Is a quick workout beneficial?
Yes! if you only have 15 minutes to spare, that's no excuse to skip exercise altogether.
Our studies have shown that you can do interval training—incorporating bursts of intensity into a shorter workout—and reap many of the benefits, such as reduced fatigue and improved heart function, that we associate with longer (40 to 60 minute) exercise routines. Interval training can be scaled to any level of fitness. If your only exercise is walking around the block, walk as fast as you can for two or three lampposts, then back off to a slower pace. If you typically go for a 30-minute jog, periodically push yourself so you get more out of breath than usual. The key is to cycle in and out of your comfort zone—ramping it up for 30 seconds to two minutes and then backing off.
—Martin Gibala, Ph.D., associate professor of kinesiology at McMaster University in Hamilton, Ontario