Regarding Skipping For Boxing?

Hi, I recently bought a skipping rope to get back in shape.My problem is that my arms will burn and tire out long before I do. I used to skip and this never happend, its mostly my deltoids and they are in good shape. When i step on the rope with one foot the two sides of the rope reach around my arm pits. I tried multiple variations of lengths around this recommended measurment. Still nothing changed, i mean i can do double skip ,cross and other kidns of skipping so im not an amatuer. Please if anyone has advice i would really appreciate it. I tried tucking my elbows in, using my wrists, forearmsn, wrists + forearms still no success. This is really frustrating because it's getting in the way of my workouts.10 points