usually pts just have any old certification just to say they have one, for liability purposes its better to have a piece of paper the says you know what your doing(even though most dont). there are some trainers who take it to the next level, and get a C.S.C.S. from nsca, it probably carries more weight than any other cert in the buisness. mostly becuase it takes a degree, and an extensive test to get the credentials. pwrmachine would know about this, i beleive he has his cscs.