Protein
Protein
Overview
1) An acute exercise stimulus, particularly resistance exercise, and protein ingestion both stimulate muscle protein synthesis (MPS) and are synergistic when protein consumption occurs before or after resistance exercise.
2) For building muscle mass and for maintaining muscle mass through a positive muscle protein balance, an overall daily protein intake in the range of 1.4–2.0 g protein/kg body weight/day (g/kg/d) is sufficient for most exercising individuals, a value that falls in line within the Acceptable Macronutrient Distribution Range published by the Institute of Medicine for protein.
3) There is novel evidence that suggests higher protein intakes (>3.0 g/kg/d) may have positive effects on body composition in resistance-trained individuals (i.e., promote loss of fat mass).
4) Recommendations regarding the optimal protein intake per serving for athletes to maximize MPS are mixed and are dependent upon age and recent resistance exercise stimuli. General recommendations are 0.25 g of a high-quality protein per kg of body weight, or an absolute dose of 20–40 g.
5) Acute protein doses should strive to contain 700–3000 mg of leucine and/or a higher relative leucine content, in addition to a balanced array of the essential amino acids (EAAs).
6) These protein doses should ideally be evenly distributed, every 3–4 h, across the day.
7) The optimal time period during which to ingest protein is likely a matter of individual tolerance, since benefits are derived from pre- or post-workout ingestion; however, the anabolic effect of exercise is long-lasting (at least 24 h), but likely diminishes with increasing time post-exercise.
8) While it is possible for physically active individuals to obtain their daily protein requirements through the consumption of whole foods, supplementation is a practical way of ensuring intake of adequate protein quality and quantity, while minimizing caloric intake, particularly for athletes who typically complete high volumes of training.
9) Rapidly digested proteins that contain high proportions of essential amino acids (EAAs) and adequate leucine, are most effective in stimulating MPS.
10) Different types and quality of protein can affect amino acid bioavailability following protein supplementation.
11) Athletes should consider focusing on whole food sources of protein that contain all of the EAAs (i.e., it is the EAAs that are required to stimulate MPS).
12) Endurance athletes should focus on achieving adequate carbohydrate intake to promote optimal performance; the addition of protein may help to offset muscle damage and promote recovery.
13) Pre-sleep casein protein intake (30–40 g) provides increases in overnight MPS and metabolic rate without influencing lipolysis.
“Higher protein intakes (2.3-3.1 g/kg FFM) may be required to maximize muscle retention in lean, resistance-trained subjects under hypocaloric conditions. Emerging research on very high protein intakes (>3 g/kg) has demonstrated that the known thermic, satiating, and LM-preserving effects of dietary protein might be amplified in resistance-training subjects.”
Timing
Protein timing vs. total CONSISTENT daily intake:
"multiple studies have suggested that total daily protein intake and distribution are more important than peri-workout protein timing when it comes to strength and lean mass gains."
"Whey protein supplementation was effective in promoting increases in SMM, muscular strength, and functional capacity in pre-conditioned older women, regardless of supplementation timing."
"regardless of supplementation timing."
Anabolic Window
“Based on current evidence, it appears clear that any effect of protein timing on muscle hypertrophy, if in fact there is one, is relatively small. Total daily protein intake is by far the most important factor in promoting exercise-induced muscle development. Research indicates that consumption of 1.6 to 2.2 g/kg per day is needed to optimize results.”
Pre-Sleep Protein
“Presleep CP [casein protein] accelerates functional recovery in professional soccer players and, therefore, provides a practical means of attenuating performance deficits in the days after a match.”
How much in one sitting?
“The preponderance of data indicate that while consumption of higher protein doses (> 20 g) results in greater AA oxidation, this is not the fate for all the additional ingested AAs as some are utilized for tissue-building purposes. Based on the current evidence, we conclude that to maximize anabolism one should consume protein at a target intake of 0.4 g/kg/meal across a minimum of four meals in order to reach a minimum of 1.6 g/kg/day. Using the upper daily intake of 2.2 g/kg/day reported in the literature spread out over the same four meals would necessitate a maximum of 0.55 g/kg/meal.”
Muscle Full Effect
“The theory behind why, with increasing protein doses, there is a ceiling on MPS has been termed the “muscle full effect”
“AAs are no longer used for MPS and are targeted for oxidation”
Type of Protein
“Whole-body protein synthesis is stimulated more with whey protein whereas whole-body protein breakdown is suppressed with ingestion of casein”
Leucine
Eat enough protein at each meal to stimulate muscle protein synthesis - at least 2.5 mg of leucine is required.
“Research suggests that meals containing ≥30 g of high-quality protein, defined by a balanced profile of essential amino acids including ≥2.5 g of leucine, can overcome anabolic resistance in older adults and optimize muscle health.”
“Skeletal muscle mass is regulated in part by the dynamic balance between muscle protein synthesis (MPS) and muscle breakdown (MPB) (i.e., protein turnover). Although MPS is stimulated by exercise and protein intake (1–3), MPB increases slightly with short-term fasting, but is more strongly stimulated during inactivity and in pathological conditions (4,5). Resistance exercise is widely recognized as a potent stimulus for increasing MPS; however, in the absence of adequate nutrition, muscle protein balance (MPS minus MPB) remains negative (2,6).”
“5 g of leucine may be “easily” obtained by the ingestion of approximately 200 g (~7 oz.) of red lean meat or 50 g of whey protein isolate”
“High-dose leucine supplementation did not enhance gains in muscle strength and mass after a 12-wk RT program in young resistance-trained males consuming adequate amounts of dietary protein.”
Not only eat enough protein throughout the day, but eat enough at one sitting to promote MPS.
Protein and Aging
“A presumed reason for the inadequacy of the protein RDA for older persons is a phenomenon known as the “anabolic resistance” of skeletal muscle. Anabolic resistance is the phenomenon within skeletal muscles of older persons when there is an attenuated response of muscle protein synthesis (MPS) to resistance exercise (3) and ingestion of protein.”
“Leucine is now recognized as a key signal in stimulating MPS in older adults (33–35) and a number of studies have shown that the provision of ≥2.5 g/meal of leucine in older persons has a “restorative” impact on MPS”
“Research suggests that meals containing ≥30 g of high-quality protein, defined by a balanced profile of essential amino acids including ≥2.5 g of leucine, can overcome anabolic resistance in older adults and optimize muscle health.”
Protein and Kidneys
“Our analysis indicates that HP intakes do not adversely influence kidney function on GFR in healthy adults.”
Protein and Bone Health
“We conclude that protein is an essential nutrient for bone health, although further research is required to clarify the mechanistic pathways through which it exerts its influence, along with the clarification of the quantities, food sources and timing to allow for the optimisation of this protective influence and ultimately a reduction in fracture risk.”
