Exercise generates immune cells in bone

A casual stroll through Wikipedia on the topics of health quickly teaches that exercise is connected to well-being of pretty much every system of the body. Including that it has anti-inflammatory effect because muscle secretes some stuff to that end, when working.

Considering that human's advantage in open-savanna hunting over animals was that humans could run steadily for dozens of kilometers without overheating, thanks to lack of fur and hence to effective sweating—I keep wondering just how much daily movement is ‘normal’ for the body. Because it sounds like we all have severely sedentary lifestyle, by prehistoric standards.

Bones are basically glands you can strengthen directly.

Why are immune / stem cell papers usually analyzing the %-ages of cells? To effect a physiological change, the total number of cells ought to matter more than their ratios. Are the totals constant (I do not believe so)?

I remember reading something where someone was thinking you could build bone mass by standing on a vibrating platform.