some keyword definitions:
Recombinant bacteria - is a microorganism whose genetic makeup has been altered by the deliberate introduction of new genetic elements. The offspring of the altered bacteria also contain new genetic elements.
Atrophy - the decrease in the size of any organ caused by disuse or disease. Atrophy is caused by mutations/poor nourishment/poor circulation/disuse/lack of exercise
Muscular dystrophy - a group of inherited disorders that involve muscle weakness, loss of muscle tissue which gets worse over time. Is a genetic [inherited] condition that gradually causes muscles to weaken
Gene doping - the non-therapeutic use of cells, genes, genetic elements or the modulation of gene expression, having the capacity to improve athletic performance.
Muscle biopsy - is a procedure in which a piece of muscle tissue is removed from the organism and is examined microscopically - shows how muscle fibres are damaged