How to Exercise in Four Minutes, by Biologist Jamie Timmons

Photograph by Elizabeth Renstrom for Bloomberg Businessweek

Toned muscles and good cardiovascular fitness are achievable even if you have only a few minutes to spare. The secret? High-intensity training, which consists of two or three brief (20-second) bursts of maximal cycling exercise, separated by two minutes of gentle pedaling for recovery. Eight years of laboratory research has proven that HIT enhances aerobic fitness and reduces diabetes risk factors. You don’t burn many calories doing HIT, but keeping your appetite in check and generating a kick to your metabolic hormones will help you lose that unwanted weight.

For HIT to be health-efficient, you need to give it your best effort during each sprint. Start with two minutes of very easy pedaling as a warm-up. Then pedal flat out against high resistance for 20 seconds. Let your muscles recover at a low intensity before repeating. At the end, cool down at a low intensity to help your blood pressure stabilize.

Not everybody responds equally. One person following a HIT program will see significant gains in aerobic fitness; others will not. The way you personally respond is predetermined by your genes. A company my research colleagues and I founded, XRGenomics, can help you find out how you respond to HIT by running a simple mail-in DNA test, done via a cheek swab, known as the XRPredict+. The results can then be used to inform you about the best way to shape your exercise regime. Whatever your personal response, it’s likely that incorporating HIT training into your workout will provide health benefits. —As told to Felix Gillette

Timmons is a professor of systems biology at Loughborough University.