There is an interesting article about fascia in this month’s issue of New Scientist (unfortunately there is a paywall, but you can get a free subscription for three months, which I highly recommend because there are lots of good articles in the magazine). These are connective tissues throughout our bodies, for example, all of our muscles are encased in them. I first learned about fascia from Yoga teachers who claimed one of the roles of stretching in keeping our bodies supple as we age is keeping our fascia from stiffening up. There is a good discussion of stretching in another New Scientist article here.
There has been some backlash against stretching recently. Previously it was thought to be useful for warming up for exercise, but stretching cold muscles is controversial. Also, there is some evidence that athletic performance actually decreases after stretching. But to me, performance has never been the most important reason for stretching. It is to remain limber as I age, and it has worked well for that. I always stretch at night when my muscles are warm. And now we know at least part of the reason is keeping fascia from tightening up with age. A study mentioned in the article also showed that stretching reduces inflammation. This is important because some conditions such as fibromyalgia and some types of back pain are now thought to be related to inflamed fascia.
I also learned from the article about a more recent finding that fascia may play an important communication role in the body- they actually have at least as many nerves as our skin does and are referred to as a “hidden neural network”.
The article concludes that fascia has not received enough attention in medical research up till now, but that will hopefully change as word of its importance gets out.