Journal Title (Medline/Pubmed accepted abbreviation): Nutr. Metab.
First Page: 40
Summary of the review article
- The combination of resistance training and protein (amino acids) leads to growth of muscle volume and strength, especially when protein/amino acids are consumed immediately after exercise.
- Muscle protein synthesis will remain above basal levels for up to 48 hours after resistance training, so consumption of protein/amino acids during this time may also aid in building muscle compared to times when exercise was not performed.
- The “window of anabolic opportunity” after resistance training does not exclude sleeping. Ingestion of protein/amino acids right before bed has also been shown to increase muscle protein synthesis.
- Although the specific details regarding the biochemical mechanism are still being worked out, it is believed that amino acids work through the mTOR signaling pathway to upregulate genes involved in protein synthesis.
- Protein from milk (whey and casein), egg, soy, and beef have been shown to stimulate muscle protein synthesis. However, these proteins differ in other characteristics such as digestibility and absorption rates.
- Whey protein has a high digestibility and fast absorption rates, making it an ideal protein choice for immediately post-workout.
- Protein in liquid form rather than solid form may be absorbed more quickly, and thereby be able to stimulate protein synthesis faster.
- Essential amino acids, especially leucine, are most effective at stimulated muscle protein synthesis.
- The optimal dose of protein for an 86 kg (190 lb) man has been proposed as 20-25 g whey protein containing about 8-10 g essential amino acids and 2.5-3.0 g leucine.
- In addition to athletes, the elderly represent another population that desire to build/maintain muscle mass for optimal health and function. Muscle protein synthesis is not as efficient in the elderly, but it has been suggested that the same tactics apply for optimizing the rate of muscle synthesis. However, the elderly may be able to celebrate addition gains with higher doses of protein (about 40 g).
- Omega-3 fatty acids, as are in fish oil, have been shown to additionally stimulate muscle protein synthesis after exercise, perhaps by increasing the sensitivity of muscle protein to insulin and amino acids.
- Ingestion of carbohydrate with the protein after resistance training stimulates the release of insulin, which decreases muscle protein breakdown, and therefore aids in net protein synthesis.
- Maltodextrin has been shown to decrease muscle protein breakdown after exercise. If other carbohydrates have been evaluated, they were not mentioned in this review.
- Aside from their role in protein synthesis, carbohydrates are crucial for regeneration of glycogen stores after a workout.
Key practice applications
In order to maximize muscle strength and size, 20-25 g of whey protein (or cow’s milk) is recommended immediately after exercise. Biochemical effects of exercise last for at least 24 hours and up to 48 hours after exercise, including during sleep, so steady consumption of protein within this time has been suggested to maximize protein synthesis.