If your knees hurt after using the treadmill, there are several things you could be doing incorrectly. You might not have proper sneakers or your shoes are worn out and need to be replaced. It's also possible that your running form is incorrect, such as your posture or stride length. Another possibility is that your body is imbalanced due to tight muscles, so you cannot evenly distribute the impact of running between all of your joints.
Running shoes differ from regular sneakers in that they are are made out of light weight material and have cushion to reduce the impact of running on your joints. Running shoes have different types of cushion depending on people's pronation, which is how the foot contacts the ground when you run. If you have a normal arch, you probably have normal pronation -- the outside of your back heel hits the ground first, and then your foot rolls inward to complete contact with the ground. People with flat feet or high arches might under-pronate or over-pronate. There is some uncertainty as to whether people should buy special sneakers to correct foot pronation. Researchers from Aarhus University in Denmark and other institutions published a study in the "British Journal of Sports Medicine" that found foot pronation is not associated with increased injury risk for novice runners. It may be more important to simply wear comfortable sneakers than to wear sneakers designed to correct pronation.
Good Running Form
An integral part to healthy running form is having good posture. When you run, your abdomen should be engaged, your shoulders relaxed away from your ears, and your spine should be tall and straight. If you don't have good posture, your joints will move out of alignment and prevent your body from effectively absorbing the impact of running. This could put unhealthy strain on your knees, hips and back. It is important to have good posture in everything you do -- walking, hiking, sitting -- to prevent straining your back and joints.
Proper Stride Mechanics
According to Chi Running, having too long of a stride can injure your knees and hamstrings. When you're running, your legs should bend at about a 90-degree angle and your feet should land under you, not in front of you. When your foot lands under you, you can effectively use your body weight to propel yourself forward. If your foot lands in front of you, however, your forward momentum will strain your knee joints.
Stretching your muscles every day for 30 to 60 minutes, helps to create balance in your body. Often, people are tighter on one side of their body than on the other. This one-sided tightness can be caused by repetitive routines, such as always hitting the gas pedal with your right foot. Body imbalances are compounded by repetitive exercises, like walking and running. When one side of your body is tighter than the other side, your body cannot evenly distribute the impact of walking or running between your joints, which can cause injuries over time.
If your knees hurt after exercising on the treadmill, there are some things you should do. First, elevate your knees, place a towel over them and ice knees for 15 to 20 minutes, three to four times a day for two or three days. Icing your knees will reduce inflammation that could be causing pain. Also, rest for a few days and avoid weight-bearing activities. When you sleep, place a pillow between your knees. If your knees still hurt after three days, call your doctor.