The effect of aquatic exercise on symptoms, function, body composition and cartilage in knee osteoarthritis

Knee osteoarthritis (OA) is the most common joint disease associated with pain and loss of functional capacity. The management of knee OA is multifaceted and covers the whole OA continuum from injury prevention to the end stage of the disease. Recently, specific focus has been on preventing the progression of cartilage degeneration and avoiding loss of function in the early phase of the disease via the provision of exercise interventions. Aquatic exercise is a popular but under-researched exercise option. Therefore, the purpose of this dissertation was to investigate the role of aquatic exercise in the management of knee OA, focusing especially the effect it evokes on both functional capacity and biochemical composition of knee cartilage. Two systematic reviews with meta-analysis were performed. The first investigated the effect of therapeutic aquatic exercise on pain and functional capacity, compared to controls, in individuals with lower limb OA; it included 11 studies. The second review evaluated the effects of aquatic exercise on different aspects of functional capacity, e.g. muscle strength, agility and walking ability, compared to control and land-based exercise, in healthy older adults and included 28 studies. Data from a 4-month randomised controlled trial with a 12-months’ follow-up period was used to investigate the effect of a progressive aquatic resistance training program on walking ability, cardiovascular fitness, muscle strength, symptoms and body composition in 87 postmenopausal women with mild knee OA. Furthermore, the effect of the intervention on the biochemical composition of tibiofemoral cartilage was investigated using T2 relaxation time (T2) mapping and delayed gadolinium-enhanced magnetic resonance imaging (dGEMRIC index). The results of this dissertation revealed that therapeutic aquatic exercise produced a small sized but statistically significant decrease in pain and improvement in walking ability and joint flexibility in individuals with lower limb OA. Compared to control interventions, aquatic exercise significantly improved muscle strength, agility, flexibility, walking speed and aerobic fitness in healthy older adults. Aquatic exercise was at least as effective as land-based exercise at improving functional capacity in healthy older adults. Following 4- months of aquatic resistance training, there was a significant increase in walking speed, improved cardiovascular fitness and a decrease in fat mass. Only improvements in walking speed were maintained at the 12-months’ follow-up. Additionally, a small effect in the biochemical composition of the tibiofemoral cartilage was detected post-intervention in both T2 and dGEMRIC index. To conclude, aquatic exercise exerts a positive effect on different aspects of functional capacity in both healthy adults and individuals with knee OA. The effect of aquatic exercise on the composition of cartilage needs to be clarified