We know for certain that one unnamed NFL team's players stood around at practice 80 percent of the time last season -- a fact that player-tracking data gives us. And the information proves helpful to both strength and conditioning coaches -- standing tightens up backs and hamstrings, pushing athletes closer to injury -- as well as position coaches planning practice.
We also know that another team was able to tie the offensive line's low-speed outputs on gameday to Thursday practices that featured high volumes of work at low intensities. Not exactly the way to train a high-power athlete 72 hours before a crucial game, or so player-tracking data tells us.
There may be three high-level "football" leagues in this world -- international soccer, Australian Rules Football and the NFL -- but the NFL lags drastically behind the others in the use of sports science. But that is likely to change.
At least 13 NFL teams -- seven publicly and at least six confidentially -- have signed up with Melbourne, Australia-based Catapult for individual athlete data-tracking capabilities so far, with the wave just now heating up, says Michael Regan, Catapult's head of sport science. And with the addition of indoor GPS technology in NFL practice venues this season, the next level of tracking will pinpoint player movements within 15 centimeters, giving coaches acceleration, distance covered, speed, explosion times, exertion, hitting force and every other imaginable piece of data on a player's specific movements, all from wearing a 3.5-ounce monitor between their shoulder blades.
This is changing the ways teams practice, recover from injuries and even plan for games.
While most NFL teams declined to comment on the Catapult system because of competitive advantage, Tom Myslinski, strength and conditioning coach for the Jacksonville Jaguars, says the system helps him train the entire team. "It takes the guess work away," he says. "I'm able to take practice and break it down and put it into their go-home workouts. It helps them train more efficiently."
The monitoring device continually transmits data to the Catapult system. The data provides baseline expectations for each individual player and even position-specific metrics.
"We're creating dashboards for the athlete's bodies," Catapult sport scientist Gary McCoy says. "This data is disruptive to today's practices and if history serves us, we'll see the evolution of the athlete and the sport."
For example, Myslinksi says, if a player trying to return from injury did about 50 percent of a practice workload, Catapult can track at what intensity it was done. "That is an important variable," he says. "Maybe the athlete has adapted to volume, but not intensity and there is a big difference in a game situation. The amount of intensity goes up."
McCoy says they get even more specific than that. If a player can accelerate 60 percent faster to his left than his right after a recent right knee injury, the data indicates that he's probably not ready for the field on Sunday.
Beyond injuries, the evidence-based data breeds changes in practice, such as redefining what Thursday practice looks like, if practices were too strenuous and made replicating it in games too difficult or how to keep players from standing too long. Myslinski has even proven to his players what a good night's sleep (or a good massage) can actually do to boost speed.
And as practices change, gameplans do too. "Through tracking movement, we can see and create a visual reference for a coach to be able to see if what they drew up was executed by all athletes and if it was executed to the athlete's maximum physical capability," says Regan. "The American attitude is 'What does it mean for Sunday?'"
As coaches can use player-specific data to craft plays and gameplans, they can also use historical data of an individual player to give them an understanding of what to expect from a player as a game wears on. Even though using high-tech tracking during games isn't currently allowed -- that may change, though -- rest assured that discussion about measuring each athlete's "PlayerLoad" exertion through practice has risen to the forefront of training, pushing NFL teams into a new technological era.
"If we are having this conversation in a couple of years, people are missing the boat," Myslinski says. "It has made me a better coach. This is where it is going."
Tim Newcomb covers stadiums, design and technology for Sports Illustrated. Follow him on Twitter at @tdnewcomb.