Do we become more active when we get fitter?

Four women running by riverWe all know that we need to exercise in order to get more fit and research has shown that high intensity training will get us fit much faster than moderate intensity training. Increasing our fitness should, at least in theory, give us more energy, which would in turn enable us to increase our daily activity levels, even when we are not exercising. We at K. G. Jebsen – Center of Exercise in Medicine at NTNU wanted to test if this was in fact true. Do we become more active when we become fore fit?

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We recruited 30 middle-aged men who did no structured exercise training and we divided them into three different groups. The first group performed 4×4 interval training (10 minute warm up, followed by four 4 minute high intensity intervals with 3 minute recovery periods between the intervals), the second group performed 1×4 interval training (10 minute warm up followed by a single 4 minute high intensity interval) and the third group performed moderate intensity training (we made sure that the energy cost of moderate training was the same as that of 4×4 training). All training was performed 3 times per week on a treadmill in our training lab. Before they started with the training program, we measured the participants’ fitness level and activity level (using an activity monitor).  The study was newly published in the Open Cardiovascular Medicine Journal.

After they completed 6 weeks of training, we repeated the same measurements.

Read also: Exercise in prevention of metabolic syndrome

“What we found was very interesting. While both 4×4 and 1×4 interval training groups increased their fitness substantially after only 6 weeks of training, the moderate intensity training group did not. Their fitness remained the same as it was before the training started. However, the moderate intensity group actually became more active, compared to the two high intensity groups” PhD candidate and first author of the study, Nina Zisko says.

This meant those who performed high intensity interval training compensated for having trained at high intensity, regardless of whether they did 1 or 4 high intensity intervals. In the case of the moderate training group, the opposite was true.  Moderate intensity training group became more active in response to training.

Phd candidate Nina Zisko“Our conclusion is that when introducing high intensity training to improve fitness in people who’ve never done it before, it is important to emphasize the importance of maintaining daily activity levels”, Zisko says.

Read also: Why do some people get fitter than others?

So if you take up high intensity interval training you should not change your other behaviors.  Avoid the “Today I’ve exercised, so I will take the elevator instead of taking the stairs like I do when I don’t exercise” mistake, because every little bit of activity goes a long way.

Nina Zisko, PhD candidate at K. G. Jebsen – Center of Exercise in Medicine

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