Overtraining (II)

Your body tries to maintain a constant environment (homeostasis) even in periods of heavy training, and one key aspect of this is satisfying the body's required energy intake, as well as supplying other various nutrients.

Overtraining, muscle damage and dietary intake all interrelate.

Research has shown that a number of athletes who are overtrained tend to have decreased hunger and appetite, which in turn leads to reduced energy intake and less than required intake of carbohydrates (for fuel) and other nutrients.

Imagine driving lots of miles each and every day and neglecting to fill the tank up regularly with petrol. It would be no surprise when the car runs out of fuel.

Your body works the same: train hard and neglect to eat and fuel correctly and you are heading for trouble. Some years ago in an article for an earlier Malta Marathon, I had discussed the case of one runner who ran 10 miles every day.

Each day a little of his leg muscle was biopsied and tested for glycogen content. Despite the fact that this individual was eating as much as he personally wanted, the tests showed that after only three days of training his muscle glycogen was virtually spent.

He had not been eating enough to refuel. If he continued, his body would begin to cannibalise itself (breaking down its own muscle tissue) to provide him with fuel.

Obviously, this is not a strategy that will lead to improved performance.

It was found that this runner had to eat as much as 150% (one and a half times) what he personally thought was enough food before he consumed enough energy to fuel and refuel his 10 miles per day training.

So, like this runner, it is very possible to think you are eating enough, and yet not be.

Some life factors can get in the way of eating enough. After a hard run, few runners feel like eating immediately afterwards, and they might consider carbohydrate drinks (which are better tolerated) at this time.

Eating habits

Athletes who live alone might not eat enough (since cooking for one can seem like a chore) or make poor food choices and just grab some fast food.

The commitment of rushing out the door to school or a job may interfere with good eating habits.

In women, bodily appearance can influence food choices. A female athlete who is concerned about her weight or figure may choose smaller than optimal food portions, or none at all, despite the fact she is hungry.

In all athletes, it has been shown that if carbohydrate intake is not sufficient, then body protein would have to be used as an energy source, thereby wasting lean body mass (in effect, you break down your own muscles for energy).

Naturally, this will have negative effects on performance.

One 15-week study of a female runner showed that while she was training seven days a week, she was regularly complaining of fatigue, poor performance and a high frequency of illness and injury.

She had not had a normal menstrual cycle for three months.

The runner's diet was supplemented with one 11-oz liquid meal replacement per day (in addition to her current food intake). This furnished her with an additional 360 kcals/serving (59g CHO, 17g protein, 7g fat) per day and she was told to have one complete rest day each week.

Her energy balance was now much improved and she showed an increase in body fat from 8.2 to a more healthy 14.4%. Just as importantly, she soon broke two school track records and qualified to race at national level. Her increase in body fat did not hinder her performance in any way.

It appears that caloric intake plays a role in overtraining, and all runners are advised to consume enough carbohydrates and fat so as not to catabolise amino acids from their muscles as a fuel source for their training.