Neurom

Question 1

Why is power important for Athletic performance?

Answer 1

Useful average power is the most important major determinant of success in athletic events and tasks that require a high velocity of the body or an object.

Hori et al., (2008) Jump height and jump peak power showed a very strong correlation of r = 0.81 of n=29 semi pro Aussie rules* this may refer to the participants.

Dal Pupo et al., 2013, showed that 200m sprint run and CMJ peak power, r=-0.69 whereby n=14 track sprinters.

Question 2

First component of power

Answer 2

Force and Torque.

Question 3

Human force torque production during isometric contractions.

We can take isometric measurements from…

Answer 3

1. Custom built dynamometers
2. Isokinetic dynamometers

Question 4

Advantages for isokinetic dynamometers

Answer 4

Isokinetic dynamometers are comfortable for the participant and robust. This is due to the padding and low rigidity within the IKD. This results in significant compliance even during isometric contraction movement.
Tsaopoulos et al., (2007) reported up to 20 degrees of movement within an Isokinetic dynamometer.

However if a customer built dynamometer was used then by Folland et al., (2014) findings there would be 4 degrees variation.

^ however, isokinetic dynanometers are not only measured at the knee, they can be taken at other joints e.g., shoulder or hip etc. So it can measure many different muscle groups at a diverse range of angles.

Question 5

Is isometric explosive strength related to athletic performance?

Answer 5

**********Vertical jump performance.**********

Isometric explosive strength measures have been reported to be related to counter movement jump height (Tillin et al., 212). With generally stronger relationships than for isometric strength (Chang et al., 2015).

Therefore, explosive strength is reported to be a better predictor of jump height than isometric maximum strength.

Sprint performance.

Explosive strength measures have been correlated with short <10m sprint performance in rugby players (r=< 0.68); (West et al., 2011)

Question 6

The second component of power AND DEFINE IT AT THE MUSCLE LEVEL

Answer 6

Velocity
At the muscle level there is a hyperbolic relationship between force and the shortening velocity of an isolated muscle. A reduction in force as the velocity of shortening increases.

Question 7

Why does force reduce as velocity increases?

Answer 7

The contractile properties actin and myosin reduce in their cross bridges which causes a reduction in the generation of force (as less actin and myosin attachment). When velocity increases, movement increases are fewer myosin heads are attached, this worsens at the highest velocities.

Question 8

Power-velocity relationship?

Answer 8

Force x velocity will give us power. That gives us the power velocity relationship.

Isometrically, there is no power because there is no velocity. However, over time as velocity increases power is generated showing an inverse parabola. Therefore demonstrates optimum power / maximum power at 1/3 maximum velocity and at 1/3 maximum force.

Question 9

How do we measure the velocity for human movements?

Answer 9

There are many methods such as the use of:

• Timing gates
• Motion analysis
• IMUs

^These would be of freely moving bodies that are not restrained.

For restrained movements: where there is a defined movement pathway:

• Isokinetic dynamometer
• Ergometer velocity

Question 10

DEFINE Isovelocity

Answer 10

= constant velocity

Question 11

Suggest isovelocity measurements

Answer 11

Isovelocity measurements:

• Isokinetic dynaometers
• Ergometers with an isovelocity function/mode (multiple joints).

Question 12

Limitations of an isokinetic dynamometer

Answer 12

Limitations of an isokinetic dynamometer:

• They cannot reliably measure at higher velocities. Which is less than the optimum velocity for power production.

Question 13

Which is the best way to measure isovelocity

Answer 13

Therefore a better way to measure isovelocity is by the method of ergometers.

Question 14

State the advantages and disadvantages of measuring using the isovelocity

Answer 14

ADVANTAGES:

• Dynamic function can be assessed which provides greater validity for the real-world athletic movements.
• A range of velocities can be assessed.

DISADVANTAGES:

• Researcher expertise is required.
• More familiarisation is required.
• There is a restrained movement path that may not be relevant to many sporting activities.
• Limited in its range of movement.

Question 15

suggest some Isoinertial tasks

Answer 15

1RM lifting strength - against a maximum load (inertia) .
isoinertial strength.

Throwing a Javelin - against a light load, the javelin

Jumping - against a medium load, body weight

Question 16

Why does a bigger muscle produce more force?

Answer 16

Because there is more sarcomeres aligned within the muscle fibres. This means that more cross bridge links can be formed between the filaments. Therefore, greater force is produced which means that the muscle is bigger.
There is a very high relationship between the CSA & Isometric strength of isolated muscles.**

Powell et al., (1984) reported a correlation between the two of r=0.98 within animals within an isolated muscle (guinea pigs).

Therefore bigger muscle can produce more force. Due to larger muscles have more sarcomeres and cross bridges in parallel. Which creates more interaction between actin and myosin.

Question 17

How does CSA affect cross bridge formation

Answer 17

The more cross bridges in parallel then the more force production.

Muscle anatomical CSA accounts for 50% f the variability in isometric strength between individuals (Bamman et al., 2000).