You should always stretch before exercise. Stretching a healthy muscle before exercise does not prevent
injury or soreness.
For many years there has been importance placed on stretching before exercise. However recent expert opinion has moved away from static stretching before activity and toward a gradual and active warm-up period before exercise which ideally mimics the activity you are about to do, but is performed at a lighter load and slower pace.
Do a short warm-up to get the blood flowing to your major muscle groups and to loosen your joints.