W.T.H. Is Tim Tebow Doing in This Gym Video?

.@TimTebow finishing the summer strong @pep_az. Great work! #relentless pic.twitter.com/80DJ2x0z5e

— PEP (@pep_az) July 27, 2015

The above video has the NFL world--and anyone who's ever stepped foot in a gym--asking if Tim Tebow has discovered the best new leg exercise since the barbell back squat, or if he's fallen for the lower-body version of Shake Weight curls.

"It's called a plyo-swing," says Pat Davidson, Director of Training at Peak Performance in New York City. "It's called that because it's designed to improve your plyometric strength."

A Soviet strength scientist named Yuri Verkhoshansky originally developed the plyometric method. It's a training tactic that includes exercises that involve the "stretch shortening cycle"--or stretching your muscles and then rapidly contracting them to produce as much force as possible.

Davidson says there are two types of plyometric exercises: high-velocity and low-velocity. "High-velocity plyometrics are typically lighter and faster, like medicine ball throws or jumps, whereas low-velocity are heavier and not quite as fast, like Olympic lifts and kettlebell swings," he says.

To understand how the method works, consider the kettlebell swing. As you push your hips back and hike the bell between your legs, your hamstrings and glutes stretch. At this point, your muscles are collecting and storing elastic energy. Then you release all of that energy by rapidly contracting those muscles, thrusting your hips forward, and launching the bell skyward with ballistic force.

Football players need to train both types of plyometrics because they show up on the field in the form of jumps, sprints, and tackles. "These are fitness qualities that football players need to have," says Davidson. "Improving them can actually increase your on-field performance if you're a low-level player. NFL players probably already have both of these qualities locked down, but they need to maintain them through training."

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Now back to plyo-swings. They fall into the low-velocity category. And even though they're far from mainstream, they're actually considered a "classic." Variations of the plyo-swing--using equally interesting equipment--appear in old Soviet exercise science textbooks, says Jim Ferris, who has trained NFL players and owns Gym Ferris Fitness in Philadelphia, Pennsylvania.

"My initial assumption from reading those old Russian texts is that there was an exploratory time when Soviet strength scientists were experimenting with all of these different, sometimes strange ways to train low-velocity plyometrics," says Ferris.

The big question: Is the plyo-swing doing Tebow any good?

Turns out, that's a tough one to call.

"It doesn't really transfer over to football all that much," says Ferris. "You're never lying horizontally then exploding from your lower body when you're out on the field." And he says there are far more practical ways to train the skill with exercises that anyone can do, like kettlebell swings. Also, barbell back squats can work, too, if you use a relatively light load--about 30 to 40 percent of your one-repetition maximum--and you explode out of the bottom of the lift.

But Davidson says that there might actually be some value in this particular exercise. "It trains that low-velocity plyometric skill you get from an Olympic lift like a snatch. But there's no learning curve and you don't have to lift heavy weights overhead, which can be dangerous if you have shoulder imbalances," he says. "That makes it a safe option for a guy whose paycheck depends on his shoulders being healthy."

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What's more, Davidson--who has workout out on a plyo-swing before--says the feeling of doing exercises on it can't be replicated. "It's a badass piece of equipment," he says. "I was sore for days afterwards."

Both men agree that the exercise isn't going to make Tebow better at performing the primary job of quarterback. "We know what his real issue is, and that's throwing a football," says Ferris, a life-long Philadelphia Eagles season tickets holder. "So it's good to hear that he's also working with an expert on his throwing mechanics."