Typical operation: you want to compare today's workout with one from a couple of months ago. The Start date doesn't go back far enough so you change it and click Filter. This gives you a long list from which to chose so you decide to do a Search. You enter whatever criteria you want and click Search. You would expect it to search among the displayed workouts but it doesn't. The Start and End dates have reverted back to default.
I would suggest that the Search button should simply search workouts for whatever dates are currently entered in the Start and End date fields.