Exercise-haters will love this one. It’s not quite there yet, but new research again reinforces the value of interval training.

Short intense training sessions have long been a tenet of Quantitative Medicine. Short in the Quantitative Medicine context means something like 45 minutes twice a week, but this includes several sorts of exercise, each serving its own health purpose. A list of an entire series of posts on this topic can be found here.

“Foul,” cries the astute reader. You lured me in with promises of a one-minute workout, suddenly it’s ¾ of an hour.

OK, OK, but here’s where the headline came from: Researchers at Macmaster University have determined that three twenty-second all-out sprints interspersed with two minutes of recover work wonders. Oh, there was also a twenty minute warm up and 2 minutes of recovery. Not really a one-minute workout, we admit, though the hard part only lasted that long. Full disclosure can be found here.

But what were the wonders worked? The researchers compared this regime to another group that spun on a stationary bike for 50 minutes. Neither group were regular exercisers.

What the researchers found was that the two regimes were equivalent in terms of several measured parameters.

The Researchers Didn’t Get It Right

The fact is that the interval exercise program has far more long-term benefits than the aerobic cycling. The group that did aerobic exercise had probably gotten all the benefit they were going to get. Their body had responded and, indeed, they had become more fit. Their body had adjusted to a 50-minute aerobic regime. However, that is not enough to ward off heart disease, whereas the short, maximum intensity regime is. But why?

Interval Exercise Places Peak Demands

In Aerobic exercise, the ever-stingy body does just enough to accommodate the moderate demand. The may even backfire. If the ancient part of the brain that controls all this concludes that such exercise is “migration,” if will conserve, refrain from building muscle, and become more efficient at storing fat.

In interval exercise, the short burst is at maximum intensity. There are several bodily mechanisms working concurrently

1. Now obviously anyone that proceeds down this path will become more and more fit, so “peak” effort will involve more and more energy recruitment., which will continue to push the body into higher and higher states of health. Aerobic, exercise on the other hand, settles in at the plateau necessary to sustain the exercise. The improvement ends there. You will become fit up to a point, but no more.
2. Heart rate variability and pushing the heart to safe extremes has huge benefits in that the artery walls get cleansed and renewed. More on that here. (See a doc first, but make him or her justify any advice that seems anemic. See below for more medical caveats.)
3. Exercise variability places demands on the energy-generating mitochondria. The more you have, and more efficient they become, the healthier and longer you will live. The demands of interval exercise cause these desirable effects to occur.

A note on pushing your heat rate to its maximum:

In interval exercise, the heart is run up to its maximum rate for short bursts. For which groups of people might this be dangerous? Short answer: If you have no significant cardiac risk, it is completely safe. For most with cardiac risk it is safe. Further, such exercise vastly reduces overall cardiac risk for everybody. But with no trouble at all, you can find recommendations to limit your heart rate. For a 70-year-old, the usual limit is 127 beats per minute. This is very low, and the results from exercising with this restriction will correspond.

There are three categories of people that should avoid maximal exercise:

If you have valvular disease, some defect in the valves of your heart, more than usual care should be observed. In such a case, be guided by your last echocardiogram and your cardiologist’s advice. He may be too restrictive, but no general advice can be offered here.

If you have mechanically unstable coronary artery disease, sometimes the shear forces that are otherwise good for the heart might “shake loose” some of the detritus and trigger a clot and subsequent occlusion or blockage, leading to a heart attack. This sounds so vague as to warrant the usual generic and tepid advice to severely limit your heart rate during exercise. Please do not hear this point in that way; superstition is not necessary. If you have any family or personal history of heart attacks, you should nail down this risk by coronary calcium scoring and other additional measures to assess any such risk. If you and your cardiologist think this is a real risk, still don’t keep your heart rate as low as the table demands, but do proceed with more than usual caution.

If you have a known serious heart conduction defect that has been clearly shown to be triggered by higher heart rates, and is potentially life threatening, then certainly observe the heart rate limits your cardiologist suggests. This electrical problem should be respected, though even here we are more likely to recommend this be repaired than drugged.