This study investigated the effects of caffeine mouth rinse on cycling time to exhaustion (TTE) and physiological responses in trained cyclists. In a double-blinded randomized counterbalanced cross-over design, 10 recreationally trained male cyclists (mean ± SD: 32 ± 3 years, 72.8 ± 5.3 kg, 1.78 ± 0.06 m, 13.9% ± 3.3% body fat, peak power output = 289.4 ± 24.7 W) completed two TTE tests cycling at 75% of peak aerobic power following 24 hr of dietary and exercise standardization. Cyclists were administered 25-ml mouth rinses for 5 s containing either 85 mg of caffeine or control (water) every 5 min throughout the exercise tests. No significant improvement in TTE was shown with caffeine mouth rinse compared with control (33:24 ± 12:47 vs. 28:08 ± 10:18 min; Cohen’s dz effect size: 0.51, p = .14). Caffeine mouth rinse had no significant effect on ratings of perceived exertion (p = .31) or heart rate (p = .35) throughout the cycling TTE protocol. These data indicate that a repeated dose of caffeinated mouth rinse for 5 s does not improve cycling TTE in recreationally trained male cyclists. However, these findings should be taken with caution due to the small sample size and blinding ineffectiveness, while further well-design studies with larger samples are warranted.

Sorghum is used to provide good quality gluten-free products due to phytochemicals and low glycemic index (GI). This study aimed to determine the chemical composition, the antioxidant activity and capacity, and the glycemic and insulinemic responses of gluten-free (GF) sorghum bread. GF bread samples were produced with three different sorghum genotypes. The samples were analyzed for chemical composition, resistant starch and dietary fiber content; antioxidant activity by ORAC; antioxidant capacity by FRAP; GI; and insulinemic responses. This double-blind, crossover, randomized clinical trial was conducted with 10 healthy men aged 28.0 ± 4.9 years (77.6 ± 11.7 kg and 24.2 ± 2.3 kg/m2). All sorghum bread showed significantly more fiber than rice bread (control). Brown sorghum bread was classified as low GI, bronze and white as medium GI, and control as high GI. Brown sorghum bread presented a low carbohydrate content, a significant amount of fiber, and a significantly lower 3 h AUC glucose response than those of the control, aside from the highest antioxidant activity value (p ≤ 0.001). Therefore, brown sorghum was superior to other genotypes analyzed in this study, and its production should be encouraged to provide gluten-free products with a better nutritional profile. More research is required to explore the effects of different sorghum genotypes in food products on human health.

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The effects of caffeine mouth rinse (Caff-MR) on sports performance have been evaluated by recent studies presenting contrasting results. Therefore, this systematic review aimed to summarize the evidence regarding the effects of Caff-MR on sports performance. According to Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations, the search through PubMed, Web of Science, and Scopus databases was performed until December 2021. A random-effects meta-analysis of standardized mean differences was performed to assess the overall effect of Caff-MR on sports performance-related outcomes. Sixteen studies met the inclusion criteria (207 participants). The meta-analysis showed no significant overall effect of Caff-MR on sports performance (p = 0.09). Moreover, no effects were shown on maximal heart rate or ratings of perceived exertion. The risk of bias for the included studies assessed using the risk of bias in randomized trials Cochrane tool presented 87.5% (n = 14) of the studies as medium and 12.5% (n = 2) as high scores. These data do not support using Caff-MR for sports performance, although more consistent and well-controlled studies are warranted. Large heterogeneity in study designs precludes making practical recommendations for exercise performance. More research is warranted to elucidate the potential of Caff-MR, specifically focusing on determining the optimal dose.