"People selected for elite sport do not represent the general population. They can afford and are educated about the right nutrition." Muscle can be conditioned and trained. The sort of exercise that rugby players do has a large component that is anaerobic - short and sharp, with a strength that builds a bigger type of muscle fibre. It appears from research that Polynesian people have more of this type of muscle than Europeans.
"The latter tend to have more aerobic muscle, which lends itself better to sports such as soccer and marathon running."
But rugby players, and others who do a lot of sport, need to be careful when their playing days are over, says Dr Rush.
"They become used to eating great quantities of food, as they need to do while they train and play. Take away the exercise and the fat may creep on."
Nicholas Gill, strength and conditioning coach for the All Blacks, says that as the players are now professional, they take their livelihoods seriously and are using the information and resources available to them.
"The strength and nutrition programmes do change their weights. Sometimes the goal of a gym programme is to increase muscle mass but more often than not it is designed to increase strength and power and prevent injury." This means that even though the All Blacks are larger than the average New Zealand man, typically rugby players have been getting leaner, with less body fat, over the past few years, says Gill.
But we still have some seriously big units in the All Black team and while we expect this trend will continue (in general, each generation is bigger than the last), we can't yet boast the tallest international rugby players of all time. That award goes to Richard Metcalfe, who played at lock for Scotland from 2000 to 2002. At 2.13m (7ft) he had plenty of reach in a lineout.
We do have the heaviest, however - Neemia Tialata weighs in at 136kg.
