Controlling the strength of a contraction (essentials)

Controlling the strength of a contraction (essentials)

by Colleen Barrett

​Fast and Slow twitch fibers

​FAST:

• short bursts of speed and energy

• ​fatigue easily

• ​respond resistance training by building more sarcomeres

• ​use anaerobic glycolysis

​Slow:

• ​slow to contract but do not fatigue easily

• ​respond to aerobic training by adding more mitochondria and blood vessels

• ​use aerobic respiration

Multiple Choice

What are the characteristics of fast twitch muscle fibres?

• Explosive activities, fatigue slowly
• Endurance activities, fatigue slowly
• Explosive activities, fatigue quickly
• Endurance activities, fatigue quickly

Multiple Choice

Which one of the following is a key characteristic of slow twitch muscle fibers? 

• They contain large amounts of Mitochondria
• They are fast to fatigue
• They are recruited last
• They contain low numbers of Mitochondria

Multiple Choice

Marathon runners can have up to ____ % or more of slow twitch muscle fibers in their bodies

• 20%
• 40%
• 60%
• 80%

Multiple Choice

Term that refers to how often stimulus is applied (or rate of delivery).

• motor unit recruitment

• wave summation

• stimulus frequency

• stimulus intensity

Multiple Choice

The image shown is an example of ____________________. This occurs if a second stimulus arrives IMMEDIATELY AFTER the RELAXATION phase has ENDED. The resulting contraction will have a slightly higher tension than the first contraction. Tension rises in stages (like a staircase, hence its name).

• treppe

• wave (temporal) summation

• complete tetanus

• incomplete tetanus

Multiple Choice

The image shown is an example of ____________________. This happens when another action potential (stimulus) occurs BEFORE the muscle is able to RELAX (before the relaxation phase). MORE calcium (Ca2+) is released resulting in MORE binding sites being revealed. As a result, MORE force is generated in that muscle fiber. In this case, twitches add to each other (get closer together in time).

• treppe

• wave (temporal) summation

• complete tetanus

• incomplete tetanus

Multiple Choice

If repeated stimuli are applied at a fast rate, then no relaxation occurs between the stimuli, muscle reaches maximum tenstion and a sustained contraction phase is obtained.

• incomplete (or unfused) tetanus

• complete (fused) tetanus

Multiple Choice

The ______________ increases, more and more motor units are stimulated, and thus the strength of muscle contraction increases.

• motor unit recruitment

• wave summation

• stimulus frequency

• stimulus intensity

Multiple Choice

The type of muscle contraction where the muscle tenses but does not shorten.  

• Isometric
• Isotonic
• Contraction
• relaxation

Multiple Choice

When a muscle in under tension, it has to be shortening or lengthening, otherwise it isn't under tension.

• True
• False