Unexplained Underperformance Syndrome – The New Over Training Syndrome

By Rick Morris

There aren’t very many things that I know for sure, but one that I do know for sure is that the science of running and exercise will never be a static subject. Things change faster than a 400 meter repeat. A recent running related change concerns the subject of overtraining syndrome (OTS) and an alternative of unexplained underperformance syndrome.

For years the any chronic problems with fatigue, sore muscles, frequent illness, depression, burn out and decreased levels of performance have been called over training syndrome or its predecessor; over reaching.

Now, scientists and researchers have come up with new name for OTS. Truth be told, it’s not really a new name. The change took place back in the year 2000 but like many changes it took a long time to take hold. Runners and other athletes like to hang on to tradition and still refer to this group of chronic fatigue symptoms as OTS, but the new term is beginning to gain some traction. What is this new term? It’s Unexplained Underperformance Syndrome (UPS).

I hate it when change is made simply for the sake of change. In this case I think the change to unexplained underperformance syndrome was warranted. There are a number of terms associated with running that are rather vague and non specific. A good example is shin splints. The term shin splits can refer to any of a number of lower leg injuries. In response, shin splits is now a seldom uttered phrase in favor of the more all encompassing medial tibial stress syndrome. The graduation of OTS to unexplained underperformance syndrome followed similar logic.

There were a couple of problems associated with using OTS to describe the various cases chronic fatigue among athletes. First, OTS insinuates that the problem is well understood and there is a specific known cause. Well, it’s not and there isn’t. Second, OTS seems to signify one specific problem when in reality there are mostly likely several causes and subgroups involved in chronic fatigue among runners and other athletes. In response to the noted inconstancies, a group of researchers met in a round table discussion at St. Catherine’s College, Oxford and coined the new term – unexplained underperformance syndrome.

Unexplained underperformance syndrome has the same following group of symptoms as OTS:

  • Fatigue
  • Increased sense of effort
  • Mood changes or mild depression
  • Decreased performance
  • Frequent infections
  • Loss of energy
  • Loss of competitive drive

While the symptoms of unexplained underperformance syndrome are the same as OTS the new term coveys a more accurate meaning because it says right up front that the syndrome is unexplained and the common and underlying result is underperformance. Whether or not over training is always involved has not been established.

Traditional OTS has always included three separate but closely related sub groups – functional over reaching, non functional over reaching and over training syndrome. Functional over reaching is something that you run into very often if you are a competitive distance runner.  During functional over reaching the negative symptoms are reversed after a planned period of recovery and in the perfect training world, results in positive performance increases. Good examples of functional over reaching are recovering and coming back stronger after a hard interval session or after your marathon taper.

Non-functional over reaching occurs when the negative symptoms of hard training do not disappear or reverse after your planned period of recovery. Using the same two above examples, non functional over reaching occurs if you fail to completely recovery from a hard interval session or you hit marathon race day when still fatigued from your marathon training program. Functional over reaching is usually caused by training at intensities or distances that are too hard or too long without sufficient planned recovery time.

The final subgroup is full blown over training in which your symptoms are more severe and long lasting. Full blown over training is the result of ignoring the warning signs of non functional over reaching.

The researchers that came up with the term UPS do not include functional over training in their definition, which makes perfect sense, because functional over reaching is a planned level of fatigue that usually results in positive performance increases.

It will take a while for the term OTS to disappear from our running vocabulary but the next time you get into a discussion about athlete chronic fatigue consider using the newer and more accurate unexplained underperformance syndrome terminology. It may not be perfect, but does more accurately describe chronic fatigue problems among runners.


Redefining the overtraining syndrome as the unexplained underperformance syndrome, Br J Sports Med 2000;34:67-68