dynamic stretch front leg raise

hey, on the above stretch, should it be done with the leg perfectly straight all the time or like a kick?
thanks

Do it with the leg straight. You're only trying to stretch out the hip, so youo needn't bend the knee like you would for a kick.

I would say do what feels natural for you. In my experience with the stretch, I think it should be done closer to a kick. With the supporting leg slightly bent, and foot at a slight angle.

I keep my leg straight... but relaxed. Do you understand? I don't necessarily lock my knee.

Yes, don't lock the knee, keep it straight but not tensed. If you tense, you'll tense your hips too, which will hamper the stretch.

Like the others, I keep my knee straight but not locked.

I like to do the bend knee, than half straight knee, than straight knee. Seems to warm me up better like that.