Those Olympic sprinters may be fast over 100 or 200 metres, but the reason they’re so muscular comes down to the mechanics of running: the intense burst of 100 per cent effort for 10 seconds is a full body workout, and many time-pressed office workers are taking up sprinting to build muscle and lose weight.

“Each stride is equivalent to one sit-up,” says Sydney-based trainer Roger Fabri. “An Olympic sprinter makes 67 strides in a 100-metre race – which is like 67 sit-ups in 10 seconds.”

But don’t expect to get away with one sprint when you work out with Fabri at his Speed Agility Academy.

“My basic workout is five 100-metre sprints, with three minutes’ rest between,” says Fabri, who has worked with clients including NRL player Jarryd Hayne, New Zealand rugby player Sonny Bill Williams and cricketer David Warner. “You’ll be feeling it half way through your third sprint, I guarantee you.”

The sprinting action itself, and the physical intensity we have to apply to run at top speed, engages not only the legs, but also the back, arms, torso, head and neck.

Fabri calls this “speed endurance training”, and the benefits include fast fat loss, a rapidly changed physique, extra strength, better balance and muscular definition. And all from a regime that can be done in 20 minutes or less.

“My clients know the improvements they can get, but they’re also aware of the discomfort,” says Fabri.

Discomfort? It’s more like pain, nausea and dizziness; the lungs scream for oxygen, the legs go to jelly, the mind says “give up”.

Fabri warns his clients about the mental barrier to the rewards, but he doesn’t back off because of it.

“My workouts are about physical change, and change hurts,” says Fabri. “Our bodies wants to find a comfort zone or a rhythm, so we get enough oxygen to feed the energy required by the activity. When you do a five-kilometre jog every evening, your body adapts. My workouts are not like that. They’re outside the comfort zone.”

They are sufficiently outside the comfort zone to be anaerobic (lactic) exercise in which the body starts to convert energy stored as fat.

Fabri’s regime starts with in-place mimes of the mechanics of sprinting: the client learns the five components of the stride pattern, which Fabri calls “neural programming”, or imprinting the correct actions onto the brain and muscles. When released in a sprinting motion the body performs optimally and with the least chance of injury.

Fabri, working with a team of coaches, writes a tailored program for every client. The sprints are usually conducted at 60 per cent effort for the first 30 metres, 80 per cent effort for the next 30m and then the final 40m at 100 per cent.

When time-poor professionals train with him, he says, they see dramatic changes in their body shape, improvements in their strength and a boost to their energy levels. They also want to quit, usually halfway through their first workout.

“I can make you physically strong, but you have to be mentally strong,” says Fabri.

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