You enjoy downhill skiing. You feel accomplished after high-mileage running. You have played some hard golf shots. You are practicing for your next powerful soccer kick. You love walking, jumping, and being active. If any of this is you, then regular stretches of the muscle groups surrounding your knee will prevent ligament and tendon injuries, such as tearing of the meniscus or chronic inflammation caused by repetitive strain.
A key to preventing knee pain is to minimize tight core muscles: quads, calves, glutes, Iliotibial Band (ITB), and hamstrings. Below are the five simple stretches that will lengthen your muscles around the knee joint and give them more flexibility.
1. Standing Quad Stretch Tight quadriceps can lead to misalignment of knee cap and can increase the risk of knee and hip injuries. People living sedentary or overly active lifestyles are vulnerable to tight quads. Do this classic stretch to improve muscle balance at knee and reduce the risk of injuries. Stand tall, resting left hand on wall or a chair to balance. Tuck your pelvis in and reach back to grab your right foot with your right hand, keeping your thighs lined up next to each other and left leg in line with the hip. Make sure you don't lock the knee of your standing leg. Hold your stretch for 15-30 seconds. Switch legs and repeat the stretch.
2. Downward Dog Stretch. Tight calves put pressure on knees and can lead to knee pain. This basic calf stretch can loosen your calves and give strength to your knees. Take a straight-arm plank position. Slowly lift your pelvis and walk your legs towards your hand until your hand, legs, and the floor form a triangle. Spread your fingers apart and press your heels into the floor. For a deeper calf stretch you can "walk the dog" by slowly by bending one knee at a time, alternating left and right knees. Do this stretch for 25-30 seconds. 3. Twisting Glute Stretch Tight glutes can lead to IT Band issues. Begin by sitting on the floor with your legs straight in front of you. Bend the left knee and bring it closer to your chest while keeping the right leg straight. Place the left heel close to your right thigh and twist until you feel a stretch in your glute. Hold for 20-30 seconds, and then switch. Repeat this stretch 2-3 times. 
4. IT Band Stretch The Iliotibial band (IT) band runs along the outside of the thigh, from just above the hip to just below the inside of the knee. IT Band stretching exercises are important for the prevention of Iliotibial band syndrome, one of the most common overuse injuries among runners. Begin by sitting on the floor with your legs bent in front of you and your arms supporting you from behind. Cross one angle over the opposite knee and scoot your bum forward until you feel the stretch in your outside hip area. Hold for 15 to 20 seconds and then switch legs. Repeat this stretch 2-3 times with each leg. 
5. Hamstring Stretch The hamstring is the single large tendon found behind the knee. It supports the knee and helps bend the knee. Therefore, it is important to lengthen hamstring muscles to prevent knee pain and injury. Sit on the floor with your left leg straight and right leg bent towards your inner thigh. Keep your chest up and slowly bend over to reach the left toe. Hold it for 20-25 seconds, and then switch legs. Repeat at least 2 times. 