In this post I will use two quotes from a recent blog post by James Steele II. Here is the first quote:
And my comment on it:
It is worse than that—muscles frequently not allowed to recover between workouts will be damaged, and this damage will turn to scar tissue, which eventually will be replaced with fat. This end result of muscle abuse is called fatty atrophy. Unlike the atrophy of disuse, the atrophy of abuse cannot be reversed.
The second quote:
Instead of a comment, a few facts and common observations. The facts and observations may at first seem disjointed, but eventually you should see a connection.
1. The glycolytic FT fibers (IIb) are the largest muscle fibers, which makes them structurally the weakest. (This is because their cell membranes and other structural elements are of the same thickness as in other, smaller fibers.)
2. It is long known that people with chronic back pain have a greater ratio of glycolytic FT fibers in their back muscles, which makes those muscles less resistant to fatigue (Biedermann et al. 1991, Mannion et al. 1997). Resistance to fatigue in back muscles—an ability to maintain steady moderate tension for a long time—is needed for those muscles’ back-stabilizing function.
3. Seriously overweight people tend to have massive leg muscles, especially calves, which usually look fat-free—so their size indicates the amount of muscle, not fluff. But when such people run or worse yet, sprint, those muscles tear—it works like clockwork—because they are made of mostly FT fibers. That’s why they are so big, and that’s why they tear so easily.
4. Muscles that are overworked are sore. Exercising them when they are still sore may damage them.
5. The weakest link in a chain determines the chain’s strength.
6. To find out when it is safe to do intense exercises (and for a sore calf, jogging and running are intense resistance exercises), press deep into the muscles to be exercised. You can poke them with your finger, you can roll on a hard roller, or you can get a deep-tissue massage. If you feel tenderness, then those muscles are not recovered sufficiently from the previous work. Change the subject of the workout. If you feel no tenderness in the muscles you plan to load, then it should be safe to do so. (Now, do you really know which muscles you are significantly loading in a given exercise? See point 8.)
7. To positively determine your readiness for intense work, use grip dynamometry or a similar holistic indicator of good neuromuscular function. How grip dynamometry is used for this purpose is described in Science of Sports Training.
8. To really know which muscles are significantly loaded and may be overworked in an exercise, check all your muscles every day for three days after the last workout with a specific exercise and note which are sore or tender. Don’t check just the “prime movers.” For example, if after heavy deadlifts the muscles around your shoulder blades are sore, then those are vulnerable to damage. If your thigh adductors or the arches of your feet are tender, then those are your weak links. If you want to get stronger, not weaker, you have to wait until these weak links are fully recovered.