In short. A line that appears only on movement answers to the muscle that makes it, and that is a different problem from a line that stays at rest. Why that matters.
Key points
- Relax your face completely for a few seconds, then look at the area in a mirror.
- A line that has gone is being produced by muscle alone.
- A line still visible at rest has something set in the skin or beneath it, and that part will not be changed by relaxing the muscle.
A line that appears only when you move your face is a mechanical event. A muscle under the skin contracts, the skin above it folds along a fixed path, and when the muscle releases the fold disappears. Everything about that kind of line follows from the muscle.
The same path, thousands of times
Each person's expressions use the same muscles along the same lines, day after day. The skin therefore folds in exactly the same places rather than randomly. That is why expression lines are symmetrical and why they appear where they do.
Why a line starts to stay
Young skin springs back completely after a fold. Two things change that. The dermis thins with age and with sun exposure, so it recovers less fully each time, and the repeated folding itself leaves a memory in the tissue. At some point a line that vanished at rest begins to remain faintly, and later becomes a permanent crease. From then on the line has two contributors rather than one.
The observation that separates them
Relax your face completely for a few seconds, then look at the area in a mirror. A line that has gone is being produced by muscle alone. A line still visible at rest has something set in the skin or beneath it, and that part will not be changed by relaxing the muscle. Both can be present in the same crease at the same time.
Which lines behave this way
The creases beside the eyes that appear with a smile, the horizontal lines across the forehead that deepen when the brows lift, and the vertical lines between the brows that appear with a frown are the classic movement lines.
What this contributor does not explain
It does not explain a fine mesh across the cheeks, lines under the eyes that worsen with fatigue, or folds that follow the shape of a face that has lost volume. Those have other causes, and treating them by relaxing a muscle addresses a contributor that may not be present. This is the commonest mismatch in facial treatment, and it costs money without producing a result.
Why movement lines are the least worrying kind
Because they are a normal feature of a face that moves, and they say nothing about health. A face with expression lines at forty is a face that has smiled, frowned and squinted for forty years. Whether to treat them is a question about preference rather than necessity.
When a change in the face is not a line
- A fold or droop that appeared suddenly, or on one side only, especially with weakness or difficulty speaking.
- Numbness, tingling or altered sensation in the face.
- A severe new headache, double vision or a change in vision alongside a facial change.
What produces a line that is still there when the face is at rest is set out in Static Lines Come From Collagen, Hydration and Sun. How the two are told apart at an assessment is described in How Fine Lines Are Assessed.
Frequently asked questions
Why does a line stay after I stop smiling?
Because the fold has become set in the skin as well as in the movement. Early on, the skin springs back completely. Over years, repeated folding along the same path, combined with the collagen loss that comes with age and sun, means the crease no longer fully recovers. At that point the line has two contributors and the muscle is only one of them.
Does relaxing the muscle remove the line?
It removes the movement component and leaves whatever is set in the skin. On a face where the line is mostly produced by movement, that difference is substantial. On a face where the line is deeply set, the movement is reduced and the line remains visible at rest. That is not a failure; it is what treating one contributor of two looks like.
Can I train myself to stop making the expressions?
People try this, and it rarely holds, because the expressions are involuntary and partly social. Consciously suppressing a frown or a smile for a few hours a day does not remove the movement over a lifetime, and the effort is usually abandoned within weeks. It also does nothing for the collagen and sun contributors, which continue regardless.
Risks & Limitations
- None of these treatments stops the underlying ageing. Lines are softened and that softening is maintained, and they return as the tissue continues to age.
- Relaxing a muscle addresses movement only and does nothing for a line set in the skin at rest. Resurfacing addresses the skin and nothing for the muscle that folds it. Volume addresses lost support and nothing for either.
- Resurfacing and energy-based sessions carry downtime and a risk of pigment change that is greater in deeper skin tones. Injectables carry risks that depend on the area treated and on the person placing them.
- Sun protection is the only step with a long-term effect on how lines progress, and it reduces further damage rather than reversing what has already happened.
When to Seek Care
- A fold or droop that appeared suddenly, or on one side only, especially with weakness or difficulty speaking — emergency care.
- Numbness, tingling or altered sensation in the face — seek medical assessment before any cosmetic plan.
- A patch that is red, scaly, sore, changing or failing to heal — have it diagnosed rather than treated.
- Widespread wrinkling that developed over months, or with weight loss, fatigue or a new medicine — seek medical assessment.
References & Further Reading
- American Society of Plastic Surgeons (ASPS) — procedure and safety guidance
- National Institute for Health and Care Excellence (NICE, UK) — relevant guidance
- Cochrane Library — systematic reviews
- Chinese Medical Association Plastic Surgery Branch — clinical guidance
This page is patient education, not medical advice, and it does not cite individual studies. Discuss your own case with a qualified clinician. To arrange an assessment at Chongqing West District Hospital, see Contact & Consultation.