Most machines you find at the gym are engineered to train specific muscles—usually a primary muscle and one or more secondary muscles. The chest press machine works your pectorals and shoulders, while the leg curl machine hits your quadriceps and hamstrings. So depending on the muscles you want to train, every machine is effective in its own way.

But let’s say you only have 20 or 30 minutes at the gym, and you’re looking for machines that offer the most total-body training benefits. “If you’re pressed for time, there are some machines that train your muscular fitness and cardiovascular fitness at the same time,” says Chris Gagliardi, a certified personal trainer and weight management coach with the American Council on Exercise.

Rowing machine

Like running or swimming, rowing is a good aerobic workout that fires up your heart and lungs, Gagliardi says. But rowing also trains a diverse set of muscles. “You drive through your hips and legs to start the rowing movement, you have to activate your core to maintain posture, and then you have arm, shoulder and back involvement,” he explains. “It’s really a great workout.”

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He recommends asking a trainer at your gym to help you with your rowing form. (In fact, that’s good advice for any machine at the gym.) When rowing, “you don’t want to lock your knees, and you also don’t want to hunch way over and arch your back,” he says. These mistakes can lead to injuries or inefficient workouts. Instead, you want to keep your legs loose and slightly bent at the knee while keeping your back straight. “The forward and backward pivoting should come from the hips, not from bending your back,” he adds. (If you don’t have access to a trainer, you can find good instructional videos online.)

Air bike

This is the stationary bike that has upright, movable handles like an elliptical machine, as well as a big air-generating fan wheel up front. It’s another great option for a total-body workout. “Again, you’re getting the cardiovascular component, but you’re also improving muscle fitness,” Gagliardi says.

Any and all types of cycling will train your lower body. And if you can find an air bike machine that has foot straps, which many do, you’ll get more involvement from your knee and hip muscles, thanks to the pulling-up motion involved in this kind of pedaling, he says. Meanwhile, the push-pull action of the upright handles works most of the major muscles of your upper body. “When you’re pushing, you’re using a lot of muscles on the front of your body—your chest and anterior shoulder muscles,” he says. “And while you’re pulling, you’re using your back and posterior shoulder muscles.” You’re also working your arms, and you’ll need to keep your core engaged for stability, he adds.

Stair-climbing machine

The stair climber also provides an excellent combination of aerobic and lower-body training. “You’ll train your hip flexors and extensors, your knee flexors and extensors, your glutes and your hamstrings,” Gagliardi says.

A great thing about the stair-climbing machine, he adds, is that it builds functional strength—meaning muscles or moves you use frequently in everyday life. Especially as you age and poor balance or stability become concerns, functional exercises are a great way to maintain your physical capabilities.

Circuit training

Rather than spend all your time on one of these three machines, squeezing in all three is a good idea, he says. Even if you can only devote five minutes to each apparatus, that’s enough to get a serious total-body burn going on—provided you push yourself.

If you’re looking for even more variety, circuit training is a great option, Gagliardi says. Circuit training is any workout that involves repeating a string or sequence of different exercises—or in this case, exercise machines.

So rather than stay put on one machine until you’re finished with it, you’ll move from one to the next and then start over again, he explains. The trick with circuit training is to make sure consecutive machines don’t engage the exact same muscles, which can wear you out quickly. “It helps to alternate upper body and lower body machines,” he says.

A personal trainer can help you develop an effective, time-efficient circuit training routine—and he or she can make sure your form is good, which will lower your risk for injuries.

These strength and cardio routines aren’t just ideal for people crunched for time. “Even if you have a lot of time, I love all these workouts,” Gagliardi says.

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