How to pull a hammy....

Warmup:
Learned Samson stretch
3x10 situps
3x10 back extensions
3x10 air squats

WOD: "Z-sprints & Air Squats"
Run z-sprints on field and 10 air squats at each end for time.

Did not finish this WOD due to a severe hamstring pull in my right leg. Not fun. Pretty frustrating for my first ever crossfit WOD.