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."