Saw a report on an interesting bit of research which showed that the training response of people can vary over a continuum from negative to some highest response level. That's right. It showed that some people doing a supervised well structured training program actually get worse, most get somewhat better and few got a heck of a lot more fit. The interesting thing was the response curve was pretty much a straight line, meaning a given individual had equal probability of falling anywhere along it. There was no grouping of response levels.