What are steroids and how do they affect muscle and bone?

The description of something as a “steroid” simply refers to the chemical shape of the molecule. There are 2 types of steroid molecules that are often talked about. It is very likely that you, or people that you know, have been prescribed the first type of steroid which is known as a corticosteroid. Synthetic corticosteroids are used to treat diseases that involve an allergic reaction such as asthma and dermatitis, and other diseases that are associated with inflammation. Unfortunately, these drugs have many side effects, one of which is loss of muscle mass. Corticosteroids block the production of proteins in the muscle and accelerate their breakdown. Because they accelerate the breakdown of tissue, corticosteroids are described as being “catabolic”. They also adversely affect bone remodelling by increasing the activity of osteoclasts and reducing osteoblast activity, causing a loss of bone strength. So why do body builders use steroids to increase their muscle mass? The answer is that they are taking a different type of steroid: an anabolic steroid, which is based on the natural hormone testosterone. Hormones that are anabolic stimulate the metabolic pathways and increase protein production. That means they increase both muscle and bone mass, and some athletes use anabolic steroids to enhance the recovery from injury. However, anabolic steroids are associated with a range of adverse side-effects, several of which can be life threatening. As men age, their testosterone production decreases. That’s one of the reasons why ageing men lose muscle mass. The decrease in testosterone also affects bone mineral density and can cause senile osteoporosis. In Australians aged 50 and over, 1 in 4 men and 2 in 5 women will experience a fracture due to osteoporosis at some time in the future.