Body composition

The term “body composition” refers to what the body is made up of. Fat, muscle, bone, and organs are the main tissues that make up the body. From an athletic performance perspective, the main concern is with fat and skeletal muscle levels within the body. Body composition is part of the physical profile that can have an impact on rugby performance. Body composition is very trainable and so when looking at a training and development pathway to prepare players optimally for performance, body composition improvements should be an aim. Rugby follows the same general trend as many sports and even the general populations’ fitness goals when it comes to body composition with increased skeletal muscle mass and decreased body fat being the aim.

Excess body fat means excess mass on the body that must be carried around a rugby pitch. Fat does not contribute to the force production needed to move the human body. Having higher levels of body fat makes the body harder to move, which can affect endurance levels, acceleration, speed etc. all of which are important to play the game.

Figure 4. Research has shown that higher body fat levels are associated with reduced acceleration and speed (Smart et al 2013)

Alternatively, skeletal muscle mass produces the force required to move the body and execute all the technical and physical skills needed in the game. The more muscle mass the greater the force production capability which for a collision sport like rugby is very beneficial e.g. when tackling scrummaging, mauling.

Body fat levels in rugby players do show positional differences. Forwards generally have higher body fat levels than backs. Forwards are usually the biggest and heaviest players on the pitch. Excess body fat levels do not suit the positional demands of back play. Body fat levels are generally lower in backs.

Figure 5. Research has shown that higher body fat levels are associated with reduced work rates (Smart et al 2013).

In research, body composition has been shown to correlate to on field performance. Smart and colleagues in 2013 looked at the relationship between physical fitness measures and game behaviours in Super 14 rugby players. They found that a high relative body fat level within players, especially forwards, may be related to a decreased work rate and poor tackle ability. This could be explained by the fact that having higher body fat levels means getting around the field is more taxing and fatigue will likely affect the ability to repeatedly perform tasks. This could lead to a decreased work rate on the field and poorer defensive positions being taken leading to more missed tackles.

Figure 6. Research has shown that while professional players are bigger and heavier compared to amateur players, they also display less relative body fat levels (Jones et al 2019).

Body composition has also been shown to be able to differentiate between playing level which again highlights its importance. Jones and colleagues in 2019 looked at comparisons in body composition between professional players in the Aviva Premiership and amateur University level players. They found that whilst the professionals were bigger and heavier than the amateur level players, they also had a lower body fat mass across both forwards and backs.