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Illness can dash the competitive hopes of even the most superbly trained athletes. At the August 1987 Olympic Trials in the United Kingdom, world record-holder and defending gold medalist Sebastian Coe failed to qualify for the Seoul Olympics because of to a severe respiratory infection. In 1992, the celebrated American sprinter Carl Lewis couldn't qualify for the 100-metre sprint at the Olympic Games due to an infection.

Although the media portray illness in highly trained athletes as a fairly rare event, the truth is that athletes often carry a higher than average risk of getting sick. For example, Lewis joined at least 52 other elite Americans who were unable to try out for the Olympic team because of illness. And over the past two decades, doctors caring for athletes at both the summer and winter Olympic Games have consistently reported that upper respiratory infections were commonplace, and that in fact the biggest medical problem faced by athletes was illness - not injuries.

Why do athletes seem to be easy prey for opportunistic microorganisms? The answer is not that rare bacteria or viruses abound in the locker room, but that there's something about strenuous training itself which increases the risk of getting ill. Exercise scientists have known for years that as individuals increase their total training load, the risk of infection also mounts. For example, runners with the highest weekly training mileages are much more likely to come down with respiratory infections, compared to those with relatively light training loads.

Even a single strenuous bout can do it However, it's not just total training volume which determines the frequency of illness: single bouts of strenuous exercise can also make athletes much less resistant to infections. This fact was verified in a study carried out by Dr. David Nieman, who checked the overall health of 2311 applicants for the 1987 Los Angeles Marathon. A very high number - 42 per cent - of the runners reported at least one infection during the two months before the race. Runners who trained more than about 60 miles per week had roughly double the risk of infection, compared with runners who ran less than 20 miles per week. In addition, about 13 per cent of runners who completed the marathon became ill shortly after the race, compared with just 2 per cent of runners who trained for the marathon but didn't actually run the race. In other words, heavy training - or a single bout of strenuous exercise - can greatly increase one's chances of falling ill.

Interestingly enough, those who exert themselves the most, at least in terms of intensity, seem to be at highest risk. For example, out of 150 runners who completed a 56-kilometre ultra-marathon race, symptoms of upper-respiratory infections were most common in the top finishers in the race. Comparable results were obtained in a study of elite Finnish runners, whose lymphocytes (immune cells) were significantly less responsive 30 minutes and three hours after a marathon, compared to middle-of the pack runners. Why exactly does strenuous training - or even a single tough workout or race - downgrade immune- system activity and promote illness? Intense or prolonged endurance exercise causes large increases in cortisol and the 'catecholamines', which are stress hormones that can decrease the activity of key players in the immune system called T and 'natural killer' (NK) cells. In addition, although the absolute number of immune cells in the blood often rises during exercise, cell concentrations tend to fall dramatically after exercise ceases, especially the concentrations of TC (CD8), TH/I (CD4), and NK cells. TC (CD8) cells, also called 'cytotoxic' T cells, are responsible for directly killing virally infected cells and invading microorganisms. TH/I (CD4) cells, or 'help/inducer' T cells, aid in the destruction of microorganisms and their toxins and are the cells which are usually critically deficient in AIDS patients. NK cells destroy microorganisms and cells infected with viruses. Unlike other immune cells, NKs don't require a previous exposure to a pathogen to begin killing. Therefore, they form an important line of defense against infectious agents encountered for the first time by an individual - and especially against new viruses which attack the upper respiratory system.

Importantly, the CD4/CD8 ratio (the number of TH/I cells in the blood divided by the number of TC cells) drops below the critical value of 1.5 after a very intense workout or after prolonged, moderate exercise. Unfortunately, once the CD4/CD8 ratio dips below the 1.5 level, resistance to viral infections is dramatically impaired. In addition, the activity of NK cells can be depressed for up to seven days following an extremely long bout of exercise. Blood lymphocyte levels also plummet dramatically after strenuous exercise, and the duration of this suppression increases with either the increased intensity or duration of a workout. In other words, the longer or harder you train, the more havoc you can potentially create with your immune system.

Mental stress is important, too
The psychological stress encountered by athletes can also impair immune function. Expectations of coaches, family, sponsors, and/or the public, as well as the stresses of competition, jet lag, loss of sleep, and periods of absence from home can all contribute to sub-par performances and increase the risk of infection. In addition, injuries, the actual stresses of competition, and the disappointments arising from unmet performance expectations can all magnify psychological stress. The resulting diminishment in immune-system responsiveness resembles what happens to people who are undergoing the stresses of academic examinations, sleep deprivation, or bereavement and is also akin to what laboratory animals experience when they are over-crowded or receive repeated electrical shocks. In a recent study, highly stressed people had double the incidence of upper respiratory tract infections over a six-month time frame, compared to unstressed individuals. The exact mechanisms underlying this 'stress-makes-you- sick' problem are unclear, although it's likely that the immune-system downturn induced by increased production of stress hormones may play a strong role.

The old enemy, overtraining
But an infection isn't the only thing that can spoil a seemingly perfect season of training. Overtraining is the other common nemesis which can lead to a crushing inability to perform as expected. An overtrained athlete has simply done too much work, or, to put it another way, hasn't balanced strenuous training with enough recovery and restoration. The result is an assortment of physical and psychological problems and an inability to perform up to par.

The renowned exercise expert Tim Noakes, M.D., of the University of Capetown, recounts the perils and near-inevitability of overtraining more articulately than any other writer, saying: 'Despite my decade of experience in the sport, each year my avaricious mind ensures that I spend a few weeks rediscovering this overtraining illness in myself. I am not alone in this, and I am frequently visited by runners whose training greed has reduced them to the walking wounded. Some suffer generalised fatigue, recurrent headaches, diarrhoea, weight loss, sexual disinterest, and little appetite for food or work. Others are no longer able to sleep properly and complain that they are troubled by early- morning wakenings, inabilities to relax, and generally listless attitudes toward life. Generalised swelling of lymph glands may suddenly appear, allergies may worsen, and colds, influenza, or respiratory infections may resist all conventional therapy. All these symptoms are diagnostic. These runners have stretched their bodies beyond their individual breaking points. They are told that rest, not more training, is required, and that all they can do is get some rest and wait for nature to heal what medicine does not yet comprehend.'

It's true that doctors and exercise scientists don't completely understand the physiology of over- training, but they do recognise two general categories of the malady. 'Overreaching' is the term used for mild, short-term forms of overtraining. An athlete suffering from overreaching has trouble completing usual workouts and experiences some declines in race times, but a few weeks of rest and recovery are usually enough to eliminate excessive fatigue and restore the ability to train normally.

The second form, called 'staleness' or the 'overtraining syndrome', is a longer-term debilitating state which usually features several of the physical and psychological symptoms described by Noakes. Overtraining takes much longer than over- reaching to resolve - sometimes up to several months. Worse yet, overtraining can literally appear 'out of the blue' after several months of seemingly excellent training and can wreck an athlete's ability to perform well in the most important competitive event of the season.

The Waitz system
Although there's a tendency to think that over- training is something experienced only by elite athletes, Noakes warns that beginning and recreational exercisers - carried away by their eagerness to improve - can also fall prey to the syndrome. However, compared to average competitors, elite a athletes are probably more sensitive to the warning signs of overtraining. Grete Waitz, the great Norwegian female distance runner, claimed that her consistently excellent performances in important races was partially due to her ability to detect the early signs of overtraining. 'I judge my fatigue by my moods. If it's hard to sleep or I'm cranky, impatient, or annoyed, I'm probably overtraining. In my case, family and friends often know when I'm overtraining even before I do. When I begin to snap at my husband Jack, he knows it's time to analyse my training and probably cut back,' said Waitz.

She eventually developed a 'system' to monitor her risk of overtraining. She believed that an affirmative answer to three or more of the following questions was a strong indicator of staleness: (1) Does my normally comfortable pace feel difficult?

(2) Do my legs feel 'heavy' for far longer than usual after a hard workout or race?

(3) Do I find it harder than usual to climb steps?

(4) Do I dread the thought of training?

(5) Is it hard to get out of bed in the morning?

(6) Is my appetite below-normal?

(7) Am I more susceptible to colds, flu, headaches, and infections in general? (8) As I carry out my normal activities, is my heart rate five to 10 beats higher than usual? (9) Is my heart rate during exercise above- normal?

However, notice that Waitz's system - and others like it which have been developed by other athletes and scientists - don't detect overtraining until after the fact, when it's too late. Obviously, it would be far better to have a way of stopping overtraining before it occurs. Note also that one aspect of the over- training syndrome involves increased rates of infection, suggesting that overtraining and illness are physiologically linked. Is there some way to reduce the risk of both - while still training strenuously?
What are the solutions?
The Western scientific literature (that is, papers published in Europe and the United States) does not offer athletes any novel solutions to the problems of immune suppression and overtraining. Regular tapering and wise periodisation of training limit the risk of overtraining somewhat, but more sophisticated and effective techniques, including the close monitoring of immune cell concentrations and scientific testing of physiological parameters, require frequent blood samples and are time- consuming and expensive. In addition, it's nearly impossible for athletes to avoid exposure to infectious micro-organisms, and it's difficult to avoid the immune-suppressing psychological stressors associated with hard training. Time constraints also make it nearly impossible for many athletes to adopt an optimal, immunologically fortifying nutritional programme.

However, the Russian scientific literature does offer athletes some help. Most notably, a variety of published papers suggest that the adaptogenic plant, Eleutherococcus senticosus (see also my earlier article in PP 57), may fortify athletes' immune systems and also lower the risk of developing the negative physiological changes associated with overtraining.

Of special interest to athletes are the observations made by 30 Olympic sprinters, decathletes, high jumpers, and marathoners in studies carried out by Professor A.V. Korobkhov at the Lesgraft Institute of Physical Culture in Moscow. These athletes reported 'increased endurance and a willingness to repeat rigorous exercises soon after their completion' when they regularly ingested an extract of Eleutherococcus senticosus (ES). In another study, a Russian scientist named Golovachieva gave ES to certain athletes during a 12-day period of bicycling races. Athletes who took ES won most of the races and noticed 'a rapid recovery of strength, pronounced sensations of muscular vigour, good sleep patterns, and good appetite' compared to individuals who didn't ingest ES. In other words, it appeared that ES boosted performance and lowered the risk of fatigue, staleness, and burnout associated with the overtrained state. ES and disease

What about disease prevention? Several experiments carried out in the Soviet Union have shown that ES, when given to athletes prophylactically, can reduce the incidence of disease by about 35 per cent. Unfortunately, the methodology used in the studies was not always described in the published papers, so it's not clear that the experiments were carried out in a 'double-blind manner', in which subjects and scientists were initially unaware of who was actually getting ES. It's also not certain that the investigations used a 'cross-over' methodology, in which athletes who initially didn't receive any ES 'crossed over' and took ES in a follow-up piece of research, while ES individuals became a subsequent placebo group. Double-blind, cross-over studies represent the 'gold standard' of supplement research. Investigations that are not carried out in this manner leave us with conclusions about nutritional supplements which are considerably more shaky.

Nonetheless, it's safe to assume that the Russian studies were honest, careful, single-blinded experiments in which the scientists - but not the subjects - knew what the subjects were getting. In one such study, carried out between 1973 and 1975, eight to 12 mg of ES extract was given to 1200 workers at the Volga Car Plant n Togliatti, Russia for two-month periods during the spring and autumn. Workers who took ES had a 20 to 30 per cent lower risk of infection, while control subjects actually suffered from a 20 to 30 per cent higher risk of disease. Risk factors and occupational hazards for the workers included emotional and physical stress from vibrations, exhaust fumes, and extreme temperature changes.

During November and December of 1975, another large experiment was conducted with 13,096 workers at the same plant. Compared to control subjects, total disease occurrence decreased by 30 to 50 per cent in individuals who received small doses of ES extract daily.

Finally, during the merciless Siberian winter of 1972, 1000 workers at the Norilsk mining and metalwork complex received two ml of ES extract each day for two months. During that winter, their influenza occurrence dropped by 30 per cent, compared to controls, thus saving the plant about half a million roubles in time lost from sickness (and those were the days when a rouble was a rouble).

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