For decades we've been told that low to moderate intensity cardiovascular exercise, such as walking for 30 minutes per day (and 45 minutes or more for weight loss), is our ticket to fitness.
Unfortunately that recommendation is one of the biggest barriers to exercise. We don’t often have the time and we find it boring. I had a client tell me last week she’d rather shoot herself than get on a cardio machine.
Is there a better way to get your heart stronger? How about 14 minutes of cardio three times per week, including warm up and cool down? How about three minutes? How about mixing it into a hike, a weight workout or anything else?
The latest trend in cardiovascular conditioning is High Intensity Interval Training (HIIT), in which you go at a sprint for a few seconds to a minute, then go at a slower pace or stop all together for a rest interval, repeated 6-12 times.
“Usually my HIIT sessions vary from 9–20 minutes and I like to include other types of training with it,” says Jonny May, a personal trainer at Body Kinetics in Novato. “I use it in my classes, it’s a great way to keep it interesting, fun and make it quick."
The benefits are big - the same cardiovascular benefit in a fraction of the time, lose belly fat, and turn your body into a carb burning machine. Can it be a magic bullet?
The research is convincing. One study showed just three minutes ever other day significantly improved blood sugar and insulin levels and is thought to be a weapon against diabetes. That’s because working at a high rate causes the body to get better at using sugar and carbs for fuel, something we rarely do in regular day to day life or even during low to moderate exercise.
Other studies show improvements in both aerobic and anaerobic fitness, increase in growth hormone and muscle tone, and greater fat loss even though training time and calories burned during exercise were substantially less. The fat-burning benefit is seen mostly from a post-exercise rise in resting metabolism. While at rest, the body is using fat as the primary fuel, so increasing resting metabolism is a plus for fat loss.
It’s also proving to be safe and effective for people with coronary artery disease. The low to moderate intensity exercise improves our ability to function at 60-70 percent capacity, whereas HIIT pushes us to function at above 100 percent and thereby increases our cardio power and our functional abilities. Suddenly bounding up the stairs is easy.
There are many different interval workout protocols, from the Tabata Protocol to the Little Method, but virtually any workout that brings you up to your maximum exertion for a brief period (not more than one minute) with just enough rest (not more than double the sprint time) has similar benefits. It’s recommended that you see your doctor before beginning an exercise program. And make sure you have a decent base fitness and good biomechanics before increasing your intensity. When you do increase, do so slowly.
“Don’t get up to 100 percent the first day or even the first couple of weeks,” says May. "But in my opinion there’s nothing better.”