Wed, Jan 02, 2019 - Page 13 News List

Exercise: what’s the bare minimum I can do?

Modern high-intensity workouts are seductively short — but do they offer the same life-extending benefits as established exercise regimes?

By David Cox  /  The Guardian


To try to make exercise more palatable, scientists have been investigating ways to get the same physiological benefits in much shorter periods of time. When it comes to cardio, one way to do this appears to be upping the intensity, as is the case with Tabata and other high-intensity interval training (HIIT) programs.

It’s thought that 10 minutes of skipping offers similar benefits to a 45-minute run.

“There’s good evidence that if you increase the intensity, workouts which involve just a few minutes of exercise in total can still be extremely effective,” says Martin Gibala, professor of kinesiology at McMaster University, Ontario, and one of the scientists who has pioneered research in this area.

Scientists think this is because the body registers that it is losing a lot of energy, and so provides more stimulation to key molecular signaling pathways involved in everything from maintaining muscle health to regulating blood-sugar levels. This can happen after 150 minutes of moderate exercise, or far shorter periods of vigorous exercise.

The most extreme end of this is something dubbed the “one-minute workout,” a form of HIIT. In total, it involves three 20-second bursts of all-out exertion, with one to two minutes of recovery in between, a three-minute warm-up, and a two-minute cool-down at the end.

Gibala believes that this can have the same health benefits as a half-hour jog in the park — ideal for busy office workers trying to squeeze in a workout in their lunch break. This is because it’s conducted at the highest possible intensity, up to 90 percent of your maximum heart rate — roughly calculated as 220 minus your age.

However, HIIT has not been without its controversies. Other scientists have found cases of a rare condition called rhabdomyolysis among HIIT newcomers unaccustomed to the intense strain of these workouts. This occurs when intracellular muscle constituents break down in an uncontrollable fashion and leak into the bloodstream, causing pain and potentially leading to kidney damage if ignored.

Wary of this, governing bodies are holding back on officially advocating these regimes to the public until more data is available on who is and isn’t suitable for HIIT training, and whether it can be done safely over the course of years and decades without risking injuries.

The latest Public Health England guidelines have still tried to embrace higher-intensity exercise, but with a more cautionary approach. They suggest a minimum of 75 minutes of exercise per week at a vigorous intensity: not as full-on as HIIT, but a brisk enough jog or cycle for you not to be able to speak in full sentences while exercising — and as the recommended alternative to 150 minutes a week of moderate-intensity exercise.

“This means you could do three 25-minute cardio workouts a week and you’re meeting the minimum health requirements,” Gottschall says. “That’s still much more feasible for people.”


While more intense workouts can cut the amount of weekly time we need to spend on cardio, the same doesn’t apply for other categories of exercise, such as strength training and stretching.

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