Every athlete knows that enough protein is a key factor in building lean muscle mass. As for optimal protein intake for maximum muscle mass, recent research suggests that more is not necessarily better
The metabolic basis for a change in muscle mass is the net muscle protein balance (NBAL). Muscle proteins as well as all other body proteins are constantly being built up and broken down; these processes run off simultaneously. The balance of these two processes determines the amount of protein in the muscle.
Strictly speaking, changes in muscle mass occur as a result of changes in
and breakdown of the contractile elements of the musculature, the so-called myofibrillar proteins. The amount of protein present in the muscle over a period of time is determined by changes in the net muscle protein balance. The increase in muscle protein occurs when a positive balance is available. If the balance is negative, proteins are degraded (see Figure 1). Food intake and weight training both have a significant impact on the duration and extent of positive or negative net muscle protein balance.
Figure 1: Muscle protein gain due to the accumulation of muscle protein after each unit Resistance training plus nutrient supply (amino acid). As an example, the theoretical daily reaction to resistance training and food intake in the 1st, 12th and 24th week of training was presented here. There was no change in NBAL baseline or response to eating plus exercise during the study period. However, muscle hypertrophy occurred as a result of protein accumulation in response to each training session. The positive range after exercise plus food intake is greater than the negative range during food-free
The extent to which muscle mass can be built up is a matter of predisposition and, accordingly, individually different. Those who gain muscle mass quickly and effortlessly can thank their parents first and foremost. But also environmental influences, such as training and nutrition, play a major role in muscle mass and decide how much mass is available at any given time. By far the biggest contributors to muscle mass, however, are the type, volume, intensity and duration of stress training. Because no matter what or how much you eat, if you are not exercising with the right load, you will only achieve minimal results (strength training and muscle mass).
Exercise and diet affect muscle mass through changes in muscle protein assembly and breakdown, which results in an increase (or reduction) in NBAL. Depending on diet and exercise, the net muscle protein balance is either positive or negative. However, this can change daily or even hourly. The length and duration of these phases of positive and negative balance are the determinants of net gain or loss of muscle mass. (1) In healthy adults with consistent muscle mass, the phases of positive and negative NBAL are therefore the same, and no growth occurs. Muscle gain occurs only with a predominantly positive NBAL (Figure 1).
The influence of diet on muscle mass has been much discussed recently. Protein and various amino acids are generally considered the most important nutrients in terms of muscle growth. Therefore, many athletes consume large amounts of protein. In a recent article, scientists from McMaster University in Canada gathered data from a number of different publications. They found that strength athletes averaged well over 2.0 g protein per kilogram of body weight (g / kg BW / day), many even up to 3.5-4.0 g / kg BW / day (2 ) This corresponds to a protein consumption of 400 g per day!
How much protein is necessary?
This raises the question of whether so much protein is necessary or desirable to increase muscle mass and muscle strength. Protein is clearly important for an increase in muscle mass. Resistance training provides increased muscle protein synthesis, which in turn provides a better muscle protein balance. (3) But without a source of amino acids, the muscle protein balance does not come into positive territory - that is, there is no muscle anabolism. (4)
Protein intake before or after exercise clearly results in positive muscle anabolism. Proteins, especially myofibrillar proteins, accumulate over time as a reaction to the individual training sessions and accompanying protein uptake. This leads to an increase in muscle mass. However, relatively little protein is needed to trigger muscle anabolism when combined with exercise - 6g of essential amino acids consumed before or after exercise already create a positive net balance. (5)
Latest data presented earlier this year at the New Orleans American College of Sports Medicine conference show that the anabolic response to post-exercise protein uptake has a ceiling effect (with no dose increase, there is no increase in effects), The intake of more than 10 g of protein slows down the muscle-building process after exercise. Apparently, large amounts of protein are therefore unnecessary. The excess protein is simply converted into energy and not used for muscle growth.
The protein requirement of athletes is a very controversial topic among scientists. (6) It is usually determined by determining the nitrogen balance. The principle of this method is based on the fact that protein is the only nutrient that contains nitrogen. By measuring the amount of nitrogen taken and excreted, one can thus determine what amount of protein in the body (not necessarily in the muscles) has been added or lost. This is the method for determining the protein requirement of different populations. Several well-controlled studies show that high-performance athletes achieve a balanced nitrogen balance with the above-mentioned protein amount, ie approx. 1.2-1.6 g / kg BW / day. (1, 6, 7)
More protein = more muscle?
But why do many athletes and coaches claim that a high protein dosage is required for an increase in muscle mass? The answer to this is probably in the nitrogen balance method itself. Athletes who want to increase their muscle mass should have a positive nitrogen balance, therefore more protein than 1.6 g / kg BW / day should be taken. When measuring the nitrogen balance, the rule of thumb is: the greater the protein intake, the better the nitrogen balance. (2) From this, athletes conclude that the more proteins they eat, the greater the muscle gain.
However, an increase in muscle mass associated with such high nitrogen balances is virtually impossible (see next chapter), not even with the help of anabolic steroids. If the muscles were actually given so much nitrogen, the athletes concerned would have an increase in muscle mass of around 100 kg in one year! (1, 7) This method of determining the nitrogen balance is certainly problematic, especially if protein is taken in high doses.
However, there is more and more direct evidence that a high positive nitrogen balance is not equivalent to an increase in pure muscle mass. Various studies have shown that athletes with a high nitrogen balance do not necessarily need to increase their pure muscle mass (1.7). This is therefore not a good basis for the high-dose intake of protein.
Recently, two studies at McMaster University in Ontario showed very clearly why high protein intake during exercise is not required to increase muscle mass. (8, 9) The athletes participating in these studies consumed between 1.2 and 12 for 12 weeks and 1.6 g / kg Kg / day protein. As part of the training increased muscle mass and muscle strength, although the protein intake - at least in the opinion of many athletes and coaches - was relatively moderate.
These studies clearly demonstrated that anabolic training actually reduces protein requirements and that muscle mass and muscle strength also grow with "normal" protein intake. Extremely high protein levels (over 2.0 g / kgkg / day) B. as a dietary supplement, however, are not required and cause no additional increase in strength and mass. Because with an additional intake of protein, the excess protein is simply converted into energy, and the nitrogen is excreted from the body via the urine pool.
Why a positive nitrogen balance is not synonymous with muscle growth
Let's say that an athlete eats 2.5 g protein / kg / day; this would give a positive nitrogen balance of about 15 g of nitrogen per day.
However, protein is only about 16% nitrogen, so the actual protein gain is 15 g N x 1 g protein / 0.16 g N, ie around 94 g protein per day.
- Since the muscles are 75% water, the muscle gain per day is 94 g protein x 25% protein in the muscle (75% water). This would be a muscle gain of 282 g per day.
- Converted to the whole year, this means: 282 g protein per day x 365 days = 102 930 g / year or 103 kg muscle gain within one year!
Is too much protein dangerous?
On the other hand, the question arises as to whether excessive protein consumption is harmful. Many scientists and physicians warn about possible health problems caused by high protein intake. Especially kidney problems and bone loss are mentioned as a side effect of high protein intake. So far, however, no case of kidney disease has been documented in otherwise healthy individuals.
Also, the problem of bone loss from high protein intake appears to be overstated dramatically. The main problem with a high-dose supply of proteins is that other nutrients will inevitably be displaced if the energy supply is not to increase. Therefore, carbohydrate intake is likely to decrease. However, carbohydrates are crucial for athletic performance, especially in endurance sports, but also for maintaining high-intensity resistance training. In order to avoid that an increased protein intake is at the expense of other nutrients, in particular that of carbohydrates, a cautious procedure is therefore recommended.
Keep energy balance positive
The most important nutritional factor in terms of increasing muscle mass is energy intake. It is very difficult, if not impossible, to develop muscle mass when the energy balance is negative, ie the energy input is lower than the energy consumption. When there is an energy deficit, it is not possible to maintain a positive nitrogen balance, even when large amounts of protein are being delivered. (10)
However, if the energy balance is positive, athletes have different ways to gain muscle mass through protein intake. About 100 years ago, it was demonstrated that soldiers training in training with relatively low protein inputs - about 1.0 g / kgkg / day - (11)
A recent study found that the increase in muscle mass during resistance training was the same when athletes consumed 2, 000 calories in addition to their normal diet either as pure carbohydrates or as carbohydrates plus protein. (12) If sufficient protein intake (1.0 g / kg BW / day is sufficient), muscle hypertrophy is dependent on adequate energy supply.
Just by eating the calories needed for training, most athletes automatically absorb enough protein and therefore do not need any further supplementation. A very frequent and broad resistance training with high stress intensity is usually also necessary for the increase of mass and strength. However, such training requires significant energy input. (13) Although protein accounts for only a relatively small portion of the diet (around 12%), dietary protein intake is sufficient to meet the increased protein needs for muscle growth based on nitrogen balance.
Since muscle mass accumulation is clearly a response to each training session (see Figure 1), studies on the acute response of muscle protein synthesis to exercise and food intake provide valuable information for describing muscle mass and muscle strengthening strategies.
A very important finding of this scientific investigation is that it is nonsense to recommend for all athletes in general a certain amount of protein as an optimal dose for the increase of muscle mass. Since there are several factors influencing the overall response, such as the timing of protein intake, the type of protein and other nutrients that are taken with the protein, 2 athletes who consume the same amount of protein do not necessarily have the same muscle gain.
Studies have shown that the nature of the protein influences the anabolic response. Recent research has shown that consuming milk stimulates post-workout muscle anabolism, and more so than eating soy. (14) These findings lead to 2 important findings: The protein in the diet acts as well as a protein supplement. And animal proteins seem to cause a stronger anabolic response after resistance training than herbal ones.
Leucine, but not a miracle cure?
It seems that the key component of the protein is the essential amino acid content. As we now know, muscle anabolism occurs only when essential amino acids are consumed, meaning that the non-essential amino acids are irrelevant to stimulating muscle growth after exercise. (4) However, this does not mean that supplementing with essential amino acids is better as with nonessential amino acids or whole proteins. It simply means that essential amino acids can stimulate muscle protein synthesis and that the increased protein synthesis is supported by enough nonessential amino acids.
The most important amino acid for stimulating muscle protein synthesis is probably leucine. Leucine as well as isoleucine and valine are branched-chain amino acids (VKAS). These are often touted as the "amino acids with the greatest anabolic effect", so many VKAS supplements are sold and consumed.
According to some animal studies, leucine stimulates the pathways in the muscle cells. This causes increased muscle protein synthesis after intense exercise in rats, although protein synthesis normally decreases. In a catabolic training, the intake of leucine therefore have a great anabolic effect. However, with regard to humans, it is not possible to make such clear statements, especially as regards the effect after resistance training.
In the Netherlands, scientists found that eating protein in addition to carbohydrates stimulates muscle protein synthesis more than eating only carbohydrates. (18) However, when added to protein and carbohydrates, leucine was not further stimulated muscle protein synthesis.
Similar results were obtained by the current study of a research group from Galveston, Texas. It shows that leucine can reduce muscle protein depletion in humans when they are not exercising. (19) As the results of the Galveston study show, the net muscle protein balance could not be improved by adding leucine, which casts doubt on the efficacy of leucine supplementation after anabolic Training in humans. However, it has to be taken into account that there have been very few scientific studies on this topic so far and that a systematic evaluation is necessary in order to be able to make a definitive statement about the anabolic effects of leucine.
Proteins: The right timing for ingestion
The timing of taking protein and amino acids has been much discussed lately. Taking an essential amino acid plus carbohydrate solution prior to resistance training, the muscle anabolism response was greater than when taking the solution after exercise. (20) Many interpreted these results as meaning that athletes should take protein before exercise.
However, a follow-up study by the same research group revealed only a marginal difference in muscle anabolism between before and after exercise - a completely different picture than the mixture of free amino acids and carbohydrates. From this it can be deduced that there is an interaction between the amino acid source and the time of ingestion, ie proteins are not necessarily all produced evenly.
The difference is probably related to the time needed to digest protein. Since free amino acids do not have to be digested in the intestine, they get into the blood very quickly. If free amino acids are taken right before training, the rate of amino acid transport into the muscles during exercise is therefore very high. However, as proteins need to be digested, the arterial blood level of the amino acid does not rise fast enough to increase the rate of transport, giving approximately the same anabolic response as post-exercise protein intake. It may be beneficial to have a protein intake 15, 20, or even 30 minutes before training. However, this possibility has not yet been scientifically investigated.
An anabolic reaction is apparently also favored when in addition to protein and amino acids, other nutrients are supplied. The consumption of carbohydrates and fat along with protein appears to increase the absorption of essential amino acids in the muscles (see Figure 2). These results also support an earlier claim that the protein in foods is as effective for stimulating muscle hypertrophy as protein supplements.
Fig. 2: Utilization of amino acids (AS) from the diet for an increase in muscle protein after resistance training. An additional intake of carbohydrates to an amino acid source improves the utilization of the absorbed amino acids.
Although protein supplements are certainly legitimate (in some situations, taking them is simply more practical), there's nothing wrong with optimizing muscle growth (such as bodybuilders) simply by eating foods that contain high-quality proteins, such as z. Eg eggs, milk and dairy products and lean meat. This fact is by no means surprising. After all, evolution does not expect us to buy individual proteins in food supplement stores, but to source and make the best possible use of the protein from the diet.
1. Applied Physiology, Nutrition and Metabolism, 2006, Vol. 31, pp. 647-654
2. Nutrition, 2004, Vol. 20 (7-8), pp. 689-695
3. American Journal of Physiology - Endocrinology And Metabolism, 1997, Vol. 273 (36), p. E99-E107
4. American Journal of Physiology, 1999, Vol. 276 (4), p. E628-E634
5. American Journal of Physiology, Endocrinology and Metabolism 2002, Vol. 283 (4), p. E648-E657
6. Clinical Journal of Sports Medicine, 2007, Vol. 26 (1), p. 17-36
7th International Journal of Sports Nutrition and Exercise Metabolism, 2007
8. Applied Physiology, Nutrition, and Metabolism, 2006, Vol. 31 (5), pp. 557-564
9. Nutrition Journal, 2007, vol. 137 (4), pp. 985-991
10. Nutrition Journal, 1984, Vol. 114 (11), pp. 2107-2118
11. Chittenden RH, The nutrition of man. London, Heinemann, 1907
12. Journal of Sports Medicine and Physical Fitness, 2002, Vol. 42 (3) pp. 340-347
13. Journal of Applied Physiology, 1992, Vol. 72 (4), pp. 1512-1521
14th American Journal of Clinical Nutrition, 2007, Vol. 85 (4), 1031-1040
15. American Journal of Clinical Nutrition, 2007, Vol. 86 (2), 373-381
16. Nutrition Journal, 1999, Vol. 129 (6), pp. 1102-1106
17. American Journal of Physiology, 1998, Vol. 274 (2), p. C406-C414
18. American Journal of Physiology - Endocrinology and Metabolism, 2005, Vol. 288 (4), p. E645-E653
19. Nutrition Journal, 2005, Vol. 135 (6), pp. 1580S-1584S
20. American Journal of Physiology - Endocrinology and Metabolism, 2001, Vol. 281 (2), p. E197-E206
21. American Journal of Physiology - Endocrinology And Metabolism, 2007, Vol. 292 (1), p. E71-E76
22. Medicine & Science in Sports & Exercise, 2003, Vol. 35 (3), pp. 449-455
23. Medicine & Science in Sports & Exercise, 2006, Vol. 38 (4), pp. 667-674
Myofibrillar proteins - proteins that are found in muscles and other tissues, that provide muscle growth and muscle size and that are necessary for muscle contraction
Essential amino acids - proteinogenic amino acids that are not self-produced by the body and therefore need to be absorbed through the diet
Kataboles Training - an experimental model that causes a reduction in muscle protein synthesis
Metabolite - a substance that arises as an intermediate in metabolic processes