Excerpted from Newton's Football: The Science Behind America's Game.


Ed Keenan deserves to be honored by the NFL. Nothing elaborate—after all, he played for only a year for the Hartford Blues almost ninety years ago. But something. A small plaque will do. In some team's weight room. Or maybe near the training table.

Keenan has the distinction of being pro football's first 300-pound player. Playing right guard for Hartford in 1926, he was listed at 6'4" and 320 pounds. For his day, Keenan was very much an outlier. It would be sixteen years before another 300-pounder, Green Bay's Millburn "Tiny" Croft, came along. Croft was listed at 300 pounds his first year but at 298, 285, and 280 in subsequent seasons—so he, too, was ahead of his time in a sport where fibbing about your weight has become as much a part of pro football culture as wearing eyeblack.

Keenan was a trendsetter, as important in his way as, say, Jim Brown or Joe Montana, even if it took a while for the rest of the game to catch up to him. As late as the 1970s, according to a study by the Associated Press, there was only one 300-pound player in the NFL, San Diego's Gene Ferguson, and in 1980 there were only three. But in the mid-1980s, that changed: By 1990 there were ninety-four.


If there was an exemplar of this trend toward behemoths on the gridiron, it was William "The Refrigerator" Perry. A defensive lineman out of Clemson, Perry was a first-round draft pick of the Chicago Bears in 1985. Larger than life, literally and figuratively, the 335-pound Perry became an iconic figure on the Bears' Super Bowl championship team. ESPN's Tom Friend called him "America's mascot—a pear-shaped, gap-toothed football player who could sing, dance, sack quarterbacks, score touchdowns and muss Mike Ditka's hair." Despite his size, Perry could throw down a 360-degree dunk on the basketball court and was the sixth-fastest player on Clemson's football team. This combination of speed and mind-blowing size caught coach Mike Ditka's attention. And while Perry's play on the defensive line was spotty—which was a source of conflict between Ditka, who drafted Perry, and defensive coordinator Buddy Ryan—what made Perry into something of a folk hero was a series of brief appearances at running back. On six offensive plays, the Fridge scored three touchdowns and added another one in Chicago's Super Bowl XX win. And thus America fell in love with supersized football players, as NFL teams began to understand the way they could change the game.

Why are football players—and, for that matter, human beings—the size they are? Why, for example, isn't a defensive lineman eight feet tall? Why isn't a running back three feet tall?

Two words: fire and falls.

According to Ohio State economist Richard Steckel, who studies human height data, the answer can be found about three hundred thousand years ago in the middle Paleolithic period. Until that time, humans occupied a place somewhere in the middle of the food chain. We were skilled hunters, but we were also prey for large, fast animals, like saber-toothed tigers. The game changer was man's use of fire. Fire was the ultimate defense against virtually any would-be predator. It moved us to the top of the food chain. According to primatologist Richard Wrangham, author of Catching Fire: How Cooking Made Us Human, using fire to cook food also contributed to our larger brains and accelerated our evolutionary development.


The ability to make a fire conferred an important adaptive advantage on humans of a specific size. Imagine asking a three-foot-tall human—someone roughly the size of a six-year-old—to fell a tree, split it into manageable pieces, carry the logs over, and then pile the wood high enough to make a fire that will last all night. It's not hard to see that a human being closer to six feet tall is better suited to all of those tasks. That, according to evolutionary biologists, is the best guess as to why humans aren't significantly smaller than we are.

But then why aren't we eight feet tall? We can lay this one at the foot of geometry. In 1638, Galileo published a book called Dialogues Concerning Two New Sciences in which he argued that the size of a human being is far from arbitrary. He posited something called the square-cube law, which suggested that volume—and hence mass—increases rapidly with small increases in height.

For a human, that means that if you increase a person's height, his or her mass will increase significantly. Evolutionary biologist J. B. S. Haldane, author of the 1926 essay "On Being the Right Size," argued that "comparative anatomy is largely the story of the struggle to increase surface in proportion to volume."


Using Perry as an example, if we double his height from 6'2" to 12'4", his weight would increase from 335 pounds to 2,680 pounds. By comparison, a Toyota Yaris weighs about 2,300 pounds, so a supersize Perry would weigh as much as a small car with two passengers in it.

And that can contribute to serious falls. Remember how you tumbled as a toddler and then giggled as you got up? The same kind of fall might send an adult to the emergency room. Beyond clumsiness, there are other problems with gigantism. Even a rather modest increase in height would require a major overhaul of our physiology.

The huge increase in mass would tax the ability of our bones to support that weight. It would challenge our lungs to absorb enough oxygen to feed all these tissues. And it would require a high-pressure circulatory system to transport that oxygen to the cells. In the few people who are more than a foot above average, one or more of these problems tends to crop up, and they often battle a variety of chronic and acute disorders.


That's the reason why you simply don't find old giants. Or eight foot-tall quarterbacks.

While William Perry's charisma brought plus-size players into the NFL limelight, there are practical reasons why so many contemporary football players are 300 pounds or close to it. The game has evolved.

As we mentioned previously, in 1978 the NFL enacted a series of sweeping rule changes designed to open up the offense. One deceptively significant tweak in the rules addressed the way offensive linemen could block: They could now use their hands. Before 1978, players were forced to block with their bodies, leaving their arms at their sides like chicken wings. They resorted to chest-bumping opposing defensive lineman or driving with their shoulders. "They'd just chug along with short, choppy steps and try to block people," explains former Cincinnati Bengals coach Sam Wyche.


When forced to block this way, foot speed was every bit as important as sheer size. A supersized offensive lineman who wasn't nimble enough to keep his bulk between the defensive end and the quarterback wasn't much good.

"They changed the rules so you could extend your hands straight out in the framework of your body," Wyche recalls. "As soon as this happened, you saw more screens, you saw more sweeps, because now you could pull that big 290-, 300-pound man out of the interior line, and he could still block that nifty 185-pound defensive back, because he could shove him. He didn't have to get that close to him to affect him. Before that, those little defensive backs would dance around those linemen. They were useless out in the open field. So the rules do make a difference."

The new rules worked in yet another way to pave the way for large blockers: They actively encouraged the passing game. Pass blocking is fundamentally different from the run blocking that Vince Lombardi so lovingly diagrammed. On a running play, the offensive linemen move forward, creating holes for running backs, and once they've done that, they continue down the field to intercept other would-be tacklers. Run blocking is a more active discipline and requires a more agile athlete. And, generally, a smaller one. On a pass play, the blocker's job is to keep the rush at bay long enough for the quarterback to find an open receiver. Offensive linemen in a pass-blocking scheme absorb the energy from the rush in a largely stationary position. "They're working in a phone booth," explains Wyche. If a lineman who's run blocking is an irresistible force, a lineman in pass-blocking mode is the immovable object. Pass blocking takes just as much skill as run blocking, but a different kind. And it requires a different body type—a bigger one.


With that development, fast hands became just as important as fast feet, and—as Vogue editor Anna Wintour might say—big was the new black.

So in the 1980s, at the same time that the United States and the Soviet Union were beginning to wind down the nuclear arms race, NFL teams started in earnest on a race of their own. With an increasing emphasis on pass blocking, offensive linemen ballooned in size. Here's a list of some Hall of Fame offensive linemen from different eras, with their listed playing heights and weights.

Frank Gatski 1946– 1956 6'3" 233
Forrest Gregg 1956– 1971 6'4" 249
Dan Dierdorf 1971– 1983 6'3" 275
Bruce Matthews 1983– 2001 6'6" 289
Willie Roaf 1993– 2005 6'5" 300
Jonathan Ogden 1996– 2007 6'9" 345


Ogden, who played for the Baltimore Ravens at the turn of the millennium, is 48 percent larger than Gatski, who was a fixture of the Browns' championship teams of the 1950s. And as the offensive

linemen grew, so did the defenders who were charged with fighting off their blocks on running plays or getting around them on pass plays.

The battle of the bulk continues to this day. As we mentioned earlier, in 1980 there were three 300-pounders in the NFL. By 2012, that number had grown to 461.


"You are what you eat."

We all buy that on some level.

But look at a Big Mac. And look at Ray Lewis. And look back at the burger. It's easy enough to toss around these nutritional truisms, but how—on a granular level—do two all-beef patties special sauce lettuce cheese pickles onions on a sesame seed bun turn into a future NFL Hall of Famer?


"One of the great human desires is alchemy," explains David Katz, founding director of the Yale-Griffin Prevention Research Center. "While we all secretly lust for the ability to turn one material into another, that's just what our bodies do every day."

And so does every NFL linebacker. Katz likens growth in our bodies to an ongoing construction project, with our food being the raw materials.

"Most of our homes are constructed largely of wood," he explains. "And we extract wood from trees. In the same way, the body extracts nutrients from food." The raw materials in food must be reduced to chemical building blocks, and that begins the moment we take our first bite. "The chemistry begins in our mouth," Katz explains. "There are enzymes in saliva like amylase and [salivary] lipase that are designed to target starch and fat at particular junctions and break down complexes of starches and fats into smaller units. That continues down into the stomach and the intestines, and by the time that chemical digestion is done, essentially what you've got is fat molecules and protein molecules and carbohydrate molecules."


But how exactly does the burger turn into a human being? The bun is made largely of starch. So the linebacker converts it into simple sugar. That simple sugar is made into glycogen, which is stored in the liver along with some smaller amounts of unconverted starch. These glycogen stores are the body's short-term energy source. The body uses these sugars to power all sorts of things: the muscular contractions that a player uses in executing a tackle, the neurological processes at work when he's listening to his coach talk about the new zone blitz package, and even the very process of converting that Big Mac bun into glycogen.

If Ray Lewis is doing two-a-day workouts at training camp, all of this glycogen is used to power his body, with little or nothing left over. However, if it's a day in the off-season when the only football he's playing is some version of Madden and he's primarily exercising his right thumb, then he'll end up with a net caloric surplus. That glycogen will move from short-term storage in the liver to long-term storage as fat in various cells.

"It's subject to the laws of thermodynamics," says Katz. "If you don't burn it, the body will store it as an excess of calories."


The fat? Some of it will be used in the walls of every cell. But beyond that it'll be stored as, well, fat. Katz explains that, in a mature individual, the number of fat cells don't change except under the most dire of circumstances. The total quantity of fat cells is set during childhood and adolescence, and in adulthood the fat cells merely change in size, growing when there are extra calories, decreasing when there's a deficit. Only in truly obese individuals do you start to see the creation of new fat cells, a condition called hypertrophic obesity.

The protein in the burger will break down into amino acids, which are used as the building blocks for new muscle cells. And unlike fat cells, the number of muscle cells will increase as the player hits the weight room. An NFL player builds muscle on an ongoing basis. But any excess protein, Katz notes, also becomes fat.

Why is the body so remarkably good at storing fat? Again, the answer is evolution. Cheap and easy access to calories is a very recent development in the human condition. The hunting and gathering that early man did was a boom-or-bust business. One day there'd be a temporary feast in the form of ripe fruits and vegetables or a freshly killed ox. But there were, of course, no Ziploc bags or Sub-Zero refrigerators in which to store the leftovers.


When the harvest was over and the hunters hit a dry spell, it was famine time. Attempts to store food were generally unsuccessful, and even when they did work, someone would have to defend the food stores against those who'd steal them, human or otherwise.

Storing excess calories as fat was an elegant solution to these problems.

"Fat is the best defense against a rainy day, and throughout human history there were lots of rainy days," Katz explains. Katz is quick to point out that a Big Mac is far from an optimal meal. "It's poor-quality fuel," he explains. "One of the problems we get into is not respecting the limits of this practical alchemy. If you put in bad fuel, it wears out the components."


This, of course, addresses the complex phenomenon of building a body over the course of just one meal. But over a longer span, it gets to be even more of a head-scratcher. Take Ray Lewis on the day he played in his first Super Bowl in 2000 and Ray Lewis on the day he played in his last Super Bowl in 2013, and you could argue that he's not the same man at all. And you'd be right: Almost all of his cells have been replaced with new ones.

Katz draws an analogy between our bodies and a river: The individual water molecules are constantly changing, but the size and direction of the river change slowly, if at all. "Our bodies are much more like a river than a mountain," he explains. "We replace all the cells on the surface layers of our skin and our intestinal tract in a matter of days to weeks. Red blood cells live about a month. Over a lifetime we replace all the cells in our bodies multiple times over. We're constantly flowing."


Or maybe it's more like dinnertime at the Corleone compound. "The way that a given body puts cells together is unique to that body, but it's the same basic set of instructions, the same recipe," Katz explains. "If you're making spaghetti and meatballs, you can double the recipe, or if you've got a group that's really hungry and carnivorous, you can keep the amount of spaghetti the same and double the meatballs. But it's the same basic dish."

And then there's the question no one wants to ask: Are a significant number of those 300-pounders in the NFL going beyond the Big Mac and taking steroids or other performance-enhancing drugs to bulk up?

Talk to Dr. Charles Yesalis, author of The Steroids Game, and his answer is a resounding yes. "God doesn't readily change the recipe," he explains. "It takes a tad more time than a decade or two. Clearly, performance-enhancement drugs have altered the equation."


Professor Jay Hoffman, a former NFL linebacker and himself a former steroid user, contends that steroid use is on the wane. "I would have agreed with him twenty years ago. I don't think steroids are used as much today."

What exactly are steroids? They're essentially synthetic testosterone, which is the sex hormone that makes men men. They build muscle, and they are used to counter bone loss for those suffering from osteoporosis. They're also used as anti-inflammatory drugs. When Yesalis interviewed elite strength athletes from the 1950s and 1960s, he found that most of them peaked at a lean 230 pounds using only resistance training. When the athletes started using steroids and growth hormones, those same athletes got to "270, 280, 290, and above," he explains. "Their training techniques were remarkably similar to the ones we are using today. If you want to increase the strength of your triceps, you add resistance against straightening your arm out. It isn't rocket science," he argues. "These drugs will take you to places that you'll never get to naturally."

Hoffman, who used steroids for several years during his brief pro football career with the Jets and the Eagles, exhibited similar gains in size and strength. "I was 245 lean, and then ten weeks later I'm 275," he explains. How would he have fared without steroids? "In a ten-week time frame I could have put on 10 pounds of lean tissue with the supplements that are out today. Maybe without steroids," he estimates, "I would have gotten to 250 to 260. But not as lean or as strong."


Hoffman further explains he made those steroid-enhanced gains with almost no additional weight lifting. "I never really lifted many weights," he says. "I never lifted much in high school. I just played lots of sports. I played the seasons. I played basketball in the winter, football in the fall, and baseball in the spring. I played lots of schoolyard basketball."

He suggests that today's pro football players are making the same kinds of gains that he made using steroids through more comprehensive strength training. "We are training better, there is more knowledge about supplements and resistance training," he says.

"There are more supplements that help athletes achieve their goals, and more coaches to help them achieve their goals."


Hoffman and Yesalis agree that most of the 300-pounders in the NFL are content to add sheer mass as well as muscle. Offensive linemen in the league sport a body mass index that puts them on the wrong side of obesity. So they're not only big, they're fat.

For Yesalis, the incentives to use steroids seem too great for many players not to use them. The motive and the opportunity are all too obvious. "There are huge amounts of money, fame, and sexual rewards," he explains. "These drugs, as well as the scientific backup to evade drug testing, are readily available to elite athletes."

While he's convinced that steroid use is prevalent among professional football players, Yesalis isn't overly worried about its effects on the players. He notes that steroids and other performance enhancers have been used as therapeutic drugs for decades, and that— used with reasonable care—they're relatively safe.


"These are not major killer drugs. No epidemiologist would put them in the same league as methamphetamine or tobacco or cocaine," he argues, while positing a thought experiment. "If I put in front of you a big bottle of Valium, a bottle of acetaminophen, and a bottle of steroids, and held a gun to your head and told you that you have to ingest one of these bottles or I am going to blow your brains out, you'd better damn well take the steroids, which will give you an upset stomach. The other two will kill you."

While he's more concerned about steroids than Yesalis is, Hoffman sees another problem facing NFL players: pain medication. "Masking injury is probably the most dangerous thing we can see in football players," says Hoffman. Before and after games athletes routinely take medications like Toradol and other potent anti-inflammatory drugs. He notes that these drugs can be dangerous in and of themselves, and furthermore, they put athletes at risk for long-term injury by covering up important pain signals. "The public looks upon a player who is willing to take medication to mask the pain as a hero," Hoffman says, "and someone who wants to maximize his performance a cheater."

Just how big is the problem of performance-enhancing drugs in the NFL? Since 2010, there have been fifty suspensions for all banned substances. Given that there are about 1,700 players in the league, that relatively small number can represent a glass that's half empty or one that's half full. A rather large number of players may be using performance-enhancing drugs and most of them are getting away with it. Or perhaps testing has proven to be a major deterrent and few players are using drugs because of the risk of getting caught and suspended. Just like a police department's surprisingly low arrest numbers, these stats can be seen either as evidence of a system that's working very effectively or one that's seriously flawed.


In any case, one of the world's foremost experts on the subject of performance-enhancing drugs remains largely unconcerned. "I purchased NFL Ticket this year, so I can watch my Steelers," says Yesalis.

"It is just that I take the whole damned thing with a block of salt, not a grain."

From NEWTON'S FOOTBALL: The Science Behind America's Game by Allen St. John and Ainissa G. Ramirez Ph.D. Copyright (c) 2013 by Allen St. John and Ainissa G. Ramirez Ph.D. Reprinted by arrangement with Ballantine Books, an imprint of The Random House Publishing Group, a division of Penguin Random House, Inc. All rights reserved.


Image by Jim Cooke/Sam Woolley