Maintain energy levels by preventing blood glucose (sugar) fluctuations.
Supporting scientific papers:
Glycemic index and sustained energy for physical performance:
A systematic review and meta-analysis. Talya Postelnik, Alan W Barclay, and Peter Petocz. GI Foundation, 2014.
- Over 50 people (adolescents – adults) of varying fitness levels participated in a range of physical activities.
- There was significant improvement in performance after a pre-activity low GI meal when participants worked to exhaustion (22%).
- As part of a healthy balanced diet, low GI foods or meals before an activity can provide individuals (male or female) with sustained energy for physical activity.
Glycemic index, postprandial glycemia, and the shape of the curve in healthy subjects: analysis of a database of more than 1,000 foods.
This study concluded that the GI provides a good summary of postprandial glycemia (after meal blood glucose levels). It predicts the peak (or near peak) response, the maximum glucose fluctuation, and other attributes of the response curve. The rate of energy release is not determined by the shape of the blood glucose response curve. It shows that low GI foods return blood glucose levels to normal levels more quickly than high GI foods. Brand-Miller et al. Am J Clin Nutr. 2009; 89: 97–105
Improve athletic performance (GI and physical performance).
Supporting scientific papers:
Glycemic index and physical performance:
A systematic review and meta-analysis. Talya Postelnik, Alan W Barclay, and Peter Petocz. GI Foundation. 2014
- Nearly 130 people (adolescents – adults) of varying fitness levels competed in a range of sporting events/physical activities.
- There was significant improvement in performance after a pre-exercise low GI meal when participants exercised to exhaustion (22%), or performed a time trial (2%).
- As part of a healthy balanced diet, low GI foods or meals before an event can lead to significant improvement in performance providing an individual (male or female) with an advantage over competitors.
Preexercise and low Glycemic Index meals and cycling performance in untrained females: randomised, cross over trial of efficacy.
The authors found that untrained female participants should consume low GI meals before they compete in endurance activities rather than high GI meals. Moore et al Res Sports Med. 2013;21(1):24-36
Effect of the glycaemic index of a pre-exercise meal on metabolism and cycling time trial performance.
The low GI meal led to an increase in the availability of carbohydrate and a greater carbohydrate oxidation throughout the exercise period, which may have sustained energy production towards the end of exercise and led to the improved TT performance observed. Moore et al. J Sci Med Sport. 2010 Jan;13(1):182-8
Effect of dietary glycemic index on substrate transporter gene expression in human skeletal muscle after exercise.
The High GI diet produced significantly greater glucose and insulin responses compared with the Low GI diet, as indicated by the greater area under the curves. The study found a significant dietary GI effect on post-exercise FAT/CD36 gene expression in human skeletal muscle. This result implicates that the differences in dietary GI are sufficient to alter fat metabolism. Cheng et al. Eur J Clin Nutr. 2009; 63(12):1404-10
Dietary glycemic index influences lipid oxidation but not muscle or liver glycogen oxidation during exercise.
The glycemic index of dietary carbohydrates influences glycogen storage in skeletal muscle and circulating nonesterified fatty acid (NEFA) concentrations. The authors found that high GI recovery diets reduce NEFA availability and increase reliance on intramyocellular triglyceride during moderate-intensity exercise. Skeletal muscle and liver glycogen storage or usages are not affected by the GI of an acute recovery diet. Stevenson et al. Am J Physiol Endocrinol Metab. 2009;296(5):E1140-7
The effects of low- and high-glycemic index meals on time trial performance.
Time trial performance was significantly improved in the low GI trial compared with the high-GI trial. The improvement in time trial performance for the low GI trial may be associated with an increased availability of glucose to the working muscles, contributing additional carbohydrate for oxidation and possibly sparing limited muscle and liver glycogen stores. Moore et al. Int J Sports Physiol Perform. 2009 Sep;4(3):331-44
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