Hi Frederick – I also use the frontier during water sports so can give you my advice for what its worth (please note I have no affiliation with Fourth – I am simply another user) The 0.25 figure in red is showing you the MAX strain that was recorded during your workout session – the 0.01 blue figure is showing you the AVERAGE strain recorded. It is very common for the MAX strain to be higher (or lower) than the AVERAGE as it signifies a single moment in time as opposed to the average which is calculated across the whole duration of your session. That said, I also notice you have a significant percentage of ‘NOISY RHYTHM’ – I came across this a fair bit when first starting to wear the monitor – I made adjustments to ensure the strap was tight enough to prevent it wriggling about whilst I was in the water… maybe this could help you get more accurate results?
Just a few thoughts anyway and hope this helps.