King Grub
2014-05-06, 08:25
With regular practice, resistance exercise can lead to gains in skeletal muscle mass by means of hypertrophy. The process of skeletal muscle fiber hypertrophy comes about as a result of the confluence of positive muscle protein balance and satellite cell addition to muscle fibers. Positive muscle protein balance is achieved when the rate of new muscle protein synthesis (MPS) exceeds that of muscle protein breakdown (MPB). While resistance exercise and postprandial hyperaminoacidemia both stimulate MPS, it is through the synergistic effects of these two stimuli that a net gain in muscle proteins occurs and muscle fiber hypertrophy takes place. Current evidence favors the post-exercise period as a time when rapid hyperaminoacidemia promotes a marked rise in the rate of MPS. Dietary proteins with a full complement of essential amino acids and high leucine contents that are rapidly digested are more likely to be efficacious in this regard. Various other compounds have been added to complete proteins, including carbohydrate, arginine and glutamine, in an attempt to augment the effectiveness of the protein in stimulating MPS (or suppressing MPB), but none has proved particularly effective. Evidence points to a higher protein intake in combination with resistance exercise as being efficacious in allowing preservation, and on occasion increases, in skeletal muscle mass with dietary energy restriction aimed at the promotion of weight loss. The goal of this review is to examine practices of protein ingestion in combination with resistance exercise that have some evidence for efficacy and to highlight future areas for investigation.
Changes in MPS are variable throughout the day on a meal-to-meal basis, and are augmented immediately and for a prolonged time period after resistive exercise. Endurance exercise also stimulates MPS, but the responses are different to those with resistance exercise, and there is far less clarity on the length of time that they persist. Dietary protein appears to be most effective when consumed after exercise, to take advantage of the ‘receptive state’ of the muscle, for mounting a robust MPS response. This would appear to be a guideline that athletes engaging in resistance and endurance training should follow to allow the synthesis of new proteins specific to their activity, and also to promote adaptive remodeling and repair of any cellular damage. The dose of protein that appears most effective following resistance exercise, and possibly endurance exercise, is approximately 0.25–0.30 g protein/kg BM/meal, at least when consuming isolated proteins. Leucine is a key amino acid in stimulating MPS and its content in, for example, whey protein is probably a primary reason why whey protein is so effective at stimulating MPS as opposed to isolated soy and casein proteins. Therefore, proteins containing a high content of leucine that are digested rapidly are most effectively directed toward MPS; however, ingestion of foods such as milk promote a robust stimulation of MPS and highlight the fact that ‘blends’ of fast and slow proteins are still effective in stimulating MPS. When protein is sufficient, dietary carbohydrate and the ensuing insulinemia does not augment the response of MPS, but carbohydrate is still a practical macronutrient to consume to promote glycogen resynthesis. Neither arginine nor glutamine have been demonstrated to be effective at promoting resistance exercise-induced anabolism in humans and their inclusion in supplements has, on the basis of current evidence, no grounds.
Sports Med. 2014 May;44 Suppl 1:71-7. A brief review of critical processes in exercise-induced muscular hypertrophy.
http://download.springer.com/static/pdf/427/art%253A10.1007%252Fs40279-014-0152-3.pdf?auth66=1399533727_3dd998fcfb0bc98d3448bbe2e7 f558b2&ext=.pdf
Changes in MPS are variable throughout the day on a meal-to-meal basis, and are augmented immediately and for a prolonged time period after resistive exercise. Endurance exercise also stimulates MPS, but the responses are different to those with resistance exercise, and there is far less clarity on the length of time that they persist. Dietary protein appears to be most effective when consumed after exercise, to take advantage of the ‘receptive state’ of the muscle, for mounting a robust MPS response. This would appear to be a guideline that athletes engaging in resistance and endurance training should follow to allow the synthesis of new proteins specific to their activity, and also to promote adaptive remodeling and repair of any cellular damage. The dose of protein that appears most effective following resistance exercise, and possibly endurance exercise, is approximately 0.25–0.30 g protein/kg BM/meal, at least when consuming isolated proteins. Leucine is a key amino acid in stimulating MPS and its content in, for example, whey protein is probably a primary reason why whey protein is so effective at stimulating MPS as opposed to isolated soy and casein proteins. Therefore, proteins containing a high content of leucine that are digested rapidly are most effectively directed toward MPS; however, ingestion of foods such as milk promote a robust stimulation of MPS and highlight the fact that ‘blends’ of fast and slow proteins are still effective in stimulating MPS. When protein is sufficient, dietary carbohydrate and the ensuing insulinemia does not augment the response of MPS, but carbohydrate is still a practical macronutrient to consume to promote glycogen resynthesis. Neither arginine nor glutamine have been demonstrated to be effective at promoting resistance exercise-induced anabolism in humans and their inclusion in supplements has, on the basis of current evidence, no grounds.
Sports Med. 2014 May;44 Suppl 1:71-7. A brief review of critical processes in exercise-induced muscular hypertrophy.
http://download.springer.com/static/pdf/427/art%253A10.1007%252Fs40279-014-0152-3.pdf?auth66=1399533727_3dd998fcfb0bc98d3448bbe2e7 f558b2&ext=.pdf