Fatigue And Performance

Fatigue and Performance


Fatigue affects the physical and mental capacity of a person to perform set tasks. It is especially noted in athletes who push themselves to the limits of endurance, and is also common among people who engage in strenuous work. The onset of fatigue can be rapid, or the result of cumulative effects after weeks or months of physical effort.


Sports and Exercise Medicine Physicians are dedicated to establishing the right balance between training, competition and recovery in order to help avoid the onset of fatigue. Appropriate nutrition, hydration, recovery and sleep are important measures that lessen the incidence of fatigue, whether it is caused on the sports field or elsewhere. Stress due to employment or study pressure is another known precursor of fatigue, as is the temptation to continue training or playing sport while carrying an existing injury.


Most episodes of fatigue can be mitigated by first identifying the cause, followed by adjustments to training or activity schedules. The symptoms of fatigue will usually disappear quickly, however, in cases where fatigue symptoms persist a medical review will be necessary.


It’s important to rule out the possibility of fatigue caused by an illness. Anaemia and iron deficiency are common causes of fatigue, as are some infections. Fatigue is a symptom of major illnesses including heart disease, diabetes, sleep apnoea and thyroid problems. A visit to your Doctor or Sports and Exercise Medicine Physician will help rule out these possibilities while honing in on the actual cause of fatigue.



Acute fatigue


The power and intensity required to perform an activity is sometimes unmatched with a person’s capacity. Muscle fatigue takes place when there is a decrease in power of the muscle, and is experienced in different ways according to the activity performed. This is the natural concept of “over-reaching”, or training progressively harder and harder in order to improve the capacity of the cardiovascular system and/or the muscles to do the desired activity.

Short/Intense activity: Requiring maximum muscle contractions in a short time-frame. Fatigue can set in when muscle tension cannot be maintained. This feels like tired or even cramping muscles that can’t continue to do the work. They will often be sore 2-3 days later as a result of acute muscle breakdown. Interval training helps by conditioning muscle fibres to respond more adequately for longer periods.

Long/Sustained activity: A typical example is long distance running or hiking, where muscles contract more slowly. Fatigue can result due to depleted energy along with sustained muscle use over a longer time. This feels like the athlete cannot continue, has “nothing left in the tank”. This level of fatigue is important in the process of cardiovascular conditioning and the development on increased fitness.


Acute fatigue can greatly impair concentration on and off the field. The attention span of a fatigued participant will be diminished, with instructions or guidelines less likely to be followed effectively.


Fatigue can be tolerated to a degree, but greater performance is reliant on energy, muscle memory and a level of overall fitness that can only be provided by professional coaching and medical staff. All the best athletes take advantage of such facilities, and regardless of your sporting or fitness goals, so can you.



Overtraining syndrome


Fatigue can result from an athlete chronically overtraining. This usually affects endurance athletes, triathletes, distance runners and others who train frequently or at a high level.

Highly competitive sports people are accustomed to strenuous activity performed either intensely or with endurance, so they are in one sense always flirting with the potential for fatigue. This is particularly the case in self-motivated individuals who train and play sport without proper training guidelines. Although acknowledging the problem, some  individuals push on regardless, sometimes training even more to make up for poor performance.

Overtraining is more likely when athletes train excessively, don’t program adequate recovery and rest, don’t hydrate or eat enough or the right type of food, have added pressures or stress like work or relationships, or have depression.


Once medical causes of fatigue (such as anaemia) are excluded, a diagnosis of “overtraining syndrome” is given.


Symptoms of overtraining:

  • Tiredness
  • Altered sleep – either excessive or not sleeping well
  • Poor performance
  • Poor recovery
  • Moodiness – depressed and/or irritable
  • Increased injury
  • Altered resting or exercising heart rate


A Sports and Exercise Medicine Physician is ideally placed to evaluate and guide athletes with fatigue or overtraining. North Sydney Sports Medicine also has a trained Sports Dietician to advise on the specific nutritional strategies around training, race day and recovery.