Osteoarthritis (OA) is the most prevalent form of arthritis and one of the leading causes of chronic disability worldwide. It is is primarily characterised by joint degeneration and chronic, sometimes severely disabling pain, as well as stiffness and swelling. Exercise is one of the key conservative therapies for the management of OA with several weeks of either aerobic or strengthening exercise shown to improve symptoms of pain and function.

Currently, clinically prescribed rehabilitation for those with OA is heavily focused on joint specific work (i.e. strengthening quadriceps for knee OA) which is not always predictive of pain relief. Aerobic exercise is more consistently associated with pain relief, but it remains unclear whether this is related to joint specific mechanical activation or a general analgesic effect of aerobic exercise.

We want to determine whether upper body aerobic exercise (i.e. not loading the joint) is effective in reducing the experience of pain in those with knee OA (KOA) in comparison with lower body aerobic exercise (i.e. loading the joint).

What's involved in the study

If you decide to take part in our study you will be asked to attend a laboratory at the University of Bath campus on 4 separate occasions. During the first visit, we will ask you to complete 3 questionnaires which will determine your baseline level of knee pain, psychological state and perception of your affected knee. We will also ask you to perform two sub-maximal exercise tests.

The first will be a cycling exercise test and the second an arm-cycling exercise test. Both tests are of an incremental nature in that the difficulty will be increased at certain timepoints based on your perception of intensity. As stated, these tests are sub-maximal, so you are unlikely to be taken too far out of your comfort zone. This visit will last approximately 60 minutes.

During the second visit, we would like you to attend the laboratory to familiarise you with the 2 exercise protocols that will be used on trial days (visits three and four). Both the cycling and arm-cycling exercise tests are of a continuous nature, that is there will be no change in difficulty throughout. The intensity at which you will perform the exercise is self-selected and individualised based off your representation of RPE 13 on a scale of 6-20 (where 6 = no exertion and 20 = maximal exertion). Instead of the 30 minutes exercise that is required on trial days, you will only be required to exercise for 15 minutes per test. This visit will last approximately 45 minutes.

During the third and fourth visits you will either perform continuous cycling or arm-crank exercise at the same intensity from your familiarisation session. Before and immediately after exercising you will complete some experimental pain tests. These tests are designed to determine your pain thresholds and involve a combination of blunt pin pricks and pressure to your knee. These tests are validated for use in health research and are designed in such a way that the pain does not last following the termination of testing.

Following the third and fourth visits, you will also be asked to track the pain in your affected knee once a day (1 hour after waking up) for 7 days on a simple 0-10 numerical rating scale. During this 1-hour period after waking up you will be asked to record your activities and to maintain the same routine when possible. We will also supply you with a wrist worn activity monitor that can be worn 24hrs a day for 7 days after each trial day, which will track your activity levels and sleep.

Eligibility

To be eligible to participate in this study, you must:

• be aged 45-75 years old
• have had chronic knee pain for more than 3 months
• have no joint related morning stiffness or morning stiffness lasting less than 30 minutes
• have activity related joint pain

What you'll get for taking part

We are not able to offer direct benefits for taking part. However, the information that you and other participants provide in this project will help the research team to understand the impact of upper body aerobic exercise on knee pain. Additionally, you will receive information on your fitness levels and we will be able to determine which exercise is best for your knee pain.

Confidentiality

Only the research team will have access to information that you provide. Your contact details will be stored separately to all data collected during the study, and all data will be anonymised. This study has received ethical approval.¹ (REACH ref: EP 18/19 088)