Lose weight and keep fit to beat knee pain
Published on 01 January 2008
Arthritis Research UK’s clinical trial in Nottingham to examine the effects of weight loss and exercise on knee pain has shown that both can be helpful. But have the people taking part in the trial managed to maintain their good, healthy habits – or have they slipped back to their bad old ways? Jane Tadman reports in the second article of a special feature on osteoarthritis.
A trial participant is put through her paces.
When Alma Armstrong volunteered to take part in Arthritis Research UK’s ambitious clinical trial to reduce knee pain in the overweight by diet and/or exercise she weighed in at almost 17 stone. Always a big woman who enjoyed her food, she had piled on the pounds after giving birth to her second child and never really lost it.
Unsurprisingly, her knees were causing pain to the point where she could no longer sleep through the night. So when Alma, aged 77, was randomised to the diet arm of the trial, she was more than happy.
At 16 stone Angela May-Bakewell, who was also classed as overweight and suffering from painful knees, was randomised to the exercise-only arm of the trial. Although over the 2 years she sometimes struggled to religiously do her knee strengthening exercises she managed to incorporate them into her daily life until she completed the trial.
Trial co-ordinator Claire Jenkinson, who along with a number of researchers had the job of recruiting and then motivating patients to stick to their diet or exercise plans, says the trial threw up a number of unexpected results.
“The main thing we were looking at was whether diet and/or knee strengthening exercise reduced knee pain – our primary endpoint – but other outcomes we were looking at were ability to do everyday activities and stiffness. The dietary programme worked, in that people lost significantly more weight than those not in a dietary group but this was not accompanied by a significant reduction in pain.
“We also expected more people to drop out of the diet groups, but that didn’t happen. Instead within the first year we had a 25 per cent drop-out rate from the exercise groups, so I think the key message from that is we have to find exercises that people like doing, rather than doing them as a chore.”
Angela admits that staying motivated to do the exercises for two years was tough. “I was given a booklet showing me how to do the exercises – mainly quadriceps strengthening through to resistance exercise, walking up and down the stairs, and so on, but they were time-consuming,” she says. “I ended up doing them during my breaks at work or while I was waiting for the kettle to boil; a few minutes here and there.”
Those on the dietary arm of the trial were encouraged to eat a low fat diet reducing calorie intake by about 500 calories a day, with the aim of losing weight slowly – and maintaining the loss. Participants were visited every month for the first 6 months, and then every other month by a dietitian.
“I realised I was carrying too much weight and I was very sedentary, especially in the winter time, and it was not helping my knees,” says Alma. She embarked on her diet of skimmed milk, low-fat margarine, no sweets, and no chocolate, with enthusiasm. By the time she finished the trial in May 2005 she had lost almost three stone and felt considerably better for it.
“I started swimming three times a week and became a lot stronger,” she adds. “And it took a long time but eventually I realised I wasn’t waking up in the night rubbing my knees – I could sleep all night.”
So did the trial instil good habits into both women – and more importantly did they manage to maintain them once the trial had ended?
Angela May-Bakewell, who was in the knee exercise-only group, went down from 16 stone to 10 stone, but since the trial ended and she has also stopped going to Slimming World she has put a stone and a half back on – deliberately – as she felt such extreme weight loss didn’t suit her.
“I still swim regularly twice a week and I can now do 40 lengths at a time, and I still try and do knee exercises,” she says. “When you do things over a long period they do become part of your life. I don’t get much pain in my knees and they are a lot stronger too – and I can walk further. Before, they used to ache a lot more much sooner. I feel a lot better physically.”
Alma Armstrong didn’t go back to full cream milk or hard fats and still eats a reasonably low fat diet although she admits that some of her weight has crept back on. She has also maintained her swimming regime.
"The trial has made me more aware of the importance of keeping my weight down and doing exercises. I’m very pleased that I was involved. I recently moved house, and I wouldn’t have been able to go up and down the stairs so often without the help of the trial. The best thing, though, is being able to sleep all night without waking up!"
The trial – significant findings
The Lifestyle Intervention for Knee Pain (LIKP) trial, led by Professor Ken Muir at the University of Nottingham and funded by a five-year £500,000 grant from Arthritis Research UK, recruited 389 overweight and obese people with knee pain from GP surgeries in the local area.
They were randomised to one of four intervention or treatment groups 1) diet plus knee strengthening exercises 2) diet only 3) knee strengthening exercises only 4) an advice leaflet.
Changes in knee pain, stiffness and physical function (ie the ability to perform everyday activities such as walking up and down stairs, getting in and out of the car and the bath, doing house work, etc) were assessed at six, 12 and 24 months. Information about quality of life, levels of anxiety and depression were also gathered at these times.
When the trial ended in February 2007, 292 people had completed it.
After two years, those in the dietary group had lost an average of 7lb (3.2kg) although researchers found that losing weight did not appear to reduce knee pain. However, they had a significant improvement in physical function after 24 months, and had lower depression scores than those not in a dietary group.
Those in the knee-strengthening group found that their knee pain reduced significantly at six, 12 and 24 months, as did knee stiffness, and physical function. In fact 45 per cent of people in the diet and exercise and exercise-only groups who complied highly with the knee exercise group found their knee pain reduced by at least 30 per cent.
So should people with knee OA exercise and lose weight?
Professor Mike Doherty, who was involved in the LIKP trial advises: "It is clear that regular exercise that strengthens the thigh (quadriceps) muscles can reduce pain and disability from knee pain and OA. Such exercise reduces the muscle weakness and impaired balance that occurs with knee pain/OA and improves the stability and health of the knee. This allows people to do more with their knee and to experience less pain.
“Weight loss in people who are overweight and have knee pain/OA also improves their outcome. However, this is mainly in terms of increasing their mobility and being able to do more, rather than by reducing their pain.
“Removing excess weight from the painful knee allows it to perform better in terms of function. Their pain does not get better however, perhaps because the health of the knee itself has not been greatly improved. Therefore it seems that the reduction in disability through weight loss most likely results from reduced stress on of the knee rather than by direct improvement of the health and stability of the knee.
Clearly, the combination of both exercise and weight reduction is recommended since both improve patient-centred outcomes - pain and disability – albeit in different ways."