The human body is a brilliant invention, apply a certain level of stress and it will respond by becoming stronger, over stress it and just like any machine it will break down. Because the human body adapts to stress by becoming stronger, athletes improve when they train regularly.

Tough training sessions or workouts stimulate the body to adapt by producing stronger tissues -- muscles, ligaments and tendons, etc, become used to the workout's specific training stresses. But too much stress too soon, or too many tough sessions without adequate recovery, prevents or overcomes this adaptation process and results in tissue breakdown.

Stress comes in many different ways, but can be divided into two main forms: macrotrauma which is one huge massive amount of stress such as being involved in a road traffic accident or undergoing surgery; and microtrauma which is a small but continuos amount of stress applied over a long period of time. This can build up to be as significant as macrotrauma in terms of pain and restricted movement.

Gravity is an unseen form of stress which, does not change so we do not notice it. But it is a force of 14lbs per square inch that is constantly pressing down upon us. The effects of gravity can be both supportive and destructive. When a child builds up a stack of building blocks, with the centre of gravity of each of the blocks vertically above the one below, gravity will support the stack but as soon as one is out of alignment gravity will cause the stack to fall down. If you watch the performance of ballet dancers or other athletes you would think their movements defy gravity. But it is because, just like the building blocks, their centre of gravity or posture is in alignment, so gravity supports them.

However most of us are not so well aligned, the cumulative effect of 'life' has modified our posture. Because the human body is so malleable, unlike the building blocks, we do not collapse in a heap on the floor, instead our bodies adapt. It is this adaptation that is the cause of so much pain and discomfort. The human body is designed to be on the move, not sat at a desk hour upon hour, answering the telephone, solving problems, or working on a keyboard. The situation is made worse by bad posture or poor alignment. Slumping in the chair, peering at the computer screen with the head protruding forward or standing with slumped shoulders, backside sticking out and knees locked, are all examples of posture which puts our centre of gravity out of alignment. Such misalignment eventually results in neck and low back pain or problems such as sciatica. Relatively simple accidents can also have dramatic effects on our centre of gravity. For example when a person stumbles and twists an ankle, not badly enough to break anything but enough to make the person limp for a few weeks, weight is shifted to the strong leg. The weight shift not only stresses the leg muscles but also the muscles in the pelvis, spine and shoulders. That is, we compensate or adapt to the injury. The limp will eventually disappear, but the shoulders, pelvic girdle and muscles throughout the body will have been altered to a varying degree. Setting up trouble for later in life.

Pain itself is only the end result, by the time it is felt the problem is already well advanced. This is one of the main reasons why injuries can take a long time to heal.

The associated muscles, tendons and ligaments etc. will have been trying to cope near their limit of tolerance for days, months or even years. Until suddenly, it's had enough. It does not necessarily have to occur during a training session. You may have turned over in bed awkwardly or spent just that one minute too long pouring over your books or peering at a computer screen. In any event, something occurs that is 'the final straw that breaks the camel's back'. The associated soft tissue gives up the battle and pain occurs. It may only be a nagging ache at first but as time progresses and nothing is done to correct the problem it will get worse.

Rod Dunn, PhD MGCP Member of the National BackCare Organisation (England) Dr. Rod Dunn came into physical therapy through his love of sport, having spent 35 years as a track athlete and coach - gaining first-hand experience of the trials and tribulations associated with sports injuries. He has worked as an academic in the biological sciences and as a journalist writing about sports injuries. He studied first at the London School of Sports Massage, then trained, taught and worked with one of the world's leading physical therapists, Dr Craig Benedict. You can learn more about Dr. Dunn at http://www.cambsphysicaltherapy.co.uk