Metabolic

Exercising within the chilly might burn extra fats, new analysis reveals

Bad weather can be a good excuse to postpone your daily jog, but new research suggests that exercising at lower temperatures can burn more fat than normal – at least when it comes to shorter bursts of high-intensity exercise.

In a study of 11 “moderately healthy, overweight” adult volunteers, lipid oxidation – the technical term for burning fat – increased more than three times while exercising in a colder environment of 32 degrees Fahrenheit (zero degrees Celsius), compared to a “thermoneutral” one “Environment around 70 degrees Fahrenheit (21 degrees Celsius).

Participants were guided through a series of standard high-intensity interval training (HIIE) workouts, also known as high-intensity interval training (HIIT), at each temperature: ten 1-minute bike sprints at 90 percent effort, followed by 90- second recovery biking at 30 Percent effort, with a cool down at the end of both sessions.

“This is the first known study that examines the effects of cold ambient temperatures on the acute metabolism during intensive interval training and on the postprandial metabolism on the next day,” the researchers from Laurentian University in Canada write in their paper.

“We have observed that high-intensity interval training in a cold environment changes the acute metabolism compared to a thermo-neutral environment. However, the addition of a cold stimulus was less beneficial for postprandial metabolic responses the following day.”

When our body becomes active, it can process nutrients and regular lipid or fat levels in the blood better. To check the effect on the study volunteers, the researchers measured skin temperature, core body temperature, heart rate, and the amount of oxygen delivered to the quadriceps muscles.

The next morning – after a high-fat breakfast – blood samples were taken to check insulin, glucose, and triglyceride levels, re-measure lipid oxidation rates, and see if the benefits from the previous night had carried over.

While exercise in the cold increased lipid oxidation by 358 percent immediately afterwards, there was no significant difference after breakfast the next morning (the “postprandial” period). In fact, the glycemic response (the change in the body’s blood sugar level after eating) was better after exercising in the thermoneutral environment as far as the readings after breakfast were concerned.

“”[W]While acute benefits appear to be present during acute HIIE in the cold, postprandial metabolic responses are less favorable when high-intensity interval training is done with acute cold exposure, “the researchers conclude.

With so few volunteers and only a few HIIE sessions, it is too early to draw any full conclusions from the study. However, this is an interesting place to start looking at how ambient temperature can affect fat burning during intense exercise bursts.

Previous studies have shown that HIIE is very effective at burning fat – which is part of its appeal – and there is also an established relationship between the body’s metabolism after exercise and the heat or cold of the environment. This new study combines these two areas of research to look for further correlations.

We know that exercise is critical to staying healthy and reducing your risk of diabetes, liver disease, cardiovascular disease, and other health problems. The more we know what constitutes efficient, useful training and what is not, the better.

The research was published in the Journal of Applied Physiology.

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