Overtraining and fatigue in athletes

It is a general assumption that a training program will always work. However, there are many factors that can interfere with the proper assimilation of training and therefore elicit a maladaptation or an overtraining state.

The first principle of training is the overload principle, where the body is stressed to elicit an adaptation and an improvement in performance, which is called supercompensation.  For a supercomensation to occur, however, it is crucial to have a correct assimilation of the training load as well as a recovery. The problem affecting many athletes is that either the training overload is too much and/or the recovery is insufficient. This will result in a maladaptation and overtraining state which will decrease and deteriorate performance.

Team sports are no exception. There is a general assumption that performance form improves during the season, when actually, it often deteriorates throughout the season. Unfortunately, even at the highest level of competition little is done in general to monitor athletes. Many athletes spend a lot of money on cutting-edge equipment for marginal gain; others keep training and competing overtrained and fatigued but never know.

Fatigue and overtraining don’t strike just elite athletes. Recreational athletes are actually the population most vulnerable for overtraining. Many recreational athletes become “competitive” athletes. They don’t run around the block or cycle to work anymore to stay fit. Instead, they enter marathons, half-marathons, triathlons or century rides. Many train with a purpose – from being the best age grouper to being the fastest in their neighborhood.

They have fulltime jobs, many times eat on the run, sleep less than seven hours a night and squeeze in trainings. They have the same overtraining features as elite athletes. Elite athletes at least have an entourage of experts to help them avoid overtraining. Recreational athletes are on their own.

Causes of Overtraining

There are different causes of overtraining, but these are the most common ones:

Excessive training. Many athletes train more than they can assimilate and/or their training overload is too much. In many cases, athletes, coaches and trainers don’t know how much training an athlete can assimilate as it is hard to quantify.

Poor recovery and assimilation. As described above, training overload on the body is followed by a supercompensation, which is the regeneration phase of the training where the body regenerates, supercompensates and gets stronger, increasing form and performance.  Proper recovery is crucial, and many times, the recovery component is absent or insufficient to elicit a regeneration. Eventually, overtraining will happen.

Improper Nutrition.  Nutrition is a key part of the training regime of any athlete. Not ingesting enough calories (Kcal) can result in important macro and micronutrient deficits for an athlete. This is especially true when it comes to carbohydrates (CHO). 

For about 100 years, it has been known that carbohydrates are crucial for performance. Multiple studies show that fatigue and decreased performance are associated with low carbohydrate diets resulting in glycogen depletion. Likewise, several studies show how low glycogen levels may cause overtraining. Since glycogen storage capacity is very limited, many high performance athletes may find it difficult to even keep up with CHO intake, and therefore have some patterns of glycogen depletion.

When glycogen levels are low or there is glycogen depletion, the muscle increases the utilization of protein and amino acid utilization to produce glucose for energy purposes. This increase in protein utilization may lead to a catabolic situation and muscle breakdown which may result in muscle damage. This interferes with performance but could also interfere with glycogen storage and synthesis.

When muscle damage occurs – which is quite common in many athletes of all levels – even a high CHO diet may not be enough to maintain muscle glycogen storages and energy levels. An athlete can enter a vicious circle which may lead to chronic overtraining, a decrease in performance and even increase in the risk of muscle injuries.

Psychological stress. Athletes may experience psychological stress which can interfere with performance. Many studies confirm the effects of psychological stress on performance.  Elite athletes typically develop a psychological stress derived from the high psychological and physiological demand of training and competition. It is not uncommon to see athletes dealing with a great deal of stress due to fear of failure.

Recreational athletes may develop a different kind of stress derived from their busy schedules, full-time jobs and the difficulty training around their schedules and busy lives.

If an athlete is overtrained and fatigued, the imact of stress may be more pronounced because of the difficulty of achieving set goals. The field of sports psychology is more popular than ever and of great help for competitive athletes. Many teams have now sports psychologists on staff, and many individual athletes use sports psychology services to improve performance

Clinical approach to monitor overtraining: The answer is in the blood

There are many indirect parameters to assess overtraining, but they may not be very sensitive and many times are difficult or ambiguous to quantify and interpret. Examining direct blood biomarkers of overtraining is a useful tool to detect and diagnose overtraining. Through the evaluation of different blood biomarkers, it is possible to monitor an athlete throughout the season to detect and/or prevent overtraining. Different hematological, biochemical, hormonal and serological biomarkers can be found in the blood as biomarkers for overtraining.

Join us on Friday, Sept. 27 at 6 p.m. at the Tivoli Lodge for an educational lecture on overtraining by the author, Dr. Inigo San Millan.