Nutrition support is crucial for a quick and effective recovery from exercise-induced injuries. Adequate amounts of macro and micronutrients, but also energy, is critical for optimal healing. However, determination of appropriate energy intake is not as straightforward as many might think and therefore it is often an underappreciated component of nutrition support for injuries.
Muscle loss is a major concern with injury
Injuries are an unavoidable aspect of exercise and physical activity for everyone, from elite athletes to those exercising for health and enjoyment. Many, if not most, injuries result in an interruption in physical activity and muscle disuse - sometimes due to limb immobilization, or simply the need to decrease training. Loss of muscle mass and function due to disuse and/or decreased activity is a major concern. Thus, any intervention, including nutrition, that can minimize the loss of muscle mass and function during a period of disuse following injury is critically important.
Muscle loss caused by inactivity
With reduced activity comes a decrease in the rate of production of muscle proteins, the main metabolic contributor to muscle loss. So, nutrition strategies following injury should aim to mitigate this reduction. A complete discussion of the metabolic changes with immobility and nutritional countermeasures is beyond the scope of this blog. Interested readers can go to a previous blog on muscle injury or to this site or one of several recent reviews (1,2,3) for more extensive discussions. Here, we will focus on muscle, but other tissues, for example tendon and bone must be considered as well.
Energy intake
One of the more difficult and perhaps less appreciated aspects of any nutritional strategy to minimise loss of muscle mass and function following an injury is determining energy intake. During a period of disuse or immobilisation assigning the energy an injured exerciser should consume is not nearly as straightforward as is usually expected. Following an injury energy expenditure certainly is expected to decrease, especially if the injury results in limb immobilization. So, athletes and the nutritionists or dietitians that advise them most likely will attempt to decrease energy intake. The problem is that energy expenditure may not decrease as much as expected and if energy intake is insufficient to match expenditure, the loss of muscle mass and function may be exacerbated.
...athletes (and the nutritionists or dietitians that advise them) often will attempt to decrease energy intake. This could increase the loss of muscle mass and function.
Do not decrease energy intake too much
The intuitive response following an injury usually is to reduce energy intake with the aim of avoiding excess fat gain during this period of reduced activity. However, the decline in energy expenditure quite often is not as drastic as may be assumed (4) and likely will be quite variable depending on the individual circumstances. The healing process itself increases energy expenditure (5). The magnitude and duration of the increase depends on the type and severity of the injury, as well as the extent of the inflammatory response. Of course, most athletes and exercisers will be unlikely to completely stop physical activity and may engage in light training. The extent of this physical activity obviously will vary and will contribute to overall energy expenditure. Also, if an athlete must rely on crutches for ambulation, getting about requires much more energy than walking. Of course, energy expenditure also will change as recovery progresses and more training is introduced. Thus, careful assessment of energy expenditure should be made at different stages of the injury recovery process.
Even a moderate energy deficit will reduce protein synthesis
The problem is that negative energy balance may very well slow recovery and lengthen the return to full training and competition. As mentioned, wound healing is energetically expensive. Thus, insufficient energy will prolong the healing process. Muscle protein synthesis also is energetically expensive. Even a moderate energy deficit will reduce muscle protein synthesis (6, 7) thus exacerbating muscle loss during this period of reduced activity/immobilisation.
Higher protein intake can reduce muscle mass loss
Higher protein intake can ameliorate some of the loss of muscle with negative energy balance (8). But, keep in mind that if calories are reduced, protein intake likely will be reduced proportionally unless a conscious effort is made to keep it high. So, it’s clear that energy deficits during recovery from injuries should be avoided.
Excess energy intake can also reduce muscle mass
On the other hand, positive energy balance is undesirable as well. Positive energy balance is associated with increased muscle mass (9). So, it might be tempting to overeat and accept a wee bit of fat gain knowing that it can be lost with the resumption of training. However, increased muscle mass with excess energy intake is limited to muscles that are training, not inactivite muscles. Excess energy intake actually exacerbates muscle loss with muscle disuse (10). So, energy balance is critical for optimal recovery from an injury resulting in muscle disuse.However, during periods of inactivity, excess energy intake actually exacerbates muscle loss. So, energy expenditure should be carefully assessed and balanced as closely as possible with energy intake.
Excess energy intake actually exacerbates muscle loss with muscle disuse
Nutrition recommendations to minimize muscle loss
First and foremost, avoid nutrient deficiencies (including energy). Avoiding deficiencies may be a wee bit trickier with decreased energy intake.
Maintain energy balance
Maintain a higher protein intake. Aim for 2.0-2.5 g protein/d/kg body mass
There is evidence for the efficacy of some nutraceuticals, e.g. omega-3 fatty acids
References
Wall, BT, JP Morton and LJC. van Loon. Strategies to maintain skeletal muscle mass in the injured athlete: Nutritional considerations and exercise mimetics, European Journal of Sport Science 15(1):53-62, 2015.
Tipton, KD. Nutritonal support for exercise-induced injury. Sports Med. Supl 1:93-104, 2015.
Close, GL, C Sale, K Baar and S Bermon. Nutrition for the prevention and treatment of injuries in track and field athletes. Int J Sports Nutr Exerc Metab, 29: 189-97, 2019.
Anderson, L, GL Close, M Konopinksi, D Rydings, J Milsom, C Hambly, C., et al. Case study: muscle atrophy, hypertrophy and energy expenditure of a premier league soccer player during rehabilitation from ACL injury. Int. J. Sport Nutr. Exerc. Metab. 29, 559–566. 2019.
Frankenfield, D. Energy expenditure and protein requirements after traumatic injury. Nutrition in Clinical Practice, 21, 430–437. 2006.
Pasiakos SM, Vislocky LM, Carbone JW, et al. Acute energy deprivation affects skeletal muscle protein synthesis and associated intracellular signaling proteins in physically active adults. J Nutr. 140:745–51, 2010
Areta JL, Burke LM, Camera DM, et al. Reduced resting skeletal muscle protein synthesis is rescued by resistance exercise and protein ingestion following short-term energy deficit. Am J Physiol. 306:E989–97, 2014.
Mettler, S, N Mitchell, KD Tipton. Increased Protein intake reduces lean body mass loss during weight loss in athletes. Med. Sci. Sports Exerc. 42:326-37, 2010.
Slater, G, BP Dieter, DJ Marsh, ER Helms, G Shaw, and J Iraki, Is an Energy Surplus Required to Maximize Skeletal Muscle Hypertrophy Associated With Resistance Training. Front. Nutr. 6, 131, 2019
Biolo G, Agostini F, Simunic B, et al. Positive energy balance is associated with accelerated muscle atrophy and increased erythrocyte glutathione turnover during 5 wk of bed rest. Am J Clin Nutr. 88:950–8, 2008.
