Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Muscles and Body Movement

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Types of Muscle Contractions  Isotonic  Myofilaments able to slide  Muscle shortens  Isometric  Myofilaments unable to slide  Tension increases

Types of Muscle Contractions 1. Isotonic Contractions – The myofilaments are successful in their sliding movements, the muscle shortens, and movements occurs. Examples: Bending the knee, smiling, rotating the arm 2. Isometric Contractions – Contractions in which the muscles do not shorten. Tension develops in the muscle and it attempts to slide the filaments Example: When you push against a wall

Resistance  Resistance – Isometric exercises in which the muscles are pitted against some immoveable object (or nearly so). Require very little time and little or no special equipment The key is forcing the muscles to contract with as much force as possible.

Results of Resistance Training  Results in increased muscle size and strength. Due to enlargement of individual muscle cells (they make more contractile filaments) Not due to an increase in their number.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Muscles and Body Movements  Movement happens because of a muscle moving an attached bone Figure 6.12

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Muscles and Body Movements  Attached to at least two points  Origin – attachment to stable bone  Insertion – attachment to bone with greater motion Figure 6.12

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Types of Ordinary Body Movements  Flexion  Extension  Rotation  Abduction  Circumduction

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Body Movements Figure 6.13a–c

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Body Movements Figure 6.13d

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Types of Muscles  Prime mover –main movement  Antagonist – opposes prime mover  Synergist – aids prime mover, resists rotation  Fixator – stabilizes origin of prime mover, posture