What is ATI or Acquired Training Intolerance?

Training Stress and Mystery Syndrome Affect Runners Differently

Sep 22, 2009

While there is no cure so far for Acquired Training Intolerance, it seems to be well within the realm of prevention.

During his 47 years of almost daily running, a dedicated runner covered 95,677 miles in training and 10,320 miles in races which included 90 ultramarathons and 122 marathons.

Then something happened when he turned 64. His body fell apart; he could not sustain any form of running workout; in fact he developed an intolerance to training. While it is easy to blame overkill for this situation, experience shows that for every runner incapacitated by high volume training, hundreds pursuing the same intense schedule remain injury-free.

Clearly some other causative factor is involved in what is now identified as Acquired Training Intolerance or ATI. In their book, The Runners' Body: How the Latest Exercise Science Can Help You Run Stronger, Longer and Faster (Rodale Press, 2009), writers Ross Tucker, Jonathan Dugas and Matt Fitzgerald provided a pretty comprehensive explanation of this relatively new diagnosis by showing the difference between ATI and training stress.

Symptoms of Training Stress

Overtraining affects athletes who are involved in heavy training over a sustained period of time. Its first sign is often moodiness, depression or a loss of interest in training. Other symptoms include persistent fatigue, muscle soreness, sleep disorders, recurring colds or infections.

Despite its presentation of problems, training stress is relatively easy to cure. All one has to do is reduce the running work load and maintain a more balanced and progressive workout schedule.

Most athletes at one point or another have experienced training stress and learned from it the limits of their bodies.

ATI is a Mystery Syndrome

Unlike athletes suffering from training stress who can recover with rest, Acquired Training Intolerance is a much more pathological event. Athletes with ATI seem unable to return to their normal running capacity - even with breaks and rest.

A great deal remains unknown about this mystery syndrome because its presentation is so unusual. For one thing, its appearance is sudden and unexplained. A trainer seems to be functioning fairly well; then all of a sudden, he has problems finishing his usual run at half the normal pace.

Secondly, when tested, he shows no signs of chronic fatigue syndrome or any other metabolic or neuromuscular disorders.

Thirdly, ATI can strike at any age, suggesting that it is not the effect of cumulative training stress or even aging. 30-year-olds with 10 years of running experience are just as vulnerable as 60-year-olds with a 40-year training legacy.

What one researcher, Dale Rae, has discovered is that ATI seems to be caused by a trigger, a stressful event like an illness or depression that is an existing condition while the victim pursues his training schedule. For example, she has found that "four out of five ATI sufferers continued high-volume training after being diagnosed with a viral infection." Other triggers include an obsessive attitude towards running, eating disorders, neuromuscular abnormality and stressors that push the body to its breaking point.

While there is no cure so far for ATI, it seems to be well within the realm of prevention. The key is to be aware of the limits of one's body. Avoiding high training volumes during stressful bouts of physical, emotional or mental strain seems to be the best way to sidestep ATI.

The copyright of the article What is ATI or Acquired Training Intolerance? in Running Training & Fitness is owned by Mary Desaulniers. Permission to republish What is ATI or Acquired Training Intolerance? in print or online must be granted by the author in writing.