Six foot six, eyes of blue, an über central defender's after you

Professor Alan Nevill of the University of Wolverhampton had a quiet smile last week when his favourite club, Arsenal, emulated Liverpool by signing a lanky new defender; and not just because he was as desperate as any supporter for Arsène Wenger to strengthen in that area.

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The German Per Mertesacker, like Liverpool's Uruguayan acquisition Sebastian Coates, stands 6ft 6in tall, confirming a trend that Prof Nevill, editor of the Journal of Sports Sciences, identified in a research paper two years ago: in short – or rather in length – footballers, especially in key positions through the middle of the team, are growing taller and leaner.

He even claimed: "The top six teams in the League appear to have more of these taller, leaner players, in comparison to the teams below them. These results suggest that football coaches and talent scouts should pay attention to body shape when selecting potential players for their squads.

"The concept of a player having to be big and muscular might've been true in the Eighties, but nowadays that kind of player isn't the key shape for Premier League players. Apart from the fact that taller players will be more successful at heading the ball both defensively and in attack, they will be able to close down or limit opposition players' ability to pass and distribute the ball."

Forty years ago, Arsenal were able to win the Double with a centre-back combination of Frank McLintock and Peter Simpson averaging 5ft 10in. Today, it is rare for a centre-half to stand less than six feet; the occasional exceptions, speedy little Des Walkers, compensating with their pace for a more ponderous big man alongside them, are disappearing.

The Arsenal of 1971 coped not just because their defenders were good in the air for their size but because, as McLintock recalls, it was comparatively rare to have a centre-forward towering over them. "There were a few like Ron Davies, Wyn Davies and Derek Dougan who were taller guys and Jack Charlton at Leeds would win the ball in both boxes," he said. "But the rest were about 5ft 9in or 5ft 10in. Six-footers were regarded as being very tall."

Tactics came into it too: "What we would do was hold the line. We hardly ever went into our penalty box when the ball was 40 yards away. Say their right-back got the ball out wide, and Derek Dougan was going to make a run into our box, I'd shout very loudly 'hold your line, he's offside,' so the linesman and ref and Derek Dougan would all hear. So he'd put on the brakes and someone like [Arsenal winger] George Armstrong would close down the guy on the ball, which was very important."

Professor Nevill and his team studied the height and weight of almost 900 players over four decades. He told the Independent on Sunday: "All our research has shown that the spine of the team, from the goalkeeper through the centre-halves and central attackers are taller and leaner. Rugby players of course are getting bigger all the time, huge now, which is a well-known trend but if you look at our research into sprinters, they're moving away from the bulky, hugely muscular ones to taller, more elegant runners, who get a bio-mechanical advantage from having a longer stride."

He acknowledges that the best football team and best player in the world appear for now to buck the trend. Barcelona are an exception in many ways, though because of Lionel Messi's size it suits them to play without a conventional central striker. At the back, Gerard Pique is a six-footer, with the shorter Carles Puyol alongside him a throwback to the days of Bobby Moore as a covering defender using his intelligence and positional sense to intercept as often as he tackles.

The Wolverhampton research also showed a small but significant change in players' body mass index, making them leaner as fitness and diet improve. "They're getting leaner because they have to train harder, just because of the workload required of them. The old stocky player can't really get away with it and I even think that extra muscle bulk might be detrimental in the long term."

A sign of that, Prof Nevill believes, is the increasing number of injuries, reflected in how few outfield players are ever-present in a season as opposed to 30 years ago. This he finds reflected at the highest level in many sports.

"I've been watching the US Open tennis this week and the number of players having to quit with injuries is just a sign of what's required of the modern-day athlete and the stress their bodies are put under. They're being required almost to over-train and over-play and they just can't cope. And look at Arsenal's injury list three games into the season."

The new 6ft 6in centre-half, he hopes, will help bring about an improvement at the Emirates, a view echoed by McLintock, who has been a critic of Wenger's transfer policy in the past and now says: "I've not seen much of Mertesacker but I hope he's a leader alongside [Thomas] Vermaelen, who's a terrific player with a good spring and gets up very well, which is what I had, a decent spring without being very tall.

"With guys who were really good headers of the ball despite not being tall, like Andy Gray and Ian St John, it was all down to aggression and desire."

Whatever the size and shape, that has not changed down the years and never will.