If you are prone to back strain, consider using a recumbent bicycle -- one of those low-lying bikes you see in most gyms -- for your cardiovascular workouts.

Recumbent bikes can:

  • Give you as good an aerobic workout as upright bikes can.
  • Strengthen your leg muscles.
  • Reduce stress on your knees as well as on your back.
  • Elevate blood pressure less than upright bikes sometimes do.

More good news: A weak back needn't keep you from a ride in the fresh air; recumbent bikes also come in outdoor models.