A focus on incremental gains has led to big advances, from sports to manufacturing. Illustration by Nishant Choksi

In the summer of 1976, Kermit Washington was in trouble. He was a power forward in the N.B.A., and had just finished his third season with the L.A. Lakers. He had been a highly touted player coming out of American University, where he averaged twenty points and twenty rebounds a game and was a second-team All-American. But with the Lakers his performance had been less than mediocre. The problem was that Washington didn’t know how to play basketball all that well. He had picked up the game late (in high school, he’d warmed the bench), and never learned the skills necessary to thrive as a big man in the N.B.A. In college, Washington’s size (he was six feet eight) and athleticism had allowed him to dominate other players, who were typically smaller and weaker. But in the pros, where most players were big and strong, Washington’s lack of skill caught up with him. By his third season, his playing time had diminished sharply, and he feared that his career was on the line.

What Washington did next changed the N.B.A.: he called a man named Pete Newell and asked for help. Newell had been a legendary college coach, and was working for the Lakers as a special assistant. But his coaching skills were being wasted, because, as David Halberstam wrote in “The Breaks of the Game” (1981), N.B.A. players didn’t want to admit that they “still had something to learn.” That summer, Newell put Washington through a series of gruelling workouts, and schooled him in the basics of footwork, positioning, and shooting. The following season, Washington improved in every aspect of the game. The next summer, he worked with Newell again, and got better still. Washington was suspended for part of the 1977-78 season after he landed a devastating punch on another player during an on-court brawl, but his performance as a player continued to improve. By the end of the decade, he had become an All-Star. Other basketball players, seeing Washington’s progress, started to ask if they could work with Newell, too, and within a few years there was so much demand for his services that he opened a training camp. During the next two decades, many of the N.B.A.’s greatest forwards and centers made the pilgrimage to work with the man who had saved Kermit Washington’s career.

Professional athletes had always worked out, of course. But, historically, practice was mainly about getting in shape and learning to play with your teammates. It was not about mastering skills. People figured that either you had those skills or you didn’t. “There is an assumption that a player arrives in the league in full possession of all the basic skills,” Halberstam wrote, describing the N.B.A. in the late seventies. “Either that, or he sinks.” Bob Petrich, a defensive end for the San Diego Chargers in the nineteen-sixties, told an interviewer that most N.F.L. players of his era even scorned the idea of lifting weights. “Most of the guys had this mental attitude that if you’re not good enough the way you are, then you’ll never be good enough,” Petrich said. The prevailing philosophy was “What you are is what you are.”

Today, in sports, what you are is what you make yourself into. Innate athletic ability matters, but it’s taken to be the base from which you have to ascend. Training efforts that forty years ago would have seemed unimaginably sophisticated and obsessive are now what it takes to stay in the game. Athletes don’t merely work harder than they once did. As Mark McClusky documents in his fascinating new book, “Faster, Higher, Stronger” (Hudson Street), they also work smarter, using science and technology to enhance the way they train and perform. It isn’t enough to eat right and put in the hours. “You need to have the best PhDs onboard as well,” McClusky says. This technological and analytical arms race is producing the best athletes in history.

The arms race centers on an obsessive scrutiny of every aspect of training and performance. Trainers today emphasize sports-specific training over generalized conditioning: if you’re a baseball player, you work on rotational power; if you’re a sprinter, on straight-line explosive power. All sorts of tools have been developed to improve vision, reaction time, and the like. The Dynavision D2 machine is a large board filled with flashing lights, which ballplayers have to slap while reading letters and math equations that the board displays. Football players use Nike’s Vapor Strobe goggles, which periodically cloud for tenth-of-a-second intervals, in order to train their eyes to focus even in the middle of chaos.

Training is also increasingly personalized. Players are working not just with their own individual conditioning coaches but also with their own individual skills coaches. In non-team sports, such as tennis and golf, coaches were rare until the seventies. Today, tennis players such as Novak Djokovic have not just a single coach but an entire entourage. In team sports, meanwhile, there’s been a proliferation of gurus. George Whitfield has built a career as a “quarterback whisperer,” turning college quarterbacks into N.F.L.-ready prospects. Ron Wolforth, a pitching coach, is known for resurrecting pitchers’ careers—he recently transformed the Oakland A’s Scott Kazmir from a has-been into an All-Star by revamping his mechanics and motion.

Then there’s the increasing use of biometric sensors, equipped with heart-rate monitors, G.P.S., and gyroscopes, to measure not just performance (how fast a player is accelerating or cutting) but also fatigue levels. And since many studies show that getting more sleep leads to better performance, teams are now worrying about that, too. The N.B.A.’s Dallas Mavericks have equipped players with Readiband monitors to measure how much, and how well, they’re sleeping.

All this effort may sound a bit nuts. But it’s how you end up with someone like Chris Hoy, the British cyclist who won two gold medals at the London Olympics in 2012, trailed by a team of scientists, nutritionists, and engineers. Hoy ate a carefully designed diet of five thousand calories a day. His daily workouts—two hours of lifting in the morning, three hours in the velodrome in the afternoon, and an easy one-hour recovery ride in the evening—had been crafted to maximize both his explosive power and his endurance. He had practiced in wind tunnels at the University of Southampton. He had worn biofeedback sensors that delivered exact data to his trainers about how his body was responding to practice. The eighty-thousand-dollar carbon-fibre bike he rode helped, too. Hoy was the ultimate product of an elaborate and finely tuned system designed to create the best cyclist possible. And—since his competitors weren’t slacking, either—he still won by only a fraction of a second.

You might think that this pressure to improve reflects the fact that the monetary rewards for athletic success have become immense. There’s something to this. It has become economically rational to invest a lot in player training. Forty or fifty years ago, professional athletes routinely had other jobs in the off-season. Willie Davis, a future N.F.L. Hall of Famer, taught mechanical drawing at a high school. Lou Groza, a legendary kicker, sold insurance. Today, athletes spend the off-season working on their game.

Yet money isn’t the whole story. We’ve seen similarly dramatic improvements in performance over the past few decades in fields where money doesn’t play a huge role. In the nineteen-seventies, there were only two chess players who had Elo ratings (a measure of skill level) higher than 2700. These days, there are typically more than thirty such players. Analyses of great players’ games from even thirty years ago uncover moves that, by today’s standards, are clear blunders. Thanks to the advent of powerful computer programs, players can now practice daily against relentlessly good opponents. They can review and analyze games (not just their own but those of other great players) more quickly and efficiently. They can instantaneously compare the consequences of potential moves. All this has led to fewer mistakes and better tactics, as chess theory has grown increasingly sophisticated.