The TRX system makes for an intense and effective 20-minute workout

I know you’re not ready to think about how busy you’re about to be this fall. But Geralyn Coopersmith has some good news for time-starved New Yorkers—sometimes 20 minutes is all you need for a good workout.

In fact, says Coopersmith, it’s becoming a more and more popular way of training, even for the very fit who typically dedicate more time to their workouts. Coopersmith, who holds a master’s degree in exercise physiology and six fitness certifications, is Equinox’s Major General of Fitness, responsible for all of the gym’s trainers. She’s also the author of Fit + Female: The Perfect Fitness and Nutrition Game Plan for Your Unique Body Type.

Last spring, Coopersmith enlightened us on the relationship between workouts and sleep. We caught up with her again to talk about the effectiveness of 20-minute fitness crams. Although we’re not suggesting you forgo your hour-long Brooklyn Bridge Boot Camp or 90-minute yoga classes, we bring you these three tips for those long days at the office when 20 minutes to workout is simply all you’ve got.

1. Make short workouts high in intensity.

Intensity and duration should always be inverse to each other, Coopersmith says. Just like you wouldn’t sprint for an hour, a light jog for 20 minutes won’t be very effective. A short workout should combine cardio and resistance training, and rest intervals should be almost nonexistent. “These 20-minute high-intensity workouts are not only efficient, they also really stoke the metabolic furnace,” she says. Meaning you’ll burn calories more quickly, even at rest.

Geralyn Coopersmith, the trainer's trainer.

2. Train with tools like kettlebells and TRX.

Training tools can make short-intensity workouts easy, Coopersmith says, who likes kettlebells and loves TRX suspension training. “I love the TRX because it attaches to a door frame, and you can work your whole body in a metabolic circuit.” In fact, when I spoke to her, Coopersmith was on her way to the Jersey Shore for the long weekend, with her TRX riding shotgun. Not going to invest in a fitness system? Coopersmith suggests using a jump rope, free weights, or a step. (Any secure step in your apartment building or outside will do.)

3. Don’t go it alone.

There are a ton of video resources available to help you focus. TRX comes with videos for a all kinds of time frames. Coopersmith suggests using Youtube for 20-minute workouts to accompany kettlebells and  other intervals. “Just check that the person in the video has good credentials or some indication of certification,” she says. In other words, not a celebrity. —Lisa Elaine Held