One of my clients is a ex-professional football player. He is 50 years old, has arthritic knees and also has a lot of discomfort in the knee joints. Any suggestions for exercise?
Your client has probably had repeated injuries to his lower limbs. And in American Football, the knees take a beating. You have not stated what type of arthritis your client has or if he has had any knee surgeries, how many surgeries and what they were for (i.e., ACL reconstruction, etc.) There are several Research Corner Q&As on the site for different types of arthritis and knee injury (perform keyword search under "Arthritis" and/or "Knee Injury" to locate these quickly). The recommended protocol for pre and post workout care is listed in some of these articles. Refer to them for your client and give it a try for a few weeks to see if helps.
My understanding on training and conditioning for people with this type of situation is first do things that do not create immediate pain. When trying “new” exercises, do them without a load to introduce the range of motion (ROM). Then, if no problems occur, add a light load. Squats are probably the most aggravating to this client’s knees. The leg press may be better for the overall training effect due to the closed chain activity. Try using the incline leg press and the horizontal leg press on different days to see if there is residual soreness and pain. I would do only one leg exercise per machine. Workout to examine what works and what does not. You can use two legs at a time to start and work into one leg at a time for unilateral strength.
Another recommendation is the upright bike. Raise the seat to a level when the leg is about 90 percent straight at the bottom of the pedal stroke. This helps alleviate exaggerated knee flexion and allows most people with knee pain some ability to crank out a pretty good workload. Try these suggestions and let us know how it goes.