Greg Eskedjian, MSc. CSCS

Director of Hockey Training & Sports Nutrition

Muscle Fibre Types

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The human body contains 3 types of muscle: cardiac, smooth and skeletal. Skeletal muscle is the type of muscle used to produce movement during exercise (ie. quads, biceps, pecs). However, our body contains different types of skeletal muscle as well, that are used in different proportions based on the type of activity performed.

The three types of skeletal muscle found in the human body are: Type 1, Type 2a, and Type 2x fibres. Each fibre type has different characteristics and responsibilities related to exercise. Although we use each fibre type during exercise, exercise intensity and duration will dictate which muscle fibre type is responsible for producing the majority of the energy needed.

Type 1 fibre or slow-twitch fibre is mostly related to endurance-based activities/sports such as long-distance running or cycling. These fibres are typically smaller, with a smaller force production, but a higher fatigue resistance. Therefore, when exercise lasts beyond a couple minutes, this fibre type is most relied on for energy production.

Both Type 2a and 2x fibres are known as fast-twitch fibres because of their speedy contractile abilities. Type 2x fibres are large, with the ability to produce high amounts of force very quickly, although fatigue sets in much faster. Very high-intensity, short duration (under 10sec) activities/sports rely heavily on these fibres, such as sprinting, power lifting, and jumping.

Type 2a fibres are known as more of an intermediate fibre, with characteristics of both Type 1 and Type 2x fibres. Type 2a fibres are intermediate in size, with the ability to produce force quickly, but are somewhat more fatigue resistant than Type 2x fibres. Type 2a fibres are mainly relied on when exercising at a high intensity for about 15sec to a couple minutes. These fibres are predominantly used in high-intensity xstop-and-go sports such as hockey, football and basketball.


Characteristics of Muscle Fibre Types

Characteristic

Type 1

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Type 2a

Type 2x

Contraction Speed

Slow

Fast

Fast

Fatigue Resistance

High

Intermediate

Low

Force Production

Low

Intermediate

High

Power Output

Low

Intermediate

High

Aerobic Enzyme Content

High

Intermediate

Low

Anaerobic Enzyme Content

Low

High

High

Fibre Diameter

Small

Intermediate

High

Reference: Essentials of Strength & Conditioning, 3rd Edition. Baechle & Earle, 2008.


Hockey

Hockey is a stop-and-go sport that combines repeated, high-intensity bursts over a prolonged period of time (3 periods). Due to the dynamic nature of the sport, hockey players rely on all fibre types during practices and games. However, Type 2x and Type 2a fibres are predominantly responsible for producing the energy needed play.

During a practice or game, Type 2x fibres are used when a player is sprinting, shooting, and checking because a large amount of energy is needed in a short period of time. During slightly longer high-intensity situations such as battling on the boards, cycling or an intense penalty kill, Type 2a fibres are mostly responsible for energy production because Type 2x fibres will fatigue at a quicker rate. As for Type 1 fibres, they are also used during a hockey game, but to a lesser extent. Towards the end of a long shift or in the 3rd period after fatigue has set it, Type 1 fibres will help us continue to play, although our ability for powerful bursts are gone.

NOTE: Your body never only uses 1 fibre type, regardless of the activity. All 3 types are always involved, however, usually we rely on one type of fibre more so than the others to produce the energy we need based on the type of activity.


Fibre Type Transitions

Based on the physical demands of ice hockey, a player can train off the ice to enhance his/her performance on the ice. This training will involve transitioning the characteristics of his/her muscle fibres to meet the demands of hockey.

The distribution of muscle fibre types is genetically determined for Type 1 and Type 2 fibres. In other words, you are born with a certain number of each fibre type, which cannot be changed. However, muscle fibre characteristics can be altered as a result of training.

For a sport like hockey, Type 2 fibres are the most beneficial, allowing players to produce high amounts of force/power and maintain it for the duration of a shift (30-60sec). Therefore, a training program that mimics the demands of hockey will maximize the ability of a player's Type 2 fibres and help improve the capacity of his/her Type 1 fibres to produce high amounts of force/power.

A training routine that combines strength training and high-intensity interval training will make a player's muscles more prepared for the demands of hockey as opposed to running for extended periods of time at a lower intensity. Below is an example of a training routine to maximize the ability of muscle fibres for a hockey player.

Click here to view a sample hockey training program.