Tag: cardio

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My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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A new study that just appeared online in the American Journal of Epidemiology (abstract here, press release here) adds to the evidence that spending most of the day sitting down has bad effects that aren’t cancelled by daily workouts at the gym. The study looked at 123,000 men and women between 1993 and 2006:

Women who reported more than six hours per day of sitting were 37 percent more likely to die during the time period studied than those who sat fewer than 3 hours a day. Men who sat more than 6 hours a day were 18 percent more likely to die than those who sat fewer than 3 hours per day. The association remained virtually unchanged after adjusting for physical activity level.

It’s that last bit that stings. The obvious question is: how much exercise did the subjects do? In their analysis, the category for “most active” was those who got more than 52.5 MET-hours per week of physical activity (including both day-to-day chores and exercise). According to the ACSM’s Compendium of Physical Activities, running burns anywhere from 7 METs (for “jogging”) to 18 METs (at 5:30/mile). Still, it suggests that the most active people in the study were doing the equivalent of almost an hour a day of jogging, which isn’t insignificant. And the lack of change with respect to physical activity (except at the very lowest level) doesn’t give us much reason to hope that just a bit more exercise — say 100 MET-hours per week — would be any different (though clearly this is a question that should be explored by future studies).

A similar study was covered a few weeks ago by Gretchen Reynolds, and another related study made news back in January, so clearly this result isn’t a one-time fluke. (Interestingly, the study reported by Reynolds focused on men, while the new study found a bigger effect in women — so no one’s immune!) As a committed desk jockey, this is somewhat worrying to me. I’m not quite sure what to do about it. Maybe those standing-desk people aren’t so crazy after all…

THANK YOU FOR VISITING SWEATSCIENCE.COM!

My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

***

The latest study from Paul Williams’s National Runners’ Health Study appears in the new issue of the American Journal of Cardiology. I like Amby Burfoot’s pithy summary of the results: “The faster you are, the longer you’ll live.”

On the surface, the study is very simple. Williams looked at the 10K PBs of 29,721 men in his survey-based study, and then followed up 7.7 years later to see who had suffered heart attacks, angina, or died of factors related to heart disease. Not surprisingly, the faster subjects were less likely to suffer any of the negative outcomes:

Each meter/second increment in running performance was associated with a 44% lower risk for CHD death and nonfatal myocardial infarction, a 54% lower risk for nonfatal myocardial infarction, a 53% lower risk for angina pectoris, and 32% lower risk for revascularization procedures (percutaneous transluminal coronary angioplasty or coronary artery bypass grafting).

(An increase of one meter/second represents the difference between, for example, a 44-minute 10K and a 35-minute 10K.)

Pretty obvious, right? But there’s a twist: the results stay roughly the same even when you control for physical activity. In other words, if you’re trying to predict how likely you are to have a heart attack, it doesn’t matter how much you run, just how fast you are. In a sense, this is sort of bad news. We’ve generally assumed that being fit and being active are essentially the same thing. But Williams notes that “up to 70% of the variation in aerobic capacity is inherited in humans,” so some people need to be far more active than others to reach the same level of fitness (or running speed). This ties into an ongoing debate about “fatness versus fitness”: researchers like Stephen Blair argue that being active is more important than being skinny. But the new data goes further and argues that being active isn’t enough — you actually have to be aerobically fit, as measured by something like a 10K race or a VO2max test.

This doesn’t mean we’re captive to our genetic fates; it just means we may need to rethink how we approach exercise, according to Williams:

The present findings are relevant to the formulation of public health guidelines. Current guidelines primarily target the volume of physical activity rather than cardiorespiratory fitness, whereas fitness-targeted guidelines would place greater emphasis on vigorous exercise and interval training.

So this sounds like another argument for “high-intensity interval training,” which is already getting lots of press. But Williams makes a further distinction. These days, most experts are touting the time-saving benefits of interval training — i.e. get all the benefits of a 45-minute run by doing four 30-second spurts on an exercise bike. Instead of using intervals (and other forms of vigorous training) to reach the same fitness level in less time, he argues, we should spend the same amount of time and reach higher fitness levels. Want motivation? Here are the graphs of relative risk,for speeds ranging from slower than 51 minutes for 10K on the left to faster than 35 minutes on the right:

THANK YOU FOR VISITING SWEATSCIENCE.COM!

My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

***

Pool running is very different from running on land. Aside from the crushing boredom, there’s also the fact that your heart rate stays lower for a given effort, and your VO2max is lower. This has been demonstrated in lots of studies, and is typically attributed to:

(1) an increase in central blood volume, as a result of the hydrostatic pressure causing a higher stroke volume and therefore lower heart rate for a similar cardiac output; (2) the thermal effect of water, since water temperatures below thermoneutral (33–35 C) reduce heart rate and increase stroke volume; (3) less muscle activity during deep water running because of the possible reduction of muscle activity of the weight-bearing muscles.

But even though most people agree about that, pool-running studies have produced conflicting results about exactly how much lower VO2max gets, what happens to your ventilatory threshold, how perceived exertion changes, and so on. According to a new study in the Journal of Sports Sciences (from which the above quote is taken), this may be because there’s a steep learning curve associated with pool running.

The study, by researchers in the U.K., South Africa and Brazil, compared 10 runners who had at least two months of pool-running training with a certified instructor with seven runners without pool-running experience. They had both groups perform VO2max tests and run at threshold, both on land and in the water. (The testing in the water was as problematic as you might guess, and the machines apparently broke down three times and data from four subjects had to be discarded.)

Going from land to water, the novices dropped the max heart rate from 186 to 172 and their VO2max from 55.1 to 44.3. In comparison, the experts went from 186 to 177 and from 53.8 to 48.3. In other words, they were able to work harder once they’d mastered pool running — probably, the authors speculate, because they’d learned to recruit more muscles.

Practical applications? Well, if you’re trying pool running for the first time, expect it to feel really hard and yet strangely unsatisfying as a workout. But be reassured that if you stick with it, you’ll be getting a better and better workout for the same effort.