Any great force can cause a micro tear in the muscles and tendons of the lower back. This injury commonly occurs in sports such as weightlifting, football, basketball, baseball or golf that require pushing or pulling or sudden twisting of the back. The risk of back spasm is greater in people with: 1  A pelvis that tips forward more than normal.  Any back weakness such as arthritis, spondylolysis, spondylolisthesis, disc rupture or a herniated disc, spinal stenosis or a tumor.
The Uniform Time Act of 1966 established a system of uniform (within each time zone) Daylight Saving Time throughout the U.S. and its possessions, exempting only those states in which the legislatures voted to keep the entire state on standard time.
Best Answer: The United States uses nine standard time zones. It depends on how one defines the United States. The U.S. proper (coterminous 48 states, Alaska and Hawaii span 6 times zones collectively. They are Eastern, Central, Mountain, Pacific, Alaska and Hawaii-Aleutian Time Zones.