You could opt for following techniques to teach your friend:
- Make him perform regular exercise as it will help to create better posture and flexibility and will help to lessen the pain.
- Make him practise good posture techniques to help avoid some of the complications of AS including stiffness and flexion deformities of the spine.
- Apply heat to the stiff joints and tight muscles as it can help reduce pain and soreness.
- Alternative treatments such as massage and using electrical stimulators for pain will also help relieve the pain.