I thought this was fascinating, as we often hear that we need to "exercise" or "increase our physical activity level" in relatively vague terms, perhaps with emphasis on frequency and duration (i.e., 3 times per week for 30-60 minutes, for instance). What we are not told is that certain FORMS of physical activity may be more beneficial or more risky related to certain conditions, depending on our health status or risk factors.
For instance, researchers studied the relationship of 4 different types of physical activity, and the incidence rates of knee osteoarthritis (OA) after a 12-year period. Please note the word "incidence" is a term that means an "association" between the two factors in the study's findings; it is not a definite cause-and-effect relationship.
Four types of physical activity studied:
1) muscle strength (my guess: this includes high strength: weight training, pilates, yoga vs. low: fishing, housework, walking short distance)
2) intensity (can be any activity, depending on effort)
3) mechanical strain (some sports, are high: volleyball, tennis, racquetball vs. lower strain: swimming, possibly cycling)
4) turning actions (high: kickboxing vs. low: swimming, walking)
The researchers surveyed over 1,500 men and women on their physical activity, and then rated each on the four types of activities listed above with scores (such as "high" or "low") in each category. (*see my disclaimer below!)
During 12 years of follow-up, 28 percent of the study participants developed knee OA.
The researchers found TWO of the FOUR types of physical activity were associated with an increased risk of OA: HIGH mechanical strain and LOW muscle strength.
"High mechanical strain activities -- for example, volleyball -- boosted risk, as did engaging in low muscle strength activities were associated with an increased risk of knee OA [after adjusting for other factors]."
"No association was observed in the intensity or turning actions physical activity."
What do you think of this study? It makes sense that low muscle strength would negatively impact one's condition, and supports the need for exercise. It also makes sense that high mechanical strain would increase risk as well. I was surprised that turning actions and intensity had no impact, and that hopefully more doctors will consult with their patients who are at risk for knee OA, and discuss the types of exercise that are most beneficial!
High strain, low strength up knee arthritis risk article published on February 13, 2008. Access original source : Physical Activity and incidental knee OA in older adults, Arthritis & Rheumatism, February 2009
*The "high" and "low" suggestions above are NOT the researcher's scores; they are my presumptions of examples. Please ask your doctor or reference the study below for the ACTUAL physical activity that you participate in for a recommendation by your doctor.
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