A form of cross-country training originally from Sweden, but adapted to a city environment. Like traditional backcountry fartlek, stoplight fartlek involves changing the tempo of the run, except instead of instinctually changing pace, the speed is governed by traffic and lights.
"I thought I'd take a leisurely jog around the park, but it turned into a stoplight fartlek when I tried to ride a greenwave and dodge a couple buses."
by Harris Bergstein July 15, 2008