Tight back muscles are sometimes an indicator of imminent back pain. Other times, tightness is a chronic concern that can create worry and discomfort for a very long time-frame.
Mule deer range from 3 to 3-1/2 feet tall at the shoulder, 4-1/2 to 7 feet long and have a tail that is 5 to 8 inches long. They can weigh between 130-280 pounds. The female deer are smaller than the male.
If you like fixed-power scopes 6X is a good compromise. My first mule deer was taken at 329 yards using a 6X42 Leupold. Variable scopes are more versatile. The ability to zoom can be a real advantage if you need to pick a deer out of some brush to make the shot, even at close range.