Whether sports' injury, muscle pain, back pain, or post-operation, pain is a subjective experience and so not surprisingly therefore, there is strong empirical evidence for using cognitive behavioural hypnotherapy to manage chronic pain.  

Our individual assumptions built up over time mean we all experience the same stimulus differently, and so some are able to tolerate a level of pain others will find unbearable.  Our thoughts, feelings and behaviour accompanying the experience of pain influences our ability to cope, and the significance we give that pain.

Muscle tension exacerbates pain - typically when we are in pain we tense our muscles, but this in turn enhances anxious thoughts and fears about what the pain means. 

The causality of pain should always be investigated by a doctor, but some pain cannot be adequately controlled with pain killers.  Mindfulness, relaxation, and self-hypnosis can help you gain control and manage residual pain, reducing the importance it assumes in your life.