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Searching the Scientific Journals: Nutrient Timing Enhances Endurance Performance


Nutrient timing (the process of ingesting mixtures of proteins and carbohydrates before, during, and after training or competition) has been proven, both experimentally and anecdotally, to increase “time to fatigue” (i.e., allowing athletes to perform longer), reduce muscle damage, improve glycogen (carbohydrate) storage, and stimulate the synthesis of specific structures (such as skeletal muscle tissue, aerobic enzymes, and mitochondria) that are critical for aerobic training adaptations and augmented endurance performance. All of these benefits extend to ALL endurance sports, but they are particularly important to the endurance athlete who trains at a very high volume (i.e., several training sessions per week) and intensity (high percentages of maximum heart rate, VO2 max, or lactate threshold). Examples of these types of athletes include long-distance endurance cyclists, marathon runners, and triathletes. In order to reduce the cumulative physiological and mechanical stresses of training, it is critical that these athletes carefully and precisely ingest nutrients around and during training to facilitate the structural and functional adaptations necessary to improve aerobic endurance performance.

Scientific Research:
New scientific evidence suggests that protein and carbohydrate ingestion before, during, and after endurance training can: (1) increase time to fatigue by 140-230%, meaning that those who ingested the protein-carb mixture exercised up to 230% longer than controls (Ivy et al, 2003); (2) reduce muscle damage by 650% (Saunders et al, 2004); and (3) increase glycogen (carbohydrate) storage by 140-700% (Zawadzki et al, 1992). Optimal ratios of carbohydrates to proteins in these drinks are approximately 2-4 to 1, and different types of sugars, along with high-quality whey protein, should comprise the primary ingredients. Due to the inability of the stomach and small intestine to digest and absorb nutrients effectively during exercise, osmolarity (particles in solution) should be limited, and the mixture must be significantly diluted to exit the small intestine quickly and enter into the blood stream for fast delivery to the working muscle.

Practical Implications:
All endurance athletes can benefit from consuming about 6-15g of whey protein, along with 20-30g of simple sugars, 15-30 minutes before exercise. During each hour of endurance exercise, the goal should be to consume 30-60g of simple sugars and 12-25g of whey protein. Lastly, immediately following exercise (within 15 minutes of ceasing exercise), at least 50g of simple sugars and 20g of whey protein should be consumed, with larger amounts being consumed following high intensity and/or longer duration bouts of endurance exercise. Two nutritional supplements currently on the market meet the criteria for an effective nutrient timing beverage for endurance athletes: Accelerade, and Endurox. AFS’ Nutrient Solution, although appropriate for the general population and non-endurance based exercise, is not formulated with the gastrointestinal needs of the endurance athlete in mind; therefore, it is not an appropriate beverage to utilize during endurance exercise (although it could be consumed before or after).

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