The physical activity paradox

What works at home may hurt at work. Being physically active has major health benefits when it’s on your own terms: “leisure-time physical activity,” or LTPA, is pure goodness.

But the same overall level of activity that’s so beneficial in a personal context can actually backfire when you do it on the job: “occupational physical activity” (OPA) is not a clear health and fitness win for people.

I don’t think many readers will be surprised by this contradiction — okay, probably none at all — but it’s quite interesting to consider how it works. Several ideas have been studied, like these five (at least):

• Low to nil autonomy. It’s harder to make sensible adjustments when it’s not your activity. For instance, how many postal workers have walked much more than they should have or would have for their own fun and fitness goals? Probably all of them.
• Heavy lifting and static and/or awkward postures are routine in many working contexts, often far exceeding anything you’d put up with for fun.
• Inadequate recovery is a big one. Even if OPA was just as healthy at LPTA in every other way, not being able to take a day off when it really counts would probably poison it. (Or even just a well-timed hour of rest.)
• Too little activity for too long. The dose of exercise per hour might small … but it adds up.
• Workers tend to have higher heart rates and … increased inflammation?! Both could have many explanations, but regardless they likely undermine the usual benefits of being active. For instance, exercising while inflamed might actually increase injury risk.

That’s a quick summary of a new BMJ editorial about recent research — just an introduction to the intriguing physical activity paradox.