Here's another advantage that you wouldn't get at the gym... after each resistance workout and before the 15-20 min of cardio exercise, the trainer stretches me out. Five different stretches for legs and four for back and arms, to loosen up the muscles we've just put through the ringer.
Why not a full stretching before the workout? Despite what we all heard growing up in gym class, stretching cold muscles before an intense workout does not loosen them up, but actually stresses them and can even tear them, causing you to become fatigued quicker and get less benefit.
It's much better to warm up jogging and go through some dynamic stretches: at the beginning of each time at Fitness Together I start with 5 minutes on the treadmill, then go through a series of hugging my knees to my chest, forward and lateral lunges, rotating my arms at the shoulder, and sometimes jumping jacks. This gets my heart rate up and my muscles ready to be worked.
And then the big stretching-out at the end has two purposes (I asked Jonathan for the details). First, when you strain muscles, lactic acid builds up in them, which is why you get sore. The trainers stretch my body in ways that are is sure to hit each muscle group that we exercised, so the lactic acid gets released. Meaning I'm not so sore the next day. Second, it helps improve flexibility - which is important not just so you can be 'bendy' but because flexibility is related to balance. And as I get older, I want to keep as much control over my balance as possible.
