Article Review:

Strategies to maintain skeletal muscle mass in the injured athlete: Nutritional considerations and exercise mimetics

Benjamin T. Wall, James P. Morton & Luc J. C. van Loon (2015) Strategies to maintain skeletal muscle mass in the injured athlete: Nutritional considerations and exercise mimetics, European Journal of Sport Science, 15:1, 53-62.

Article Summary:

Injuries in cycling can be caused by crashes, overuse or from poor bike fit. Regardless of the cause of a severe injury, recovery often involves a period of immobilization and associated muscle disuse, which can result in a rapid muscle loss and reduced functional capacity.

The decline in muscle mass and strength is most profound during the first 1–2 weeks post-injury, when interventions are not conventionally considered a priority for the athlete. The muscle loss is primarily due to a reduction in basal muscle protein synthesis rate and the development of anabolic resistance to dietary protein intake.

Although further work is required to translate research findings directly to managing athlete injuries, the following recommendations are presented for practitioners to limit the loss of muscle after injury in their athletes.

Key nutritional considerations during the period of disuse:

  • Daily protein intake of 1.6–2.5 g per kg of body mass:
    1. Ideally through regular (4-6 times daily, every 3-4 hrs) consumption of adequate amounts (20–35 g) of rapidly digested protein sources with a high content of the branched chain amino-acid, leucine (2.5–3 g); and
    2. Including dietary protein with breakfast and prior to sleep.
  • Intake of specific nutritional compounds that may also promote the maintenance of muscle protein synthesis rates such as:
    1. omega-3 fatty acids, branched chain amino acids (including leucine), creatine, and HMB (a metabolite of leucine).
  • It is challenging for athletes to achieve optimal macronutrient intakes to maintain skeletal muscle mass but prevent any gains in fat mass, due to the reduced energy expenditure during the recovery period.

Additional interventions that can attenuate muscle loss, include:

  • Utilizing neuromuscular electrical stimulation (NMES) to invoke involuntary muscle contractions, which can stimulate muscle protein synthesis rates.
  • Prescribing an exercise stimulus (particularly resistance exercise) for the uninjured muscle groups to minimize or prevent unwanted reductions in regional muscle mass that may result in reduced whole-body muscle mass and affect metabolic function.

Questions for Discussion:

Recovery from cycling injuries may involve total or partial immobilization. What are the major causes of injury in cyclists that cause total or partial immobilization? What are specific considerations for an injured cyclist during rehabilitation?

NMES represents a practical strategy for maintaining a degree of physical activity during the early stages of recovery from injury. The potential for structured and supervised NMES to maintain muscle protein synthesis rates, metabolic health and muscle mass and function during more prolonged rehabilitation requires future investigation. It would be worthwhile to consider developing optimal parameters for NMES protocols, in terms of duration, stimulation intensity and other specific parameters, for recovery from common cycling injuries.

In addition, although beyond the scope of this article, recent studies have examined the effect of NMES on post-exercise recovery. Future work to develop parameters for NMES could also investigate the potential benefits of NMES and optimal protocols for post-race recovery for cyclists competing in stage races.

The summarized dietary manipulations can help to minimize muscle loss during injury. What are the effects of these manipulations on long-term recovery of muscle mass and strength?

Future studies are warranted to enhance our understanding of how the known acute effects of dietary manipulation impact upon long-term measures of muscle mass, function, rehabilitation time and the duration required to return to competition.

Written By: Felice Beitzel, PhD, LMT

Reviewed By: Alexandra Flis, MD