The use of protein in sports nutrition is in a state of change.
Originally associated with bodybuilders wanting to primarily increase muscle mass and aid muscle recovery, protein and protein supplements are now used by all types of athletes to enhance performance. And protein research, which has traditionally focused on supplementation post-exercise and its impact on the rate of muscle synthesis, has begun to look more closely at the impact of protein supplementation prior to exercise.
As a result of these new studies, scientists now have a better (though still developing) understanding of the optimal amount and timing of protein needed to achieve the best gains in muscle strength, size and/or conditioning. This is welcome information for both recreational and competitive athletes, who are always looking for nutritional solutions to help them get more out of their training and competitions, as well as to recover more quickly.
The function of proteins and daily recommendations has already been addressed in Shana Maleeff's PTontheNet article How Much Protein Does Your Personal Training Client Really Need? This article goes further to discuss the timing of protein intake before and after exercise, and the type and amount of protein that may be optimal to maximize performance for the clients and athletes you train.
Understanding Amino Acids: The Building Blocks of Protein
Protein is critical to all tissues in the body and is made up of building blocks called amino acids. Of the twenty amino acids, nine are essential and eleven are non-essential. The nine essential amino acids — histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine — are critical to survival and can only be obtained through the diet and/or the breakdown of the body’s own protein stores (Tarnopolsky, 2007). All amino acids are key for building muscle mass, but leucine is of particular importance because it stimulates pathways in the body that lead to muscle protein synthesis. While protein is vital for everyone, research continues to support its particular importance to achieving positive results for athletes.
The Science Behind Performance-Based Protein Timing
Protein intake can influence gains in muscle size, facilitate muscle damage repair, and enhance muscle conditioning for both resistance and endurance training. To achieve these benefits, a positive protein balance needs to be achieved, which means that more muscle needs to be built than broken down over the course of the day. Both endurance and resistance exercise stimulate both the breakdown and building of muscle proteins during the immediate post-exercise stage, therefore the intake of protein around the time of training is key to maximizing muscle repair and reconditioning.
Protein Before Training
The majority of research looking at protein and exercise has historically focused on protein consumed in the recovery phase. There has been only a small amount of research analyzing the impact of protein consumed before exercise, and even less comparing the effects of pre- versus post-exercise protein consumption.
Some of the pre-exercise research that has been done indicates that protein consumed before exercise could have a beneficial effect on muscle protein (Tipton, 2007). An early investigation looked at the impact on muscle protein balance when 6g of free amino acids were consumed with 35g of carbohydrate before, compared to immediately after, resistance exercise. The researchers found that muscle uptake of the amino acids was greater when the free amino acids and carbohydrate were consumed before rather than after exercise. Furthermore, when these results were compared to a similar study, pre-exercise ingestion was shown to have a greater anabolic effect compared to post-exercise (Tipton, 2007).
This result is not always consistent, however, and appears to be impacted by the type of protein, the energy content of the meal and the nutrients that the protein is ingested with. For example, in one study researchers gave volunteers 20g of whey protein either immediately before or one hour after exercise. For this sample group, researchers did not find that the timing of the whey protein ingestion made any significant difference in the participants' utilization of the amino acids.
The discrepancy between how free amino acids and whey protein (an intact protein) are consumed before exercise may be due to the digestibility of the protein and, therefore, the availability of the amino acids. While whey protein is easily broken down in the body, it will take longer for those amino acids to reach the muscles than when free amino acids are consumed. To counteract this, it could be beneficial to consume a high quality protein, such as whey, around an hour or so before starting a training session. This provides enough time for the protein to be broken down into free amino acids and enter the circulation for uptake into the muscle (Tipton, 2007). Co-ingestion with carbohydrates, which can influence insulin response (and which may have an anabolic effect), could further enhance the benefits.
Protein Intake After Training
It is well established that protein intake after endurance and resistance training session can help facilitate muscle damage repair and aid muscle mass gains.
Further, for muscle protein gains after resistance exercise, it appears that supplementation immediately afterward is much more beneficial than delaying consumption by a number of hours. While there is evidence that muscle is sensitive to nutrients for up to three hours after exercise, other research indicates that the greatest gains in muscle mass and strength come when protein ingestion takes place immediately after training. Waiting even two hours after training can negatively impact muscle mass and strength gains.
Co-ingestion of protein with carbohydrates immediately after exercise is likely to augment training benefits. The level of carbohydrate shown to have this benefit is around 35g, which is less than the 1g carbohydrate per kg body weight recommended to restock muscle glycogen levels (Phillips, Moore & Tang, 2007). This could come, for example, from a large banana and a large tub of Greek yogurt, a bowl of cereal with reduced fat milk, or a protein and carbohydrate shake.
Protein in Practice: Recommendations for Your Clients and Athletes
When
While many other factors influence muscle conditioning and there is an insufficient body of evidence to make absolute recommendations, it may be reasonable to recommend to your clients that they consume protein both before and immediately after exercise to support their adaptation to training, particularly if they do not have any gastrointestinal issues with eating or drinking before exercise and their schedules can accommodate it.
What Type
Consuming a high quality protein will help provide an optimal level of essential amino acids in the body. Most high quality proteins are around 40% essential amino acids. Therefore, 20-25g of a high quality protein will provide around 8.5-10g of essential amino acids (Phillips, Moore & Tang, 2007). This can be found in 750ml of skim milk, 4-5 eggs or 100g of cooked lean beef. Milk proteins and their isolated forms (whey and casein) appear to offer particular advantages over soy protein for promoting muscle growth, although vegetable sources such as soy can still have a beneficial effect, which can be a particularly good option for vegetarians (Beelan, Burke, Gibala & van Loon, 2010). Soy is a high quality protein, but because soy’s leucine level is lower than that found in animal proteins, a slightly higher intake is required to gain the same benefits.
The main beneficial effect of protein bars, drinks and other supplements is the convenience. Protein from foods can be just effective as that from supplements; however, circumstances can sometimes make protein-rich sports nutrition products a better option. For example, if access to food is limited, if there is little time to cook or prepare food, or if an athlete or client struggles to eat after heavy sessions, then protein-rich drinks — either in the form of milk or protein shakes that contain the full range of amino acids (particularly the essential amino acids) — can be a good alternative.
How Much
For years, both recreational and elite athletes have been consuming large amounts of protein “just in case,” but very large intake may be burning money rather than building muscle. While protein needs vary between athletes and are impacted by genetic factors, other dietary components, and training schedules, recent evidence indicates that high volume protein consumption is not necessary to achieve the desired gains in muscle mass.
Phillips et al. (2007) reported that the amount of protein required to maximally stimulate muscle protein growth after a bout of resistance exercise is 20-25g of protein. Above this level, the rate at which muscle protein is built appears to plateau; therefore, there may be no additional benefit with higher consumption.
One option for athletes is to have a number of small meals throughout the day that provide around 20g of protein, thereby ensuring that the daily protein needs of the body are met, amino acids are regularly available to the muscle, and a positive muscle protein balance is maintained. This would be in addition to protein intake tailored around the exercise schedule.
**
The table below provides an example of protein intake for 180lbs/82kg power sports athlete (with a target of 115-140g of protein) (Gilbert, 2009).
| Meal/timing |
Food |
Protein content (g) |
| Pre-exercise meal |
Half pint of milk or protein shake |
10g |
| Breakfast (immediately after morning training session) |
One bowl of breakfast cereal with milk |
15g |
| Snack |
Two slices of toast |
7g |
| Lunch |
Four egg omelette
|
20g |
Snack (1hr before training)
|
Pint of milk |
20g |
| Dinner (within 1hr post-training) |
One chicken breast
2 cups cooked pasta
Yogurt
|
40g
10g
7g |
| |
TOTAL
|
129g |
The same principles should be followed on match days as on training days. Recovery from matches, races or competitions is the first stage in preparing for the next session.
Key Points for Trainers and Coaches
- Tailor the timing of athletes' protein intake around exercise.
- Injesting high quality protein about one hour before exercise will allow enough time for the protein to be broken down into free amino acids for uptake into the muscle.
- Post-exercise protein intake should take place immediately after training or a competition ceases.
- Athletes should consume high quality proteins – such as that found in milk, meat and eggs – when possible. Protein supplements that contain complete, high quality proteins may be appropriate based on convenience and individual preference.
- 20-25g of high quality protein appears to be the optimal level for muscle growth; beyond this, the muscle protein growth rate plateaus.
References
Beelan, M., Burke, L.M., Gibala, M.J. & van Loon, L.J.C. (2010). Nutritional strategies to promote post-exercise recovery. International Journal of Sport Nutrition and Exercise Metabolism, 20(6): 515-532.
Gilbert, N. (2009). Symposium on “Performance, exercise and health.” Practical aspects of nutrition in performance. Proceedings of Nutrition Society, 68: 23-28.
Phillips SM, Moore DR, Tang JE. (2007). A critical examination of dietary protein requirements, benefits, and excesses in athletes. International Journal of Sport Nutrition and Exercise Metabolism, 17: S58-S76.
Tarnopolsky, M. (2007). Chapter 4: Protein and amino acid needs for training and bulking up. In: Burke l & Deakin V. Clinical Sports Nutrition, 3rd Ed. North Ryde.
Tipton, K. (2007). Role of protein and hydrolysates before exercise. International Journal of Sport Nutrition and Exercise Metabolism 17: S77-S86.