Unsafe Exercises MSN: 5 Common Exercises You Should Never Do

One that both surprised and delighted me:

Sit-ups: Not only are sit-ups bad for your neck, but they're also one of the least-effective abdominal exercises you can do, according to a recent study at San Diego State University.
Safe Alternative: Bicycle Crunches: That same study found the bicycle maneuver works the abs and obliques 250 percent better than traditional crunches or sit-ups. Lie on your back with your feet up in the air, then bend your knees at a 90-degree angle. With your hands behind your ears, pump your legs back and forth while moving your armpits (not your elbows) toward the opposite knees.