Diet after sports injuries. When athletes injure themselves, one important aspect of the healing process is often neglected - the diet. While there is plenty of literature on proper nutrition for injuries, surprisingly little is based directly on current scientific research.
Diet after sports injuries
Athletes who have sustained a stress-induced injury during their sports activities often can not train optimally and thus can not achieve the desired success in the competition. Just the possibility of such an injury stops many from doing sports and doing something for their health.
A quick recovery after a sports injury is therefore absolutely important for professionals as well as recreational athletes. To speed recovery, athletes usually repair themselves after an injury with immobilization, cooling, stretching, etc., and often overlook the importance of nutrition. This article therefore focuses on nutrition and acute / traumatic sports injuries as well as limb immobility issues.
The injury phases
Stress-induced injuries usually go through two main phases. And both can be influenced by the diet.
1st Phase: Immobility / Atrophy (Immobility / Degradation of Muscles and Tendons) - Depending on the type and severity of the injury, the immobility phase lasts several days to several months. Due to inactivity, metabolic changes in the tissue occur during this time, leading to loss of strength and function (see Fig. 1). That such functional problems arise from muscle breakdown is well known. Lately, scientists have therefore increasingly with other tissue such. As the tendons, deals.
Phase 2: Rehabilitation and increased activity of the injured limbs - This phase will follow once mobility has returned. It comes to building muscle and the return of functionality. The complete restoration of strength and function after an injury-induced immobility unfortunately takes much longer than the degradation process.
Optimal nutrition looks about the same in these two phases, but you'll need to consider some important differences.
Fig. 1: Flow chart of the changes resulting from a stress-induced injury with regard to the metabolism and the functions. © trainingsworld
Figure 1 shows the changes that occur as a result of stress-induced injury in terms of metabolism and function. Decreased protein formation in muscles and tendons as well as decreased stimulation by amino acids leads to a rapid and dramatic reduction in muscle size and strength, tendon structure and function. Here (as well as in Fig. 2) double arrows are pointing downwards for a strong decrease, single arrows downwards for a small decrease. Single arrows upwards signal a small increase and double arrows upwards a strong increase. Dotted arrows between the fields indicate a less strong relationship between cause and effect.
Can the inflammatory response be reduced?
Immediately after a severe injury, an inflammatory reaction sets in, which is also required for a good healing process. The duration of the inflammatory phase depends on the type and severity of the injury and varies between several hours and several days. But as so often too unhealthy is here too. Therefore, it is often recommended to reduce the inflammatory response (using anti-inflammatory agents etc.). But since inflammation can be crucial for a good cure, an artificial inhibition of inflammation would be unwise.
Consequently, it seems sensible to avoid excessive inflammation. Nutritionists therefore recommend avoiding excessive levels of omega-6 fats after an injury. But these recommendations seem to be based solely on test tube studies. In view of this limitation, the view that inflammation can be reduced by adding more omega-3 fats and fewer omega-6 fats may initially be considered only a preliminary approach.
Do omega-3 fats help with inflammation?
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Omega-3 fats are found mainly in fish oil, linseed oil, walnuts, etc., therefore, a corresponding dietary supplement is often recommended. Omega-6 fats are generally included in vegetable oils such as corn oil, sunflower oil, etc. Since neither the mechanism of action of the inflammatory process is known in its entirety, nor can it be said with certainty that the inflammatory process after injury is reduced when more omega-3 than omega-6 fatty acids are ingested through the diet, none can be found here reliable recommendations.
Probably the best method should be the principle of avoiding damage or risk-benefit considerations. To absorb less sunflower, corn germ or cottonseed oil through the diet is z. B. no great renunciation. And if the assumption is correct, you can thereby prevent excessive inflammation after injury.
Muscle loss as a result of immobility
In phases of immobility there is a loss of muscle mass. This change is very noticeable and leads to a reduced muscle function. A rapid muscle wasting is therefore due to inactivity. From the metabolism side, muscle loss is mainly responsible for the degradation of muscle protein, in particular the reduced formation of myofibrillar proteins. Interesting and perhaps surprising for many is the fact that protein degradation is also decreasing. More muscle protein is broken down than built up, resulting in a negative protein balance in the muscle.
The muscle protein balance is the metabolic factor responsible for a change in muscle mass. If the net muscle protein balance over a period of time is negative, it means the loss of muscle protein. In order to minimize the phases with a negative muscle protein balance, care should therefore be taken in the diet to minimize the decrease in the formation of muscle protein.
An increased protein intake
Increased protein intake is often the first countermeasure to avoid muscle atrophy. It is known that the supply of protein or essential amino acids promote the formation of muscle protein both at rest and after exercise, resulting in a positive muscle protein balance. However, when inactivated, the oral intake of protein does not necessarily have the same effect.
Earlier studies in older participants showed that the muscles are resistant to the anabolic - ie the metabolism-promoting - stimulus of amino acids. A recent study by researchers at McMaster University in Canada found that in the case of immobility, the ability of myofibrillar proteins to react to amino acids is reduced. (1)
Thus, not only does immobility lead to a decrease in the basal levels of muscle protein formation, it also causes the muscles to no longer respond properly to protein intake. As far as maintaining muscle mass is concerned, increased oral protein intake during physical inactivity does not necessarily have the same effect as studies based on active, healthy muscles.
The influence of protein on muscle mass
Therefore, a larger intake of protein obviously has little effect on the loss of muscle mass and strength in inactive muscles (also called anabolic resistance). However, there is another way that, at least potentially, this resistance can be lowered. In cell cultures and studies with rats, it has been shown that leucine (an amino acid that serves as a building block for proteins) promotes protein formation. Although leucine has little effect on muscle growth, it helps to overcome the anabolic resistance of muscle protein formation.
Studies in the elderly indicate that anabolic resistance can be overcome by increasing the leucine content of the amino acids added. (2) In order to study the effect of leucine on muscle protein formation, a catabolic model was used in the rat studies. This means that muscle protein production is reduced. By the oral supply of leucine, it is usually increased again to a normal level. Taken together, these studies indicate that the anabolic signaling pathways in the muscles are blocked in these "catabolic states, " resulting in a decrease in protein production.
But so far, no study has specifically investigated the consequences of muscle protein formation and muscle loss on immobile human muscles when leucine is added to the protein. This aspect would certainly be interesting and worth investigating. The amount of leucine in relation to the protein as well as other details of such an intervention would of course have to be determined experimentally.
The role of energy intake during rehabilitation
Another important consideration in injury-induced immobility is the total energy intake (ie calorie consumption). In immobility, the total energy consumption inevitably decreases. Depending on which limbs are affected, there is a significant decrease in the total energy consumption, because a sporting activity during this time difficult to accomplish or is unfavorable. In addition, reduced protein turnover can also lead to a slight decrease in energy consumption.
Both the formation and degradation of muscle protein are processes where energy is consumed. If these processes are suppressed as a result of an injury, the energy requirement can be further reduced. To avoid weight gain, many injured athletes need to reduce their energy intake.
These factors should be considered
However, there are a few factors to consider. On the one hand, it is clear that the energy consumption during the healing process is increased by 20%, especially at the beginning and in case of severe injuries. But even though overall energy consumption should be reduced, this does not necessarily mean serious calorie restriction.
In the calorie intake, other aspects play a role, eg. B. the energy expenditure during locomotion. If you have to move on crutches after an injury, the energy consumption can be two to three times greater than during normal walking. Depending on how much an injured athlete runs on crutches, the energy intake may not be so much restricted.
Immune energy intake can also affect muscle protein production. It is important to ensure that the calorie intake is not limited so much that the formation of muscle protein can no longer be optimal. A decrease in muscle protein production is the main cause of muscle breakdown. So try to find a good balance here. In my opinion, one should rather accept a slight increase in weight, than to supply too few calories. This ensures a good healing of the muscles and limits the breakdown of muscle protein.
Regeneration: phases of inactivity
In periods of inactivity, while the focus is usually on muscle breakdown, but also tendons and ligaments can be affected in a immobility. The tendons consist essentially of the connective tissue protein collagen. Immobility leads to changes in the mechanical properties of tendons, which is associated with a decrease in collagen formation in the tendons. (3)
Little is known about the influence of diet on the metabolic situation in the tendons. We know z. For example, the extent of collagen formation in the tendons and muscles is not dependent on increased amino acid uptake (from protein), suggesting that protein supplementation would not have much effect on the tendons. (4) On the other hand, collagen formation in bone ( an important condition for the healing of the bone) to an increased amino acid concentration. (4)
Although the process has not been studied in humans, there is reason to believe (at least theoretically) that protein intake could accelerate bone formation. In addition, we know that for optimal bone regeneration after a bone fracture, a sufficiently large intake of calcium and vitamin D is also very important.
Rehabilitation and muscle building
The functional aspects and metabolic requirements during the rehabilitation phase may differ significantly from those during the forced immobilization of the limbs (see Fig. 2). Probably the total energy consumption will increase more or less. As activity increases, regressive muscles begin to enlarge again through cell growth. In addition, muscle protein production is an energy-intensive process that further increases energy requirements. And while it may seem a bit contradictory, there is ample evidence that increased muscle protein breakdown occurs during rehabilitation in building muscle, which is likely to promote better muscle rebuilding.
Fig. 2: The flow chart shows the changes that occur in terms of metabolism and function in the muscles and tendons © trainingsworld
Figure 2 shows the changes in metabolism and function in the muscles and tendons when activity is restored after injury-induced immobility. Sporting activity and amino acids have a stimulating effect on the muscles, and the sport promotes the development of the tendons, so that muscle size and muscle function are rebuilt. Reconstruction of muscle mass and muscle strength, however, takes much longer than degradation during the immobility phase.
This increased muscle turnover contributes to an increased energy requirement during the recovery, so the energy intake must increase to some extent - depending on the nature of the injury and the corresponding immobilization of limbs and joints even significantly. It can certainly be said, however, that in view of the protein metabolism necessary for muscle building, it makes no sense to limit the calorie intake.
Increased protein intake can increase protein turnover. Of course, as the availability of amino acids increases after exercise, it also stimulates muscle protein formation, resulting in a positive net muscle protein balance (and muscle growth). An acute study, which came with some questionable results, suggests that increased protein intake accelerates recovery after immobilization. (5) The big question of how much protein should actually be delivered through food, however, could not yet be resolved get answered. This requires further studies.
More proteins - more muscle?
In healthy young men, muscle gain occurs at a much lower dietary protein intake than some people deem necessary (eg 1.2 g per kg of body weight per day). As long as certain limits are taken into account with regard to the total calorie intake and the carbohydrate quantity or intake of essential fats is not restricted, an increase in protein intake should not be problematic.
It is unacceptable to believe that an increase in protein intake leads to a proportional increase in muscle size and function. There are other, much more important factors. Both the timing of protein intake associated with exercise and the type of protein being consumed, as well as other nutrients ingested at the same time, and the interactions between these factors may affect the utilization of amino acids from the protein delivered. (6) The total amount of protein is therefore probably not the most important nutritional factor for building muscle mass.
Vitamins, minerals and the recovery process
Also, other nutrients that can affect the recovery process have been widely reported in the press. However, the evidence is often derived and not unique. Those who propagate the efficacy of such nutrients often rely on solid theoretical foundations and cite these as evidence of efficacy in terms of faster recovery from injury. For example, there is evidence that zinc is crucial for cell differentiation, which plays an important role in wound healing. Vitamin C is necessary for collagen formation.
Sufficient intake of these nutrients is of course important. But that does not mean that supplementation beyond the measure of a balanced diet is beneficial. Due to mutual influences on intake and metabolism, the supplementation of individual micronutrients may even lead to an imbalance of other nutrients.
Conclusion: diet after sports injuries
The previous discussion was mainly about protein and energy. Other nutrients are considered equally important for optimal recovery after an inactive phase. However, as with many other athletic nutrition issues, there is little evidence from studies specifically dealing with exercise-induced injuries. In healthy young people, creatine supplementation clearly resulted in faster recovery of muscle mass and function following a cast. (7) However, such a supplementation with creatine did not show differences, according to a study on patients with ACL )
It is easy to imagine that an injury in itself has an impact on the metabolic response of the body and consequently the supply of creatine after an injury is less effective. Which mechanisms of action in the metabolism are responsible for this difference, however, can not be deduced so easily. However, there are no corresponding proofs yet.
At this point, however, I would like to warn of certain substances. In general, after an injury, especially in the initial phase, anti-inflammatory drugs are taken. Use such medicines extremely sparingly. There is ample evidence that anti-inflammatory drugs hinder and delay the healing process in soft tissues such as muscles, tendons, ligaments, and bone fractures.
It has also been suggested that oxidative stress plays a major role and has a deleterious effect on muscle atrophy in periods of inactivity. For this assumption, however, there is no evidence at all. Antioxidant supplements are unnecessary and could even have unwanted side effects. In rehabilitation after an injury, it would even be particularly important not to take any antioxidant dietary supplements, as the oxidative stress due to the burden known to promote the conversion process.
And last but not least, cold beer is certainly not a problem, but it has been proven that excessive consumption of alcohol can affect muscle protein formation and delay healing. Therefore, you should reduce the alcohol consumption as much as possible, even if the temptation is great to drown the injury frustration in alcohol!
Practical tips for regeneration
- Athletes should provide adequate energy and protein while immobilizing limbs and joints. Also worth considering is the addition of leucine to overcome anabolic resistance.
- During rehabilitation, additional protein (especially in conjunction with exercise stress) can strengthen muscle growth and speed recovery of full performance.
- Sufficient energy is needed for optimal recovery, so the overall calorie intake should not be overly limited.
- Although the supplementation of micronutrients such as zinc and vitamin C was theoretically proven during the healing phase, the athletes should rather try to obtain these nutrients mainly from food.
- Athletes should resist the temptation to artificially reduce inflammation unless excessive or chronic inflammation has been noted. The use of anti-inflammatory drugs and antioxidant supplements may prove counterproductive.
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Kevin Tipton is a professor at the School of Sports and Exercise Science at the University of Birmingham, England. His specialty is the load metabolism.
- Basal - refers to the condition at rest and sober
- Kataboles model - a model with reduced net muscle protein balance
- Myofibrillar proteins - structural proteins responsible for muscle contractions
- Omega-3 fats - essential fats, especially in oily cold-water fish, eg. As mackerel, salmon, herring, and in linseed oil occur
- Omega-6 fats - essential fats found in vegetable oils such as sunflower oil, soybean oil, peanut oil, etc.
- Oxidative stress - a damage of tissue such. As the cell membranes, important proteins, DNA, etc., which is the result of short-lived chemical substances that inevitably arise in normal metabolic processes
- Cell differentiation - means that originally similar cells develop into those with different functions and structures
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- The Journal of Physiology 2001, Vol. 536, p. 625-633.
- The American Journal of Sports Medicine 2004, Vol. 32, pp. 383-388.