When it comes to finding relief from knee aches and discomfort, it can be a case of no pain, no gain.
Many people begin having problems with their knees as they age.
Kneeling down, going up and down stairs, getting up quickly from a chair--these can all be enough to send a jolt of discomfort through the knee.
Some people avoid going out just to prevent using their knees.
But according to Yasufumi Hayashi, an orthopedic specialist and director general of the Tokyo Metropolitan Rehabilitation Hospital, not using your knees can make them even more troublesome.
Hayashi recommends knee pain sufferers get proper exercise to stretch the muscles and joints around their knees to help them function smoothly.
People often begin feeling knee pain in their late 40s, and the number of people suffering from the ailment increases with age, according to Hayashi.
One estimate suggests about 25 million people in Japan have some trouble with their knees.
"Knees aren't strong enough to support the frames of people with larger physiques or made to endure the longer lives many people live nowadays," Hayashi said. "So to some extent, knee pain is inevitable as you get older."
The surface of each knee bone is covered with cartilage about 4 millimeters thick to prevent it from rubbing against other bones.
If the cartilage wears thin, the knee begins to ache, Hayashi said.
If part of the cartilage is thinner due to the way a person walks, that part loses stability.
As a result, the worn-down part of the knee slips horizontally with each step, causing the muscles around the knee to strain and inflict pain.
"Even if you have chronic knee pain, you need to move the knees every day," Hayashi said.
"If you don't exercise them, the muscles and joints around the knees stiffen. If the condition worsens, it could lead to a loss of mobility and--in the worst case--eventually a reliance on nursing care."
In adult knees, once cartilage wears out, it never recovers.
Keeping knees healthy
To ease the pain, it's important to reduce the strain on the knees and train the muscles that support the bones.
Hayashi has four recommendations for keeping knees healthy:
-- Overweight people should lose weight. Use a walking stick to reduce the strain on the knees.
-- Walk every day to help knee joints function smoothly. Walking in water works well for people who are overweight.
-- Do four to five squats each morning and evening to train the muscles in your lower body. Once you get used to the exercise, do 10 squats each time. If a full squat is too difficult, bending the knees slightly also works.
-- Keep your knees warm.
If the knees swell and the pain becomes severe, stop exercising and see a doctor right away, Hayashi said.
Using your knees properly is also crucial for keeping them in good shape.
Emiko Kuroda, a certified health and exercise instructor, said that when squatting, each knee should bend toward the tip of your toes.
"If you bend your knees in different directions, it will shorten their useful life," said Kuroda, who wrote "Hiza Chan Taiso," a book on how to keep knees healthy, published by Kanki Publishing Inc.
Kuroda recommends first checking whether your knees move properly by doing a simple test.
Stand with your knees about a fist-width apart. Then place your fist between your knees and bend them slightly.
If any space appears between your fist and knees or if your fist feels squeezed, it means your knees are moving in different directions from the tips of your toes.
To learn the correct method of movement, Kuroda suggests light bending and stretching exercises, as shown in Illustration B.
These are warmup exercises. Doing them for a few minutes before going out can reduce knee pain and make walking easier. When doing the exercises, be sure to bend your knees in the same direction as your toes, Kuroda said.
Rubs, massages and stretches also relax the stiff muscles surrounding the knees and makes leg movement easier.
"Keep taking care of your knees while wisely treating the pain," Kuroda said.