Everywhere you look, doctors and other health care professionals are touting the benefits of “moderate exercise.”  I’ve seen it recommended for fibromyalgia, depression, migraines and even GI problems. But how often do they define what “moderate exercise” means? A few years back, “perceived exertion” was the way to go; if you couldn’t talk while working out, that was a harder workout than you should do. The Center for Disease Control puts it like this:

Moderate-intensity aerobic activity means you’re working hard enough to raise your heart rate and break a sweat. One way to tell is that you’ll be able to talk, but not sing the words to your favorite song.

On the other hand, CrossFit often talks about pushing the envelope to make yourself more fit. So what is the “right” thing to do?

You can find reasons to be afraid of pushing yourself or “intense exercise” in various articles, like this article from the Los Angeles Times, “Mixing Illness and Exercise“:

[T]here is also evidence that too much exercise, or extremely intense exercise, can reduce immunity. This is important for people who push themselves intensely when they work out and for those who train and compete in long events, such as marathons.

[The italics are mine.] So what is the right amount of exercise?  Like so many answers in life, it depends. Are you healthy for your age? Are you overweight? Are you recovering from a major illness or surgery?

WebMD takes a stab at defining “moderate exercise” by referring to a study published in the American Journal of Preventive Medicine:

To see how many steps per minute were needed to achieve moderate-intensity exercise, investigators monitored oxygen uptake in 58 women and 39 men while they completed four different 6-minute sessions on the treadmill at speeds ranging from 2.4 to 4.1 miles per hour. All of the participants also wore pedometers during the exercise sessions.

The results showed that for men the number of steps per minute to reach moderate-intensity exercise was between 92 and 102. For women, the range was between 91 and 115 steps per minute.

Interesting. But this study contains within it the same problem all studies have: It may be valid for a group whose members meet the same demographics as the group studied, but it may or may not be applicable to any particular individual. I can bet you that my hoss hubby walks this fast in his everyday walk, and to follow this recommendation would actually put his fitness level back a few steps.

For me, when I started this fitness journey, I probably would have been winded by this prescription because I was so very deconditioned. I understand the goal of the medical community: They want some sort of quantifiable amount that they can give patients without worrying about putting them in the hospital. It would be nice if there was a one-size-fits-all, but I don’t think that’s possible.

So let’s go back to the Los Angeles Times article, which goes on to make a very important point (and illustrates why you shouldn’t stop reading after the first couple of paragraphs):

This doesn’t mean you’ll get sick more often if you train hard. It does suggest that, to reduce the risk of illness, intense or longer workout days be followed with rest or with less-intense training days to give your body a break.

Hello.  The article is focusing on the effect of exercise on the immune system, but you could substitute “injury” for “illness” in the above quote and still be correct. In order to avoid illness or injury after working out to what you perceive as hard, you need to take adequate rest days for your body to repair itself. Wait? Isn’t that something we’ve already said that CrossFit preaches: Three days on, one day off is the optimal mix of exercise and rest.

The body has amazing plasticity: It can become accustomed to what exercise you’re doing so that doing the same thing may keep you from going downhill, but it certainly won’t make you any fitter. Even the brain, which was at one point believed to be pretty fixed in its abilities after adulthood, is now believed to be able to make amazing adjustments. That’s part of why you find a medicine, say an antihistimine, works for a while and then stops. The body adjusts. So why is “moderate exercise” always recommended?

My guess: It’s a safer recommendation. Doctors take an oath that says “Do no harm.” Some of us manage to get injured even with moderate exercise. However, there is a greater risk of harm if you take on a challenging fitness program and you (or your coach) does not know how to evaluate what your start point is and what your limitations are.

This point was re-emphasized recently by the CrossFit Journal in an article by Dr. Will Wright called “Rhabdomyolysis Revisited“:

New or prospective affiliate members should be introduced to the CrossFit methodology gradually. We need to take extra time to determine the baseline and capacity of these individuals as we introduce them to the CrossFit prescription. This includes inquiring about fitness levels, medical conditions, physical limitations, recent illnesses and family history. An introductory workout should be tailored to the individual. “On-ramp classes” are often employed at many affiliates, and these too should be structured to slowly increase the work capacity of the client as the intensity and breadth of workouts is increased.

This article was a response to a particular serious condition, rhabdo for short, that can occur if people do not start at the correct level, do not hydrate properly and do not get enough recovery time between workouts.

On the other hand, there are studies suggesting that interval training, defined as “short bursts of intensive effort interspersed with more moderate stretches” of activity is actually more effective than moderate exercise at both burning fat and increasing fitness. Shorter, high intensity interval training also helps overcome the main objection to exercise in the frantic, fast-paced world we live in: It takes less time to accomplish the same goals as “moderate exercise” prescriptions.  Yet another study indicates that the kind of training in CrossFit is better heart prevention than the longstanding “go walk” advice.

And it’s way less boring.

So, if done with a coach who is sensitive to your particular needs, the kind of varied, intense bursts of training that CrossFit integrates may be even better than that hour-long walk. And, for my money, you see results more quickly, which helps you stay on the wagon. I was thrilled when my daughter told me a couple of days ago that she actually saw the beginnings of a muscle in my arm. Who knew it was possible? So hang in there, folks, it’s worth the time and effort.

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Comments
  1. Laura says:

    Ahhh, I think you summed that up nicely! I appreciate your posts, they tend to give a more comprehensive idea to my jumbled thoughts.

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