The 15-Minute Cardio Workout

Short Circuit
Circuit training, a lifting regimen that gained popularity a couple of decades ago, is still going strong in some circles. You're probably wondering why we're mentioning lifting weights in a chapter on cardiovascular training. Because the benefits of circuit training are both increased cardiovascular training and strength. By quickly moving from one weight station to another – ideally limiting the time between exercises to 30 seconds – you not only strengthen your muscles, but you also enjoy a cardiovascular training effect.

Sounds great, right? The problem is that as exercise goes, circuit training falls under the category of jack-of-all-trades, but master of none. Here's why. The short rest between sets are great for saving time, but prevents you from fully recovering and recruiting as much muscle as possible when lifting. Also, while your heart rate does remain elevated throughout such a workout, the physiological mechanism that causes your heart to pump rapidly during weight lifting is different than the mechanism that raises your heart rate when you go for a run or step on the StairMaster. That's because when you go for a run or a ride, not only does your heart rate increase, but so does your stroke volume, the amount of blood ejected from your heart with each beat. When you lift, your heart rate goes up, but your stroke volume stays stable, and sometimes even decreases. In other words, 140 beats is not always the same as 140 beats. If this were true, watching scary movies or riding roller coasters would also qualify as cardio work.

That said, if you have just 15 minutes to spare, circuit training is a good quick workout since it improves both your muscular and cardiovascular systems. Since we're assuming that your 15-minute workout is taking place away from the gym, the routine we're outlining uses dumbbells or resistance bands. Whether you use dumbbells or bands, either one can be easily stored in your home or office. Both routines require no other equipment or benches.

Choose a weight (or in the case of resistance bands, choose the appropriate resistance) for each exercise that allows you to complete between 12 and 15 reps without sacrificing form. Remember that maintaining good form is key – don't let the fast pace of the circuit translate to sloppy technique and fast movements.

Ten exercises at about a minute each with 30 seconds recovery allows time for 10 exercises in 15 minutes.

Dumbbell or resistance band circuit

Lateral raise	Military press
Lunges (dumbbells) or leg press (bands)	Biceps curl
Standing calf raises	Triceps extension
Chest press (lie on the floor)	Crunch
Bent row (one arm at a time)	Upright row

Remember that your workouts don't have to be an all-or-nothing proposition. Sure, you'd be better off going for a long run or bike ride than squeezing in 15 minutes. However, as we've told you before, 15 minutes is far better than nothing – for both your body and your mind. As the world-class multisport athlete Steve Ilg says, "Fitness training improves not only your physical well-being but also your determination. You are developing inner strength in addition to outer strength." In other words, even if you don't have 30 minutes or more to spare, don't blow off a good opportunity to squeeze in a short but effective 15-minute workout. With a little creativity and ambition, you can gain significant mental and physical benefits from even the briefest of workouts.