We all know that a lot of good things come from exercise that we can’t see. But even then, it was surprising to see a new study showing that our molecules — 9,815 of them in this instance — changed during exercise.

Stanford researchers and others took 36 men and women between the ages of 40 and 75 of widely varying fitness profiles. They were given blood draws and then ran on a treadmill as it kept getting faster until they had to stop. The typical session tended to take around nine or ten minutes.

Then more blood was drawn and more was taken later. We assume the subjects were quite sick of being poked by the end, but all that blood let the researchers look at the molecules of their body to see how they had changed after only a brief bout of exercise. And here is what they found, according to this article:

They wound up measuring the levels of 17,662 different molecules. Of these, 9,815 — or more than half — changed after exercise, compared to their levels before the workout. Some increased. Others declined. Some gushed immediately after the exercise, then fell away, while others lingered in heightened or lowered amounts for an hour after the workout. 

The types of molecules also ranged widely, with some involved in fueling and metabolism, others in immune response, tissue repair or appetite. And within those categories, molecular levels coursed and changed during the hour. Molecules likely to increase inflammation surged early, then dropped, for instance, replaced by others likely to help reduce inflammation.