Combined Application of Electrical Stimulated Antagonist Contraction During Walking (Walking Study)

Osteoarthritis of the knee (KOA) is the most common cause of disability in older adults. Osteoarthritis involves a loss of cartilage, which acts like a cushion between the bones as well as changes in the bones of joints. Once the joint cartilage is gone, the body does not produce new cartilage. Joint damage can contribute to pain. Currently, treatment for pain associated with knee osteoarthritis includes exercise. However, exercise at a medium- to high-intensity level can be problematic for people with knee pain. Because exercise is a common treatment for knee pain but many people experience pain during exercise, researchers hope to find a safer and more effective exercise method to strengthen the muscles around the knee. Both aerobic exercise and resistance exercise are recommended for the treatment of people with knee pain. However, pain can be a barrier to participating in exercise at a moderate or vigorous intensity. Electrical stimulation of muscles holds potential to allow effective exercise to be completed at tolerable intensities. Transcutaneous electrical nerve stimulation (TENS) is the use of very low electric currents produced by a device to stimulate the nerves, to treat pain. Neuromuscular electrical stimulation (NMES) uses low electrical current to cause muscles to contract. By doing this study, the investigators hope to learn if a hybrid training system (HTS), using a combination of NMES and walking, is effective in strengthening muscles in people with knee pain, aching or stiffness. In this pilot study, the investigators will use walking with TENS as conventional exercise. Randomized controlled trial will be conducted to compare the effect of walking augmented by HTS with walking without HTS. The investigators will evaluate the relative advantages of training that combines HTS with conventional walking exercise on the improvement of muscle strength, physical function, and pain relief in obese women with frequent knee symptoms. Study Hypotheses: Compared with walking with sensory TENS, walking with HTS will: * 1 increase quadriceps muscle strength. * 2 decrease knee pain. Exploratory Hypotheses: * 3 improve physical function. * 4 increase PPT (improve central sensitization). * 5 improve self-reported quality of life.