The Protein Intake for Strength Athletes Debate
By James Collier BSc (Hons) RNutr, Nutrition Consultant
It is a fact that there is little in the way of sound scientific research to support the claim that strength athletes (by definition, strength athletes are those sportsmen and women who rely predominately on strength and power for their sport) require high protein intakes; yet it seems to be universally accepted in the world of bodybuilding that we do advocate a very high protein diet, whereas dietitians and conventional nutrition experts would advise a lot lower intakes. So, do we need to consume a lot of protein, or is this just a myth perpetrated by supplement companies to sell us more protein powder?
Recommended Protein Intakes for Strength Athletes
Protein is important for the support of muscular adaptations to training stimuli and it is acknowledged that strength athletes and bodybuilders do need a higher than normal protein intakes. It has been indicated that habitual protein intakes of athletes involved in regular strength training is often in the region of 2-4g/kg body weight per day (Phillips 2004). This is more than twice the dietary reference value for protein, i.e. 0.8g/kgBW/day (DoH 2003).
Arguments for this high intake come from the nitrogen balance method of estimating protein requirements which assumes as protein intake increases, so too do gains in body proteins. Many argue against this approach because when protein intakes are high, estimates of calculated gains in lean mass are clearly unrealistic; for example an intake of 2.5g/kgBW/d would equate to roughly a 500g gain in body mass per day which is as much as 100kg per year; now that would be very nice!
There is clearly no single recommended figure for strength athletes as the amount recommended will depend on the intakes of other nutrients, particularly carbohydrates for energy which will have a protein-sparing effect, the type of sport, the individual and other lifestyle factors.
In their article, Witard & Tipton (2012) examined a few of the popular claims made in respect of protein and strength training and discussed the evidence. I have included their arguments and added some other thoughts:
Claim 1) A high intake of protein is necessary for an athlete to achieve gains in muscle mass
Witard & Tipton state that it is not necessary to ingest very large amounts of protein during strength training as muscle and strength can be increased on a relatively low protein intake shown between 1.2 and 1.6g/kgBW/day (Hartman et al 2006). It has also been shown in one study that no greater intake in muscle mass was demonstrated at 2.6 g/kgBW/day compared to 1.35 g/kgBW/day (Lemon et al 1992).
Excess protein is oxidised for energy, and carbohydrates will also have a protein sparing effect, meaning diets with sufficient carbohydrate will not require excess protein.
So the key point in this whole debate is at what level does protein intake become 'excess'? We'll look at this point again later.
Claim 2) Very high intakes of protein may be harmful to the athlete's health
Although there are warnings by the medical profession that diets high in protein may be harmful to athlete's health, there are little or no reports of kidney problems or loss of bone density in athletes consuming high protein diets. Indeed, it's been suggested that a good protein intake in athletes is imperative for collagen anabolism and bone health.
Claim 3) To achieve gains in muscle mass, a source of protein must be ingested immediately following resistance exercise
Timing of protein intake does affect the growth of muscle following resistance exercise (Tipton et al 1999, Tipton et al 2001). Reports have claimed that muscle remains responsive to nutrient ingestion for 45-60 minutes following exercise (Ivy & Portman 2007, Lemon et al 2000). However, other studies have demonstrated a similar response when protein was consumed up to three hours following resistance exercise (Rasmussen et al 2000), and the anabolic response of muscle tissue remains for at least 24 hours.
In reality, it depends on what was also consumed in the hours before exercising. If there is still protein present in the digestive system (which there more than likely will be) then this will continue to be digested and leach into the blood. However, there is an opportunity to take some easy-to-consume protein immediately after exercise and doing so will certainly do no harm.
The optimal time point to consume protein in relation to maximising muscle and strength gains is currently unknown; indeed, it's unlikely that there is one as it's all about maintaining a positive nitrogen balance at all times.
Claim 4) Protein supplements stimulate superior muscle anabolism compared to food
This was a statement made by Witard & Tipton that claims are made to this effect. Whilst that may be the case, it's not accepted in the bodybuilding community; indeed, most accept that food is superior to supplements. A protein source containing all essential amino acids is required, be that from a high quality supplement or from food. Protein supplements do have their place as they are very convenient and easy to ingest, especially post workout when eating food can be a struggle.
Claim 5) Adding extra leucine to a source of protein will further stimulate muscle growth following exercise
This is a fairly new claim in the bodybuilding world. The branched chain amino acids (BCAAs), in particular leucine, are often touted as the most anabolic amino acids. BCAA supplementation has been shown to increase muscle cell signalling following resistance exercise (Karlsson et al 2004) and this has lead to claims that additional leucine may maximise the anabolic response. However, studies indicate differently (Koopman et al 2007) and there is currently no evidence to suggest this benefit. This does seem to be a case of clever marketing which has now lead this 'fact' to be accepted in the bodybuilding community with little justification. Whey protein and most high protein foods are naturally high in BCAAs, so a good protein intake will cover the need for additional BCAAs.
What is the optimum amount of protein for strength athletes?
So, we've agreed that high protein intakes aren't harmful and that protein supplements are no superior to real food sources of protein. We've also discussed that there may be a role for protein – more conveniently from protein supplements – in the time immediately post exercise. I'm sure many will continue to argue the case for BCAAs over and above normal protein intake, but the evidence doesn't support this.
However, the one area which continues to be of debate is what amount of protein is optimal for strength athletes. Going back to claim 1, we asked at what point does protein intake become 'excess'. I would argue that the protein intake just below this excess amount would be optimal, provided that, of course, your intake of other macronutrients, especially carbohydrates, is optimal.
But what is this figure that protein becomes 'excess'? Indeed, should we be looking at total daily figures in grams per kilogram bodyweight? Shouldn't we also be emphasising that protein intake should be spread through the day too? We've discussed the issue of timing and there is no conclusion, but for sheer practicality, strength athletes should be consuming protein at least five times per day, even if we were to agree the low intake of 1.2g/kgBW/day, just to avoid discomfort, remembering that carb foods, fruit and veg need to be eaten also.
Bodybuilders notoriously want figures put on everything. I argue that we do not need figures. Food tables are not wholly accurate and we are not robots. I argue that you should eat quality high protein foods at even, convenient times throughout the day along with carbohydrate and essential fat sources at appropriate times. Food choice is important; is macronutrient choice as important?
The issue of anabolic steroids and performance enhancing peptides further confounds the debate. These drugs increase the requirements for protein for strength and size gains and, to a degree, the requirements for protein increases as dose administered increases.
Broadly speaking, if I was forced to put a vague figure on the protein requirements for strength athletes, I would say it's something in the region of 1.5 to 2.3g/kgBW/day, but that's assuming that the individual is a hard training strength athletes with regular gym sessions, has moderate to low body fat, has adequate intake of essential fats, carbohydrates, vitamins, minerals and fibre, eats a varied diet with several meals through the day.
Strength athletes do have higher protein requirement than non trainers and, for sure, there's an element of sports supplement companies continual marketing having an effect on the consensus of opinion that we need more protein than we actually do.
- Department of Health. Dietary reference intakes for energy, carbohydrate, fibre, fat, fatty acids, cholesterol, protein, and amino acids, part I. Washington, DC: National Academy Press, DC; 2003
- Karlsson HK, Nilsson PA, Nilsson J, Chibalin AV, Zierath JR, Blomstrand E. Branched-chain amino acids increase p70S6k phosphorylation in human skeletal muscle after resistance exercise. Am J Physiol Endocrinol Metab. 2004 Jul; 287: E1-E7
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- Tipton KD, Rasmussen BB, Miller SL, Wolf SE, Owens-Stovall SK, Petrini BE, Wolfe RR. Timing of amino acid-carbohydrate ingestion alters anabolic response of muscle to resistance exercise. Am J Physiol Endocrinol Metab. 2001 Aug; 281: E197-E206
- Witard OC, Tipton KD. Issues Surrounding Recommended Protein Intake for Strength Athletes. NHD 2012 Apr; 73: 10-11