One thing I forgot to mention was this article I found You're Never Too Old to Start Weight Training According to Dr Mercola: "By slowing your movements down, it turns your weight-training session into high-intensity exercise. The super-slow movement allows your muscle, at the microscopic level, to access the maximum number of cross-bridges between the protein filaments that produce movement in the muscle.
This is a beneficial and safe way to incorporate high-intensity exercise into your workouts if you're older and have trouble getting around. You only need about 12 to 15 minutes of super-slow strength training once a week to achieve the same human growth hormone (HGH) production as you would from 20 minutes of Peak Fitness sprints, which is why fitness experts like Dr. Doug McGuff are such avid proponents of this technique."