Aerobic Exercises
Aerobic exercises cause increased heart and lung activity and are done to improve cardiovascular fitness.  Rhythmic, repetitive, dynamic activities such as running, bicycling, swimming, and walking that are sustained over a sufficiently long period of time, usually 20 to 30 minutes, are considered aerobic exercises.

Although one normally thinks of aerobic exercises as being beneficial for the heart and lungs, studies show that individuals who are in good cardiovascular shape are less likely to suffer from neck and back injuries.  Therefore, the benefit of this type of exercise cannot be overlooked if you want to have a healthy neck and back.

Running, walking, swimming, bicycling and sports activities are all good for the back if approached in a common sense manner.

For an exercise to be aerobic, heart and breathing rate must be increased to an exercise level.  As a general rule, a recommended exercise heart rate is 220- age x .7.  If you are 40 years old, that would be 220 - 40 = 180 x .7 = 126.  Another way of judging if an activity is within the aerobic exercise range is to notice a definite increase in breathing rate but at the same time still be able to carry on a conversation without difficulty.