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Iron Vs. Air: Why Pneumatic Resistance Might Be the Next Big Thing

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Photos by Jason Kirby

Over thirty years ago in a small factory in Frenso, a pair of brothers set out to make pumping iron passé. The product that emerged had no weights, pins, or pulleys; the resistance came entirely from compressed air, or pneumatics. By 1978, the Keiser brothers were peddling the world’s first air-powered variable resistance machines.  

To no surprise, the technology’s earliest adopters included Olympic and professional sports teams, along with some of the country’s leading performance training facilities. Today, Athletes’ Performance, Peak Performance, Mike Boyle Strength and Conditioning, and LA Fitness are just a few of the big name facilities buying into the air-powered equipment. The U.S. Armed Forces (Navy SEALs and Special Forces included), physical therapy facilities, and nursing homes are also incorporating pneumatic resistance into their training routines — with no real competitors in sight. According to Keiser reps, sales of Keiser’s pneumatic cable pulley systems and racks have increased by 68 percent over the last three years.

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 [1] [2].

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.

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. 

As for big box gyms, cost may be the biggest limitation. While LA Fitness and a number of boutique fitness studios across the U.S. have begun stocking spin rooms with Keiser’s $1,695 M3 Indoor Cycle, an air-powered spin bike, it’s hard to say if other chains will follow suit. Keiser Vice President Darrin Pelkey credits an increase in sales of the company’s second best-selling model, the Functional Trainer, to a recent influx of fitness studios. The multi-functional cable machine starts at $2,955.

Budgets aside, whether or not a facility 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 and more places,” Rice says. “That is, ultimately, where the big box gyms are going to go.”

Coming Up for Air — The Takeaway

Until then, is compressed air worth seeking out? If there’s a machine within reach, pneumatic resistance is definitely worth a try (provided you’re healthy, injury-free, and have an experienced professional to show you the ropes). Though it’s still relatively new in the grand scheme of performance training, it appears there’s always something to be learned from the pros and a technology they’ve made their own over the last 30-plus years. Best-case scenario, we get faster, stronger, and maybe even better at what we do. Worst case, we walk away with a power output to use as a benchmark for improvement. And that’s never just a load of hot air.

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Works Cited

  1. Validity and reliability of a controlled pneumatic resistance exercise device. Paulus, DC, Reynolds, MC, and Schilling, BK. Department Mechanical Engineering, University of Arkansas-Fort Smith, Fort Smith, AR. Biomedical Sciences Instrumentation, 2008;44:53-8.
  2. Pneumatic strength assessment device: design and isometric measurement. Paulus, DC, Reiser, RF 2nd, Troxell, WO. Department of Applied Science & Technology, University of Arkansas-Fort Smith, Fort Smith, AR. Biomedical Sciences Instrumentation, 2004;40:277-82.