Muscle Fibre Types

Question 1

Type 1 muscle fibre information:

Answer 1

• Slow twitch fibres contract slowly and with less force.

• They’re slow to fatigue and suited to longer duration aerobic activities.

• These fibres have a rich blood supply and contain many mitochondria to sustain aerobic metabolism.

• Type 1 fibres have a high capacity for aerobic respiration.

• They’re used for lower intensity, longer duration activities.

Question 2

Type 2a muscle fibre information:

Answer 2

• Fast twitch or fast oxidative fibres are fast contracting, able to produce great force and are also resistant to fatigue.

• These fibres are less reliant on oxygen for energy supplied by the blood.

• They therefore fatigue faster than slow twitch fibres.

• Type 2a fibres are suited to speed, power and strength activities such as weight training with 10-12 repetitions.

Question 3

Type 2x muscle fibre information:

Answer 3

• Fast twitch or fast glycolitic fibres contract rapidly and have capacity to produce large amounts of force.

• But they fatigue more readily, making them better suited to anaerobic activity.

• They depend almost entirely on anaerobic respiration - they’re used for higher intensity, shorter duration activities.

• They’re important for sports that include many stop-go/change of pace activities such as football.