Overtraining

Overtraining occurs when the volume and intensity of an individual's exercise exceeds their recovery capacity. They cease making progress, and can even begin to lose strength and fitness. Overtraining is a common problem in weight training, but it can also be experienced by runners and other athletes.

Causes
Improvements in strength and fitness occur only during the rest period following hard training. This process takes at least 12-24 hours to complete. If sufficient rest is not available then complete regeneration cannot occur. If this imbalance between excess training and inadequate rest persists then the individual's performance will eventually plateau and decline. For some overtrained professional athletes, it may take several days of rest or reduced activity to restore hormonal levels to normal after overtraining has taken place.

Overtraining occurs more readily if the individual is simultaneously exposed to other physical and psychological stressors, such as jet lag, ongoing illness, overwork, menstruation, poor nutrition etc. It is a particular problem for bodybuilders and other dieters who engage in intense exercise while limiting their food intake.

A number of possible mechanisms for overtraining have been proposed:
 * Microtrauma to the muscles are created faster than the body can heal them.
 * Amino acids are used up faster than they are supplied in the diet. This is sometimes called "protein deficiency".
 * The body becomes calorie-deficient and the rate of break down of muscle tissue increases.
 * Levels of cortisol (the "stress" hormone) are elevated for long periods of time.
 * The body spends more time in a catabolic state than an anabolic state (perhaps as a result of elevated cortisol levels).

Other symptoms
Overtraining may be accompanied by one or more concomitant symptoms:
 * Persistent muscle soreness (Delayed onset muscle soreness)
 * Persistent fatigue
 * Elevated resting heart rate
 * Increased susceptibility to infections
 * Increased incidence of injuries
 * Irritability
 * Depression
 * Loss of motivation
 * Insomnia
 * Decreased appetite
 * Decreased sexual performance
 * Weight loss

Treatment
Allowing more time for the body to recover:
 * Taking a break from training to allow time for recovery.
 * Reducing the volume and/or the intensity of the training.
 * Suitable periodization of training.
 * Splitting the training program so that different sets of muscles are worked on different days.

Changing diet:
 * Ensuring that calorie intake at least matches expenditure.
 * Ensuring total calories are from a suitable macronutrient ratio.
 * Addressing vitamin deficiencies with nutritional supplements.

Some claim spa treatments are effective:
 * Deep-tissue or sports massage of the affected muscles.
 * Self-massage of the affected muscles.
 * Cryotherapy and thermotherapy.
 * Temperature contrast therapy (contrast showers etc).

Planned Overtraining
Overtraining can be used advantageously, as when a bodybuilder is purposely overtrained for a brief period of time to super compensate during a regeneration phase. These are known as "shock micro-cycles" and were a key training technique used by Soviet athletes.