Directed Tasks (Year 2)

Question 1

Explain briefly the importance of impulse for sprinting performance and describe how this mechanical variable may change during different stages of the 100 m race.

Answer 1

• Impulse is a key determinant
• Propulsive impulse > Breaking = Acceleration
• Propulsive impulse < Breaking = Decceleration
• Proposition = Breaking during constant velocity phase
• Vertical impulse = Flight time
• Anterior-posterior impulse = Take-off

Question 2

Discuss the key factors influencing performance in the Women’s shot put with reference to the key differences between the glide and rotation technique.

Answer 2

• Release velocity, height & angle are key
• Release velocity = Biggest factor of performance
  ____
  ____
  ____
• Spin technique = High release velocity, low everything else
• Glide technique = Low release velocity, high everything else

Question 3

Explain the key biomechanical considerations for a cyclist when selecting saddle height.

Answer 3

• Effects hip, knee & ankle* flexion & extension
• Effects muscles length and force
• Hip and knee extensor muscles kept as close to favoured position as possible
• Change in range of motion of ankle = Impact on angular velocity

Question 4

Explain briefly how moment of inertia and sequencing of the lower limb segments is relevant to optimising a soccer kick when the goal is maximal distance.

Answer 4

• Decreased inertia of leg due to flexion = Increased angular velocity of kick
• Increased angular velocity & proximal-distal sequencing = Increased impacted velocity and distance

Question 5

Briefly explain what the torso-pelvic separation (X-factor) angle refers to in terms of the golf swing and then explain its relationship with the stretch shortening cycle. Consider how this links with increased club head velocity.

Answer 5

• X-factor refers to the relative separation between torso & pelvis
• Measured from top of backswing or max value beginning of the downswing

- Maximised by moving hips towards target before backswing is completed 
\_\_\_\_
\_\_\_\_
\_\_\_\_
\_\_\_\_

• Stretch-shortening cycle = Active stretch of a muscle followed by immediate shorting
• Maximised by enhanced stretching of upper back muscles during backswing & therefore greater contraction & velocity

Question 6

1. What are eddies and why do they slow movement through the water so much?
2. What profile is optimal to adopt in the water to reduce eddies?
3. How can a swimmer reduce drag forces on the body?

Answer 6

1. Turbulence occurs in the wake of an object, small whirlpools of water (or air). Energy taken from the person or object to form eddies, hence slowing the object down.
2. Reduce by tapering the end of the object so its streamlined. This shape is called an aerofoil (in air) or a hydrofoil (in water).
3. Reduced by decreasing the frontal surface area; surface drag can be reduced by removing body hair or wearing special swimsuits; wave drag can be reduced by swimming underwater for as long as legally allowed.