Coaches have traditionally started with the softly-softly approach with overweight runners, but research shows that short, hard bursts are more effective for weight loss and building functional strength.
Canadian researchers found that while moderate exercises burn twice the calories of high intensity interval training (HIIT), the latter burns more subcutaneous fat [the stuff close to the skin's surface]. The high intensity stimulates your metabolism and creates an excess post-exercise oxygen consumption that increases calorie burn for 48 hours after the session, apparently. Translation: bye-bye doughnut gut. And the bonus is it takes less time.
"The key is intensity, regardless of impact," explains Jamie Atlas, a coach with 20 years' experience training marathon champs and recreational runners in Colorado (bonzabodies.com). "An easy going approach doesn't teach the body to run, but teaching someone to run in fast 20-second blocks means they'll run with good stride length, not with a slow shuffle."
So is there a risk if you haven't exercised before? The good news is that "if you're unconditioned, you'll lack the muscle to drive your heart rate to a dangerous level over a 20-second sprint," he says.
But too much running, too soon, is bad news. "Getting an overweight person to run a mile equates to around 1,500 strides, and each stride loads around three times their body weight," says James Dunne, sports injury rehabilitation specialist from Kinetic Revolution (kinetic-revolution.com). "In an overweight individual, the return in calories burned through running one mile definitely does not justify the cost in terms of impact loading and overuse of certain muscle groups."
It's a case of short and sweet. If you have any health concerns, though, consult your GP before embarking on an exercise programme.
The Training Schedule
The good news is, it's only 20-30 seconds at a time. The bad? It has to feel hard. The power walk sessions will boost your exercise tolerance without high impact.
Run 1: 6x30sec, 2min rest
Run 2: 6x30sec, 2min rest
Run 3: Power walk 30min
Run 1: 8x30sec, 90sec rest
Run 2: 8x30sec, 90sec rest
Run 3: Power walk 40min
Run 1: 8x20sec, 1min rest
Run 2: 8x20sec, 1min rest
Run 3: Power walk 45min
Run 1: 10x30sec, 2min rest
Run 2: 10x30sec, 2min rest
Run 3: Power walk 50min
Run 1: 10x30sec, 90sec rest
Run 2: 10x30sec, 90sec rest
Run 3: Power walk 55min
Run 1: 10x20sec, 1min rest
Run 2: 10x20sec, 1min rest
Run 3: Power walk 60min
The Key Exercises
Discover the four key exercises that'll make up your twice-weekly circuit.
The Food Plan
Eat right to lose big.
Skip carbs pre-workout: Unless you're very athletic or looking to bulk up - which you're not. "Having a carb drink before a workout teaches your body to depend on carbs rather than body fat, for fuel," says Laurent Bannock, sports nutritionist for London Irish rugby team (guruperformance.com).
Time your nutrients: "One to two hours after exercise is the best time to consume your energy-rich food," says Bannock. "If you consume most of your calories (especially carbs) after exercise the fat loss effect is better. At other times, eat protein and nutrient-rich fruit and veg."
Fuel your liver: "The efficiency of your liver is crucial to weight loss and fat metabolism," says sports nutritionist Lucy-Ann Prideaux (simplynutrition.co.uk). "Foods that support liver function include broccoli, rocket, watercress, mustard, onions and garlic."