Aside from the fact that walking on a treadmill is an impact sport, knee pain can be caused by a lack of spinal rotation when striding, over pronation and incline running. Also, the treadmill maintains a steady speed which impedes your body's natural tendency to adjust its pace as necessary.

Knee injuries, however minor, can cause pain and discomfort that prevents you from engaging in your normal daily activities.

The anterior cruciate ligament, or ACL, is vital for athletes, especially in sports that require starting and stopping. There are some players who can function without an ACL and still play effectively, even in the demanding running and cutting sport of soccer.

Many people include squats in their regular exercise routines to strengthen and tone their legs, hips, thighs and buttocks. Although squats can be a helpful part of your exercise routine, doing them incorrectly or with bad form can potentially result in a variety of knee injuries.

A muscle spasm, or muscle cramp, is a sudden involuntary contraction of one or more muscles, states MayoClinic.com. A muscle cramp may be sudden or occur gradually. Most muscle spasms are mild; however, a spasm may also cause excruciating pain.

Knee injuries are a common hazard in almost every sport. Like other major joints, knees combine several bones, muscles and ligaments in a confined space. However, knees endure more strain than many other joints because they support the body's entire weight.

According to the American Academy of Orthopaedic Surgeons, surgeons perform approximately 581,000 knee replacement surgeries each year.

Fluid on the elbow is a condition known as elbow bursitis or olecranon bursitis (or sometimes “popeye elbow”). The bursa is a lubricated sac located between the tip or bend of the elbow and the overlying skin. It helps reduce the friction between bones and skin, muscles or tendons during movement.

Arthritis can be painful and make your knee joints stiff, limiting your mobility and making everyday tasks difficult. To counteract this, you need to exercise to keep the legs muscles strong and the knee joint flexible. Walking is a great form of exercise. It is free and can be done anywhere at any time.

Your ankles carry a lot of force and weight everyday, especially if you work in a job where you are on your feet all day or if you perform high-impact exercises like running or competitive sports. The ankle bone connects the shin bone to the 28 bones and 30 joints of the foot.

The facet joints in the spine help you to move and twist. The cervical spine facet joints are located in the back and side of the neck. When you injure this area -- such as after experiencing whiplash -- you may feel pain not only in the neck, but also in the shoulders and arms.

The term “fluid on the knee” refers to a condition called prepatellar bursitis, also known as knee effusion, water on the knee and housemaid’s knee. As these names suggest, this condition is characterized by inflammation of the protective layer of tissue that lines the patella, or kneecap.