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Rational couch potatoes unite! Or, are you a non responder? Would you want to know?

A few years ago a friend of mine took part in a research study to measure responsiveness to physical training.

Some people, she told me, are rational couch potatoes. Working out doesn’t improve their fitness. They can follow a regular program of exercise without improvements in cardiovascular capacity. At the end of the program they’re just as slow and unfit as when they began.

I think she was hoping to turn out to be a non responder so her friends (okay, me) would quit nagging her to go to the gym.

I was skeptical but it turns out she was right. Not that she was a non responder. She turned out to be a mere low responder but rather she was right that such people exist.

The human population, it turns out, can be divided into the following groups:

  • non-responders (whose fitness levels don’t improve with exercise , making up about 20% of the population)
  • responders (who respond as expected to exercise, comprising about 65% of the population)
  • super-responders (who respond extremely well to exercise, and make up the remaining 15% of the population)

Those figures are from a terrific BBC program on fitness, in which host Michael Mosley found out he’s a non responder.

I think I’d be very sad if I was a non responder. Fitness is such a source of joy in my life. But of course there are other joys and maybe you wouldn’t miss it if you’d never had it. That’s what my low responding friend claimed.

I hadn’t noticed non responders before but while taking various running clinics I did notice that people varied quite a bit. Some people could skip half the work outs and progress just fine while other people doggedly did all the work but made very slow gains. I’ve blogged about that here as one of the things you learn from working out with others.

I also see it every spring on the bike as many of us go from not riding at all to getting fast again. How many weeks, rides, kilometers does that take? No surprise. It varies.

There’s also the vexed question of how much fitness you retain through periods of inactivity. Again, there’s lots of variability.

So I think the one size fits all, x weeks to x km programs can mislead us into thinking that we are all alike. We’re not. Athletes work hard it’s true but most come blessed with bodies that respond very well to training.

But given that most of us are training for fun and for health, how much should it matter if we get faster slowly or not at all? I’ve argued for fitness goals in terms of performance rather than physique but what if the performance goals are beyond your reach too? (You can read some about fitness goals here and here and here.)

It turns out that ‘non responder’ is a bit of a misnomer. The non responders don’t get faster or fitter but they do benefit in other ways.

“In a study carried out at Louisiana State University, researchers found that 10 to 15% of the volunteers they tested experienced no increase in aerobic capacity after a 20-week exercise program that involved gradual increases in exercise intensity over time. On the other hand, the lead researcher in this study emphasized that despite the lack of obvious improvement in aerobic fitness, all of the individuals experienced some physical improvements as a result of working out.” (Exercise Non-Responders: Not Everyone Responds to Exercise the Same Way)

What kind of benefits? Well, they burn calories, for one. On its own that’s not that important but they also experience the metabolic effects of exercise that help protect against diabetes.

Here’s another complication. Some people respond to cardio training but not strength training, and others vice versa. And of course, some people do well at both and others neither.

A Finnish study of 175 adults found that some didn’t improve their strength or fitness level at all after a 5-month exercise program.

“Finnish researchers asked these previously sedentary adults to work out regularly for 21 weeks. Some walk or jogged while others trained with weights. Some did both. At the end of the 21 weeks, they tested their aerobic fitness and strength. What they found was surprising. Some of the volunteers improved their aerobic fitness or strength by as much as 42 percent, while others actually experienced a decline in their strength and aerobic capacity after 21 weeks of exercise. Some showed strength gains, but not an increase in aerobic capacity, while others boosted their aerobic capacity but showed no gains in strength. An unfortunate few had no improvement in either area.” (Exercise Non-Responders: Not Everyone Responds to Exercise the Same Way)

You can now test your responsiveness to physical training with a simple mail in genetic test. Gretchen Reynolds writes about that here.

What’s fascinating are the elite athletes. They’re not all super responders as you might expect. Some are mediocre genetically but work very very hard. So effort can trump bad genetic luck.

I know I’m not a non responder to either cardio or strength training. My body seems to like exercise.

But if I didn’t know, I’m not sure if I’d want to find out.

How about you?