Great question. The best source to write fitness programs is using what I learned from NSCA’s CSCS certification. Having a solid understanding with structural exercises(lat pulldowns, shoulder press, leg press) as compared to non structural(calf raises, tricep pressdowns) and how the larger muscles of the body such as Lat’s, quads, are essential as they require more ATP, then the smaller non structural exercises.
It always is fundamental to analyze the initial history taken, understand and medical or complicated issues and then examine their workout history/diet to begin to design exercises.
This is the science we should use not relying on a computer program. Thinking and justifying to ourselves as fitness professionals is vital then relying on a computer.
“Understand the science behind the movement” is VITAL!!