Biomech
6/3/1999

Stretching
•	Stretch the muscle tendon when stretch
•	Do not stretch the ligament
•	Know the O and I of muscle and separate them
•	How long should I do it?  Max is 30sec
•	How fast should I do it?  Slow so muscle does not respond quickly and contract (muscle fusiform (spindles))
•	Increase ROM—only one that we actually get
•	Not sure of  lengthening or strengthening
•	Increase flexibility
•	Reduce/prevent injury
•	Don’t see any physical change
•	Stress relaxation
•	Build up tolerance to change
•	Warm up a muscle before stretch—increase blood flow, less likely to tear (no affect on stretch)
•	Not exactly sure what it does, but can’t hurt if done properly

3 Different Types of Muscle Pain
1.	during the workout
•	lactic acid build up—not by itself, there are many other chemicals like hormones
•	not exactly sure why
2.	aches after 1 to 2 days
•	inflammation due to tearing of the fibers
•	should not exercise when you have this pain—will not work the correct muscles (performance will be done and muscles are not ready to work)
3.	cramps
•	electrolyte imbalance—not really
•	dehydration—no
•	nerve firing is causing the spasm of the muscle
•	affect the muscle to stretch using agnostic muscles

Disc in the Spine
•	function—like a ligament
1.	motion b/w segments
2.	shock absorption—transmit energy from one above to one below—decreased size will allow more energy to be transmitted
3.	height of IVF—decreased size of disc, decreases the size of IVF
4.	delays shock
•	components
1.	water (mostly by weight)—strength, ability to have flexibility, nutrition
2.	proteoglycans—keep water in disc
3.	collagen—holds it all together
4.	cells—makes and breaks everything down

•	in young, have a larger ratio (1:1) almost the same size as body of the vertebra
•	in 20’s, have a 1:3 (disc is 1/3rd the size of the body)
•	determining spinal ROM is determined by disc size
•	have 1/3 ratio in cervical spine
•	about 1/6 – 1/8 in thoracic—disc size determines ROM
•	have ¼ in lumbar spine

Normal Function of disc
Annullus—collagen, connect end plate to end plate (nutrition), tensil load
Nucleus—higher water, absorbs, rotation
End plate compression fractures—weakest portion
Overlap at 67 degree angle
When twist, have the fibers are stretched and the other half are relaxed
Compression—all are under pressure to help w/stand—circumferential bulging
Lean to the right—disc bulge to the right (1-2mm)

•	young disc—can almost see through (grayish white)
•	old disc—almost all yellow (cannot distinguish b/w the two structures)
•	nucleus bulge seen most in 20-40y/o