When athletes are injured, they usually turn to the traditional injury therapies - rest, icing, compression, elevation, as well as anti-inflammatory medications. Few athletes realize that in some cases unique nutritional strategies may also help them get well.
The fact that nutritional aspects of recovery are overlooked is a mystery to many sports nutritionists. After all, it is clear that a major injury alters an individual's nutritional requirements. Studies suggest, for example, that athletes who have broken their femur (the large bone in the upper part of the leg), may experience an increase in basal metabolism of around 20 per cent (because their bodies 'gear up' to repair the injured bone). Thus, a female athlete who might 'burn' 1600 calories during a typical, non-workout day could see her caloric requirements shoot up to 2000 calories because of the bone break. However, the changes in nutrient requirements in response to an injury are not simply a matter of increased caloric needs; various parts of the body have unique nutritional demands, and the optimal nutritional plan to restore an injury to cartilage might differ from the best scheme for repairing muscle or nerve.
Close-up on Finnish rats
One of the most exciting areas in the field of restorative nutrition centres around the strategy of directly supplying nutrients to injured sites (rather than taking nutrients orally, individuals have needed substances injected into trouble spots). In research carried out at the University of Turku in Finland, scientists implanted hollow, cylindrical sponges near wound areas in laboratory rats. A mixture of amino acids, salts, glucose, B vitamins, and vitamin C was injected daily into the sponge cavities of one group of rats, while a second group received only sham injections of water. After 14 days, the rats receiving the vitamins, glucose, amino acids, and salts had less haemoglobin in their wound sites (indicating less bleeding was occurring), higher oxygen uptakes, and greater concentrations of DNA and RNA, pointing to an acceleration of the healing process. There was also increased production of collagen, a unique protein which helps to strengthen damaged areas. Bringing essential nutrients directly to the area of injury seemed to markedly enhance healing ('Local Hyperalimentation of Experimental Granular Tissue,' Acta Chir. Scand., vol. 143, p. 201, 1977).
Since amino acids are required for protein formation and thus proper healing of injuries, a variety of different amino acids has been utilized in this 'direct-supply' research. In particular, an amino acid called arginine has been closely examined, since work with laboratory animals has indicated that it becomes a critically essential amino acid during periods of tissue growth ('Nutrient Modulation of Inflammatory and Immune Function,' American Journal of Surgery, vol. 161, p.230, 1991). Studies have suggested that arginine may stimulate insulin production (insulin is one of the body's most potent 'anabolic' (tissue-building) hormones, enhance the production of critical protein structures, improve immune function, and also increase the synthesis of nitric and nitrous oxide, which dilate blood vessels and promote the delivery of oxygen to damaged tissues.
In a unique study carried out at Sinai Hospital and Johns Hopkins University in Baltimore, Maryland, researchers subcutaneously implanted polytetrafluoroethylene tubing (with a length of five centimetres and an outside diameter of one millimetre, plus 90-micrometre pore size) into the deltoid muscles of three groups of individuals. One group received a placebo in their tubing, a second group was given 30 grams of arginine hydrochloride, and a third group got 30 grams of arginine aspartate daily for a period of two weeks. Compared to the placebo, arginine hydrochloride supplementation significantly boosted collagen deposition (remember that collagen helps to strengthen damaged parts of the body), and arginine aspartate hiked hydroxyproline content of the tissues, a sign that greater protein synthesis was taking place ('Arginine Enhances Wound Healing and Lymphocyte Immune Response in Humans,' Surgery, vol. 108, p. 331, 1990).
Branched-chain amino acids
Supplementation with other amino acids may be beneficial for recovery from injury: glutamine has been linked with improved connective-tissue repair, ornithine is believed to stimulate wound healing, and phenylalanine may reduce the pain associated with musculoskeletal trauma.
Another supplement which has created a huge stir in the injury-rehabilitation field is called HMB (see also PP 84, December 1996), a convenient abbreviation for the compound's rather difficult chemical name - beta-hydroxy-beta-methylbutyrate. HMB is closely chemically related to an important 'branched-chain' amino acid called leucine.
Leucine has been a key player in a scientific quest which has taken place over the past three decades - the search for supplements which would boost recovery after musculoskeletal injury or surgery. Scientists have known that individuals suffering from physical trauma need to rapidly manufacture new body tissues while making sure that any cells not affected by the injury remain healthy and viable. To quickly create the new tissues, the body uses amino acids to assemble the mint-condition proteins which will be the foundation for the new muscles, tendons, and ligaments.
Leucine comes into the picture because it's one of the three so-called branched-chain amino acids (the other two are isoleucine and valine). Some studies have shown that branched-chain amino acids have a special capacity to boost protein synthesis and inhibit protein breakdown. None of the other amino acids have as strong a protein-preserving effect as the branched-chains.
Of the three branched chains, leucine has seemed to be the most potent, but the research has been equivocal; sometimes leucine spurred tissue growth, while at other times it didn't. In an attempt to find out more about leucine, scientists begin feeding some of its metabolites to laboratory animals. One of its metabolites, HMB, consistently boosted muscle growth in laboratory chickens. Subsequent research found that HMB also sparked muscular protein synthesis in lambs, pigs, and cows ('Colostral Milk Fat Percentage and Pig Performance Are Enhanced by Feeding the Leucine Metabolite Beta-Hydroxy Beta-Methylbutyrate to Sows,' Journal of Animal Science, vol. 72, pp. 2331-2337, 1994). Of course, exercise scientists pricked up their ears at this research, since muscle injuries are common in sports, and injured athletes would love to get their hands on a supplement which enhanced the synthesis of new muscle.
Putting out brush fires
Follow-up studies with humans indicated that a daily dosage of 1.5 to 3 daily grams of HMB could reduce muscle damage in athletes undergoing extremely strenuous weight training. Interestingly enough, this was true both for inexperienced and experienced athletes ('Effects of Beta-Hydroxy Beta-Methylbutyrate Supplementation on Strength and Body Composition of Trained and Untrained Males Undergoing Intense Resistance Exercise,' FASEB Journal, vol. 10, p. A287, 1996). The positive effects seemed to be particularly good news for endurance athletes, even though the work was carried out with strength trainers. That's because most exercise scientists believe that the majority of injuries incurred by endurance athletes are 'overuse' maladies, e. g., those resulting from chronic stress to muscles and connective tissues. The idea is simply that the body can't quite keep pace with the small-scale muscle, tendon, and ligament irritations which occur during daily training (eg, the body doesn't complete the repair process before a new bout of exercise is initiated). As a result, niggling irritations gradually increase in magnitude until they are full-blown injuries. If HMB could thwart the damage portion of this 'tear down-build up' equation, then it would be easier for the body to put out small 'brush fires' before they became full-scale injuries.
HMB's actual mechanism of action was delineated when scientists took a close look at a chemical called 3-methylhistidine, which is a marker of protein degradation: during very heavy-duty training, athletes often produce a lot of urinary 3-methylhistidine as their muscles 'break down'. In the strength-training study, 3-methylhistidine levels soared by 94 per cent after one week in the subjects who were not taking any HMB - but swelled by only 50 per cent in individuals who were taking 3 grams of HMB per day.
At the end of the second week, the subjects were adjusting to the training, so 3-methylhistidine was up by only 27 per cent in the non-HMB subjects. The really good news, though, was that 3-methylhistidine was actually down by 4 per cent in the 1.5-gram group - and plummeted by 15 per cent in the 3-gram per day supplementers. In other words, muscle breakdown was lower than it would have been if the subjects had been involved in a sedentary lifestyle, in spite of the fact that they were actually engaged in a very vigorous resistance-training programme. Plasma levels of two key muscle enzymes which are often considered to be markers of muscle damage, CK and LDH, also were lower in the HMB groups. HMB seemed to do a great job of holding muscles together during very strenuous training and thus may be helpful in lowering the risk of overuse injury.
Dietary intake and total body stores of a key mineral - iron - may also have some effect on an athlete's risk of injury, according to research carried out at the Center for Sports Medicine in San Francisco, California. In this study, 101 female high school runners were monitored over the course of a cross-country season. These female runners' blood levels of ferritin - the body's primary iron-storage molecule - averaged a rather low 20.5 ng/ml. Concentrations below about 20 ng/ml indicate that total iron stores are extremely depleted.
During the cross-country season, there were 71 injuries severe enough to cause lost training time. Those runners who were injured had average ferritin levels which were about 40-per cent lower than those found in non-injured runners. In addition, the 34 runners with the lowest ferritin concentrations had twice as many injuries as the 34 runners with highest ferritin.
The researchers concluded that low ferritin is related to an increased risk of injury in female cross-country runners. Since iron is a key component of haemoglobin, the compound which carries oxygen to muscles and other tissues, it's possible that athletes with low ferritin had decreased oxygen delivery to tissues and therefore became fatigued more easily during workouts and races, compared to individuals with normal ferritin. Their exhausted muscles would then be less able to stabilize and support the knees and ankles - two key sites of injury in the study. Low ferritin might also decrease the rate at which muscles and connective tissues are repaired, allowing minor injuries to blow up into major problems (Medicine and Science in Sports and Exercise, vol. 25(5), Supplement, p. S25, 1993).
Should you take iron supplements? Iron deficiency may be the most common nutritional deficiency in the world, and a fair number of athletes - especially females and individuals maintaining low body weights - suffer from iron depletion, in which the body's stores of iron are very low. A poor diet, along with iron losses due to sweating or menstruation, can gradually deplete an athlete's iron levels.
Since iron is used to make haemoglobin, which carries oxygen in the blood, and myoglobin, which handles oxygen inside muscles, abnormally low iron levels can potentially harm endurance performance. To prevent iron-deficiency anaemia from developing, many athletes take iron supplements and eat iron-rich foods like meat, poultry, fish, eggs, fortified cereals, and certain vegetables. Other strategies include the consumption of vitamin C with meals (vitamin C enhances iron absorption), and cooking with cast-iron frying pans (some of the iron from the pots flakes off into food).
However, recent research suggests that unusually high levels of iron may be linked with an increased risk of heart attack., and excess dietary iron can inhibit the absorption of another crucial mineral - zinc. In addition, it's probably best not to take iron supplements when you are sick. During an infectious illness, your body temperature rises, and the amount of iron in your blood drops. The iron fall-off doesn't mean that more iron should be ingested, though. The fever-plus-low-iron combination acts as a sort of natural antibiotic, because many microorganisms are simply unable to grow when they are confronted with higher temperatures and reduced levels of iron. Iron supplementation - by giving the little bugs what they are lacking - might actually exacerbate your disease!
The link between depressed iron and stunted bacteria isn't exactly common knowledge. Even though many scientific studies have connected low blood-iron with reduced bacterial growth and high iron with bacterial booms, only 10 per cent of doctors and 5 per cent of pharmacists in the United States are aware that iron supplementation might be harmful for infected patients.
Don't throw away your iron supplements - just use them with caution. It makes sense to back away from excess iron when you're ill, and - because of the possible link between high iron levels and heart attack - it's wise to work closely with a qualified nutritionist or medical doctor to make sure you're not overloading your body with the important mineral (Medicine and Science in Sports and Exercise, vol. 25(2), pp. 303-304, 1993).
C for collagen
If your athletic injury is severe enough to require surgery, you certainly will want to consider supplementing your diet with vitamin C. Using C to promote healing has a long history, dating back to the 1940s. During World War II, many British citizens had marginal or inadequate vitamin C intakes, due to the rationing of fresh foods. Of course, injury and surgery rates were high, due to the constant bombing of Britain by the Luftwaffe. At St. Bartholomew's Hospital in London, doctors began routinely giving their surgical patients 1000 mg of vitamin C daily for three days before surgery, followed by 100 mg of daily C during recovery. After this supplementation began, 'wound disruption' (failure of wounds to heal properly) decreased by 76 per cent ('The Role of Vitamin C in Wound Healing,' British Journal of Surgery, vol. 28, p. 436, 1941).
In a follow-up study, when surgical patients were given 1000 mg of vitamin C per day, there was a three- to six-fold increase in wound strength, compared to a dose of only 100 daily mg ('Vitamin C and Wound Healing, II: Ascorbic Acid Content and Tensile Strength of Healing Wounds in Human Beings, New England Journal of Medicine, vol. 226, p. 474, 1942). In other studies, patients who took only 500 mg of C per day post-surgery experienced declines in blood vitamin-C levels, and it was shown that individuals who don't supplement with C at all after surgery may have steep plunges in plasma vitamin-C concentrations. Russian research indicates that surgical patients who supplement with C are discharged from the hospital one to two days earlier, compared to individuals who receive no C ('Vitamin C Correction in Patients with Complicated Cholecystitis,' Vrach. Delo., vol. 11, p. 21, 1988).
Why might supplemental C be beneficial during the healing process? Vitamin C plays a critical role in collagen formation (collagen is the major component of connective tissues and is essential for repair and healing processes to occur). Vitamin C also boosts the activity of many enzymes which are critical for normal metabolism, acts as a direct antioxidant (and thus limits free-radical damage to tissues), may be immunostimulatory, and boosts the growth of fibroblasts and chondrocytes, key cells which produce connective-tissue fibres and cartilage, respectively. A dose of 1000 mg of C per day is considered safe, although it does produce digestive-system upsets in some people.