Unilateral Fluid Absorption and Effects on Peak Power After Ingestion of Commercially Available Hypotonic, Isotonic, and Hypertonic Sports Drinks

Abstract

Isotonic sports drinks are often consumed to offset the effects of dehydration and improve endurance performance, but hypotonic drinks may be more advantageous. The purpose of the study was to compare absorption and effects on performance of a commercially available hypotonic sports drink (Mizone Rapid: 3.9% carbohydrate [CHO], 218 mOsmol/kg) with those of an isotonic drink (PowerAde: 7.6% CHO, 281 mOsmol/ kg), a hypertonic drink (Gatorade: 6% CHO, 327 mOsmol/kg), and a noncaloric placebo (8 mOsmol/kg). In a crossover, 11 cyclists consumed each drink on separate days at 250 ml/15 min during a 2-hr preload ride at 55% peak power followed by an incremental test to exhaustion. Small to moderate increases in deuterium oxide enrichment in the preload were observed with Mizone Rapid relative to PowerAde, Gatorade, and placebo (differences of 88, 45, and 42 parts per million, respectively; 90% confidence limits ±28). Serum osmolality was moderately lower with Mizone Rapid than with PowerAde and Gatorade (-1.9, -2.4; mOsmol/L; ±1.2 mOsmol/L) but not clearly different vs. placebo. Plasma volume reduction was small to moderate with Mizone Rapid, PowerAde, and Gatorade relative to placebo (-1.9%, -2.5%, -2.9%; ± 2.5%). Gut comfort was highest with Mizone Rapid but clearly different (8.4% ± 4.8%) only vs PowerAde. Peak power was highest with Mizone Rapid (380 W) vs. placebo and other drinks (1.2-3.0%; 99% confidence limits ±4.7%), but differences were inconclusive with reference to the smallest important effect (~1.2%). The outcomes are consistent with fastest fluid absorption with the hypotonic sports drink. Further research should determine whether the effect has a meaningful impact on performance.

Whey or Casein Hydrolysate with Carbohydrate for Metabolism and Performance in Cycling

“…The PL trial served mainly to provide correction for background enrichment and comparison of outcome variables with the PL trial is only done when it aids in supporting identified changes between the 3 energy drink trials. To allow comparison with a large proportion of the recently published studies in this field, data were analysed using probabilistic magnitude-based inferential analysis, which has been recommended as the way forward [1,12] and has been described previously [2,28,29,[33][34][35][36][37]44] for analysing the physiological magnitude of effect. Inferential analysis was performed using published spreadsheets [9,11].…”

“…The metabolic and psychometric data was described by mechanistic inferences, where the magnitude of effect was tested for significance against the standardised (Cohen) change of 0.2 times the between-subject standard deviation for the reference condition (namely, CHO-only), and uncertainty was described by 90 % confidence intervals. Performance data was described by clinical inferences, where the threshold for substantial change was given by 0.3 times the within-subject variability between trials to test for a small effect (0.7 % change), while moderate and large performance effects were described by 0.9 and 1.6 of the within-subject variability (2 % and 3.5 % change), respectively, as previously described [29,33]. Accordingly, an estimated sample size of 8 was sufficient for identifying the smallest harmful/beneficial effect which equated to 12.1 s, given that the expected typical within-participant error in cycling TT time in well-trained cyclists over a similar distance to the current study is 0.7 % [47] and therefore the typical within-error for the current study is 11.8 s based on the overall average TT time for all trials of 28.1 min [10].…”

“…For this reason, we chose to include a 0.8:1 ratio of fructose: maltodextrin as the carbohydrate source in all beverages. Furthermore, we chose a recommended carbohydrate ingestion rate (63 g/h) [15], low carbohydrate concentration (7 % w/v) and total osmolality (~200-300 mOsm/L) to support fast gastric emptying and favourable gastrointestinal comfort [33,35]. Similarly, protein hydrolysates were ingested at a similar rate (15 g/h) and concentration (1.7 % w/v) as has been previously employed when promoting ergogenic effects (9-19 g/h and 1.2-2 % w/v) [13,22,[38][39][40]48].…”

Assessing a commercially available sports drink on exogenous carbohydrate oxidation, fluid delivery and sustained exercise performance

“…Whilst the benefit of sports drinks on fluid delivery has been contested [13], with higher carbohydrate delivery, there is recent evidence to suggest that combined transportable sugar beverages may enhance fluid delivery [8,14-16], which may benefit the athlete when net fluid loss may impede late stage exercise performance. Less is known about commercially available sports drinks [17], particularly maltodextrin-fructose formulas, on fluid delivery.…”

O uso do carboidrato antes da atividade física como recurso ergogênico: revisão sistemática

“…Esse aumento da performance foi obtido mesmo quando comparado a utilização de carboidratos com alto índice glicêmico 41,53,54,56 e baixo índi-ce glicêmico 53 ou mesmo com a ingestão concomitante dos dois tipos de carboidratos não obteve piora nas marcas de tempo e/ou distância 38,50 .…”