Overtraining—what happens when you do too much

In order to reach your peak of performance, both physically and mentally, you have to push your training beyond what’s comfortable to realize continued performance gains.. However, it is possible to do too much if you don’t take appropriate rest periods and if you don’t get optimum nutrition. The result is chronic fatigue, declining performance, and other symptoms of what is known as “overtraining syndrome” or OTS. Recovering from this condition can take a warrior out of active duty for weeks or even months while recuperating.

Key Points

  • Reaching peak performance levels usually requires that you train beyond your body’s normal comfort range.
  • Too much training without adequate recovery periods can lead to overtraining, which can require months of recuperation.
  • The most consistent symptoms of overtraining are chronic fatigue and decline in performance despite continued training.
  • Overtraining syndrome includes both physical and mental components.
  • Overtraining is difficult to diagnose and difficult to predict, so it is important to practice preventive measures during training.


For Warfighters to develop the total fitness and resilience needed to face the demands placed on them, they have to train much the same as if they were elite athletes. Thus we can learn important lessons from those athletes and the studies surrounding professional athletes. One of those lessons is that it is possible to do too much, leading to extreme, persistent physical and mental fatigue. The results are known as “functional overreaching” (FO), “nonfunctional overreaching” (NFO), and, at the worst, “overtraining syndrome” (OTS). The only significant difference between the three is the severity of the symptoms and how long it takes to recuperate before training—and in the case of Warfighters, active duty—can resume.

Myths and/or Claims

The myth that generates OTS is that “more is better.” In fact, more is not always better; in training, more can reach the point of “too much.” And more training needs to be accompanied by more strategic rest periods and more optimum nutrition.


Overtraining occurs when aggressive physical training is not accompanied by appropriate periods of rest and optimum nutrition. It ranges from FO, which usually requires days to recover, through NFO, which takes weeks for recovery, to OTS, which needs months or even years of recuperation. The best course is to avoid overtraining altogether, but the difficulty is that it is hard to draw the line between enough training and too much when pushing to limit to achieve peak performance. In addition, the symptoms of overtraining are diverse, and it is only when they become chronic that NFO or OTS has set in—by which time it is too late.

The most pervasive symptoms are a decline in physical performance despite continued training accompanied by pronounced, persistent fatigue. Other symptoms include insomnia, change in appetite, irritability, restlessness, excitability, anxiousness, loss of weight, loss of motivation, inability to concentrate, depression, apathy, and changes in resting heart rate and blood pressure. In fact, some of the best warning signs that an athlete or warrior is approaching overtraining come from some of these more subjective symptoms.


The extreme environments and/or high-intensity operational demands to which Warfighters are routinely subjected can increase susceptibility to OTS, so military personnel need to take extra precautions to ensure that physical activities are punctuated with adequate rest periods and good nutrition. Chapter 9 of the Warfighter Nutrition Guide provides information for Warfighters both in training and deployed.


Because NFO and OTS lead to significant down time for Warfighters and other military personnel, prevention is crucial. This means design of training programs that incorporate both appropriate rest periods and diet. HPRC provides information on Warfighter-specific nutritional needs on its Performance Nutrition page. Training adaptations that target OT prevention include adjustments to running mileage, use of interval training, and graduated training periods, along with close monitoring of both physical and mental conditions of trainees. Detailed information and references to specific studies are provided in the HPRC’s Research Summary “Overtraining: How to Avoid It; How to Detect It.”