Personal trainers really seem to run the gamut. One of my BIL's closest friends is a personal trainer in LA. He has a Master's in kinesiology, decades of experience as a trainer, and his business has been referral only for as long as I've known him. None of that is likely true for the personal trainers at the local gym.
FWIW, during my 20s and early-30s I was a power-lifter and in the gym 5-6 days a week. I read all kinds of books on body building and consumed ungodly amounts of calories. By my mid-30s I realized that yoga was much kinder on the body, but in the 15 years I was a gym rat, I never met a personal trainer that had a clue about anything other than the latest exercise trend.
FWIW, during my 20s and early-30s I was a power-lifter and in the gym 5-6 days a week. I read all kinds of books on body building and consumed ungodly amounts of calories. By my mid-30s I realized that yoga was much kinder on the body, but in the 15 years I was a gym rat, I never met a personal trainer that had a clue about anything other than the latest exercise trend.