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Nutrition and Exercise: Timing is Everthing

  • 2/19/2018 8:30:00 AM
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Nutrition and Exercise: Timing is Everthing

Tyler Grubic, M.S.

Intense weight lifting and/or sprints, including acute single bouts, can promote exercise-induced stress responses, characterized by muscle damage and inflammation similar to stress associated with cardiovascular events and illnesses [10-12]. Decreased performance due to muscle soreness is not the direct result of inflammation, but rather a product of pain and mechanical receptor sensitivity to products of muscle breakdown, such as circulating chemicals and intramuscular proteins [13-15]. 

Timing in relation to carbohydrates and proteins may play a key role, and be of relative importance in relation to a training session, energy substrate use, and potential recover [2]. People often ask how important is nutrient timing, and the answer is, "it depends", mainly on the duration and intensity of the exercise.

Nutrient timing involves the purposeful ingestion of nutrients to favorably impact adaptive responses to acute and chronic exercise such as muscle strength and power, body composition, substrate utilization, and physical performance [16-18]. Carbohydrates are of maximal importance when the training involves one or more glycogen-depleting bouts in a single day, for example a high volume resistance workout followed or preceded by a high intensity cardiovascular training session. The importance of carbohydrates in maintaining blood glucose significantly increases as the exercise time starts to exceed 2 hours, especially training that approaches 3 hours [19]. Protein timing in relation to resistance training in a fasted state, which is the case with most current research, seems to provide evidence for maximal importance if consumed more than three hours prior, especially approaching or exceeding four hours prior. 

When carbohydrates are ingested, insulin is secreted as blood glucose is elevated out of the normal range of 70-110 mg/dL [4]. Insulin plays a larger role in anabolism inside the muscle cell. If blood glucose levels can be maintained better with the food bar (FB), one might expect to see a more anabolic environment and/or lead to less stress and inflammation, and better overall recovery. Researchers have begun to explore the specific timing of ingesting carbs and protein prior, during, and post-exercise in order to enhance the bioavailability of essential amino acids (EAA) and facilitate adaptations to resistance exercise [20]. 18g of whey protein contains about 6g of EAA, and it's recommended to ingest 3-6g EAA prior to, and following exercise. 

By consuming adequate protein and carbohydrates, one might enhance recovery and tissue repair, augment muscle protein synthesis, ameliorate muscle damage, promote euglycemia, facilitate glycogen resynthesis, and improve mood states following high-volume or intense exercise [21, 22]. If rapid restoration of glycogen is required, such as a 48-h recovery workout, combining carbohydrates with protein could prove highly beneficial [23]. 



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