Can carbohydrate mouth rinse improve performance during exercise? A systematic review

The purpose of this review was to identify studies that have investigated the effect of carbohydrate (CHO) mouth rinse on exercise performance, and to quantify the overall mean difference of this type of manipulation across the studies. The main mechanisms involving the potential benefit of CHO mouth rinse on performance was also explored. A systematic review was conducted in the following electronic databases: PubMed, SciELO, Science Direct, MEDLINE, and the Cochrane Library (Cochrane Central Register of Controlled Trials), without limit of searches. Eleven studies were classified as appropriate and their results were summarized and compared. In nine of them, CHO mouth rinse increased the performance (range from 1.50% to 11.59%) during moderate- to high-intensity exercise (~75% Wmax or 65% VO2max, ~1 h duration). A statistical analysis to quantify the individual and overall mean differences was performed in seven of the 11 eligible studies that reported power output (watts, W) as the main performance outcome. The overall mean difference was calculated using a random-effect model that accounts for true variation in effects occurring in each study, as well as random error within a single study. The overall effect of CHO mouth rinse on performance was significant (mean difference = 5.05 W, 95% CI 0.90 to 9.2 W, z = 2.39, p = 0.02) but there was a large heterogeneity between the studies (I2 = 52%). An activation of the oral receptors and consequently brain areas involved with reward (insula/operculum frontal, orbitofrontal cortex, and striatum) is suggested as a possible physiological mechanism responsible for the improved performance with CHO mouth rinse. However, this positive effect seems to be accentuated when muscle and liver glycogen stores are reduced, possibly due to a greater sensitivity of the oral receptors, and require further investigation. Differences in duration of fasting before the trial, duration of mouth rinse, type of activity, exercise protocols, and sample size may account for the large variability between the studies

Adenine, guanine and pyridine nucleotides in blood during physical exercise and restitution in healthy subjects

Maximal physical exertion is accompanied by increased degradation of purine nucleotides in muscles with the products of purine catabolism accumulating in the plasma. Thanks to membrane transporters, these products remain in an equilibrium between the plasma and red blood cells where they may serve as substrates in salvage reactions, contributing to an increase in the concentrations of purine nucleotides. In this study, we measured the concentrations of adenine nucleotides (ATP, ADP, AMP), inosine nucleotides (IMP), guanine nucleotides (GTP, GDP, GMP), and also pyridine nucleotides (NAD, NADP) in red blood cells immediately after standardized physical effort with increasing intensity, and at the 30th min of rest. We also examined the effect of muscular exercise on adenylate (guanylate) energy charge—AEC (GEC), and on the concentration of nucleosides (guanosine, inosine, adenosine) and hypoxanthine. We have shown in this study that a standardized physical exercise with increasing intensity leads to an increase in IMP concentration in red blood cells immediately after the exercise, which with a significant increase in Hyp concentration in the blood suggests that Hyp was included in the IMP pool. Restitution is accompanied by an increase in the ATP/ADP and ADP/AMP ratios, which indicates an increase in the phosphorylation of AMP and ADP to ATP. Physical effort applied in this study did not lead to changes in the concentrations of guanine and pyridine nucleotides in red blood cells

Research into the Health Benefits of Sprint Interval Training Should Focus on Protocols with Fewer and Shorter Sprints

Over the past decade, it has been convincingly shown that regularly performing repeated brief supramaximal cycle sprints (sprint interval training [SIT]) is associated with aerobic adaptations and health benefits similar to or greater than with moderate-intensity continuous training (MICT). SIT is often promoted as a time-efficient exercise strategy, but the most commonly studied SIT protocol (4–6 repeated 30-s Wingate sprints with 4 min recovery, here referred to as ‘classic’ SIT) takes up to approximately 30 min per session. Combined with high associated perceived exertion, this makes classic SIT unsuitable as an alternative/adjunct to current exercise recommendations involving MICT. However, there are no indications that the design of the classic SIT protocol has been based on considerations regarding the lowest number or shortest duration of sprints to optimise time efficiency while retaining the associated health benefits. In recent years, studies have shown that novel SIT protocols with both fewer and shorter sprints are efficacious at improving important risk factors of noncommunicable diseases in sedentary individuals, and provide health benefits that are no worse than those associated with classic SIT. These shorter/easier protocols have the potential to remove many of the common barriers to exercise in the general population. Thus, based on the evidence summarised in this current opinion paper, we propose that there is a need for a fundamental change in focus in SIT research in order to move away from further characterising the classic SIT protocol and towards establishing acceptable and effective protocols that involve minimal sprint durations and repetitions

Intermittent fasting with or without exercise prevents weight gain and improves lipids in diet-induced obese mice

Intermittent fasting (IF) and high intensity interval training (HIIT) are effective lifestyle interventions for improving body composition and overall health. However, the long-term effects of IF and potential synergistic effects of combining IF with exercise are unclear. The purpose of the study was to investigate the long-term effects of IF, with or without HIIT, on body composition and markers of metabolic health in diet-induced obese mice. In a randosmised, controlled design, 8-week-old C57BL/6 mice (males (n = 39) and females (n = 49)) were fed a high fat (HF) and sugar (S) water diet (30% (w/v)) for 24-weeks but were separated into five groups at 12-weeks: (1) 'obese' baseline control (OBC); (2) no intervention (CON); (3) intermittent fasting (IF); (4) high intensity intermittent exercise (HIIT) and (5) combination of dietary and exercise intervention (IF + HIIT). Body composition, strength and blood variables were measured at 0, 10 and/or 12-weeks. Intermittent fasting with or without HIIT resulted in significantly less weight gain, fat mass accumulation and reduced serum low density lipoproteins (LDL) levels compared to HIIT and CON male mice (p < 0.05). The results suggest that IF, with or without HIIT, can be an effective strategy for weight gain prevention despite concurrently consuming a high fat and sugar diet