Those with scoliosis often demonstrate strong superficial muscles but dysfunction of deeper proprioceptive ones (i.e. rotatores, mutifidi, and intertransersarii, etc), the ones that convey information of where your body is in space.
Scoliosis may create a respiratory compromise due to a smaller and stiffer chest. An abnormal spinal curvature can also affect the normal biomechanics of the ribs. The chest is stiffer because of the surface tension placed on smaller alveoli (small vessels in your lungs).
How can a chiropractor help? Well, depending on the severity of the curve and level of spinal maturity, interventions range from merely observing the condition for progression, stimulating and/or strengthening proprioceptive input (muscles and joints) through adjustments and exercise, offering heel and/or ischial lifts to drive a lumbar curvature, bracing in a bit more advanced cases, and potential referral for surgical consultation in very severe circumstances.