In a relaxed state, muscles do not require much blood and the supply of blood matches the muscle's demands. When the muscles are involved in rhythmic contractions, such as during walking, running or cycling, the blood circulation to the muscles increases and matches the increased demands of the muscles (unless the activity is very intense). When a muscle is contracted for a prolonged duration, the blood supply to the muscle is restricted due to continuous compression of the blood vessels by the muscle. At the same time, the muscle's requirement for oxygen has increased due to the contraction, so the blood supply to the muscles is not matching the muscles demands.When this chronic, static muscle contraction occurs, your body responds by sending cells to the area that will lay down fibrous connective tissue within the muscle to help re-enforce and support the muscle. Over a long period of time, the muscle slowly becomes weaker, more ”leathery”, and painful knots or trigger points will develop in the muscle.The most common cause of static muscle contraction is poor posture. Poor posture can occur while standing, sitting, sleeping, playing sports, working, or doing hobbies. The most effective approach is prevention, which can be addressed by the individual or the activity.Individual interventions may include:•Postural education for sitting, standing and sleeping.•Stretching and strengthening exercises.•Nutritional advice.•Advice on technique and biomechanics of the activity.