Study under review: Effects of High vs. Low Glycemic Index of Post-Exercise Meals on Sleep and Exercise Performance: A Randomized, Double-Blind, Counterbalanced Polysomnographic Study
Getting enough quality sleep is important for overall health. Although the function of sleep is not yet fully understood, it is generally accepted that by promoting the maintenance and recovery of the central nervous system and physical recovery, sleep serves as an important regulator of numerous biological aspects, maintaining vital physiological functions, metabolic homeostasis, learning, and memory.
In recent years, there has been a growing interest among the scientific community in the potential effects of sleep on athletic performance, since there are many reasons why sleep could theoretically impact it, as outlined in Figure 1. Despite the finding that athletes generally seem to exhibit similar, or even slightly better, sleep duration and quality than the general public, many athletes have been consistently shown to sleep less than recommended. Moreover, sleep in athletes can also be undermined by competition, not just due to disturbances in mood, anxiety, and psychological stress, but also because of the great physical stress of high-volume or high-intensity exercise.
With sleep being an important part of the post-exercise recovery process, adequate quality sleep after exercise and before subsequent exercise bouts or athletic events is imperative for promoting sufficient recovery and optimal performance. As such, several strategies, including nutritional interventions to improve sleep, have been investigated. One such nutritional intervention involves carbohydrate consumption, as some research suggests that high carbohydrate or high glycemic index meals ingested close to bedtime may improve sleep by increasing blood tryptophan levels.
Despite the potential effects of carbohydrate consumption on sleep, and the potential effects of sleep on exercise performance, relatively little research has been conducted to investigate the links between these variables. Moreover, there is currently no research examining the effects of post-exercise carbohydrates on sleep and the subsequent effects on next-day exercise performance. The study under review aimed to add to the literature by investigating the effects of a high vs. low glycemic index (GI) meal after an evening high-intensity training (HIT) session on sleep quantity and quality, and on the following morning’s exercise performance in recreationally-trained men.
Sleep has been identified as an important factor contributing to optimal exercise recovery and athletic performance. However, the physical stress of high-intensity exercise may negatively affect sleep. While scientific evidence suggests that nutritional interventions involving carbohydrate ingestion close to bedtime can potentially improve sleep and subsequent exercise performance, little relevant research has been conducted to date. The study under review was the first to investigate the effects of a high vs. low glycemic index meal after an evening high-intensity exercise session on sleep and next-day exercise performance.
Other Articles in Issue #52 (February 2019)
Individual differences in cardio-metabolic response to caffeine may not predict its benefits on endurance performance
Caffeine doesn't benefit every athlete to the same extent. This study aimed to discover if the ergogenic effects of caffeine could be predicted by certain physiological responses to it.
Carnivores convert carnitine, but can vegetarians?
Trimethylamine N-oxide (TMAO) is associated with an increased disease risk. It's manufactured with the help of the gut microbiome from L-carnitine. Vegetarians make less TMAO from L-carnitine than omnivores do. The question is: why?
Can lemon balm help manage type 2 diabetes mellitus?
Lemon balm is a plant that may have antidiabetic and cardiovascular effects. This study explored how it impacts glycemic control and cardiovascular risk factors in people with type 2 diabetes.
Do low carbohydrate diets increase cardiovascular risk?
This meta-analysis found that low carb diets bump up LDL-C levels slightly. What's less clear is how much this matters.
Interview: Jason M. Valadão, MD, MA, MLS, Lieutenant Commander, US Navy
We chat with physician, naval officer, and author Jason Valadão about the nutritional strategies he uses with his patients, his top tip for gaining control of exercise and diet routines, and more.
The anti-inflammatory effect of a vegan versus American Heart Association-recommended diet in coronary artery disease
Inflammation plays a major role in cardiovascular disease. This study examined whether a vegan or AHA-recommended diet can make a bigger impact on a major inflammatory marker in people with coronary artery disease.
Interview: Shavawn M. Forester PhD, RDN
In this chat with the Chief Science Officer of The Nutrient Institute, we discuss science communication, her take on some popular nutrition topics, and more.