Discussion
This paper describes the rationale and design of a randomised control trial investigating the effect a progressive aquatic resistance training program will have on patellofemoral and tibiofemoral cartilage, properties of bone and body composition and physical function in post-menopausal women with mild knee osteoarthritis.
Exercise is one of the main non-pharmaceutical treatments recommended in the management of lower limb OA. It is presumed that training in an aquatic environment has benefits for persons suffering from lower limb OA, however exact content and intensity of optimal training remain unclear. For persons with knee and/or hip OA there is strong evidence to suggest aquatic exercise can cause a small but significant reduction in pain, improves self-assessed and measured function with a small to moderate effect size. In addition, there is moderate evidence to show that aquatic exercise can cause a small but significant improvement in aerobic fitness. Further there is limited data to suggest aquatic exercise can increase lower limb strength and improve balance and decrease risk of falling. Intensities of interventions in previously studies may not have been high enough to produce large changes in muscle strength and cardiovascular fitness but reporting of exercise programs used are in most cases incomplete. There are few studies investigating the effect of a progressive resistance program using specifically designed resistance equipment to manage symptoms associated with knee OA even though there is accumulating evidence to suggest it can be effective in improving neuromuscular function. Also, there is some evidence to suggest water based exercise can either maintain or slightly improve the properties of bone as measured with DXA. However these are of low quality evidence and further research is required to validate the findings.
Both dGEMRIC and T2 relaxation MRI can distinguish between normal and OA cartilage. These techniques have been shown to be sensitive enough to demonstrate acute changes in human cartilage dGEMRIC and T2-relaxation times. These methods are therefore suitable for use in our study, and it is known that correct biomechanical loading of cartilage is important in maintaining cartilage health whereas obesity and trauma are risk factors for the development of OA. Although there is evidence to show that biochemical characteristics of cartilage can be negatively affected with changes after periods of joint immobilization and non-weight bearing. No evidence exists to show the impact of an intensive non-impact exercise on cartilage.
As far as we know there have been no publications investigating the effect of aquatic exercise on cartilage and properties of bone in persons with knee OA. The aim of this study is to use repetitive aquatic resistance program with high intensity and repetition to discover what effects non-impact training has on knee cartilage, properties of bone and physical function. The information gained will help improve our understanding of the effects of exercise on the biochemical properties of cartilage and improve prescription of aquatic exercises in the management of OA.