One player, William O’Connell of Ireland, is not listed in the international programme another player TE Reid is listed. In two cases, it was not possible to obtain the matchday programme of the team’s first game (1955 France vs Scotland, 2005 Italy vs Ireland) so data from the next game the team(s) were involved in were used. The players’ names are in online supplementary appendix A. For RU matches, the body mass and height of players representing their international team for that country’s first game of the Five Nations in 1955, 1965, 1975, 19, and for 20, the Six Nations, were recorded. We also sought to characterise the changes in body mass and height according to playing position on the field.ĭata were collected from matchday programmes. In addition, we compared changes in body mass in international RU players to rugby league (RL) players, which has incorporated professionalism since 1895.
We hypothesised that since RU turned professional in 1995, player body mass would significantly increase. Although not all players in RU are primarily selected to directly engage with the opposition and carry the ball into contact or to make tackles on opponents (eg, the scrum half, traditionally thought of as small and nimble, is at least partly employed to pass the ball from a set piece engagement of forwards to the players in the back line), it makes sense that greater body mass will limit the discrepancy. 6 In addition, bigger players will generate greater force in scrums where the eight forward players from each team push against each other to try to win the ball as a means of restarting the game. Heavier players have greater momentum, and any advantage gained in a tackle can afford greater opportunity to continue an attacking move or regain the ball. 5 The advantages of size in a game where players wrestle and grapple the ball from one another and attempt to cross the gain line by outpacing, outsmarting or overpowering the opposition are clear. 4 Indeed, it has been suggested that players may approach contact areas without checking their speed, in order to register high G-forces on impact and perhaps impress or satisfy their coaching staff. 1–3 The forces involved when players make contact with each other are thus increasing, and many players are now fitted with global positioning system (GPS) devices and acceleration sensors during matches. Rugby players appear to be getting bigger although the extent to which this has occurred since the game became professional has not been described previously for northern hemisphere players. Most humans cannot significantly increase their maximum running speed or their acceleration, but it is possible to modify body mass. In rugby union (RU), a sport in which words such as ‘hit’, ‘collision’ and ‘smash’ are commonly used to describe contact between players, these equations are important. Isaac Newton’s Second Law of Motion states that force applied is the product of mass and acceleration.