Lecture 1 Flashcards
(24 cards)
What is power?
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.
What is the formula for power in mechanical systems?
Power = Force/Torque x Velocity
What types of tasks are described in relation to power?
- Strength tasks (high force/torque production)
- Speed tasks (high velocity)
Why is power important for athletic performance?
Power is a major determinant of success in athletic events/tasks requiring high velocity of body or an object.
What is the correlation between jump height and jump peak power?
r=0.81 (Hori et al 2008)
What is the correlation between seasons best 200m cycle sprint and cycling peak power?
r=0.75 (Dorei et al 2005)
What level of power is required for mobility and everyday tasks?
A certain level of power is required for mobility, independent living, and physical activity.
What are the SI units for force and torque?
- Force = Newtons (N)
- Torque = Newton metres (Nm)
What is strength typically defined as?
Strength is the maximum force/torque/load a person can generate or lift in a given task/mechanical situation.
What is the relationship between torque and force?
Torque = Force x Distance (perpendicular distance from the line of action of force to the pivot)
What is isometric contraction?
Isometric contraction is defined by a fixed joint position and constant muscle-tendon unit length.
What is the fundamental influence on human muscle function?
The angle-torque relationship has a fundamental influence on all human muscle function.
What explains the inverted ‘U’ shape of the angle-torque relationship?
- Sarcomere length (actin-myosin overlap)
- Joint mechanics (moment arm)
What is the function of the sarcoplasmic reticulum?
The sarcoplasmic reticulum surrounds each myofibril and contains calcium ions that are critical for muscle contraction.
What is explosive strength?
Explosive strength is the ability to increase muscular force/torque as quickly as possible from a low or resting level.
What is the correlation between isometric explosive strength and vertical jump performance?
Isometric explosive strength measures relate to CMJ height, typically with stronger relationships than for isometric max strength.
What are the advantages of isometric measurements?
- Simple to use for investigator and participant
- Provides controlled neuromuscular situation
- High reliability (CVs of roughly 3% for isometric strength)
- High sensitivity
What are the disadvantages of isometric measurements?
- Limited validity to functional movements
- Isometric contractions have 0 velocity, so power is 0
- Highly specific to joint angle measured
What is the role of explosive isometric strength in human movements?
Explosive isometric strength may be a better indicator of performance in tasks that require rapid force/torque production.
What percentage of cross-bridges are formed during an isometric maximum voluntary contraction?
Roughly 80% of cross-bridges are thought to be formed.
How many myofibrils are there in an adult muscle fiber?
Roughly 2000 myofibrils.
What is the definition of (maximum) strength?
Maximum strength is the maximum force/torque/load a person can generate or lift in a given task/mechanical situation.
How is muscular torque related to muscular force?
Muscular torque = muscular force x perpendicular distance (moment arm) from the line of action of the muscular force to the pivot.
What is the relationship between explosive strength measures and sprint performance?
Explosive strength measures have been correlated with short sprint performance in rugby players (r=0.63-0.68).