Family doctor

Which athletes are most at risk of fatigue?

Probably the most common non-injury problem that I see presenting in sports medicine practice and usually several times a week is the "fatigued athlete".

The sporting background that "the afflicted" athlete/patient most often comes from is triathlon, multi-sport, cycling or distance running. Why this is the case is not the subject of this article. Suffice to say that the potential for athletes to overtrain in these sports is huge due to the physical and "time" demands of training intensively in more than one discipline.

Most sportspeople that I know in the sports of triathlon/multi-sport are also very goal-driven people. Most are already involved in or studying towards careers that are also very time-consuming and there is only "X" number of hours in the day. The aforementioned athlete may therefore have great difficulty in "fitting it all in". In struggling to do so, sleep, something every athlete needs plenty of, is the area where the athlete tries to make up some time from.

The multi-sport athlete who presents with unexplained fatigue will often fit into the above basket of simply too much work/training and not enough rest. However we cannot make that diagnosis without ruling out some of the medical causes for fatigue and staleness.

Iron deficiency in athletes

You probably all know that iron deficiency is a common cause for fatigue and that is easily ruled out by a blood test. Some of you, particularly women, will have experienced the symptoms of iron deficiency and will not want to "go back there again". The rest of this article will discuss some issues with regard to diagnosis and management of iron deficiency.

There is considerable debate over appropriate treatment of iron deficiency so I emphasise that what follows is "my" approach to assessment and treatment. Other sports medicine specialists and other doctors might not adopt the same stance in terms of levels deemed acceptable for iron stores in the body and also for methods used to restore optimum iron levels.

My management however of iron deficiency has developed from dealing with large numbers of iron deficient athletes (certainly most commonly women runners and triathletes) over the years who have come to me because they have had problems with low iron levels affecting their sporting performance. Many of them have not previously been diagnosed as iron deficient. A significant number having been diagnosed have not been able to satisfactorily resolve their problems.

I am not going to go into detail about the biochemistry of iron in the body - you do not need to know that to understand my viewpoint.

Iron levels in the body depend on the difference between intake into the body through the diet, and losses from the body (blood losses via periods, urine, bowels and sweat losses). If losses are greater than intake then you are going to end up iron deficient further down the track. Because iron is such an important component of haemoglobin (the molecule that carries oxygen around in the bloodstream) you can readily understand that low iron levels may result in low levels of haemoglobin that will affect your aerobic performance.

What are normal iron levels for athletes?

The contentious area in medical circles is what is normal and what is low for an athlete - should we use the same levels as for the sedentary population of what is normal and abnormal (i.e. low)? I do not believe so.

There is a huge range of "normal " levels. In the ideal world, where we would all eat diets rich in iron, we would all absorb the iron well we do take in from our diet and we wouldn't have excessive blood or other losses of iron, then we might all be in the normal range AND at our optimum levels. BUT, the ideal world does not exist. Iron is a very "poorly" absorbed mineral even in the best absorbers (only 10%).

The only real way to know if your levels are "optimal" for you (and not just in the "normal range for the general population") is to have a course of iron therapy with pre and post blood tests. If you find your haemoglobin (Hb) count rises from 124 to say 134, with treatment (both these levels being within the "normal range" for a young woman), and you find that you feel aerobically much fitter and your performance is better, then that increment in your blood count, which is the equivalent of an extra litre of oxygen carrying capacity, is probably responsible. In the meantime, your iron "stores" as measured by your "ferritin" levels may have also increased from 20 to 50, again both in the "normal" range as quoted by the labs for the general, mostly sedentary population.

For what its worth, the levels that I use, which are considerably higher than what the labs use as lower limits of normal for these tests, are an Hb of 130 and ferritin of 30 for a female athlete, and an Hb of 140 and a ferritin of 50 in a male athlete. For athletes whose levels are below the above mentioned, who are struggling to find "their form", and in whom there is no obvious medical diagnosis to explain their fatigue, I recommend a trial of iron supplementation. The aim being to try and get them up to their optimum level (or see if they are already at their optimum).

Nutrition issues

Dietary assessment is hugely important and this has been covered in previous issues but to reiterate, a "several day dietary recall" is useful to see just what the average daily intake is. Diet alone is pretty slow in resolving significant iron deficiency so supplements (pills) are usually necessary to help bring levels up or see an effect more quickly.

Ideally after achieving optimum levels, the diet should aim to maintain these improved levels.

Intramuscular iron injections

In some women, who absorb iron even more poorly than most, and who have a very slow or minimal response to iron medication by mouth, there is I believe justification for intramuscular iron injections. Once again this is a contentious issue medically because there have been no controlled studies showing that this works better than tablets but anecdotally there is no doubt in my mind. There are risks with iron therapy intramuscularly, but these are very rare and far less common than risks associated with far more frequently used medications.

I will "not infrequently" use intramuscular iron in athletes, usually female, who have presented with fatigue, with low blood counts and iron levels, who have failed on an iron-rich diet + an iron medication programme to increase their iron stores and blood counts. It usually results in significant increments in both scores "quickly" which gives them the benefit of training at their optimum blood count and iron levels, and they will quickly tell me whether they feel any different or not. It then is important to make sure the improved status is maintained with serial blood testing.

Beware of other causes of fatigue in athletes

Not all fatigue however is iron deficiency. Not infrequently, athletes presenting with fatigue may have undiagnosed asthma, underlying viral or another infection they were not aware about, or other conditions like an overactive or underactive thyroid, heart disease, high blood pressure, diabetes, kidney disease, depression or even cancer.

Every athlete presenting with fatigue needs a full work-up with a full history of their fatigue, clinical examination, and blood tests before assuming that overtraining is the culprit - it however often is!