Anatomical Kinesiology: HES 207

What type of muscle contraction occurs when the muscle contracts and shortens?

The Musculature:  

∙ Fibers Continued:  

 Fiber Architecture  

o Strap

o Fusiform

o Triangular

o Pennate

∙ Fiber Arrangements  

 LOA = Line of Action (pull)

o Goes in same direction as fiber  

o Needs to offset from joint center

What happens during an eccentric muscle contraction?

o Creates a moment arm  We also discuss several other topics like How have humans evolved as part of the natural world, how have environmental changes affected human development?

 Angle of Attachment  

∙ Muscle Contractions  

 Concentric: Shortening occurs  

o muscle contracts with greater force than resistance and  shortens If you want to learn more check out How does the criminal justice system respond to crime?
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 Eccentric: Lengthening occurs  

o muscle contracts with less resistance force less than  resistance and lengthens

 Isometric: No change in length  

o muscle contracts but does not change length

 Isotonic: Same force (tension)

 Isokinetic: Same Speed

 Passive:

o Lengthening  

o Shortening  

o When muscles on one side of a joint are active, the other  side is passive

∙ Muscles Play Different Roles  

What are passive leg exercises?

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 Agonist: Prime Mover

 Antagonist: Opposes the action of agonist Don't forget about the age old question of What is the meaning of population ecology?

 Synergist: Perform or help agonist perform same motion   Stabilizer: Prevents movement at a joint other than where motion is wanted  

 Neutralizer: Eliminates the undesired effect at joint of desired  movement  

∙ Muscle Force

 Max Force (along line of action)

o Physiological Cross-Sectional Area (PCSA)

 Larger cross-sectional area = more sarcomeres =  

more muscle fibers  

 Perpendicular to muscle fibers If you want to learn more check out What is anton van leeuwenhoek's contribution to cell theory?

 Accounts for all of the fibers

o Pennation Angle

 Disadvantage: Limited distance of muscle travel  

 Force Modifiers

o Length (relative to resting length)

o Velocity of Shortening/ Lengthening  

o Activation Level

o Others  

 Factors that Influence Force  

o Temperature: Hot is better because the muscle and  

tendons are more elastic

o Recent stretch history: Sarcomeres at optimal length

o Fatigue: Force production might go down, if lactate and  hydrogen ion production is faster than the body can buffer  causes that “burn”