO was higher in SCI than in noninjured men (0.27 ± 0.07 vs. 0.17 ± 0.07 g/min; 5.39 ± 1.30 vs. 3.29 ± 1.31 [mg·min⁻¹]·kg⁻¹ whole-body lean mass; 8.28 ± 2.11 vs. 5.08 ± 2.12 [mg·min⁻¹]·kg⁻¹ upper-body lean mass). Fat_max was found at a significantly higher percentage of VO₂peak in men with SCI (33.6% ± 8.2% vs. 23.6% ± 6.4%). Differences persisted and even increased in the fully adjustment model and at any intensity. Men with SCI showed significantly higher gross mechanical efficiency at 35 and 65 W than the noninjured group. Men with SCI showed higher fat oxidation when compared with noninjured men at any intensity, even increased after full adjustment for lean mass, fat mass, and cardiorespiratory fitness. These findings suggest that SCI men could improve their metabolic flexibility and muscle mass for greater efficiency, not being affected by their fat accumulation.