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Muscular Performance. Isotonic: the muscle contracts and shortens (muscle length changes), giving movement. Nearly all training you do is isotonic. Isometric: muscle contracts but does not shorten, giving no movement. Muscle length doesn’t change, tension does. Ex. Pushing against a wall.
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Isotonic: the muscle contracts and shortens (muscle length changes), giving movement. Nearly all training you do is isotonic.
Isometric: muscle contracts but does not shorten, giving no movement. Muscle length doesn’t change, tension does. Ex. Pushing against a wall
TWITCH A single stimulus-contraction-relaxation sequence in a muscle fiber.
LATENT PERIOD Between stimulus & response (contractile mechanism is not yet activated but calcium is beginning to spread) 0.001 sec.
STIMULUS • Nerve muscle arrives
CONTRACTION • Sarcomeres shorter (active sites and cross bridges are interacting) • .o4 sec.
RELAXATION • Cross bridges detach • 0.05 sec
SUMMATION • Sending an impulse before muscle is relaxed • Incomplete versus Complete Tetanus
TETANUS • Sustained contraction due to continued stimulus
MUSCLE TONE • Some fibers are always contracting to help maintain posture, balance, and firmness of muscles. Question: If your muscle has little muscle tone will it appear solid or limp?
MUSCLE SPINDLES • Specialized sensory cells responding to stretch-increases muscle awareness
Energy for Contraction 1- stored ATP: 3-6 seconds of energy 2- Creatine Phosphate (cp): 6-10 seconds of energy ADP+CPATP+creatine 3- Aerobic 36 ATP out of 1 glucose 4- Anaerobic- 2 ATP out of 1 glucose a. Lactic acid builds up and muscles fatigue b. Oxygen debt
Rigor Mortis: • Muscle stiffness after death • when you die, calcium seeps out of SR (In the absence of ATP the cross-bridges are not able to detach from the active sites and the muscle locks in the contracted position)
Enzymes eventually break down the myofilaments 15-25 hours later!
Cramp • Lactic acid causes contraction without impulse