So, you’re injured. Fear not. In the time you have finished reading this, I will most likely have also sustained an injury of some description, so you don’t have to go it alone. Part I discussed the role of energy balance in injury and recovery, and hopefully from reading that you understand some of the fundamentals. We want to limit the catabolic processes of injury – and tailoring our macronutrient intake can play a huge role.

Protein: The Glue Holding Your Gains Together

As we stated in the previous article, the key nutritional considerations for injured athletes include limiting body fat gain and optimising muscle-protein synthesis to facilitate recovery. Assuming the athlete is sufficiently intaking enough energy overall, protein can make or break recovery.

The Role of Protein in Preserving Muscle Mass

A higher protein intake can be highly beneficial in optimising body composition whilst injured. In order for skeletal muscle to grow, muscle-protein synthesis must exceed muscle-protein breakdown, creating a positive nitrogen balance^[1]. Translation: we need to be building more protein than we break down! This is the case for all individuals, injured or not. However, with injury, this becomes more pertinent. Injured or immobilised individuals have elevated rates of protein breakdown (due to the injury!), and reduced muscle protein synthesis^[2]. Yikes.

Dietary protein is a powerful stimulant of muscle-protein synthesis^[3]. We can use protein to provide amino acids that the body uses as “building blocks” for skeletal muscle. Sounds exactly like what you want for your injured athlete, right?

There are number of strategies recommended for the injured athlete to optimise their protein intake for recovery. For optimal muscle-mass retention, it is suggested that athletes consume 4-6 small, high-protein meals per day. An elevated daily intake overall of 1.6-2.5g/kg bodyweight can support muscle maintenance during immobilisation periods for athletes^[4]. We want high-quality protein here, and in a big enough serving (20-35g) to fully get the benefit. It is also advisable to bookend your day with protein to ensure you limit the time spent in a negative protein balance^[4].

Of course, this does not mean you need to hop off the operating table and straight into the protein shakes. Nor should you demand they pump whey into your IV. It is merely a consideration on how to structure your nutrition as you recover.

The Role of Protein in Limiting Body Fat Gain

In Part I of this series, we spoke about how we want to limit body fat gain when injured. This is not because putting on body fat is bad, or indicative the athlete has failed in some way, but rather because it makes returning to peak athletic performance more challenging. Excess body fat is linked with decreased performance. But you already knew that, because you read Part I.

Protein can be our secret weapon in this instance, as the athlete grapples with the challenges faced by injury and a reduction in energy expenditure. We covered this in a lot more detail in Part I, but in essence, most athletes will struggle with their appetite in the acute post-injury period. Athletes are used to expending a huge amount of energy in the gym and on the pitch. They are also used to eating a TON to fuel the demands of their sport. Their overall expenditure may have greatly reduced, and their target intake reduced accordingly, but our appetite is a lot slower on the uptake.

Enter protein. Protein can be used help athletes adjust to their lower intake without feeling too hungry. Protein is the most satiating macronutrient^[5]reasons. Indeed, a high-protein meal has been shown to significantly increase satiety, more so than those higher in carbohydrate and fat^[6]. Across the board, high-protein diets are consistently linked with increased satiety and preservation of fat-free mass^[7],[8],[9].

All good things here, innit. We want to optimise satiety, because it makes eating more enjoyable. Being hungry all the time is not the vibe, injured or not.

Carbohydrates

Having sufficient carbohydrate in the tank is essential for performance^[10]. Low availability of glucose affects muscle protein synthesis^[11]. However, the function of dietary carbohydrate specific to recovery and injury is not clear cut. Therefore, at the minute, we don’t need to focus on manipulating an athletes’ carbohydrate intake beyond ensuring they are sufficiently fuelled for daily life^[11].

Carbohydrates & Protein: Together at Last

Carbohydrates and protein are the Montagues and Capulets of influencer nutrition. One good, one bad. And now, Romeo and Juliet come along to optimise your recovery from injury.

Much like Romeo and Juliet, we aren’t really sure what the hell is going on when you combine the two. Some studies have suggested that having carbohydrate alongside a protein serving optimises post-prandial muscle protein synthesis^[12]. Very fancy way of saying after you eat you are more sensitive to stimulating muscle protein building.

Lovely little hypothesis, and it would be stunning if that were true. Science is a cruel mistress however, and it has been demonstrated in young and old male subjects that this effect did not occur^[6],[12].

Fat

Similar to carbohydrate, we don’t really need to tailor our intake following injury^[6].

However, getting them omega-3 fatty acids into you can benefit us injured individuals.

Inflammation is essential for damaged muscle tissue recovery^[13]. Eicosapentaenoic (EPA) and docosahaexaenoic (DHA) acids (part of the omega-3 fatty acid fam), in addition to being great fun at parties, act to reinforce muscle cell membranes. They also help modulate the inflammatory response^[14]. Omega-3 fatty acid supplements that come from fish oil may help the injured athlete, as they have anti-inflammatory properties^[6].

Deficiencies in fat-soluble vitamins are also not the vibe and can exacerbate injury. Vitamin A deficiency is associated with poorer wound healing^[15]. Vitamin D and K deficiency is associated with poorer bone health and muscle weakness^[11],[16], none of which sets the athlete up for an easy rehabilitation.

Conclusion

Energy balance remains king, as it always does. Carbohydrate and fat take a back seat in terms of optimizing nutritional intake, and protein comes to the forefront. It may be advisable for athletes to:

• Increase their daily protein intake to 1.6-2.5g/kg bodyweight.
• Have a serving of high-quality protein (>20g) 4-6 times per day, evenly spread throughout the day
• Ensure to have a serving of protein soon after waking and before bed
• Supplementation with omega-3 fish oils may help inflammation.

The final article in this series will discuss the role of supplementation in injury.

References

1. Tipton, K., Wolfe, R.R. (2012) ‘Exercise, protein metabolism and muscle growth’, International Journal of Sport Nutrition and Exercise Metabolism, 11(1), pp. 109-132.
2. Paddon-Jones, D., Sheffield-Moore, M., Cree, M.G., Hewlings, S.J., Aarsland, A., Wolfe, R.R., Ferrando, A.A. (2006) ‘Atrophy and Impaired Muscle Protein Synthesis during Prolonged Inactivity and Stress’, The Journal of Clinical Endocrinology & Metabolism, 91(12), pp. 4836-4841.
3. Mamerow, M.M., Mettler, J.A., English, K., Casperson, S.L., Artentson-Lantz, E., Sheffield-Moore, M., Layman, D.K., Paddon-Jones, D. (2014) ‘Dietary Protein Distribution Positively Influences 24-h Muscle Protein Synthesis in Healthy Adults’, The Journal of Nutrition, 144(6), pp. 876-880.
4. Wall, B.T., Morton, J.P., Van Loon, L.J. (2014) ‘Strategies to maintain skeletal muscle mass in the injured athlete: Nutritional considerations and exercise mimetics’, European Journal of Sports Science, 1(1).
5. Pesta, D.H., Samuel, V.T. (2014) ‘A high-protein diet for reducing body fat: mechanisms and possible caveats’, Nutrition & Metabolism, 11(53).
6. Stubbs, R.J., Van Wyk, M.C., Johnstone, A.M., Harbron, C.G. (1996) ‘Breakfasts high in protein, fat or carbohydrate: effect on within-day appetite and energy balance’, European Journal of Clinical Nutrition, 50(7), pp. 409-417.
7. Westerterp-Plantenga, M.S., Lejeune, M.P., Van Ooijen, M., Kovacs, E.M. (2004) ‘High-protein intake sustains weight maintenance after body weight loss in humans’, International Journal of Obesity, 28, pp. 57-64.
8. Bray, G.A., Smith, S.R., De Jonge, L. (2012) ‘Effect of dietary protein content on weight, energy expenditure and body composition during overeating’, JAMA, 307(1), pp. 47-55.
9. Layman, D.K., Evans, E., Baum, J.I., Seyler, J., Erickson, D.J., Boileau, R.A. (2005) ‘Dietary protein and exercise have additive effects on body composition during weight loss in adult women’, The Journal of Nutrition, 135(8), pp. 1903-1910.
10. Burke, L.M., Deakin, V. (2015) Clinical Sports Nutrition. Australia: McGraw-Hill.
11. Papadopoulous, S.K. (2020) ‘Rehabilitation nutrition for injury recovery of athletes: The role of macronutrient intake’, Nutrients, 12(8), p. 2449.
12. Gorissen, S., Burd, N., Hm, H., Gijsen, A., Goren, B., Van Loon, L. (2014) ‘Carbohydrate co-ingestion delays dietary protein digestion and absorption but does not modulate postprandial muscle protein accretion’, Journal of Clinical Endocrinology and Metabolism, 99(6), pp. 2250-2258.
13. Bryhn, M. (2015) ‘Prevention of Sports Injuries by Marine Omega-3 Fatty Acids’, Journal of American College of Nutrition, 34(1), p. 60.
14.  Thielecke, F., Blannin, A. (2020) ‘Omega-3 Fatty Acids for Sport Performance – Are They Equally Beneficial for Athletes and Amateurs? A Narrative Review’, Nutrients, 12(12), p. 3712.
15.  West, K.P., Darnton-Hill, I. (2008) Nutrition and Health in Developing Countries. United States: Humana Press.
16. Holick, M.F. (2007) ‘Vitamin D Deficiency’, New England Journal of Medicine, 357, pp. 266-281.