Horizontal forehead lines are caused by contraction of the frontalis muscle consistently over time both consciously and subconsciously.
In our younger years the movement of the muscle does not cause the skin to develop lines, as the skin just springs back. As our years progress these lines become permanent even when we are at rest.
By relaxing the muscles just enough to continue to make expression without severely contracting, we can begin to prevent further line formation and also in many cases, improve their appearance.
In order to effectively treat these lines it is necessary to also treat the depressor muscles in the glabella region. For more information see ‘11’ lines.