The purpose of training in sports is to stimulate the human body, not to annihilate it! 

A fitting metaphor for this statement is: exposure to the sun can give energy and vitality, but in excess it can cause sunburn and skin cancer. 
Training for a bike racer should aim for enhanced performance following objective-specific programs. 

If the organism is over-stimulated, or stimulated incorrectly, the athlete’s psycho-physical state and performance will suffer adverse effects. 

What is “over-training”? How and when does it occur? 

Let’s analyze two elements of “performance reduction”: over-reaching and over-training. 

Over-reaching refers to short-term performance drops that develop as a result of exceptionally intense training sessions (the so-called “high-load” period). Symptoms are those of normal fatigue, a sense of general fatigue caused by intense training. 
Over-reaching is therefore a physiological phenomenon that need not compromise improvement or maintenance of performance levels. 

Over-training, on the other hand, is a much longer-term problem (which can even last for a period of months). Principal symptoms are: 

- performance drops 
- decreased muscle strength 
- loss of coordination and efficiency 
- differences in FC between prone and standing positions 
- T wave anomalies seen in ECGs 
- Changes in FC at rest, during training and during recovery 
- Headaches 
- Lymph gland swelling 
- Herpes 
- Decrease of over 30% in the comparative levels of Free Testosterone and Cortisol 
- Decreased concentrations of Lactic Acid at maximal and sub-maximal effort levels 
- General feeling of fatigue, even during rest periods 


The most frequent causes of over-training are: excessive increase in training loads, insufficient recovery periods, insufficient diet (inadequate quantity of CHO or especially fluids), travel factors, lack of training variety.

 

In endurance sports, the maximum recommended “load” period (including over-reaching) is about 3 weeks, although “load” periods of 2 or even 1 week are also possible. 
Unvaried training programs, programs without alternating periods of high and low “load”, severely increase the risk of over-training. 

Here are some suggestions for avoiding over-training: 

- the “load” period should not last longer than 3 weeks 
- alternate sessions of hard training with easier sessions 
- incorporate at least one day of full rest per week 
- reduce exterior stress factors 
- avoid excessive racing periods 
- in the 4th week, training intensity should be reduced and the number of rest days increased. The purpose of this “off week” is to recover from over-reaching and allow for a full regeneration of the athlete.