Getting injured is part and parcel of any competitive sport, with team sports typically exhibiting a higher rate of injury than endurance sports. At the elite level of sport, there are major economic costs to a team or organisation if a given athlete can’t compete. So naturally, research into methods and techniques to speed recovery from injury is a key area.
One of the key issues with injury is the inevitable muscle loss that can occur, particularly in the case of having a joint of limb immobilised in a plaster cast. While sport-related injuries can occur in many forms, knee injuries tend to be amongst the most frequent and often the most serious in terms of recovery time, intensity of medical attention required during rehabilitation, the psychological stress imposed on the athlete and the overall financial burden.
Nutrition & Muscle Loss
But unbeknown to some, there are select proven nutritional strategies that can significantly improve the rate of recovery and minimise the amount of muscle loss (and associated decline in functional strength) normally associated with immobilisation of a limb. A recent study published in the European Journal of Sport Science sought to provide an overview of key strategies effective for improving recovery time1.
Many of the key recommendations of the study are summarised in the graphic below.
Muscle Loss & Injury
When a muscle/limb is immobilised the most rapid phase of muscle loss occurs during the first 1-2 weeks1. This is due to the sudden decline in the level of muscle contraction and weight bearing activity due to the limb being immobilised. While factors such as gender, training status, muscle group and age call all affect the rate of muscle lose, studies suggest inactive muscle tissue generally breaks down at a rate of approximately 0.5% per day1.
Amount of Protein During Injury
Recent research in elderly (>65 years) subjects has uncovered a phenomenon called anabolic resistance, whereby the normal muscle protein synthesis response following ingestion of protein is diminished2. That is to say that a dose of ~20g of protein in healthy, young men, which is normally sufficient to elicit maximal muscle protein synthesis does not product the same response in elderly. Instead a 35-40g dose of protein seems to be required to maximise muscle protein synthesis.
Composition of Protein During Injury
The same phenomena is said to occur in muscle tissue that has been immobilised for 1-2 weeks1. This is why current recommendations suggest consumption of a minimum of 20g of protein at regular intervals throughout the day1. The total amount of protein needed to maximise muscle protein synthesis can be offset depending on the total leucine content. Because of its powerful role in regulating muscle protein synthesis, studies have shown that whey protein with a relatively high leucine can lead to similar rates of protein synthesis in the elderly as high protein doses of ~35-40g.
Timing of Protein Ingestion During Injury
The other key factor regulating muscle protein synthesis and breakdown is the timing/frequency of protein intake. Regular protein intake provides repeated stimulus to muscle tissue, which serves as an effective way of preventing muscle tissue breakdown. While there is an argument to use casein protein for the continued amino acid release over several hours, studies have proven that repeated doses of whey protein are the most effective for stimulating muscle protein synthesis throughout the day. This is because plasma levels of amino acids such as leucine need to reach a critical level in blood in order to optimally stimulate muscle protein synthesis. With casein protein, the levels of amino acids in blood are lower because of the lower rate of digestion.
Protein Feeding Strategy for Preventing Muscle Breakdown
Focusing on the correct protein, in the correct amounts and at the correct time as outlined above allows for maximal muscle protein anabolism for 6-12 hours of the day, thus providing the best opportunity to minimise muscle breakdown associated with injury. Indeed a recent study employing this type of protein feeding strategy demonstrated favourable 24-hour muscle protein synthesis rates compared with individuals fed equivalent amounts of daily protein, but with quantities unevenly spread across the three meals3.
Injury & Nutrition Case Study
A recently published case study concerning an English Premier League soccer player recovering from anterior cruciate ligament surgery reported less than half the muscle atrophy from the immobilised leg than would be expected using the protein nutrition principles (among other things) highlighted in this article4. The individual lost only 1.35kg of muscle as opposed to the expected 3kg despite being highly trained with a greater initial leg muscle mass than an untrained person; characteristics that some studies suggest result in an accelerated rate of muscle loss5. As such, this case study serves as an example that nutritional and other interventions (e.g. neuromuscular electrical stimulation) that were implemented were effective in attenuating muscle atrophy, at least to a certain extent.
1. Wall BT, et al. Strategies to maintain skeletal muscle mass in the injured athlete: Nutritional considerations and exercise mimetics. European Journal of Sport Science. 2014 Jul 16:1-10. [Epub ahead of print]
2. Cuthbertson D, et al. Anabolic signalling deficits underlie amino acid resistance of wasting, aging muscle. Federation of American Societies for Experimental Biology. 2005;19:422–424.
3. Mamerow MM, et al. Dietary protein distribution positively influences 24-h muscle protein synthesis in healthy adults. Journal of Nutrition. 2014;144(6):876–880.
4. Milsom J, et al. Case-study: Muscle atrophy and hypertrophy in a premier league soccer player during rehabilitation from ACL injury. International Journal of Sport Nutrition Exercise Metabolism. 2014;24(5):543-552.
5. Miles M, et al. Prior resistance training and sex influence muscle responses to arm suspension. Medicine and Science in Sports and Exercise. 2005;37:1983–1989.