Glycemic Index and Endurance Performance

Abstract

The aim of this review is to provide an up-to-date summary of the evidence surrounding glycemic index (GI) and endurance performance. Athletes are commonly instructed to consume low-GI (LGI) carbohydrate (CHO) before exercise, but this recommendation appears to be based on the results of only a few studies, whereas others have found that the GI of CHO ingested before exercise has no impact on performance. Only 1 study was designed to directly investigate the impact of the GI of CHO ingested during exercise on endurance performance. Although the results indicate that GI is not as important as consuming CHO itself, more research in this area is clearly needed. Initial research investigating the impact of GI on postexercise recovery indicated consuming high-GI (HGI) CHO increased muscle glycogen resynthesis. However, recent studies indicate an interaction between LGI CHO and fat oxidation, which may play a role in enhancing performance in subsequent exercise. Despite the fact that the relationship between GI and sporting performance has been a topic of research for more than 15 yr, there is no consensus on whether consuming CHO of differing GI improves endurance performance. Until further well-designed research is carried out, athletes are encouraged to follow standard recommendations for CHO consumption and let practical issues and individual experience dictate the use of HGI or LGI meals and supplements before, during, and after exercise.

Impact of postprandial glycaemia on health and prevention of disease

“…Generally, a high‐postprandial blood glucose response following carbohydrate ingestion prior to exercise has large effects on insulin response, fat mobilization and substrate utilization during the onset of exercise. Lipolysis and fatty acid availability is suppressed, inducing a reduction in fat oxidation (287,298,299). Carbohydrate intake during exercise also inhibits fat oxidation by hindering the transport of fatty acids into the mitochondria (297).…”

Glycemic Response of a Carbohydrate-Protein Bar with Ewe-Goat Whey

“…Most studies show that consuming LGI carbohydrate before exercise results in a favourable metabolic profile during exercise, but with limited positive effect on actual performance [28]. No research has indicated that consumption of HGI foods prior to exercise negatively affects exercise performance [28,29]. In a study, consumption of LGI vs .…”

Comparison between Preexercise Meals Intake Effect with Different Glycemic Load on Exercise Performance in Female Athletes

“…These food were chosen from food items which are used in Iranian dietary habits. It should be mentioned that Donaldson et al expressed feeding time at one hour or less before exercise, accompanied with higher blood glucose and free fatty acids concentrations at the end of exercise; however, feeding at one to three hours prior to exercise results in higher blood glucose or free fatty acids during athletes' exercise [30]. Based on this finding, we selected three hours as suitable feeding time, before exercise.…”