Lecture 1 Flashcards

(24 cards)

1
Q

What is power?

A

Power is the rate of doing physical work or the rate at which energy is transferred from one form to another in a specific task.

SI units for power are watts (W) = J/s.

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2
Q

What is the formula for power in mechanical systems?

A

Power = Force/Torque x Velocity

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3
Q

What types of tasks are described in relation to power?

A
  • Strength tasks (high force/torque production)
  • Speed tasks (high velocity)
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4
Q

Why is power important for athletic performance?

A

Power is a major determinant of success in athletic events/tasks requiring high velocity of body or an object.

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5
Q

What is the correlation between jump height and jump peak power?

A

r=0.81 (Hori et al 2008)

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6
Q

What is the correlation between seasons best 200m cycle sprint and cycling peak power?

A

r=0.75 (Dorei et al 2005)

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7
Q

What level of power is required for mobility and everyday tasks?

A

A certain level of power is required for mobility, independent living, and physical activity.

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8
Q

What are the SI units for force and torque?

A
  • Force = Newtons (N)
  • Torque = Newton metres (Nm)
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9
Q

What is strength typically defined as?

A

Strength is the maximum force/torque/load a person can generate or lift in a given task/mechanical situation.

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10
Q

What is the relationship between torque and force?

A

Torque = Force x Distance (perpendicular distance from the line of action of force to the pivot)

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11
Q

What is isometric contraction?

A

Isometric contraction is defined by a fixed joint position and constant muscle-tendon unit length.

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12
Q

What is the fundamental influence on human muscle function?

A

The angle-torque relationship has a fundamental influence on all human muscle function.

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13
Q

What explains the inverted ‘U’ shape of the angle-torque relationship?

A
  • Sarcomere length (actin-myosin overlap)
  • Joint mechanics (moment arm)
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14
Q

What is the function of the sarcoplasmic reticulum?

A

The sarcoplasmic reticulum surrounds each myofibril and contains calcium ions that are critical for muscle contraction.

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15
Q

What is explosive strength?

A

Explosive strength is the ability to increase muscular force/torque as quickly as possible from a low or resting level.

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16
Q

What is the correlation between isometric explosive strength and vertical jump performance?

A

Isometric explosive strength measures relate to CMJ height, typically with stronger relationships than for isometric max strength.

17
Q

What are the advantages of isometric measurements?

A
  • Simple to use for investigator and participant
  • Provides controlled neuromuscular situation
  • High reliability (CVs of roughly 3% for isometric strength)
  • High sensitivity
18
Q

What are the disadvantages of isometric measurements?

A
  • Limited validity to functional movements
  • Isometric contractions have 0 velocity, so power is 0
  • Highly specific to joint angle measured
19
Q

What is the role of explosive isometric strength in human movements?

A

Explosive isometric strength may be a better indicator of performance in tasks that require rapid force/torque production.

20
Q

What percentage of cross-bridges are formed during an isometric maximum voluntary contraction?

A

Roughly 80% of cross-bridges are thought to be formed.

21
Q

How many myofibrils are there in an adult muscle fiber?

A

Roughly 2000 myofibrils.

22
Q

What is the definition of (maximum) strength?

A

Maximum strength is the maximum force/torque/load a person can generate or lift in a given task/mechanical situation.

23
Q

How is muscular torque related to muscular force?

A

Muscular torque = muscular force x perpendicular distance (moment arm) from the line of action of the muscular force to the pivot.

24
Q

What is the relationship between explosive strength measures and sprint performance?

A

Explosive strength measures have been correlated with short sprint performance in rugby players (r=0.63-0.68).