Curvilinear Dose–Response Relationship of Carbohydrate (0–120 g·h−1) and Performance

Abstract

CHO beverage ingestion and endurance (∼160 min) performance appear to be related in a curvilinear dose-response manner, with the best performance occurring with a CHO (1:1:1 glucose-fructose-maltodextrin) ingestion rate of 78 g·h(-1).

The Ingestion of 39 or 64 g·hr−1 of Carbohydrate is Equally Effective at Improving Endurance Exercise Performance in Cyclists

“…participants would be required to make meaningful comparisons between solutions, leaving no clear picture into the optimal dose of CHO. In a follow up investigation, Smith et al (2013) reported that optimal performance gains with CHO ingestion were likely to occur at rates as high as 78g·h -1 when consuming multiple forms of CHO. However, the optimal dose for the greatest improvement in performance was unclear in the 40 to 80g·h -1 range and interpretation is limited by the choice of study design.…”

“…Carbohydrate (CHO) intake during exercise has consistently been shown to improve exercise performance (Smith et al, 2013;Smith et al, 2010) and extend exercise capacity (Galloway & Maughan, 2000;Watson, Shirreffs, & Maughan, 2012). CHO is thought to act in many ways to enhance performance: sparing of muscle glycogen (Bjorkman, Sahlin, Hagenfeldt, & Wahren, 1984;Stellingwerff et al, 2007); enhancing and maintaining elevated CHO oxidation rate; maintenance of blood glucose concentration (Coyle, Coggan, Hemmert, & Ivy, 1986); elevated exogenous CHO oxidation rate (Galloway, Wootton, Murphy, & Maughan, 2001); and central and peripheral neural up-regulation (Carter, Jeukendrup, & Jones, 2004;Chambers, Bridge, & Jones, 2009;Nikolopoulos, Arkinstall, & Hawley, 2004).…”

“…In a recent study Smith et al (2013) expanded on these data and examined fifty five participants spread across four sites.…”

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

“…With respect to the consumption of large amounts of carbohydrate, Smith and colleagues recently demonstrated a curvilinear dose-response relationship of carbohydrate intake (fructose-glucose source ratio of 0.5, carbohydrate ingested in the range of 0-2.0 g/min) with endurance exercise performance with optimal performance identified at an ingestion rate of ~1.3 g/min (range 1.1-1.5 g/min) and decrements in performance observed at higher ingestion rates (Smith et al, 2013). Although not reported, it is possible that gastro-intestinal symptoms were influential in the reduction in performance at very high ingestion rates (i.e., >1.5 g/min).…”

Gut-training: the impact of two weeks repetitive gut-challenge during exercise on gastrointestinal status, glucose availability, fuel kinetics, and running performance

“…Despite carbohydrate intake rates of 78 g·h -1 (1:1:1 glucose-fructose-maltodextrin) during 2 h of steady state exercise being reported to be generally well tolerated in response to a 20 km cycling time trial and in a cycling focused population (Smith et al 2013), field-based studies report average ad libitum carbohydrate intakes during a marathon of 35 g·h -1 , and ultra-marathon events ranging from 24 to 37 g·h -1 , irrespective of ultra-marathon runners carrying multiple-transportable carbohydrate rich foods and fluids equating to >60 gCHO·h -1 in the latter (Costa et al 2013;Pfeiffer et al 2012). …”