Protein: The role within the body for exercise

Proteins are used by the body for cell growth, repair and protein synthesis (Barasi, 2003). The topic of protein within the diet is often met with uncertainty about the amount of protein that is needed, when to take protein and the best food sources. The following information is based on research and literature to give a brief overview of this macronutrient for health and fitness.

How much protein do I need?

The recommended protein requirement for sedentary adults is 0.8g/kg body weight per day to maintain muscle mass (Katch et al. 2013). Those in endurance training should consume approximately 1.0 – 1.6 g/kg body weight/day and those who engage in resistance training need approximately 1.6 – 2.0 g/kg body weight/day, according to The International Society of Sports Nutrition (Antonio et al. 2007).

Protein requirements are based on individual need and should be adapted based on a number of factors such as training frequency and intensity, lean body mass, muscle mass and personal preference regarding protein sources (Box, 2015).   
It is necessary to experiment with different levels of dietary protein in order to determine the intake which leads to the best response. This can be achieved by assessing outcomes in performance and body composition (Brown and Chandler, 2009). 

What food sources are high in protein?

Protein requirements can be achieved with a diet including whole-foods rich in protein and high quality supplemental protein sources such as whey and casein. The table below gives examples of food sources that are high in protein and which are readily available. It is necessary to take into account the nutritional content of these foods as some are high in fat. 

Food source	Protein (g) per 100g
Cod	63g
Salmon	62g
Tofu	48g
Whole egg	47g
Parmesan cheese (low sodium)	42g
Lean beef	36g
Lamb	36g
Chicken breast	33g
Pork tenderloin	32g
Peanuts	28g
Lentils	26g
Kidney beans	25g

(Self Nutrition Data, 2015)

When should I consume protein?

It is recommended that protein should be consumed throughout the day to enhance recovery and hypertrophy (Burke and Deakin, 2010). For those with the goal of muscle retention and growth, a snack containing protein and carbohydrates would be beneficial for those who finished their last meal 4-6 hours prior to exercise (Aragon et al. 2013). 


Calculate your daily protein requirement and be consistent with reaching your macro nutrient goals and over time evaluate it's effect. Modify the amount of protein you take in order to determine the amount that is beneficial to your health and fitness goals. 

Reference list:

Antonio, J., Burke, D Campbell, B., Kreider, R.B., La Bounty, P., Landis, J., Lopez, H., Roberts, M. and Ziegenfuss, T. (2007) ‘International Society of Sports Nutrition position stand: protein and exercise’, Journal of the International Society of Sports Nutrition, 4(8), pp.1-7. [online]. Available at: http://www.jissn.com/content/4/1/8 (Accessed: 21 May 2015)

Aragon, A.A., Krieger, J.W. and Schoenfeld, B.J. (2013) ‘The effect of protein timing on muscle strength and hypertrophy: a meta-analysis’, Journal of the International Society of Sports Nutrition, 10(53), pp. 1-13. [online]. Available at: http://www.jissn.com/content/10/1/53 (Accessed 23 May 2015).

Barasi, M (2003) Human Nutrition. 2nd Ed. London: Hodder Arnold.

Box, S. (2015) Fat Loss Part 1. Available at: http://bodytypenutrition.com/blog/fat-loss-q-part-1/ (Accessed: 21 May 2015).

Brown, L.E. and Chandler, T. J. (2013) Conditioning for strength and human performance. London: Wolters Kluwer Health.

Burke, L. and Deakin V (2010) Clinical Sports Nutrition. 4^th Ed. London: McGraw-Hill.

Katch F.I., Katch V.L. and McArdle W.D (2013) Sports and Exercise Nutrition. London: Wolters Kluwer Health.

Self Nutrition Data (2015) Nutrition data. Available at: http://nutritiondata.self.com/ (Accessed: 23 May 2015).