Healthcare costs are increasing alarmingly, which will impose an overwhelming economic burden on an aging society like that of Hong Kong. For example, knee pain attributable to osteoarthritis (OA) is a common disabling problem. The therapeutic effects of PEMF in the field of orthopedics have been recognized and approved for clinical use for over 40 years. PEMF may provide moderate benefit for OA sufferers in relieving knee pain, but the improvements in function and quality of life are not significant, probably due to persistent muscle weakness. However, significant variations in treatment conditions still present major obstacles to optimizing the therapeutic effects of PEMF, such as device parameters (frequency, amplitudes symmetry, and field gradient). Moreover, there is room for further improvements in PEMF treatment for knee pain relief with respect to function and quality of life. Our approach is unique in that we target muscle to act as a delivery system for regenerative agents that will promote healing naturally. And many studies have proved that quadriceps muscle strength plays a vital role in pain relief. Therefore, A muscle-specific, low energy (1.5 mT, 15 Hz, 10 minutes/week) PEMF therapy was applied in this project, and this PEMF paradigm has been demonstrated effective in promoting muscle regeneration in humans by activating mitochondrial activities. Our project would be the first project to examine the effect of PEMF on older adults with knee pain to improve quadriceps muscle strength and relieve pain symptoms.