Paul Ingraham of PainScience is a science-journalist and has an SBM or science-based medicine approach to all-things massage therapy related.  This is one of his most popular articles – it has been a rather controversial one.  The article suggests that it isn’t the epsom salt that is helping your sore muscles, but rather the warm water you’re sitting in!

https://www.painscience.com/articles/epsom-salts.php