Re: A Change of Pace
First and foremost, it is to avoid injury. Training to failure and beyond with heavy weight is best done with machines so you don't crush yourself under really heavy weight on your last struggling rep.
Secondly, you can skyrocket in strength with machines. The reason for this is that unlike freeweights, you are not bringing stabilizer muscles into play with machines. The goal with HIT and similar training programs is purely to build strength and size, so in this case, we are not concerned with training stabilizer muscles. They are a nonfactor here. Now that we have determined this, machines allow you to focus all your energy on purely lifting the weight without dispersing any additional mental effort in balancing the weight. All you need to do is PUSH! Zero mental or phsyical effort going towards balancing a weight means more concentration on contracting those deep muscle fibers to lift that heavy weight, which therefore will increase intensity, and in turn stimulate greater growth.
Now with that said, machines are not worse or better than freeweights. This boils down to the principle of specificity. Meaning, you do that which is specific to your goal(s). My goal is to simply build larger and stronger muscles, so I have no concern for stabilizer muscles or increasing a skill in a specific activity or exercise. Therefore, if I had access to nautilus machines, I would use them all the **** time! Funny thing is I used to be vehemently anti-machine, but then I realized what I just told you guys!
But above all, remember... it's not the machine or the freeweight barbell that builds muscle, it's YOU. Unless a machine feels awkward for you (as is the case with me with a few machines), then simply don't use it.
"Some people call me a fat pig in the off season, but when I step on stage those same people are kissing my @ss" - Lee Priest
"That last rep where you're trying as hard as you can and you barely make it! That is what turns on the growth mechanism in your body. That last almost impossible rep where you're bearing your teeth, you're shaking all over, you need assistance! That rep is very special, that rep is very different. There's something special going on inside your body when that happens." - Mike Mentzer