A chiari malformation is a medical condition where the brain stem herniates into the spine. It is either congential - meaning you were born with it, or it is acquired, which means it developed due to other reasons, and over time.
I have an acquired chiari. Mine developed due to the shunt I have for my brain cyst, over-shunting for many months. The shunt drained too much cerebral spinal fluid and caused my brain to sag, which then ultimately caused the base of my brain to herniate, or fall below the skull line and into the spinal column. It can be dangerous to live with this condition, depending on the seriousness of it. However, you can also live as close to a normal life as possible - and you should.
Exercise has always been a big part of my life. I love to workout. It gives me energy, helps me maintain my weight, and it keeps me in good spirits. People with chiari malformations are encouraged to continue to workout and get plenty of exercise. You may need to tweak your workout to create a plan that will not be too strenuous on your neck and head, but it is recommended that you keep up with an exercise routine. There are plenty of exercises that are considered low-impact. There is swimming, and biking, walking, pilates, and a host of other exercises. Depending on the type of chiari you have and the degree in which it is, you may still be able to do things like jog or aerobics. Many people with chiari malformations are able to keep up with their normal, regular exercise routines.
People living with chiari malformations, however, should not use weights over fifteen pounds. This can put a strain on their neck and cause more problems. Light weights are okay, but you should not strain your neck.
When exercising, you should always pay close attention to your body. Listen to what your body is telling you and do not push it too hard. If you start to feel weak or dizzy, you should stop right away. Do not overexert yourself.
Talk to your doctor first, before starting any new workout regimen. She will know if your condition will allow you to do a more strenuous workout, or if you should keep it light.