England fitness coach Dave Reddin reveals how rugby union players have got bigger and stronger as the game has toughened up.

Ever since the early days of professionalism, there has been a big change in the shape of players, their bodyweights and their body compositions.

Pre-professionalism, the average back would have weighed 80 to 85 kilos. Now it is more like 95 to 100kg.

And then you have players like Ben Cohen (wing) and Mike Tindall (centre), who are nearly 110kg.

But while players are getting heavier, you are also seeing less body fat.

In the amateur days, body fat for an average back would have been around 12 to 15%. Now it's closer to 10%.

Players are now much faster, stronger and therefore the impact in the tackle is that much greater

So while players are gaining more weight, a huge proportion of that increase is muscle.

However, we are not trying to get the players bigger and bigger because bigger doesn't necessarily equate to stronger.

If you look at former Olympic triple jump champion Jonathan Edwards, he weighed only 71 to 72kgs when he was breaking world records.

But he was stronger than most of our players, he could squat more weight than any player we've got.

If the players get heavier, their endurance will be compromised, along with their ability to continually be part of the game for 80 minutes or more.

Jason Leonard retired from rugby aged 35

We are trying to get a balance between the two points - any increase in weight has to be accompanied by an increase in strength.

Players are much faster and stronger now and therefore the impact in the tackle is going to be that much greater.

So inevitably you are going to see more contact injuries.

But the flip side of that is in the pre-professional era, players were not as well conditioned, the tackles weren't quite as hard, relatively speaking, and the players were less accustomed to the big hits.

But the incidence of injuries in the professional era has been compensated largely through improved training methods and prevention strategies.

We don't want to see players finishing their careers in their mid-20s because of injury.

We want to see guys achieve what Jason Leonard and Dorian West have done, playing well into their mid-30s and getting better as their careers progress.