Effect of graded fructose coingestion with maltodextrin on exogenous ¹⁴C-fructose and ¹³C-glucose oxidation efficiency and high-intensity cycling performance

Abstract

Rowlands DS, Thorburn MS, Thorp RM, Broadbent S, Shi X. Effect of graded fructose coingestion with maltodextrin on exogenous 14 C-fructose and 13 C-glucose oxidation efficiency and high-intensity cycling performance. J Appl Physiol 104: 1709-1719, 2008. First published March 27, 2008 doi:10.1152/japplphysiol.00878.2007.-The ingestion of solutions containing carbohydrates with different intestinal transport mechanisms (e.g., fructose and glucose) produce greater carbohydrate and water absorption compared with singlecarbohydrate solutions. However, the fructose-ingestion rate that results in the most efficient use of exogenous carbohydrate when glucose is ingested below absorption-oxidation saturation rates is unknown. Ten cyclists rode 2 h at 50% of peak power then performed 10 maximal sprints while ingesting solutions containing 13 C-maltodextrin at 0.6 g/min combined with 14 C-fructose at 0.0 (No-Fructose), 0.3 (Low-Fructose), 0.5 (Medium-Fructose), or 0.7 (High-Fructose) g/min, giving fructose:maltodextrin ratios of 0.5, 0. 8, and 1.2. Mean (percent coefficient of variation) exogenous-fructose oxidation rates during the 2-h rides were 0.18 (19), 0.27 (27), 0.36 (27) g/min in Low-Fructose, Medium-Fructose, and High-Fructose, respectively, with oxidation efficiencies (ϭoxidation/ingestion rate) of 62-52%. Exogenous-glucose oxidation was highest in Medium-Fructose at 0.57 (28) g/min (98% efficiency) compared with 0.54 (28), 0.48 (29), and 0.49 (19) in Low-Fructose, High-Fructose, No-Fructose, respectively; relative to No-Fructose, only the substantial 16% increase (95% confidence limits Ϯ16%) in Medium-Fructose was clear. Total exogenous-carbohydrate oxidation was highest in Medium-Fructose at 0.84 (26) g/min. Although the effect of fructose quantity on overall sprint power was unclear, the metabolic responses were associated with lower perceptions of muscle tiredness and physical exertion, and attenuated fatigue (power slope) in the Medium-Fructose and HighFructose conditions. With the present solutions, low-medium fructose-ingestion rates produced the most efficient use of exogenous carbohydrate, but fatigue and the perception of exercise stress and nausea are reduced with moderate-high fructose doses. dose response; dual-tracer method; substrate metabolism; gastrointestinal distress; fatigue IT IS NOW WIDELY ACCEPTED that ingestion of carbohydrate solutions can delay fatigue and improve endurance performance during high-intensity exercise of ϳ60 min or longer (reviewed in Ref. 25). The proposed mechanisms for performance enhancement are related to the prevention of hypoglycemia and the maintenance of high carbohydrate-oxidation rates during the later stages of exercise, when endogenous muscle and liver carbohydrate stores may become depleted (8). For these reasons and for reasons relating to hydration, there is interest from industry, scientists, and athletes in finding the formulation that will best optimize performance.During exercise, ingested glucose is rapidly absorbed into the circulation and oxidized b...

Physiological and performance effects of carbohydrate gels consumed prior to the extra-time period of prolonged simulated soccer match-play

“…20 Urine and plasma osmolality (Advanced Model 3300 Micro-Osmometer; Advanced Instruments Inc., USA), urine-corrected mass changes, ratings of perceived exertion (RPE) 21 and abdominal discomfort (AD; similar to the methods of: 22 ) were recorded during each trial. Environmental conditions were measured during exercise (Technoline WS-9032; Technotrade GmbH, Germany) and heart rate (HR) was recorded (Polar RS400; Polar Electro, Finland).…”

Is There a Specific Role for Sucrose in Sports and Exercise Performance?

“…Across three separate studies (O'Brien & Rowlands, 2011;O'Brien et al, 2013;Rowlands et al, 2008), these researchers demonstrated that higher rates of exogenous carbohydrate oxidation could be elicited when consuming fructose-glucose source solutions with a 0.8 fructose-glucose source ratio as compared with a ratio of 0.5 or 1.2-1.25. From these data it would appear that fructose-glucose ratios approaching unity (i.e., consistent with the constituent carbohydrate ratio of sucrose) might yield the highest exogenous carbohydrate oxidation rates during exercise when large amounts of carbohydrate are consumed.…”

l-Arginine but not l-glutamine likely increases exogenous carbohydrate oxidation during endurance exercise

“…In terms of carbohydrate provision, factors intrinsic to the gut, such as epithelial transport, appear to limit exogenous glucose absorption and oxidation (Jeukendrup 2004). Consequently, researchers have examined various strategies to increase intestinal carbohydrate absorption: for example, the inclusion of multiple sugars absorbed via different intestinal transporter proteins Rowlands et al 2008b). Additionally, several groups have conducted trials on the efficacy of L-alanine, glycine, L-glutamine, and L-arginine amino acids in promoting fluid, sodium, and glucose absorption in both animal and human models (Coeffier et al 2005;Lima et al 2002;Nath et al 1992;Wapnir et al 1997).…”