Unless you have been living in the most desolate, remote part of the planet, you are probably aware that the 2014 FIFA World Cup has just taken place in Brazil. Often called “The Beautiful Game,” football (also known as soccer or footy/footie) is played between two teams of eleven players and is the “most widely viewed and followed sporting event in the world.” Being British, I eat, sleep and breathe football, but what does it take to be a footballer? More specifically, what are their muscles like?
On average, there are approximately 650 muscles in the human body, making up about half of your body weight. There are three types of muscle tissue: visceral (found inside organs like your stomach); cardiac (heart); and skeletal. It’s the skeletal muscles that we’ll be focusing on.
Skeletal muscle is the only voluntary muscle tissue in the human body—meaning it is controlled consciously. Every physical action that you consciously perform, such as running after a football, requires this type of muscle. The function of the skeletal muscle is to contract and move parts of the body closer to the bone that the muscle is attached to. Most skeletal muscles are attached to two bones across a joint, so the muscle serves to move parts of those bones closer to each other. Skeletal muscle fibres contract and relax at different speeds and vary in which reactions they use to generate adenosine triphosphate (ATP). They also vary in how quickly they fatigue. There are three different fibre types:
- Type 1 (slow twitch or slow oxidative): the smallest in diameter and thus the least powerful type of muscle fibres. They contract slowly, but keep going for a long time as they release energy gradually during steady-state activities, such as longer distance running (like marathons), cycling and other endurance sports.
- Type 2a (fast twitch or fast oxidative-glycolytic): these are intermediate in diameter (in between the other two types of fibres). They can generate considerable ATP by using oxygen, which gives them a moderately high resistance to fatigue. They contribute to activities such as walking and sprinting.
- Type 2b (fast twitch or fast glycolytic): these are largest in diameter and can generate the most powerful contractions. Due to their large size and their ability to hydrolyze ATP rapidly, these fibres contract strongly and quickly. These fast-twitch fibres are adapted for intense anaerobic movements of short duration, such as weight lifting or throwing a ball, but they fatigue quickly.
During a 90-minute football game, elite players “run about 10km at an average intensity close to the anaerobic threshold (80–90% of maximal heart rate).” These athletes spend a substantial amount of time trying to improve physical capacities, including aerobic endurance and strength and the strength derivatives of speed and power. Knowing that, we can imagine that a football player’s muscle composition might have a higher proportion of Type 1 and 2a muscles, but possibly less of Type 2b.
So if you’re looking to be the next Cristiano Ronaldo, you might have your aerobic work cut out for you.
If you’d like to learn more, an interesting article on endurance versus strength can be found here.