When they take to the field at the Camp Nou for their Champions League match against Celtic, Barcelona's team will be stocked with short players.

When, for example, Lionel Messi, Xavi Hernandez and Andres Iniesta line up alongside David Villa, who is just returning to his old self after a broken leg, and Pedro – or Pedrito, little Pedro – for Barcelona's famous five attacking line, they average 5ft 7in, the height, as it happens, of both Alexis Sanchez, the Chilean striker who joined Barca in July 2011, and also of the tearaway left-back Jordi Alba who signed with the club on the eve of Spain's triumph in this summer's European Championship.

Messi wasn't always so tall. When he arrived in Barcelona as a 13-year-old from Argentina during the Sydney Olympics in 2000 he was 4ft 6in, nearly one foot shorter than the average height for a boy of that age. As a child, Messi was diagnosed with a rare growth hormone deficiency. The condition affects one in 20 million people.

The average cost of treatment, which involves subcutaneous injections every day for three to five years, is about £100,000 a year. This kind of money was beyond the means of Messi's parents. Messi began his treatment in 1998. (He himself used to administer the injections into his legs every night.)

At the time, his father worked in a steel-making company; his mother at a magnet-manufacturing workshop. The medical insurance they used to cover the treatment costs ran out after two years. Messi's club, Newell's Old Boys, offered to pay for every second injection, but when payments started arriving late, Messi's parents got the hump and took their talented son for a trial to Barcelona when the chance arose.

What is perhaps the most arresting thing about Messi is not his size (Diego Maradona is an inch and a half shorter) but his speed. Frank Rijkaard, who gave Messi his league debut for Barcelona in 2004 aged 17, says that Messi has better acceleration than Maradona, against whom Rijkaard played many times.

Messi uses his low centre of gravity. He's great at winning "the second ball". Sometimes when he's tackled, the ball bobbles in the air between himself and his tacklers. Because he's so low to the ground, he is invariably the one to lure it back to earth. It helps to be short.

In a 2012 study by the Professional Football Players Observatory of the top-flight leagues in 33 nations, Barcelona's squad was the smallest in height. But Barcelona are happy their players are short. It's part of a distinct philosophy.

"In Barca, we look first for talent. When Messi was 11, he was this height," says Carles Folguera, resting his fingers on the edge of an oak table in La Masia, the stone farmhouse where Barcelona's football academy originated, "but it was obvious he had talent".

Folguera, director of La Masia, and a former roller hockey player at the club, says a Napoleon complex feeds into the selection criteria of their 40-odd scouts.

"No-one knew if Messi was going to stay small," he adds. "The physical part of a player like Messi is important but it's not the most important thing. If I have two players, one big and one small, with the same technical skill, I will keep the small one as he will overcome the big one. He will have to work harder and he will be more resourceful. He will need to come up with clever strategies to compensate for his lack of size. The bigger guy won't try as hard. Messi, Xavi, Iniesta, Pedro are all like this."

That study of UEFA football leagues found that the most-picked players in a squad tend to be shorter than their team-mates. This wasn't always the case. There is a shortage of room in football today. Players are fitter. They quickly close down space. In a 90-minute match, Barca's playmaker Xavi will run almost three times further than Paul McStay did when he broke into Celtic's midfield 30 years ago.

Most of the frenetic running is done in the middle of the pitch. Midfield, as Jorge Valdano, Real Madrid's onetime guru, puts it, is "a good place to meet people". Until a few years ago, big players with boundless reserves of stamina were prized assets in this hunting ground. Men such as Patrick Vieira and Yaya Toure stalked the midfields of the Champions League like human wrecking balls. It was all about knockdowns and rebounds.

But in a short space of time, Barca have introduced a corrective to that ideal physique. Their game is played on the ground. In short, they move the ball so rapidly that big, strapping opponents can't get at it.

Other teams, such as Athletic Bilbao and Villarreal, and those abroad such as Arsenal, try to emulate Barca's style – the result of more than 30 years' indoctrination at La Masia. It has also filtered through to the Spanish national team where, at all age levels, teams are peppered with Barca's short players.

Former Real Madrid player Fernando Hierro was a sporting director for the Spanish Football Federation from 2007 to 2011: "People used to think the Spanish type of player – small, skilful, technically good – would not make it at the professional stage. Now that we've won European Championships and the World Cup, the world loves these types of players and says: 'Look how well these people play football!'"

n Richard Fitzpatrick is the author of El Clasico: Barcelona v Real Madrid, Football's Greatest Rivalry, published by Bloomsbury.