As our understanding of the biology behind depression and related conditions has been developed, many conditions that are considered to be purely psychological now known to have specific links biochemical changes in the brain. As a result, treatment for depression is increasingly dependent on drugs designed to moderate the level of certain compounds in the nervous system.

Most drugs used to treat depression by increasing the amount of available serotonin or dopamine in the body. These chemicals regulate how brain cells to talk to each other, and also help coordinate the interactions between different brain regions. Low levels of serotonin and dopamine have been associated with alterations in mood and antidepressants are designed to increase the available amount of these chemicals.

Serotonin and dopamine, however, play an important role in many parts of the body outside the brain, and antidepressant drugs are increasingly used to treat a variety of conditions such as chronic pain. Both compounds are known to affect the heart and blood vessels. In concentrated doses, dopamine is used as an emergency medicine to support (increase) in blood pressure during surgery and when certain conditions - such as infection throughout the body - cause low blood pressure beyond the capacity of body to correct. To a lesser extent, serotonin have similar effects of increased blood pressure and may increase the sensitivity of the heart and vessels are for the effects of dopamine.

STRENGTH AND ENDURANCE TRAINING

Since reduced inspiratory muscle strength is evident in patients with COPD, considerable efforts have been made to define the role of Inspiratory muscle training in this setting. Theoretically, an increase in inspiratory muscle strength (and perhaps endurance) could result in improved respiratory muscle function.

Strength training — Training for strength is achieved by a high intensity, short duration stimulus, such as performance of inspiratory maneuvers against a closed glottis or shutter. An increase in maximal inspiratory pressures has been demonstrated when the respiratory muscles have been specifically trained for strength [7,8]. Respiratory muscle strength has also been shown to increase as a by-product of endurance training. It is therefore possible that some of the observed benefits reported after endurance training may be related to the associated increase in strength.