Endurance athletes rarely compete in the fasted state, as this may compromise fuel stores. Thus, the timing and composition of the pre-exercise meal is a significant consideration for optimizing metabolism and subsequent endurance performance. Carbohydrate feedings prior to endurance exercise are common and have generally been shown to enhance performance, despite increasing insulin levels and reducing fat oxidation. These metabolic effects may be attenuated by consuming low glycemic index carbohydrates and/or modified starches before exercise. High fat meals seem to have beneficial metabolic effects (e.g., increasing fat oxidation and possibly sparing muscle glycogen). However, these effects do not necessarily translate into enhanced performance. Relatively little research has examined the effects of a pre-exercise high protein meal on subsequent performance, but there is some evidence to suggest enhanced pre-exercise glycogen synthesis and benefits to metabolism during exercise. Finally, various supplements (i.e., caffeine and beetroot juice) also warrant possible inclusion into pre-race nutrition for endurance athletes. Ultimately, further research is needed to optimize pre-exercise nutritional strategies for endurance performance.

There is good evidence that mouth rinsing with carbohydrate (CHO) solutions can enhance endurance performance (≥30 min). The impact of a CHO mouth rinse on sprint performance has been less consistent, suggesting that CHO may confer benefits in conditions of ‘metabolic strain’. To test this hypothesis, the current study examined the impact of late-exercise mouth rinsing on sprint performance. Secondly, we investigated the effects of a protein mouth rinse (PRO) on performance. Eight trained male cyclists participated in three trials consisting of 120 min of constant-load cycling (55% W_max) followed by a 30 km computer-simulated time trial, during which only water was provided. Following 15 min of muscle function assessment, 10 min of constant-load cycling (3 min at 35% W_max, 7 min at 55% W_max) was performed. This was immediately followed by a 2 km time trial. Subjects rinsed with 25 mL of CHO, PRO, or placebo (PLA) at min 5:00 and 14:30 of the 15 min muscle function phase, and min 8:00 of the 10-min constant-load cycling. Magnitude-based inferential statistics were used to analyze the effects of the mouth rinse on 2-km time trial performance and the following physiological parameters: Maximum Voluntary Contract (MVC), Rating of Perceived Exertion (RPE), Heart Rate (HR), and blood glucose levels. The primary finding was that CHO ‘likely’ enhanced performance vs. PLA (3.8%), whereas differences between PRO and PLA were unclear (0.4%). These data demonstrate that late-race performance is enhanced by a CHO rinse, but not PRO, under challenging metabolic conditions. More data should be acquired before this strategy is recommended for the later stages of cycling competition under more practical conditions, such as when carbohydrates are supplemented throughout the preceding minutes/hours of exercise.

The present study investigated the effects of a multi-ingredient dietary supplement (MIDS) containing caffeine, conjugated linoleic acid (CLA), green tea, and branched-chain amino acids (BCAA) taken for 8 weeks on body composition, blood lipid profile, glucose, insulin, adiponectin, leptin, and high-sensitivity C-reactive protein (hs-CRP) in overweight and obese men and women.

While prior research reported altered fuel utilization stemming from pre-exercise modified starch ingestion, the practical value of this starch for endurance athletes who consume carbohydrates both before and during exercise is yet to be examined. The purpose of this study was to determine the effects of ingesting a hydrothermally-modified starch supplement (HMS) before and during cycling on performance, metabolism, and gastrointestinal comfort. In a crossover design, 10 male cyclists underwent three nutritional interventions: (1) a commercially available sucrose/glucose supplement (G) 30 min before (60 g carbohydrate) and every 15 min during exercise (60 g∙h⁻¹); (2) HMS consumed at the same time points before and during exercise in isocaloric amounts to G (Iso HMS); and (3) HMS 30 min before (60 g carbohydrate) and every 60 min during exercise (30 g·h⁻¹; Low HMS). The exercise protocol (~3 h) consisted of 1 h at 50% W_max, 8 × 2-min intervals at 80% W_max, and 10 maximal sprints. There were no differences in sprint performance with Iso HMS vs. G, while both G and Iso HMS likely resulted in small performance enhancements (5.0%; 90% confidence interval = ±5.3% and 4.4%; ±3.2%, respectively) relative to Low HMS. Iso HMS and Low HMS enhanced fat oxidation (31.6%; ±20.1%; very likely (Iso); 20.9%; ±16.1%; likely (Low), and reduced carbohydrate oxidation (−19.2%; ±7.6%; most likely; −22.1%; ±12.9%; very likely) during exercise relative to G. However, nausea was increased during repeated sprints with ingestion of Iso HMS (17 scale units; ±18; likely) and Low HMS (18; ±14; likely) vs. G. Covariate analysis revealed that gastrointestinal distress was associated with reductions in performance with Low HMS vs. G (likely), but this relationship was unclear with Iso HMS vs. G. In conclusion, pre- and during-exercise ingestion of HMS increases fat oxidation relative to G. However, changes do not translate to performance improvements, possibly owing to HMS-associated increases in gastrointestinal distress, which is not attenuated by reducing the intake rate of HMS during exercise.