The decline of “mud bath” football pitches is the reason modern players are leaner and fitter, a study has shown.
Analysis of professional players’ physical characteristics since 1973 showed that while they have continued to grow in height, the average weight has gone down over the last 15 years.
The study by three British universities found this correlated with improvement in playing surfaces.
While slow, muddy pitches tend to favour more muscly players, these footballers perform less well on better preserved grass.
This, coupled with the increasing intensity and average running distance demanded by the modern game, mean stockier players such as Wayne Rooney are likely to become less common in the future, the study authors said.
The average height of footballers in the top divisions was just above 1.77 metres in 1973, rising to just below 1.82 in 2013.
However, while the average body mass index - a measurement calculated by dividing weight kilograms and the square of height in metres - rose between 1973 and 1993 from 22.9 to about 23.5, a decade later it had declined slightly, and by 2013 it had sunk to around 22.75.
Lead researcher Professor Alan Nevill, professor of sport at the University of Wolverhampton, said: "Footballers of today have adapted to the modern game, and as a result their body shape has altered.
"Modern players are ectomorphic, characterised by a lean, slender body, as opposed to the muscular, mesomorphic builds which were more common in the 1970s and 1980s.
"A lot of this can be attributed to the increased quality of playing surfaces where footballers train and compete."
Portsmouth and Cardiff Metropolitan universities also contributed to the research, which is published in the Journal of Sports Science and Coaching.