Accelerometers give LSU football a look inside the impact of practice

Since August, a routine has unfolded behind the scenes after every LSU football practice.

It all starts with a 3-inch long purple device stuck to a player’s helmet.

A team staff member removes the device, retrieves data from it from that day’s practice and inputs the numbers into a steadily growing spreadsheet.

How many hits, in G-force, did left tackle La’el Collins sustain in Thursday’s practice?

The data can tell you.

“We’re looking at who’s taking the brunt of the blows,” said Jack Marucci, LSU’s director of athletic training.

LSU is using accelerometers to measure the force of collisions during football practice, breaking in a somewhat new technology amid the recent wave of head-related issues in the game.

Marucci has headed the eight-month experiment, a pilot program for the Maryland-based company Brain Sentry. It’s on its last leg: Data will be compiled after spring practice.

Marucci’s goals: discover what positions are more prone to head trauma and send that data to the NCAA to assist in policy-making.

“The NCAA is revamping things now based on what data we’re turning in,” LSU equipment manager Greg Stringfellow said.

Stringfellow handles the physical part of the acceleration sensor — the application and adjusting of it on a player’s helmet. The sensor is fastened with double-stick tape.

Marucci takes care of the computer side — compiling and interpreting the data. What he’s found so far may be surprising.

“Basically,” he said, “offensive linemen have the highest blows.”

Head-hunting linebackers and lead-blocking fullbacks might get the hard-hitting glory, but linemen suffer the most collisions.

Over 10 days of fall camp, a starting offensive lineman averaged about 80 to 100 blows of near 30 Gs, Marucci said. Defensive linemen averaged around 50 collisions of 30 Gs, and linebackers and fullbacks were next at about 20.

“My theory on the linemen is, it’s like a boxer,” Marucci said. “They take blows, multiple blows. Those are the ones we have to protect.”

For perspective, heading a soccer ball produces a G-force of about 20 to 30, said Stefan Dumas, the department head of biomedical engineering at Virginia Tech.

Concussions in college football players are normally seen when a G-force of 80 to 100 is reached, experts say.

LSU began using the accelerometers a few days into fall camp in August. They were used at 44 practices through the season, and about 25 players wear them during spring drills. The sensors were not used during games.

The heaviest hitting, as expected, came during fall camp, Marucci said.

The numbers, at first, puzzled Marucci and his staff. While offensive linemen led all position groups, collisions ranged greatly from one lineman to the other.

They finally realized why.

“Some linemen have better technique than others,” Marucci said.

Offensive linemen are taught to use their hands more than anything, especially in pass-blocking. Collins, for instance, has one of the lowest collision rates of any linemen. He’s an experienced veteran whom many expect to be a first-round NFL draft pick next year.

“He uses his hands more,” Marucci said. “He has better technique.”

Marucci has shown the data to new offensive line coach Jeff Grimes. He also has shown it to coach Les Miles, a former offensive lineman.

Marucci said Miles is “concerned” with the data showing the high collision impact for linemen.

Three LSU players have suffered concussions since fall camp, Marucci said. Two happened during the season and the other, to offensive lineman Josh Williford, during August practice. Williford’s concussion forced trainers and the coaching staff to disqualify him from playing.

Experts still aren’t sure what affect multiple small blows — in the range of 30 Gs — have over a long period. Marucci is hoping data from the accelerometers will help solve that mystery.

But the data aren’t perfect, said Dumas, an expert on head-related issues and football collision sensors. Dumas said he was the first to use sensors during live football practices, doing it at Virginia Tech in 2003.

The issue with them: the correlation between hits to the helmet and blows to the head. An accelerometer might measure a blow to be 30 Gs on a helmet, but what’s that mean for a player’s head? Maybe it felt a blow of 20 Gs. Or even less.

“You have to separate the helmet from the head,” Dumas said. “That’s the challenge. How do you separate those two?”

LSU is using accelerometers donated to the school from Brain Sentry, a 3-year-old company specializing in helmet-mounting sensors. Several schools, Dumas said, are using sensors to measure hits these days.

Starting at Virginia Tech more than 10 years ago, research by Dumas and others has helped curb the physicality of football practices. Nationwide, he said, practices are becoming less hitting-oriented.

“What we’ve found is practice is focusing less on running players right at each other and more on skill set,” Dumas said. “You don’t have to run the Oklahoma Drill twice a practice to be a good football player.”

LSU had a hand in that.

When Nick Saban coached LSU, the staff was “instrumental,” Marucci said, in the NCAA ending the practice of teams having two-a-days on consecutive days.

With this data, Marucci hopes to eliminate two-a-days all together.

It’s something several college football coaches have encouraged, namely Missouri’s Gary Pinkel, whose team did not hold any two-a-days last August.

Still, that’s a long ways away. For now, the ritual of inputting data will continue at LSU through at least spring practice.

Stringfellow and Marucci hope for change.

“It’s just more ammo we have,” Marucci said, “to protect the players.”