Running only requires that you can move your legs in the functional range, so if you can run comfortably and without injury, there is no need to stretch.
However, warm up activities do prevent injury and improve performance, so time is best spent warming up the muscles rather than stretching before activity.
Should I stretch before or after running?
I recommend that you stretch after your run—or at least after a warm-up—when muscles are warm and more pliable. Warm up by walking or jogging slowly for five to 10 minutes–not by stretching “cold” muscles.
When should Runners stretch?
The dynamic warm up phase should take about 10-15 minutes. The issue then becomes, when to stretch? Recent research indicates that stretching before running may not be the best time because muscles are cold and therefore, not as elastic and may be more prone to injury if lengthened.
How important is stretching for runners?
Stretching Before Running
That leads to less force production, so your speed will go down.” When it comes to staying injury-free, functional range of motion is more important than flexibility. They also increase heart rate, body temperature, and blood flow so you feel warmed up sooner and run more efficiently.