12 days of fitness, Day 12

For the final day in this series, I want to share an insight I’ve learned that has had the most value to me in my over 15 years of training myself, training clients, consulting with people, and studying and seeking out the best information I can find.

This valuable insight is: Doing more exercise can improve your results. But most people are sabotaging their results by trying to do more exercise the wrong way.

A story about London double-decker buses will help clarify what I’m talking about…

Double-decker buses and exercise

In the 1950s, a study that observed London transportation workers revealed that conductors on double-decker buses had half the heart disease mortality as the drivers of those buses. This study has sometimes been cited as the beginning of modern medical exercise science.

The standard explaination of this is that the conductors, who walked up and down stairs all day collecting fares, were far more active than the drivers; and their increased activity caused their health benefits.

Seems plausible, right? But what does more activity really mean?

The assumption was that “more activity” meant more volume of activity. After all, those double-decker bus conductors were more active for *hours* every day. So, the thinking goes, if you’re not seeing the desired results then you need to spend more time being active!

At least, that’s the conventional wisdom.

But, doing more activity could also mean something that is at odds with spending more time exercising.

If that doesn’t make sense at first, stay with me…this gets interesting.

First, think about the “sedentary” drivers in that study: they were active. They were turning the steering wheel, pressing the accelerator and brake pedals, talking to people, etc. In fact, they were more active than someone reading a book or watching TV. In this way, the drivers on these routes were actually doing increased activity for the exact same duration as the conductors. The bus conductors were doing the same total duration of activity, but their activity was more intense.

This suggests that we must look for answers to two separate issues:

    1. How much should you increase your intensity beyond “average” or “sedentary”?

    2. For how long do you need to maintain that intensity to achieve the exercise benefits you desire?

Note: an aspect of #2 above is: how often should you repeat this activity?

As we look for answers, this point is critical:

You can only increase or decrease the level of activity your body is doing. You cannot completely “do” or “not do” when it comes to your activity level. There are only degrees of doing.

Take, for example, this moment…

Right now you’re blinking your eyes and scrolling this email. If you’re standing, you’re experiencing a slightly higher intensity of activity than if you’re sitting. As long as you’re alive, you’re body is producing some degree of metabolic activity. For 24 hours a day you are already doing activity; you cannot increase your activity volume beyond 24 hours a day…so no more duration of activity is possible. And no less duration of activity is possible as long as you are alive.

What you can increase is the intensity of your body’s activity for some time during that 24 hours. We can think of intensity as roughly the amount of metabolic activity happening per second.

Every moment we exist somewhere on a continuum of activity level–of intensity. And again, two important questions to ask about exercise are:

    1. How much should you increase your intensity beyond “average” or “sedentary”?

    2. For how long do you need to maintain that intensity to achieve the exercise benefits you desire? (And how often should you repeat it?)

These questions are especially important because…

Your degree of increased intensity is at odds with how long you can sustain it.

Here’s a personal example: when I ran track I would run distance practices where I’d run continually for thirty minutes or longer. But when I ran my event, the 800 meter race, at the end of the race I was DONE. I would lie on the ground for several minutes afterwords and still feel utterly depleted for quite some time later. This was only around two minutes of activity, but because I was raising my intensity so high, there’s no way I could have continued for even three minutes…let alone thirty.

The higher your intensity level, the less duration you can sustain.

Most people assume that any above-sedentary-level activity is good–whether walking or swimming or cycling, or whatever; and they further assume that more of such activity must be better. But striving for more duration necessarily limits the intensity possible to us. If I wanted to be able to run for twenty minutes (or three minutes!) I would have to lower my intensity below the level of my 800 meter race effort. If I wanted to be able to exercise in the gym for longer than 20 minutes, I’d have to lower my intensity below what it normally is when I exercise–because my intensity does not permit me to exceed 20 minutes. In any challenging workout, we have to make a choice between duration of the workout and intensity of the workout.

You’ll often hear that you should increase your activity level for x hours per day or week. But would we be better served by thinking in terms of the intensity level, rather than the hours we spend? For example, “Increase your activity level to a high intensity that does not permit you to continue past 3 minutes”?

And as it turns out, there is some interesting evidence about the relationship of intensity and the duration an increased intensity is sustained.

Now that the questions are clear, lets look at the evidence about them.

First I’m going to repeat the two questions one more time because they’re so important:

    1. How much increased intensity is desirable—above the sedentary level of activity we’ll already be doing?

    2. For how much duration do we need to sustain this increased intensity to achieve the exercise benefits we desire?

A somewhat recent Harvard study on the relationship between exercise and heart disease looked at 12 years of data from 44,000 people who had engaged in a variety of activities and exercise routines. This study observed that there was no difference in heart disease risk when looking at how much or little time people spent per week exercising; but it did find that increased intensity of activity associated lowered heart disease risk independently of duration or frequency of activity. For example, people in the study who trained with weights for just 30 minutes per week had a lower risk than people who walked for 30 minutes every day. That’s presumably because the intensity of weight training was higher than in walking. Across all the various activities that were seen, the people who trained more intensely lowered their risk to a greater extent. And their volume and frequency of increased activity didn’t matter. The observed trend was that higher intensity mattered, and frequency and volume did not…all the way down to the lowest volumes of exercise measured.

The problem with these studies…

Both this Harvard study and the double-decker bus study are just observational studies. And there are many similar studies that show the same trends. This type of study is good for finding hypotheses to test more rigorously. But observational studies, even lots of them, just aren’t reliable for showing causation.

We need controlled studies to see whether these hypotheses hold up when they are isolated. Fortunately, such research exists…

Higher quality evidence…

At McMaster University, trials have recently been conducted to compare randomized groups of people assigned to do either traditional intense “cardio” training routine of 4 to 6 hours per week, or assigned to do only intense 30-second interval “sprints” for a total of 6 to 9 minutes per week. The outcome was that both exercise and muscle biopsy tests showed that the people doing the intense 6-9 minutes per week got equal “cardio” benefits to those who did “cardio training” for 4-6 hours. That’s a dramatic reduction in exercise time, with no loss of benefits.

These results shocked a lot of people in the exercise world. The researchers at McMaster were forced to do this study a couple of different ways because people didn’t believe there could be such impressive benefits from so little time invested. The results were consistently impressive, and all the more solid due to the additional study.

What this is all boiling down to: intensity matters—big time.

In fact, there’s much more upside potential to intense workouts than what we’ve seen so far…

First, the intensity involved in most of these studies is no where close to a typical high intensity training sessions. The actual cardiovascular benefits of precise, slow, and therefore more intense, exercise (like I do personally) may greater yet.

Second, the studies I’ve mentioned so far look only at cardiovascular benefits. But I haven’t even mentioned studies of other exercise benefits like strength and bone density improvements–which is where more intense training shines even brighter.

Now, you will still be confused by news reports on exercise–until you stop and think for a couple of seconds…

I have no doubt that in your daily life you will soon read or hear about studies that show benefits with high volumes of activity. But take notice of this: such reports often don’t mention the increase the intensity of the activity.

The reports usually focus on how many hours per week people exercise, so you have to be a detective and question what was happening with the intensity levels of the groups that are being compared. Based on what I’ve seen, whenever a group of people benefiting from a high volume of activity are compared to a group who does a higher intensity, but for much less time, the higher intensity group comes out at least equal, if not better.

The lesson here is the payoff to increasing exercise intensity is huge. One workout per week done very well may indeed be far more valuable than four or five workouts done moderately well. In fact, as intensity rises, working out less often becomes necessary–your body needs extra recovery time (that’s when you’re actually getting the benefits). Working out too frequently can lead to overtraining syndrome.

What about fat loss?

Okay, so you probably see a strong case here for using increased exercise intensity for cardiovascular health, strength, bone density, etc. But you might be wondering: don’t we need hours of activity to burn calories in order to lose fat and get lean?

There’s a lot of research about exercise and weight loss, and the evidence is solid that increased activity simply does not cause fat loss. There is interesting evidence that the calories burned through physical activity are nearly always compensated for by a combination of a lowered metabolism and increased hunger following exercise.

You might make weight loss progress in spite of increased durations of exercise, but not because of it.

Weight loss is almost completely about your diet. And, once again, intense exercise may confer some benefits to your weight loss goals, as well as providing muscle strength and definition that you probably want to have go along with your weight loss. But the strong scientific evidence is that large volumes of activity won’t help weight loss at all, as counterintuitive as that might sound. If you want more clarity about the fastest method to fat loss, you can look up things I’ve written previously, or we should talk to discuss how to make this work for you.

It’s been a fun 12 days of fitness, and I’ll talk to you soon.

To health and life,

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