Athletes Performance Inc (API)

Not familiar with them.
I'd really suggest you look into ASMI.org, though. Dr. Andrews is the renowned authority & has been studying performance enhancement & injury prevention for decades. He has also "teamed" with a training facility, with Alan Dorfman. You should be able to google them, infact, the group are sponsors here on hsbaseballweb, too.
Tom House has a great program, as does Alan Yeager.

My son has conditioned with API off season for a little over a year. He has gotten excellent conditiioning, we feel. We think they have great trainers who know how to condition different athletes for their respective sports and their respective positions. In our area of the country, they have several well known professionals (in sports of football, baseball, s****r specifically) who work with them.