02 During - Drink mix, bar or gel: which is the best during training?

1. Introduction

Athletes have long explored nutritional supplements as a means to optimize performance and recovery. This article provides a comprehensive analysis of these supplements, categorizing them based on their primary constituents and administration forms.

Carbohydrates serve as a pivotal energy source for athletes. Supplementation with carbohydrates has been shown to bolster endurance performance and sustain blood glucose levels during physical exertion (Campbell et al., 2008; Pfeiffer et al., 2010). These supplements are available in various forms, including sports drinks, gels, and bars. The efficacy of these administration forms in influencing exercise performance remains a subject of scientific debate (Guillochon & Rowlands, 2017).

Empirical studies comparing gels and sports drinks have not identified significant differences in carbohydrate oxidation rates. Both forms exhibit comparable GI disturbance prevalence (Pfeiffer et al., 2010). Furthermore, no discernible differences in race completion times were observed between carbohydrate drinks and gels among runners and triathletes (Lee et al., 2014; Sareban et al., 2016).

5. Gastrointestinal implications of carbohydrate supplementation

Although carbohydrate intake has a positive effect on exercise performance, the intake of carbohydrates is also associated with symptoms of GI distress. The presence of GI dysfunction is backed up by multiple laboratory studies that found a correlation between GI problems and large amounts of carbohydrate ingestion (O’Brien et al., 2013; Rowlands et al., 2012; Triplett et al., 2010). It was found that this occurrence is due to delayed gastric emptying by a high carbohydrate concentration and osmolarity (E. P. de Oliveira & Burini, 2014). For instance, a study found that consumption of carbohydrate-containing sports drinks during an 18 km run led to a higher incidence of GI complaints compared to plain water (Van Nieuwenhoven et al., 2000). This finding is also supported by the study of Zhang, O’Kennedy, and Morton (2015), who studied the composition of several energy gels on the market (Zhang et al., 2015). They concluded that the higher the energy density of the gels, the stickier the composition was, which induced GI issues during exercise. GI issues especially occurred in the absence of fluid intake when taking a gel. Another study by Pfeiffer et al. (2010), reported that 10-20% of runners, who consumed a carbohydrate gel during exercise, experienced GI issues during a 16 km run. However, no biological markers of GI dysfunction were found in these athletes. Besides this, the study of Pfeiffer et al. (2009) found that GI problems mainly occurred in athletes with a history of GI complaints. The severity of the GI distress was associated with the severity of the GI problems they experienced before.