1. Muscular Performance

2. Isotonic: the muscle contracts and shortens (muscle length changes), giving movement. Nearly all training you do is isotonic.

3. Isometric: muscle contracts but does not shorten, giving no movement.
Muscle length doesn’t change, tension does.
Ex. Pushing against a wall

4. Which one is A? B?

5. A single stimulus-contraction-relaxation sequence in a
TWITCH
A single stimulus-contraction-relaxation sequence in a
muscle fiber.

6. LATENT PERIOD
Between stimulus & response (contractile mechanism is not yet activated but calcium is beginning to spread)
0.001 sec.

7. STIMULUS
Nerve message arrives

8. Sarcomeres shorten (active sites and cross bridges are interacting)
CONTRACTION
Sarcomeres shorten (active sites and cross bridges are interacting)
.o4 sec.

9. RELAXATION
Cross bridges detach
0.05 sec

10. Sending an impulse before muscle is relaxed
SUMMATION
Sending an impulse before muscle is relaxed
Incomplete versus Complete Tetanus

11. TETANUS
Sustained contraction due to continued stimulus

12. MUSCLE TONE
Some fibers are always contracting to help maintain posture, balance, and firmness of muscles.

13. MUSCLE SPINDLES
Specialized sensory cells responding to stretch-increases muscle awareness

14. Energy for Contraction
1- stored ATP: 3-6 seconds of energy
2- Creatine Phosphate (cp): 6-10 seconds of energy ADP+CPATP+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

16. 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)

17. Enzymes eventually break down the myofilaments 15-25 hours later!

18. Cramp
Lactic acid causes contraction without impulse