The most important number for any football player is also the one most often hidden, lied about and fussed over.
The 40-yard dash is the gold standard in football, a sport increasingly obsessed with speed. That obsession hits fever pitch this month for hundreds of college football players hoping to turn pro.
They may not play football sprinting in a straight line in track spikes, but trimming a few tenths of a second off their 40-yard dash times can mean millions of dollars to players preparing for the NFL draft in April.
For the past month, two dozen NFL prospects have been training at IMG Academy in Bradenton, their agents paying up to $15,000 for a six-week training regimen that includes every aspect of the 40-yard dash — from how to warmup (less stretching, more calisthenics) to how many steps it should take to cover 40 yards (21).
Speed coach Loren Seagrave teaches sprinting like an applied physics course. The classroom is a narrow strip of turf and a small practice field behind a gym on IMG's 400-acre campus.
Instead of using a blackboard, an assistant coach films the sprints with a handheld video camera, showing the footage to players after they run so they can instantly correct their technique.
The start is the most important part. Crouched down with one hand on the ground, the runner's first step needs to cover about 31/2 feet, his right leg firing out toe-up, the foot so low it almost drags on the ground.
"Just like you're trying to kick somebody in the shin at close range," Seagrave told his pupils on a recent Thursday as they heaved and sweated their way through a 90-minute session, working on mechanics that should become second nature to them.
Seagrave expects students to improve their times by up to four-tenths of a second.
Former NFL quarterback Vinny Testaverde, who was drafted in 1987, visited IMG in late January to see the kind of training he missed by 20 years.
"They may have had this when I was coming out, but I didn't know about it," said Testaverde, who lives in Tampa and helps out with the Jesuit High football team. "I just wanted to see what this was all about. We never did any of this. They've got it down to a science now."
In football circles, a player's time in the 40-yard dash is guarded like a state secret, which only adds to the intrigue.
Popular sports Web sites and magazines rarely get the correct 40-yard-dash times of players during all the run-up to the draft.
The NFL Scouting Combine, now broadcast on Cable TV, gets considerable attention because it is one of the few places where scouts, coaches and fans can actually watch the players run and get an accurate time.
More intrigue: Some marquee players choose not to run the 40 in the Combine, a decision generally greeted with suspicion and hours of on-the-air debate.
Central Michigan linebacker Nick Bellore has been preparing for the Combine at IMG since Dec. 12 — with a brief break for the holidays — as he tries to go from about 4.8 seconds to 4.6 in the 40-yard dash.
He thinks Seagrave is helping him get there.
"I was pretty well schooled up on all this stuff because I had good strength coaches in high school and college," Bellore said.
"But the first day, he taught me about 10 things I had never heard before."
After a month of training, Bellore says when he lines up to run, he focuses on two things: driving his knee forward and throwing his left arm up violently on his first step, like he is trying to break something over his head.
Bellore will join most of the other players training at IMG in Indianapolis at the Combine, which starts Feb. 24.
A four-year starter at Central Michigan and all-conference player, Bellore knows that scouts and coaches have already seen film of him playing.
Now it is time to show off the speed.
"I want to do as well as I can in all of the drills, but the 40 is the No. 1 thing people look to," Bellore said. "For a guy like me, I was very productive in college. People just want to see me run."
NFL coaches and scouts are looking for 300-pound linemen who are able to run 40 yards in about the time that it took you to read this paragraph — five seconds.
St. Louis Rams offensive tackle Rodger Saffold pulled it off last year.
Saffold trained at IMG before the NFL Combine, where he says "we broke down every single little detail. We didn't just run 40s. We learned."
At last year's combine, Saffold ran the 40 in 4.9 seconds and displayed athleticism that made his stock rise after some draft watchers had predicted he would go in the third round.
Instead, the Rams picked him at the top of the second round and signed a four-year contract worth more than $6 million — substantially more than he would have made as a third-round pick.
He had a stellar rookie season, allowing just three quarterback sacks in 16 games and making a number of postseason all-rookie teams.
This winter, Saffold is back at IMG, trying to keep his edge.
"I had two weeks off, felt like crap, so I came here," he said.
On Thursday, while he sweated with the NFL Class of 2011, Saffold got word that he had been named to yet another all-rookie team.
The players stopped sprinting for a few seconds and gave him high-fives.
Then they went back to work.