A recent study posted in the Journal Of Strength and Conditioning Research aimed to find if there is a correlation between size and on field performance. It’s obvious that over the years rugby players have become bigger and bigger. Many top clubs now focus intensely on getting their players bigger and heavier to aid them on the field.

Injuries

Recent data has shown that there are now more rugby players retiring due to injuries than ever. An 80% increase in career ending injuries in the last 5 years is enough to show that there some kind of problem with the game and how players are adapting more intense training systems and games. Eventhough there is no scientific data to support the theory that there are more injuries due to players getting bigger and more conditioned, it’s logical to assume that it’s the main culprit behind the increase in serious injuries. 

In simple physics, a larger and faster moving object creates a larger force in a collision. This is a very simple explaination of how a bigger and faster player can produce more force. The evolution of rugby since it turned professional has been nothing less than incredible. The average weight of the England team in 1994 (Just before turning professional) was 92.3 kg (14 stone 5 lb.) and in 2014 it is 105.3kg (16 stone 6 lb.). That’s an increase of 13kg on average or just over two stone! It’s important to note that this weight gain isn’t simply fat either, it’s near a 100% gain in fat-free mass. This simply means rugby players have packed on over 2 stone of muscle on average over a 20 year time period!

The Study

The study tested thirty rugby players. All the players had a computer scan of their bodies to create a digital model of themselves. This digital model gave the researchers measurements such as bodyweight, height, circumference, length and other data. All players were also tested for their one-rep-max (1RM) strength on squats and deadlifts. Power outputs were also measured on jump squats and a fast deadlift. Once all this data was taken the researchers then put together the factors that affected sprint performance, vertical jump and change of direction. This data was then used to see if a bigger and heavier player would perform better on the field. 

The Results

The study showed that bigger muscles were negatively correlated with performance in ALL of the tests. Whatever the muscle group, this data showed that bigger muscles made the athletes slower, less agile and less powerful on their vertical jumps. The test even showed that the more important that muscle group for performance the worse the performance was as the players got bigger. 

These results might be confusing as these players have probably increased their 1RM and muscular endurance in the gym over the years but it all comes down to relative strength on the field. Although the players are getting stronger as their muscles grow but their total bodyweight also increases and muscle is far denser than fat. This increase is likely to be disproportionate in most players and that is the key element behind why on field performance does decrease as weight increases.

Conclusion

Relative strength is the main indicator behind on field performance. 1RM of the squat and deadlift exercises were divided by the athlete’s bodyweight and the results showed that the greater the relative strength the better the performance. This study shows that size isn’t everything, in fact size can be detrimental to on field performance. Several articles have been published on this website putting huge emphasis on increasing speed, power and size in PROPORTION. 

The study does show that the heavier and faster you can lift a given bodyweight, the better you will perform in field tests. Adding muscle mass for the sake of becoming bigger is likely they main culprit behind decrease in on field performance. The blame cannot be solely put on the player as many clubs do emphasis size over everything. The mindset must be changed and relative strength must be measured closely and players must increase their bodyweight at a slower and more proportional rate. 

 

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