The quad muscles cover the front of the thigh, and are often injured because they cross two joints: the hip and the knee. A quadriceps strain is a condition that is frequently seen in kicking and running sports. Since the quad muscle is a strong muscle involved in supporting the body’s movement while upright, pulled quads can be painful and crippling injuries.
The quadriceps is responsible for straightening the knee during activity and controlling knee and hip movements and is particularly active during sprinting, jumping, hopping or kicking. Whenever the quadriceps muscle contracts or is put under stress, tension is placed through the quadriceps muscle fibers. When this tension is excessive due to too much repetition or high force, the quadriceps muscle fibers may be torn. When one or more parts of the quadriceps muscle tear, the condition is known as a quadriceps strain.
Small tears in the small muscle fibers of your quadriceps can cause bleeding, inflammation, and swelling on the front of your thigh. You may see bruising, and your thigh may appear larger or puffier than usual. Difficulty bending and straightening your knee joint is another sign of a pulled quad. At the time of injury, you may have heard a popping sound near your joint. Your quads may feel overly tired, stiff, and weak after a muscle pull. When using your quadriceps muscles, your experience of pain and weakness may increase.