Four muscles in the front of your thigh, known as your quadriceps, work together to extend your knee. Tight quadriceps are a risk factor for injury, especially if you're involved in sports and activities that require sudden, forceful contraction of the quads. Of the four quad muscles, only the rectus femoris attaches to the pelvis and assists with hip flexion. It's also the most vulnerable to strain, according to a study published in "Current Reviews in Musculoskeletal Medicine" in 2010. Whether you're an avid runner, soccer player or aerobic dancer or just a big fan of squats, stretching the rectus femoris keeps it long and supple, which boosts performance and wards off injury.
Do a brief warm-up to increase circulation and raise muscle tissue temperature in your thighs. March or jog in place while pumping your arms, moving at a brisk pace for five to seven minutes or until you break a light sweat. Progress to a dynamic quad stretch -- such as butt kicks -- to round off your warm-up and prepare your quadriceps, hips and knees for more intense static stretching. Kick butt for 30 seconds, starting slowly and gradually picking up the pace. Aim for smooth, continuous, flowing movement.
Lengthen the rectus femoris from a standing position, using a classic quad stretch that combines knee flexion and hip extension. Stand facing a stationary object, such as a wall, tree or beam. Rest the fingertips of your left hand on the object for light support. Grasp the top of your right foot with your right hand and gently pull the foot toward your right buttock. Keep your inner thighs together and avoid arching your lower back. Increase the stretch by slowly moving your right knee back, lengthening the front of your right hip and thigh. Hold the position for up to 30 seconds, relax briefly and repeat up to four times before stretching your left leg.
Move to the floor for a kneeling quad stretch. Starting on both knees, step forward onto your left foot, aligning your left knee over your left ankle. Bend your right leg and reach back with your right arm. Take hold of the top of your right foot and gently pull the foot toward your buttocks. Place a folded towel under your right knee for comfort, if necessary. Hold the position for up to 30 seconds. Release the stretch, repeat up to four times and switch to your left leg.
Pull up a firm, stable chair and stretch from a seated position. Scoot to the right side of your chair so only your left buttock and thigh are on the seat. Grip the top of your right foot with your right hand and draw the foot toward your right buttock, directing your right knee toward the floor. Hold the position for up to 30 seconds. Repeat up to four times before sliding to the other side of your seat and stretching your left thigh.
Perform all variations -- standing, seated and kneeling -- with excellent form. Maintain a straight spine and avoid leaning to either side. Press your shoulders down and slightly back and keep your head centered over your spine. Engage your abdominal muscles to keep your pelvis stable and to prevent lower-back injury. Focus in front of you and consciously relax your face, jaw, neck and shoulders. Contract the buttock of the leg you're stretching to intensify the stretch.