Exercise is one of the key recommendations for sufferers of osteoarthritis. Strong muscles protect weakened joints, lessening the pressure on them, and helping slow the progression of this degenerative condition.
Unfortunately, the pain of osteoarthritis leads many sufferers to become less active. Now, Australian scientists have discovered another problem. People with osteoarthritis are unable to activate muscles as efficiently as those who don’t have joint problems.
“When they’re trying to build muscle, they don’t get as strong, as quickly,” says Myles Murphy, a sports and exercise physiotherapist as well as a researcher at Edith Cowan University.
He was interested in finding out why arthritis sufferers weren’t getting the gains in strength and pain reduction that exercise rehab aims to provide. “We wanted to explore whether there was something going on in the brain that could be causing a bit of a roadblock to their recovery.”
Murphy and his team examined 41 people, 17 of whom were suffering from hip osteoarthritis, studying brain function and how it affects muscle power. All the participants were aged 59, since osteoarthritis tends to strike in middle age.
Irrespective of their strength, the hip arthritis group were unable to activate their muscles properly. “The brain is actively putting on the brake to stop them from using the muscle,” explains Murphy. “We suspect this is a short-term protective response gone wrong.”
In the early stages of an injury, this may be useful, preventing us from doing too much and causing more damage. In a chronic condition, like osteoarthritis, it can end up being a barrier to recovery.
The participants in the Edith Cowan study were all asked to do an exercise that measured their leg strength whilst working at their maximum capacity.
“We asked them to push at 100%. We were yelling at them to go really hard,” says Murphy. “Even though they thought they were contracting at 100% the hip arthritis patients were really only activating about 90% of their muscle fibres, whereas the group that didn’t have a problem were activating about 95% of their muscle fibres. And it wasn’t for lack of trying. They were doing everything they could.”
What the researchers did next was provide a boost, by sending an electrical signal through the nerve in the hip that activates the leg muscles, and so over-riding the brain. This revealed the difference between what a person’s body was willing to do and what it was actually capable of. “Not the nicest of tests but it gives us some good data,” says Murphy.
There is no cure for osteoarthritis but exercise rehabilitation, supervised by a physiotherapist or exercise physiologist, can help reduce pain and improve physical capability. There are also some useful online tools – Arthritis New Zealand has a YouTube channel that includes exercises to help manage arthritis. A blend of cardio, strength, stretch and balance exercises is ideal.
People with osteoarthritis will need to work extra hard to strengthen muscles and keep them strong. There are a couple of tricks that may interfere with the brain’s overprotective response, however.
“One is to do your exercises to the beat of a metronome,” says Murphy. “Play it over your headphones if you’re at the gym and do your exercises slowly to the beat, focusing on it. That enables the brain to be over-ridden a little bit.”
The other technique he suggests is blood flow restriction training. BFR involves wearing a pressurised band – much like a blood pressure cuff – while training. This traps lactic acid in the muscle tissue which tricks the brain into thinking you are working harder than you are, as a result building muscle and improving strength without aggravating painful joints. There is some science to show it can help those with knee osteoarthritis.
Meanwhile Murphy is working on a more novel approach. “We’re looking at how we can improve outcomes for people with hip osteoarthritis by running a small electrical current through the brain. So, they’re doing the standard physio rehab exercises but wearing a fancy headset that gives them a bit of external help to take off the brake and override the problem that we’re seeing.”
