Abstract
To determine the effects of pre-sleep supplementation with a novel low glycemic index (LGI) carbohydrate (CHO) on next-morning substrate utilization, gastrointestinal distress (GID), and endurance running performance (5-km time-trial, TT). Using a double-blind, randomized, placebo (PLA) controlled, crossover design, trained participants (n = 14; 28 ± 9 years, 8/6 male/female, 55 ± 7 mL/kg/min) consumed a LGI, high glycemic index (HGI), or 0 kcal PLA supplement ≥ 2 h after their last meal and <30 min prior to sleep. Upon arrival, resting energy expenditure (REE), substrate utilization, blood glucose, satiety, and GID were assessed. An incremental exercise test (IET) was performed at 55, 65, and 75% peak volume of oxygen consumption (VO2peak) with GID, rating of perceived exertion (RPE) and substrate utilization recorded each stage. Finally, participants completed the 5-km TT. There were no differences in any baseline measure. During IET, CHO utilization tended to be greater with LGI (PLA, 56 ± 11; HGI, 60 ± 14; LGI, 63 ± 14%, p = 0.16, η2 = 0.14). GID was unaffected by supplementation at any point (p > 0.05). Performance was also unaffected by supplement (PLA, 21.6 ± 9.5; HGI, 23.0 ± 7.8; LGI, 24.1 ± 4.5 min, p = 0.94, η2 = 0.01). Pre-sleep CHO supplementation did not affect next-morning resting metabolism, BG, GID, or 5-km TT performance. The trend towards higher CHO utilization during IET after pre-sleep LGI, suggests that such supplementation increases morning CHO availability.
Highlights
The importance of pre-exercise nutrition for exercise performance has been well documented [1,2,3,4,5,6].given that many competitive endurance activities are scheduled early in the morning, there exists a major limitation: inadequate time in the morning prior to the event to properly fuel for sport
The primary findings were as follows: (1) supplementation had no significant effect on resting energy expenditure (REE), CHO, or FAT utilization at rest, though females tended to utilize more CHO in the high glycemic index (HGI) and low glycemic index (LGI) supplement at rest; (2) supplementation had no significant effect on substrate utilization during graded submaximal exercise; (3) blood glucose was not different among supplements at any point during the trial; (4) perceptions of gastrointestinal distress (GID) were not different among supplements; (5) supplementation had no discernable significant effect on 5-km TT performance
The present study is the first to assess the effects of pre-sleep LGI versus HGI CHO supplementation on next-morning exercise metabolism, GID, and endurance performance in male and female endurance athletes
Summary
The importance of pre-exercise nutrition for exercise performance has been well documented [1,2,3,4,5,6].given that many competitive endurance activities (training and/or competition) are scheduled early in the morning, there exists a major limitation: inadequate time in the morning prior to the event to properly fuel for sport. Endurance athletes seldom consume much, if anything, before training or competitions of 75–90 min in duration [7,8,9,10,11]. This behavior may result in sub-optimal physiological conditions such as carbohydrate depletion, dehydration, and fatigue [12], Nutrients 2020, 12, 2888; doi:10.3390/nu12092888 www.mdpi.com/journal/nutrients. Nutrients 2020, 12, 2888 which will adversely impact training quality and performance This issue highlights the need to develop strategies to provide adequate nutrition from foods, beverages, and/or supplements that athletes can consume pre-sleep without inducing gastrointestinal distress (GID) or disrupting normal sleep patterns [6,8]. The incorporation of a pre-sleep meal may provide an added “window of opportunity” for optimizing next-morning pre-race carbohydrate (CHO) availability and exercise performance
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
