Pace
From Openwaterpedia
noun - Pace is the rate of speed at which a swimmer swims, especially relative to time or other competitions in a pool or an open water swimming race.
The young woman's pace was quicker than the veteran swimmer during the second half of the race.
Origin
Middle English, from Old French pas, from Latin passus, from past participle of pandere, to stretch, spread out; see pet- in Indo-European roots.