The Air Advantage

So why swap traditional stacked weights for the unseen? “Pneumatic machines are the closest you’ll get to true isotonic exercise,” (or moving a fixed amount of resistance through a specific range of motion), says Andrea Hudy, strength and conditioning coach at the University of Kansas.

Of course, moving a barbell or a stack of weights might appear to accomplish the same thing, but there’s actually a whole lot more at play. Inertia, acceleration, and other factors (like friction from cams and pulleys) can cause the amount of force on the body to change at various points throughout the movement. For a barbell bench press, for example, if you push the weight fast for the first half of the move, the barbell will become lighter, perhaps even weightless, during the second half of the motion due to momentum. By comparison, with pneumatic resistance, no matter how fast you move, the resistance stays the same. 

Equipped with a 2 ½-inch wide cylinder of compressed air, each pneumatic machine can produce up to 500 pounds of force with only three pounds of actual moving weight. The result: a more consistent and controlled resistance compared to free weights or weight machines Trusted Source.

As for the mechanics at play, it’s surprisingly simple: When you depress the right thumb button (+), air flows from the compressor to the cylinder. The longer you hold the button down, the more air flows into the cylinder, increasing the force it produces.

Keiser Squat

Don’t expect an easy-breezy workout, though. Because pneumatic resistance is uniform, key stabilizers can’t go to sleep as the weight begins to accelerate, says Tristan Rice, Performance Manager at Athletes’ Performance San Diego. “Those muscles have to remain active and engaged throughout the entire range of motion, throughout a range of velocities.” In the long-term, Rice says, “that can set you up for a reduced incidence of injury,” (though, because all training involves a certain amount of stress on the body, no form of training is entirely injury-proof, of course).

But perhaps the biggest benefit of air training is speed. 

“Athletes can suddenly train [closer to] the speed they would perform at,” says Dan Taylor, Director of Global Communications at Keiser Corporation. With pneumatic resistance, explosive movements can be replicated at game-speed, conditioning the muscles to fire faster. “Train slow, be slow,” as the saying goes.

So while a golfer might try to strengthen their stroke with a woodchopper exercise, moving a traditional stack of weights up the cable column can only happen so quickly. Pneumatic resistance, on the other hand, would allow that same athlete to reach speeds closer to what they’d hit on the fairway. Air adds up when it’s time for NFL Combine training, too. At Athletes’ Performance, everything from air-resistance squats to air-powered cycling has helped the bottom line — faster 40s and higher verticals included, Rice says.

Measurable feedback is also a plus. Instead of speculating how fast a movement looks, Keiser machines display a power output corresponding to each rep, allowing athletes and trainers to quantify — and track — power in real time. Once those starting points are accurately measured and accessed, then the true work can commence.

Of course, power isn’t the only advantage to working with air. Resistance on pneumatic machines is selected by the push of button, instead of by loading heavy plates or reaching down to adjust a pin in a weight stack (less ideal for older or injured trainees). Resistance is also available in more precise increments, down to the ounce.

Keiser has some safety benefits, too, such as being able to hit the ( – ) button mid-rep if the load feels too heavy. The uniform resistance also helps eliminate higher impact loads experienced on the connective tissues and joints while starting and stopping a traditional weighted movement. Still, it’s important to note that impact isn’t necessarily a bad thing: “It’s crucial to our survival, health, and optimal bone mass,” says Peak Performance trainer Jonathan Angelilli. The tricky part is making sure impact is increased properly, Angelilli says.

Resisting Air Resistance

Still, pneumatic training isn’t for everyone. Though 29 MLB teams and about two-thirds of NBA, NHL, and NFL teams train with Keiser products, according to Taylor, many high-level programs aren’t in a rush to change things up. The Kansas Jawhawks, for example, are sticking to Hudy’s ground-based weight training program.

“It’s not necessarily that these newer forms of training aren’t valuable to our guys,” Hudy says. “We have an evolving program, but the foundations of the exercises — the clean, jerk, Olympic snatch, squat, front squat — those never change.” Of the handful of Keiser machines in the KU weight room, athletes use them for rotational exercises — and not much else, she says.

By the same token, it’s unlikely powerlifters, Olympic lifters, and CrossFit athletes would gravitate toward a program that abandoned iron altogether. At the end of the day, competitive lifters will always need to be comfortable moving traditional weights. That’s not to say that pneumatic resistance couldn’t be beneficial as a supplemental form of training. With potentially less high-shock impact than traditional forms of weight training, working in some airtime might not be a bad thing. “If people are looking for variety or variability in a program, pneumatic is great,” Hudy says.

Budgets aside, whether or not a facility or home gym will invest in pneumatic training comes down to education, Rice says. “As training theory and knowledge becomes disseminated across a much wider field, you’re going to see better availability in more gyms,” Rice says. “That is, ultimately, where the big box gyms are going to go.”