Sleep extension in athletes: what we know so far - A systematic review.

OBJECTIVE: This study reviewed systematically the effects of sleep extension on sports performance. DESIGN: Systematic review. METHOD: The systematic review was conducted in November 2020. Articles published in English were searched in PubMed, Virtual Health Library, SPORTDiscus, and Web of Science and Scopus databases. The search terms used were "sleep extension" AND athlete. The measures of interest were sports performance. Studies were included if they were a) original articles, b) published in English and peer-reviewed article, c) had only athletes as participants, d) experimental protocol whose objective was to investigate the effects of sleep extension on sports performance, including randomized (RCT) and non-randomized controlled trial (nRCT), and e) at least a sports performance measure as a dependent variable. RESULTS: The primary search revealed that a total of 5 out of 74 articles were considered eligible and 2 studies were subsequently included. The studies used different strategies to extend time in bed or total sleep time (extending 26-106 min). From fifteen sports measures, six presented a large effect size, and the others ranged from trivial to medium. Overall, the risk of bias was high to RCT and low to nRCT and the quality of evidence ranged from very low quality to moderate quality in ten outcomes. CONCLUSIONS: The limited evidence suggests that sleep extension interventions may be beneficial to improve sports performance in athletes where the magnitude is dependent on the variable assessed, although such conclusions are tentative because of the quality of the evidence and risk of bias.

Can IGF-1 Serum Levels Really be Changed by Acute Physical Exercise? A Systematic Review and Meta-Analysis.

BACKGROUND: Physical exercise plays an important role in metabolic health, especially in the insulin-like growth factor-1 (IGF-1) system. The objective of this study was to perform a systematic review and meta-analysis to evaluate the effects of a single endurance and resistance exercise session on IGF-1 serum. METHODS: The systematic review was performed in SPORTDiscus, MEDLINE, PubMed, and Google Scholar databases. All analyses are based on random-effect models. The study identified 249 records of which 21 were included. RESULTS: There was an effect of endurance exercise on total IGF-1 (P = .01), but not for free IGF-1 (P = .36). Resistance exercise similarly only affected total IGF-1 (P = .003) and not free IGF-1 (P = .37). The effect size indicated that total IGF-1 is more affected (ES = 0.81) by endurance than by resistance exercise (ES = 0.46). The present study showed that IGF-1 serum concentrations are altered by exercise type, but in conditions which are not well-defined. CONCLUSIONS: The systematic review and meta-analysis suggest that there is no determinant in serum IGF-1 changes for the exercise load characteristic. Therefore, physical exercise may be an alternative treatment to control changes in IGF-1 metabolism and blood concentration.

Which parameters to use for sleep quality monitoring in team sport athletes? A systematic review and meta-analysis.

BACKGROUND: Sleep quality is an essential component of athlete's recovery. However, a better understanding of the parameters to adequately quantify sleep quality in team sport athletes is clearly warranted. OBJECTIVE: To identify which parameters to use for sleep quality monitoring in team sport athletes. METHODS: Systematic searches for articles reporting the qualitative markers related to sleep in team sport athletes were conducted in PubMed, Scopus, SPORTDiscus and Web of Science online databases. The systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. For the meta-analysis, effect sizes with 95% CI were calculated and heterogeneity was assessed using a random-effects model. The coefficient of variation (CV) with 95% CI was also calculated to assess the level of instability of each parameter. RESULTS: In general, 30 measuring instruments were used for monitoring sleep quality. A meta-analysis was undertaken on 15 of these parameters. Four objective parameters inferred by actigraphy had significant results (sleep efficiency with small CV and sleep latency, wake episodes and total wake episode duration with large CV). Six subjective parameters obtained from questionnaires and scales also had meaningful results (Pittsburgh Sleep Quality Index (sleep efficiency), Likert scale (Hooper), Likert scale (no reference), Liverpool Jet-Lag Questionnaire, Liverpool Jet-Lag Questionnaire (sleep rating) and RESTQ (sleep quality)). CONCLUSIONS: These data suggest that sleep efficiency using actigraphy, Pittsburgh Sleep Quality Index, Likert scale, Liverpool Jet-Lag Questionnaire and RESTQ are indicated to monitor sleep quality in team sport athletes. PROSPERO REGISTRATION NUMBER: CRD42018083941.

T-Shirt fabric and color affect the physiological strain but not 10 km outdoor running performance.

BACKGROUND: The aim of the present study was to evaluate the effects of T-Shirt fabric and color on the 10 km outdoor running performance. METHODS: Six men and six women (mean±SD: age: 27±5 years; height: 1.70±0.13 m; weight: 64.0±12.7 kg; body surface area: 1.73±0.29 m2; Σskinfolds: 107±24 mm; VO2max: 40.2±8.4 mL.kg-1.min-1) took part in five experimental trials, during each of which they wore: 1) no T-shirt (CON); 2) white polyester T-shirt (WP); 3) black polyester T-shirt (BP); 4) white cotton T-shirt (WC); and 5) black cotton T-shirt (BC). Average running velocity (pace) was calculated from each 2 km running time. Rectal, skin and T-shirt temperatures, heart rates and Physiological Strain Index (PSI) were measured before and after the 10 km runs and at the end of each 2 km. RESULTS: There were no differences in pace, heart rate, rectal and skin temperatures among conditions (P>0.05). PSI was higher in BC and WC conditions when compared to BP and WP conditions. T-shirt temperature was higher for the BC when compared to WP, BP and WC conditions. Rectal temperature and heart rate increased simultaneously with reduced pace throughout self-paced running (P<0.05). CONCLUSIONS: Despite fabric type T-shirt altered PSI, running performance in the 10 km run was not affected by T-shirt type or color.