02/06/2021

Protein – Maximising Adaptation and Recovery

As an essential molecule that serves an important structural function, protein’s importance in the post-exercise period has been well established (21). However, the quantity, the type and the exact timing of protein intake have been one of the most debated areas in nutrition (17). Traditionally, strength training individuals consume extremely high protein intakes, often in the belief that ‘more is better’ (5). Many individuals engaged in regular exercise fail to recognise proteins importance, in the process, consuming well below protein requirements in the post-exercise period (5).

Regardless of our wellness goals, we all require protein after exercise to maximise adaptation (3). If we are concentrating on increasing muscle mass by strength training, we not only need to hit our daily requirements, we also need to consider muscle anabolism (7). For endurance training, we will also need to increase our protein intake above basal levels due to the increase in protein oxidation and subsequent muscle breakdown (12). Due to a new method to analyse protein synthesis (fractional synthesis rate – FSR) (8) and developments in overall protein balance studies (15), we now have accurate guidelines for protein intake.

 

Amount Required

The graph below was taken from a ground-breaking study (14), showing that maximal stimulation of protein synthesis was found when ingesting 20 grams of whole egg protein after resistance exercise. Any extra protein did not appear to have any extra effect and was oxidised (20). This is a far cry from the extremely high consumptions regularly seen in gyms and sports clubs. Ultimately the protein supplementation industry is a big business and misleading the public into believing ‘more is better’ is a common occurrence. For the individual with a larger body mass (>80kg), the absolute maximal requirement to promote optimal synthesis would be 25-30 grams (5).

 

 

Type of Protein

Now that we have established the right amount of protein we require after exercise, we now need to ask the second important question ‘What type of protein is best to maximise synthesis?’ The type of protein we consume will have a significant impact on protein synthesis and ultimately the results you will gain (5). It has been well established that milk-based proteins have the largest FSR (10) and therefore are recommended in the post-exercise period. Further research concluded the reason behind this was the whey protein component in milk (14) and even more specifically the leucine content in whey protein (11), making low fat flavoured milk an attractive option in the post-exercise window (18). Leucine is one of the three branched chain amino acids and is considered the optimal amino acid to consume for anabolic purposes as shown below which clearly indicates the added benefit of leucine, compared with just CHO and CHO + Protein. (12)

 

 

Since 25 grams of whey protein provides 3 grams of leucine this is usually enough in the post-exercise period to maximise protein synthesis (19). However, the addition of 3 grams of leucine in individuals with insulin resistance would be recommended, due to the compromised efficiency of breaking protein down into its constituent amino acids in insulin-resistant individuals (5). Individuals with muscular dystrophy have also benefited from both protein and carbohydrate after exercise (1).

Timing (Is there an anabolic window?)

Research into the optimal timing of protein intake has been equivocal. Some suggesting we need to consume protein immediately on completion exercise (5), whilst in contrast, there has been research suggesting the ‘anabolic window’ may be exaggerated and it’s the type and amount of protein that needs to take preference (2) Whatever the desired outcomes, both protein and CHO intake should be encouraged on completion of a training session. This is to provide a ‘safety net’ to ensure individuals hit their dietary requirements and maximise training adaptation. Although this may put more emphasis on planning and specific timing, in the long run, the benefits will be greater.

 

Importance of Energy and Carbohydrate

As well as trying to maximise protein synthesis, it is equally logical to attenuate protein breakdown as much as possible to increase overall protein balance. The two main contributors to this, other than protein intake, are total energy intake (6) and carbohydrate intake (19). To increase muscle mass, it is advised to

 

be in a positive energy balance (energy intake>energy expenditure) (5). Research has conclusively shown individuals in a negative energy balance will not gain large amounts of muscle mass (6). This is important, as individuals continue to believe they can put on large amounts of muscle and lose fat at the same time. Therefore, it is logical to consume carbohydrate during (30-60 grams per hour) and immediately after exercise (> 50 grams) when doing strength training to maximise muscle mass. The carbohydrate intake during these sessions can be in the form of sports drinks, gels or even solids.

For fat loss goals we still need to consume carbohydrate immediately after exercise (>50 grams) with protein (>20 grams) to preserve as much muscle mass as possible. However, it is advised to refrain from any carbohydrate during exercise, when fat loss is the main goal unless you are doing constant durations more than 2 hours. This is due to the attenuation of lipolysis in the presence of insulin when carbohydrate is ingested (5)

 

Is too much protein dangerous?

It has been generally accepted that protein intakes below 2.8 grams/per KG/BW per day will not cause any impairments in kidney function (22). However, many individuals are consuming way over this amount and can be at risk of several potential issues (5). An increase in calcium excretion because of regularly high protein intakes (23) is a potential threat, putting us at greater risk of calcium deficiency and is particularly dangerous in the female population with low energy intakes and amenorrhea (absence of menstruation) (5). However, it has now been established that high protein intakes increase calcium absorption, which eliminates this threat. (9).

There has also been a link between renal disease and high protein intake, however, research has suggested this only occurs when a renal condition already exists (4). Therefore, the high protein intake will only exacerbate an already existing renal condition and not create one. We also need to be aware of the potential contamination in protein supplements, particularly in the less well-known brands. As with most exercise nutrition intervention strategies, ensuring we hit our targets with food, should take priority over supplementation.

  1. Andersen et al (2014) Protein-Carbohydrate supplements improve muscle protein balance in muscular dystrophy patients after endurance exercise: a placebo-controlled crossover study. Am J Physiol Integ Comp Physiol 308:R123-R130
  2. Aragan, A. Schoenfeld, B (2013) Nutrient timing revisited: Is there A post exercise anabolic window? J Int Soc Spo Nut. 10:5
  3. Bosse, J. Dixon, B (2012) Dietary protein to maximise resistance training: a review and examination of protein spread and change theories. 9:42
  4. Brenner, B. Meyer, T. Hostetter, T (1982) Dietary protein intake and the progressive nature of kidney disease: the role of hemodynamically mediated glomerular injury in the pathogenesis of progressive glomerular sclerosis in aging, renal ablation and intrinsic renal disease. N Eng J Med 307:652-9
  5. Burke, L, Deakin, V (2010) Clinical Sports Nutrition. Fourth Edition. McGraw Hill.
  6. Carbone, J. McClug, J Pasiakos 2012 Skeletal Muscle Responses to Negative Energy Balance: Effects of Dietary Protein. Am Soc Nutr 3:119-126
  7. Cerimak et al (2012) Protein supplementation augments the adaptive response of skeletal muscle to resistance-type exercise training: a meta-analysis. Am J Clin Nutr 96: 1454-64
  8. De Boar et al (2007) The temporal responses, gene expression and cell signalling in human quadricep muscle and patella tendon disuse. J Physiol 585:241-51
  9. Hunt, J. Johnson, L. Roughead, Z (2009) Dietary protein and calcium interact to influence calcium retention: a controlled feeding study. Am J Clin Nut. 1357-65.
  10. Kanda et al (2016) Effects of whey, caseinate, or milk protein ingestion on muscle protein synthesis after exercise. Nutrients. 8:339
  11. Kato et al (2015) Leucine-enriched amino acids attenuate muscle soreness and improve muscle protein synthesis after eccentric contractions in rats. Amino Acids 47:1193-1201.
  12. Koopman et al (2004) Combined ingestion of protein and free leucine with carbohydrate increases post exercise muscle protein synthesis in vivo in male subjects. Am J Physiol Endocrinol Metab 288: E645-E653
  13. Lamont, L. McCullough, A. Kalhan , S. (1999) Comparisons  of leucine kinetics in endurance trained and sedentary humans. J Appl Physiol 86:320–5
  14. Mitchell et al (2015) Consumption of milk protein or whey protein results in a similar increase in muscle protein synthesis in middle aged men. Nutrients 7:8686-8699
  15. Moore et al (2009) Ingested protein dose respone of muscle and albumin protein synthesis after resistance exercise in young men. Am J Clin Nutr 89:161-8
  16. Pellet, P (1990) Protein requirements in humans Am J Clin Nutr51:723-37
  17. Phillips, S (2006) Dietary protein for athletes: from requirements to metabolic advantage. Appl Physiol Nutr Metab 31: 647-54
  18. Roy, B (2008) Milk: The new sports drink? J Int Soc Sports Nut 5:15
  19. Stark et al (2012) Protein timing and its effects on muscular hypertrophy and strength in individuals engaged in weight training. J Int Soc Sports Nut. 9:54
  20. Tarnopolski (1992) Evaluation of protein requirments for strength trained athletes. J App Phsiol. 73:1986-95
  21. Tarnopolski (2004) Protei requirments for endurance athletes. Nutr 20:662-8
  22. Williams, M (2005) Dietary supplements and sports performance: Amino Acids. Int Soc Sports Nut 2(2) 63-67
  23. Whiting, S. Anderson, D. Weeks, S. (1997) Calciuric effects of protein and potassium bicarbonate but not of sodium chloride or phosphate can be detected acutely in adult women and men. Am J Clin Nutr. 65:1465-72

 

 

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