Not so gentle giants: how rugby players are getting bigger

The weight of rugby union players has grown three to four times faster than young men in the wider community. AAP Image/Tony McDonough

They’re the giants of Australian sport – and if you’ve suspected rugby players are getting bigger, you’re right. But while stronger, bulkier bodies might have more entertainment value, the focus on girth and force is holding back the sport.

We know that in the wider community, people are growing taller and heavier in parallel with socioeconomic development, with each generation increasing around 2.5cm in height and 4.5kg in weight.

These trends have implications for impact sports, where it has been estimated that a 20% increase in height results in a 44% increase in strength and a 73% increase in inertia.

Over the past 25 years, the weight of rugby union players has grown three to four times faster than young men in the wider community. The nature of the game has also changed, with the ball in play for a higher proportion of the game and more contact events.

Rugby shouldn’t be a game for big men only. AAP Image/Ross Setford, SNPA

The game of rugby has always prided itself in catering for players of all shapes and sizes – from small halfbacks to tall locks, and from slightly-built, fast-running wingers to “stocky” front-row forwards.

But this all-encompassing environment is rapidly changing to favour bigger players in all positions and exclude the extremes of physiques.

This transformation largely occurred in the 1980s and 1990s, when rugby went from a largely amateur to a professional sport. With professionalisation came a decrease in the number of players and an increase in injury. These days, professional level rugby has the highest injury rate of all levels of competition.

To determine when rugby players got so big, I analysed the height and weight of from 700 All Blacks profiles from the New Zealand Rugby Museum website dating back to 1884. I found the height and weight of the players increased by 2.35cm and 4.9kg per generation (25 years), which is consistent with the change expected of healthy males from developed countries.

Back then, the increase in height and weight was in line with the broader community. Wikimedia commons, CC BY

If these trends in player size were to continue, the average height and weight of all players would increase over the next generation from the present 185.4cm and 96.5kg to 188.4cm and 101.4kg respectively by the year 2039. This is only marginally greater than expected from the general population of males in height (2.5cm) and weight (4.5kg).

However, the change in height and weight showed a marked increase in rate of change from about 1980 onwards, which coincided with increased professionalism in rugby. Based on these trends, players’ height and weight could be expected to increase by 5.1cm and 15.4kg over this period (25 years), which is more than double the trend of height and more than three times the trend in weight for other men.

If these trends were to continue over the next generation, the average height and weight of All Blacks would be 195.4cm and 119.3kg, or more than 10% taller and heavier than they are at today.

In recent years, the nature of the game has also become more physical, with greater emphasis on scrummaging technique, physical confrontation, and designated runners barging ahead to set a ruck or maul to draw in defensive players rather than to elude players. Such tactics require big, strong, physical players.

All Blacks and other successful international teams favour bigger, stronger players. Sonya & Jason Hills, CC BY

A more insidious effect of the increase in player size is the threat of a drop in player numbers in rugby, particularly at the secondary school level. Former All Black coach J.J. Stewart lamented that rugby was:

…becoming a game for big men only; and at lower grades and schoolboy grades, of becoming a game for big, strong, early maturing boys only.

He felt this would rob the game of its traditions and ethos of it being a game that caters for all physical types. He also feared rugby would ultimately follow other football codes of becoming a game of relatively few highly paid athletes performing for large crowds.

J.J. Stewart was right. Increasing player size poses a new series of challenges for rugby administrators who have to match the demands of the viewing public with the need to foster the game and provide a pool of players at the “grass-roots” level from which to develop and select future players.