Slow Down to Speed Up

High-intensity interval training is all the rage but, says Damian Hall, most runners would actually benefit from more low-intensity running

run slow to run quick

Marcus Scotney (pictured) believes all runners can benefit from slowing down

Why should I practise running slow?” legendary distance runner Emil Zátopek is meant to have said. “I already know how to run slow. I want to learn to run fast.” But the Czech Locomotive was one of a kind, a superman, hardly a standard runner like the rest of us.

On this, Zátopek may well have been wrong. “Most of the people I coach come to me to run faster,” says GB international ultrarunner and coach Marcus Scotney. “I tell them to run slower.

“I think a lot people believe that to become a better or faster runner they have to always be running fast and hard – at tempo pace or anaerobically,” says Marcus, who won the inaugural 400K Cape Wrath Ultra in June. “But training constantly at tempo pace tends to lead to injuries.”

That’s because the body isn’t getting the opportunity to rest and develop aerobically. “My clients are usually reluctant to spend more time running slowly, but they always get faster because of it. Almost everyone could benefit from running more slowly.”

The benefits of slow running

Slow running has at least three key benefits. Firstly, it aids the growth of capillaries, which means more oxygen creation. “Slow running promotes greater capillary density, so oxygen can move to the cells of your exercising muscles quicker – making you more efficient physiologically,” says Marcus.

Secondly, it promotes both more and bigger mitochondria to develop in your cells. “Mitochondria are like mini power stations,” says Marcus. “These are where the energy in fat and glycogen gets turned into an energy source your body uses to run. The bigger, more powerful and plentiful these are, the more efficient your physiology can be when you run.”

Thirdly, slow running also aids fat adaptation. “Running at an easy pace teaches your body to burn fat instead of glycogen for fuel,” says Marcus. “Body fat is almost limitless, whereas glycogen from carbohydrates runs out after 90 minutes or so. If your body is fat-adapted, you’re much more comfortable when you run out of glycogen stores – which during a marathon often means hitting the dreaded ‘wall’. But you also become more economical with fuel overall.”

Even the skinniest runners can run comfortably for hours, without extra fuel, once they become fat-adapted. “Slow running builds strong foundations for the runner, whereas fast work undoes a lot of that good work. For example, when you run fast, you’re destroying muscle capillaries. Plus you’re pushing yourself closer to injury.”

It’s not that we should never run fast – we wouldn’t after all be very, er, fast if we neglected speed work all together. But according to the traditional periodisation model for a marathon or ultramarathon training programme, runners should concentrate on building base endurance first. Which means lots of easy runs.

“This also strengthens muscles,” says Marcus. “We recover quicker from easy runs as well, meaning we aren’t tired for several days post-long run. Slow running also has the benefit of massively improving your general cardiovascular fitness.”

At the beginning of their running season, Marcus has his clients do six weeks of low-intensity running – and nothing else. “After about six weeks of slow running, the runner would introduce a mixture of faster running (in heart-rate zones three to five) to improve speed and stamina.”

Have some heart

A heart-rate monitor (HRM) is a great way to ensure easy runs really are easy. Only data from our heart rate can reliably tell us how hard we’re working. If we rely on guesswork, numerous factors influence our estimations: the weather, terrain, tiredness, work or family stresses. Those instances and others conspire to give us false information about how hard we’re really running.

“With a HRM, you can clearly see how hard you are working,” says Marcus. “A HRM will show you that. And show when we were in danger of overtraining.” Each training run would be done in a specific heart-rate zone – there are usually between one and five zones stipulated – sometimes switching between them during a session.

Using a HRM has revolutionised Marcus’ running. “I took 20 minutes off my 100K PB in 2015, running 6:56:13 at the World 100K Championships in Winschoten,” he says, “and I have been able to increase my training load and not get injured.” And then in June he won the 400K Cape Wrath Ultra. Again he trained using the same method. Patiently running in lower heart-rate zones, watching his aerobic fitness slowly grow and grow, until running below his lactic threshold became a fast pace.

This writer has also tried Marcus’ approach. All I did for the first six weeks was run slowly. “How would that improve my running?” I thought. “Anyone can run slowly.” But a lactate test at Accelerate UK in Sheffield had shown I ran too much at a medium pace, which offers little to no improvements.

At first it was difficult keeping my runs as slow as Marcus stipulated. I kept asking him for tougher, faster sessions – hills and intervals – but, just like Yoda, he kept telling me to be patient and trust in the approach. But after just three weeks of training, impatience got the better of me and – against his orders – I raced a local half marathon. And won it.

There were no Kenyans present, only 100 or so runners pounding along winding Cotswold B-roads in the rain. But I’d never won a half marathon before. It was a revelation. Three weeks later I ran a PB by 10 minutes at the London Marathon. Running slower – and controlling that pace with an HRM – had made me faster.


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