The article is needlessly verbose. Here's the one paragraph that contains all of the information you need:
> If you’re currently sedentary or have a serious chronic illness, check first with your doctor. But as soon as you get the go-ahead, start a strength-training program using free weights, resistance bands or machines, preferably after taking a few lessons from a physical therapist or certified trainer.
> If you’re currently sedentary or have a serious chronic illness, check first with your doctor. But as soon as you get the go-ahead, start a strength-training program using free weights, resistance bands or machines, preferably after taking a few lessons from a physical therapist or certified trainer.