A) Mr. Khan is a 60-year-old male truck driver. He has been referred to physical therapy with a diagnosis of osteoarthritis of the left knee and an order to evaluate and treat. He reports that he has had arthritis in the left knee for the past 5 years, and that he recently started performing exercises that have increased the strength, stability, and endurance of his legs but cause knee pain and thigh muscle soreness the next day. His goals in therapy are to control this post-exercise discomfort to allow continuation of his exercise program. He performed his exercises yesterday. Which physical agents required to be intervened and how to be intervened properly?