The Effects of Low and High Glycemic Index Foods on Metabolism and Performance During a Simulated Soccer Match
Bibliographic record
Abstract
The glycemic index (GI) of a carbohydrate source consumed prior to and during exercise may influence fuel utilization and endurance performance. Previous research has focused on steady-state submaximal exercise. Many team sports, including soccer, involve high-intensity intermittent activity. PURPOSE: To examine the performance and metabolic effects of low and high GI foods consumed before and during a simulated soccer match. METHODS: Six active men (age = 24.0±4.1 yrs, VO2max = 56.2±4.1 ml/kg/min) performed a treadmill soccer match simulation on 3 different occasions separated by one week. Lentils (low GI) or mashed potatoes plus egg whites (high GI) were consumed 3 hr before and at halftime of the simulated match. A control condition where no meal was consumed was also employed. Meal order was randomized and balanced across subjects. Meals were matched for macronutrient content and were designed to provide 2.0 g (pre-exercise) and 0.25 g (halftime) carbohydrate per kg body mass. Finger prick blood glucose samples were obtained every 30 min throughout the postprandial period and every 15 min of the match. Expired gas samples were collected for 3-min periods every 15 min during exercise to estimate the rate of carbohydrate and fat oxidation. Performance was assessed by the maximal distance that could be covered during a repeated sprint test in the last 15 min of the match. RESULTS: Blood glucose rose immediately after the high GI meal so that it was higher than the low GI meal from 165 to 135 min before the exercise test (p<0.05). This trend was then reversed so that blood glucose was lower 60 min before the exercise test for the high versus low GI condition (p<0.05), but stabilized thereafter. Blood glucose concentration and carbohydrate and fat oxidation rates were not significantly different during exercise between conditions. Distance covered during the repeated sprint test was greater in both meal conditions (low GI = 1593±209 m, high GI = 1603±234 m) compared to control (1345±362 m) [p=0.05], with no difference between low and high GI. CONCLUSIONS: The results indicate that consuming carbohydrates before and during a soccer match is beneficial, but under the conditions studied the GI of the carbohydrate source did not have an effect on fuel selection or repeated sprint performance. Funded by the Saskatchewan Pulse Growers.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".