A number of methods which might improve the detection of carriers of Duchenne muscular dystrophy, based on the estimation of serum creatine kinase (CK), have been tried in an attempt to improve the 70% detection rate obtained with random samples. One series of experiments involved controlled exercise on a bicycle ergometer, the second series was based on sampling of muscle venous blood after controlled ischaemic exercise, and a third series of experiments was carried out to see whether the rate of enzyme inactivation was different in carriers of Duchenne dystrophy compared with controls. These methods were not found to improve the carrier detection rate based upon serum CK estimation.
