For instance, beagle dogs that completed a 60 minute race (
at a leisurely
jogging speed of 5.6 mph) sustain a moderate CK increase of 2.5 fold (80 vs 240 u / L — still in the
normal range)(ref); whereas CK blood levels reached over 4,000 u / l after sled dogs ran 320 km in an Alaskan endurance race.