An acute strain is caused by trauma or an injury such as a blow to the body; it can also be caused by improperly lifting heavy objects or over-stressing the muscles. Chronic strains are usually the result of overuse--prolonged, repetitive movement of the muscles and tendons.
Dynamic stretches are part of an effective warm-up because they can help build endurance for the activity. They also help in flexibility and range of motion in the human body.
