Get this. People who complete a six-week sprint interval program can improve their aerobic capacity by almost 10 percent and slash body fat by just as much. An interval program also helps you increase your peak speed by almost 5 percent. Alternating between intense bouts and recovery periods induce physiological changes that drive up not only calorie burn but also your VO2 max – how quickly you can bring in and utilize oxygen – for the next 24 hours. Your cardiovascular system becomes able to transport oxygen more efficiently to your muscles, and your muscles become more efficient at using the oxygen, so now you can run faster, longer – enhancing what you call your “running economy”.
The treadmill can be the perfect tool for mastering intervals. Outside, when you are propelling your own pace, you may start to slow down unknowingly, but the consistent movement of the belt allows you to maintain your speed. And without other runners to worry about, dips in the road, or sudden events to slow you down, you can completely zone in on your workout. Once a week, run all out for 30 to 40 seconds, walk for a minute, run all out for 50 to 60 seconds, walk for a minute, then run all out for 70 to 80 seconds, and walk for two minutes. Do one to three rounds. A good measure of your improvement is not just your peak pace but how quickly you can recover after hitting it.