Exercise intolerance refers to the inability of an individual to reach or maintain a level of exertion that other people of their general condition and fitness level can. It is not a condition itself so much as a symptom that can be the result of any number of underlying causes. Heart problems are one major cause of exercise intolerance, since certain cardiac issues can reduce the availability of oxygenated blood to the various muscles of the body. Metabolic muscle diseases can also cause an intolerance to exercise, since these conditions can result in individual muscles not having enough energy. Other conditions that can cause similar symptoms include anemia, chronic fatigue syndrome, and back pain, which can make it difficult to maintain exercise levels.
Many of the conditions that can result in exercise intolerance involve the heart or other muscles of the body. The heart in particular can suffer from conditions such as myocardial infarctions, aortic valve insufficiencies, and arrhythmias that can affect proper blood circulation. Conditions such as these can lead to a shortness of breath that contributes to the inability to reach or maintain a desired exertion level when exercising.
Another cause of exercise intolerance can be traced to metabolic muscle diseases. These conditions typically prevent the mitochondria within cells from producing enough energy, which can result in muscle fatigue. The molecules that the mitochondria are supposed to convert into energy may also gather inside the cells and cause more issues. As the muscles are not capable of exerting properly, exercise intolerance can also be experienced.
Other conditions, such as chronic fatigue syndrome, anemia, and chronic pain, can all lead to exercise intolerance as well. Each underlying cause can manifest in different ways, though the end result is similar. Chronic back pain does not directly cause shortness of breath or muscle problems, but it can affect the ability to achieve and maintain the desired level of exertion for exercise.
In order to work around exercise intolerance, a number of different methods can be employed. This can be especially necessary during rehabilitation for individuals that suffer from any of the various conditions that can result in an intolerance to exercise. Passive physiotherapy is one method that can be used if the patient is completely unable to exercise on his own. Depending on the underlying cause, oxygen supplementation may be helpful, or a mixture of helium and oxygen may be used. Combination therapy that puts together a number of these options may be useful as well.