Participants attend the laboratory on two or three occasions and wear accelerometers for the 10 days in between the first and second laboratory session. The first laboratory session involves urine sample collection, the completion of questionnaires, blood sample collection, acquisition of cross-sectional images of the thigh and calf, and a whole-body composition scan. The researchers will use the accelerometers at the wrist to measure time spent in moderate to vigorous physical activity, and the accelerometers at the ankle as an analogue for knee joint loading. The second laboratory session will consist of a 30-minute run on an instrumented treadmill (measures force of each step taken) whilst wearing non-invasive reflective markers, electromyography devices, and an accelerometer at the ankle. Participants are also invited to undergo optional repeated blood sampling to measure levels of markers of cartilage production and breakdown during rest and in response to a 30-minute run. If participants volunteer for the optional repeated blood sampling, they will be asked to attend a third laboratory session where blood samples will be taken at 24 hours after the run in the second laboratory session.
The purpose of this study is to investigate the association between time spent in moderate to vigorous physical activity and markers of cartilage metabolism in the years following anterior cruciate ligament reconstruction.