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Throw out your fitness tracker suggests Kiwi research

Fuseworks Media
Fuseworks Media

Counting the calories burned in a workout could soon go the way of leg-warmers and leotards, according to ground-breaking new research.

The New Zealand study - published this month in the Journal of Science and Medicine in Sport - showed that certain types of exercise can trigger far greater fat-burning and other healthy responses in the body than simple calorie counting suggests.

The results fundamentally challenge the way we think about calories. They demonstrate that different workouts have different effects on the hormonal and physiological changes that take place in people’s bodies, even if they burn the same number of calories.

Conducted by researcher Nigel Harris of Auckland University of Technology, the study aimed to identify the underlying causes of clear differences in body fat reductions resulting from resistance training - in the form of BODYPUMP, a low-weight, high-repetition resistance training class created by Les Mills International - compared to more intense cardiovascular workouts, that an earlier study had shown.

By comparing the levels of Human Growth Hormone (HGH) present in subjects after they had completed resistance training and cardio cycling workouts, it was shown that HGH was 56 percent higher after resistance training.

Bryce Hastings, Head of Research for Les Mills International, says "Human Growth Hormone oxidizes fat and builds lean muscle tissue. That’s important for ongoing calorie expenditure because muscle burns more calories than fat. The more muscle you can build, the more calories your body will burn long-term. Combine that with increased fat loss and the result leads to rapid changes in body composition."

Similarly, blood lactate levels were up to 81 percent higher after resistance training sessions compared to cycling sessions. Lactate levels build when the muscles work hard, and it is the accumulation of lactate from exercise that sparks the previously mentioned growth hormone response.

In fact, it is widely accepted that exercising at an intensity above the lactate threshold, for a minimum of 10 minutes within a workout, is the greatest stimulus there is to the secretion of HGH.

In short, the beneficial effects of certain exercise types - such as resistance and high-intensity training - can last long into the recovery period after the actual workout is over.

The results also have implications for the exercisers relying on wearable devices to measure their calorie output during workouts or training sessions, according to Dr Harris.

"Calories matter," Harris says, "but so does the effect of an exercise session on hormonal and physiological responses, which are known to have positive, long-term effects on body composition. A wearable device which only measures heart rate and calorie count may therefore be too limited a tool to get adequate understanding of the other, arguably more important, adaptations taking place in our bodies when we exercise."

Overall, says Hastings, the study points to how much more people need to know about the effects of certain exercise types. "It’s complex, he says, "and just counting calories misses a big part of the jigsaw. We now know that."

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