In a previous post we discussed the 2020 USMS ePostal results, and hypothesized that declines in average distances swum by older age groups are caused by higher proportions of weaker swimmers participating in older age groups, rather than age based declines.

Every year US Masters Swimming runs an event called the 1 Hour ePostal. Rules are simple - athletes swim as many lengths of a 25 yard (or longer) swimming pool as possible in one hour, during the month of February, and without the aid of equipment beyond a legal suit and goggles.