"Epigenetics is typically defined as the studyof heritable changes in gene expression that are not due to changes in DNA sequence. Diverse biological properties can be affected by epigenetic mechanisms: for example, the morphology of flowers and eye colour in fruitflies.
Epigenetic changes are crucial for the development and differentiation of the various cell types in an
organism, as well as for normal cellular processes such as X-chromosome inactivation in female
mammals and silencing of mating-type loci in yeast. However, epigenetic states can become disrupted by environmental influences or during ageing, and the importance of epigenetic changes in the development of cancer and other diseases is increasingly being appreciated."
Also see Bird's article "Perceptions of epigenetics" in the 5/24/07 issue of Nature (page 396). Based on what I know at this point, can I rule out that IS training may result in epigenetic modifications within cells? No. Can I say that IS training definitely results in epigenetic modifications? No. It remains an open question...one that could be testable, assuming we knew where in the human genome to look for these possible epigenetic modifications.
very interesting concept...