Something I learned recently that I anecdotally believe based on my own experience is that synthetics get smellier faster, trap body odor and enable some types of odor producing bacteria to grow better than most natural fibers which I found interesting as all the exercise materials that are marketed as breathing better are synthetic or blends. I am not certain if there is a specific way to clean these materials to to avoid that but I have always found that if anything starts to smell ensuring that I hang it outside and let the UV go to work always helps but I am in Australia so our UV punches above many other parts of the world from what I have been told.