BBC Radio 4 – Just One Thing – with Michael Mosley – Michael Mosley: Why HIIT is an efficient way to get FIT

HIIT for long life

In a five-year Norwegian study looking at 1500 adults, participants were placed into three groups: HIIT, moderate exercise and following the government’s activity guidelines. Those in the HIIT group had the biggest reduction in death from all causes.

Our peak oxygen uptake is much higher following a HIIT session and this increased oxygen uptake could have serious, long-term positive impact.

Short bursts are the way to go!

In the Just One Thing podcast, Michael Mosley talks to Prof Martin Gibala from McMaster University in Ontario. For his 2006 study, participants were placed into two groups: sprint interval training and moderate intensity exercise. The sprint group spent around 25 minutes per session training, while the moderate intensity group trained for two hours or so per day. Now you might expect the group training for longer to be fitter. But in fact he found that the two groups had similar performance – even down to the cellular level. “The increase in markers of their mitochondrial capacity, at least early on, was very similar,” explains Prof Gibala.

HIIT for mighty mitochondria

Mitochondria are the powerhouses of your cell, producing ATP or the energy you need to live your life! As we age, mitochondria slowly begin to power down. Exercise, however, can get rid of old mitochondria and stimulate new mitochondrial growth. But HIIT is particularly good at this process!

Why is HIIT so effective?

You might find it strange that HIIT can be as effective as other exercises in so much less time. How does the process even work?

“I think it comes down to intensity,” explains Prof Gibala. “And so we can think of these molecular fuel gauges in muscle that regulate the amount of energy that we have. And when we do traditional, moderate intensity exercise, you can imagine it’s a bit like pushing halfway down on a gas pedal. And so the fuel in your car starts to slowly go down.”

“Well, when we do high intensity exercise, it’s a bit like really stomping on the pedal and dropping those fuel gauges very, quickly, then that leads to the process of cellular remodelling. And that remodelling enhances our physiological capacity. Even if it doesn’t take very long, we can see these similar responses in much less time.”