We’re told to exercise to keep healthy, but we’re also told that osteoarthritis is a wear-and-tear condition that creeps up on us as we use and stress our joints.
That’s why a new study in Arthritis & Rheumatology asks this important question: Is it safe to exercise if we want to avoid this type of arthritis?
For some time, researchers have tried to answer this question, but with conflicting results—possibly because they all used slightly different definitions of osteoarthritis and physical activity.
This prompted a research team led by the University of Southampton to combine six previous studies using definitions that were clear, measurable, and similar.
Their data came from six large global studies of people who had no knee arthritis when these studies began, neither rheumatoid arthritis nor osteoarthritis.
The 5,065 participants reported their own physical activity, such as participation in sports, walking, or cycling. They also reported the frequency, duration, and intensity of these activities.
The researchers converted this information into a metabolic equivalent, or MET score, for each participant. This is a standard way for researchers to compare different types of activities with each other.
For example, running has a higher MET than swimming, and doing an activity quickly carries a higher MET than doing it slowly. The MET refers to how much an activity increases your metabolic rate.
Thus, each participant had a MET score and a days-per-week score.
The researchers in the respective studies followed their participants for 5–12 years to see whether they developed knee arthritis, as confirmed by a radiographic scan or simply knee pain.
They found no differences between participants as far as osteoarthritis or knee pain, suggesting that neither the duration of exercise nor the energy expended during exercise affected the participants’ risk of developing knee osteoarthritis or painful knees.