Some of the biggest news in exercise science this year concerned the tiniest impacts from physical activity, which does not mean that the impacts were inconsequential. It means they were microscopic.

We learned this year, for instance, that exercise changes how our cells communicate with one another, as well as how rapidly they age. This new research began to detail the many, pervasive ways in which working out alters the inner workings of our bodies and contributes to better health.

There were other, broader themes, too, in 2018’s fitness-related science, including about how older people can be enviably youthful if they are active and the unexpected roles that weight training may play in our health.

But for me, the most exciting exercise research in 2018 went small. A study that I wrote about in January, for instance, found that people’s blood contained more of certain vesicles, which are tiny bubbles filled with biological material, after aerobic exercise.