question: Why does building muscle cause stretch marks?
comment: stretch mark is literal. It's a mark you get when your skin stretches. getting muscles that are bigger than the ones you had before makes your skin stretch
passages: A number of additional factors appear to promote the appearance of stretchmarks: one study of 324 women, done just after they had given birth, demonstrated that low maternal age, high body mass index, weight gain over 15 kg (33 pounds) and higher neonatal birth weight were independently correlated with the occurrence of striae. Teenagers were found to be at the highest risk of developing severe striae.
   Examples of cases where stretch marks are common, also given by the Mayo Clinic, include weight gain (in the form of fat and/or muscle), pregnancy, and adolescent growth spurts, though it is also noted that some medications, as well as other medical conditions and diseases, may increase the likelihood of stretch marks appearing. In the case of medication, the Clinic points to "Corticosteroid creams, lotions and pills and chronic use of oral or systemic steroids" as a common contributing factor; in the case of medical conditions that can contribute to stretch marks, examples given include Ehlers-Danlos syndrome, Cushing's syndrome, Marfan syndrome, and "adrenal gland diseases".
   Striae, or "stretch marks", begin as reddish or purple lesions, which can appear anywhere on the body, but are most likely to appear in places where larger amounts of fat are stored; the most common places are the abdomen (especially near the navel), breasts, upper arms, underarms, back, thighs (both inner and outer), hips, and buttocks. Over time, they tend to atrophy and lose pigmentation. The affected areas appear empty, and are soft to the touch.
   Mechanical distension and rapidly developing areas of the body during pregnancy (such as the abdomen, breasts, and thighs) are most commonly associated with striae formation. Some have suggested that relaxin and estrogen combined with higher levels of cortisol during pregnancy can cause an accumulation of muocopolysaccharides, which increases water absorption of connective tissue, making it prime for tearing under mechanical stress. There also seems to be an association between higher body mass indices and in women with bigger babies and the incidence and severity of striae. Also, younger women seem to be at higher risk of developing striae during pregnancy.
   Section::::Prevention.
  
  A systematic review has not found evidence that creams and oils are useful for preventing or reducing stretch marks in pregnancy. The safety in pregnancy of one ingredient, Centella asiatica, has been questioned. Evidence on treatments for reducing the appearance of the scars after pregnancy is limited.
  
  Section::::Treatment.
  
  There are no clearly useful treatments for stretch marks, although there are many different suggestions on how to remove them or lessen their appearance.
   Stretch marks occur in the dermis, the resilient middle tissue layer that helps the skin retain its shape. No stretch marks will form as long as there is support within the dermis; stretching plays a role in where the marks occur and in what direction they run, however, there are a number of contributing factors (see: "Causes", below) to their formation.
   The prevalence and severity of striae gravidarum varies among populations. The current literature suggest that in the general population of the US, there is a 50%-90% prevalence of striae associated with pregnancy, partly as a result of the normal hormonal changes of pregnancy and partly due to stretching of skin fibers. Many women experience striae gravidarum during their first pregnancy. Nearly 45% percent of women develop striae gravidarum before 24 weeks of gestation. Many women who develop lesions during the first pregnancy do not develop them during later pregnancies. Genetic factors such as family history and race also seem to be predictive in the appearance of striae.
   Various efforts that have been tried including laser treatments, glycolic acid, and microdermabrasion. Topical tretinoin is categorized by the FDA as a known teratogen (causing malformations in fetuses) in animals, without adequate human studies on safety in pregnancy.
  
  Carboxytherapy is a known procedure; however, there is a lack of evidence to support how effective it is.
  
  Section::::History.
  
  Since ancient times, pregnant women have sought remedies to prevent stretch marks during pregnancy. Both ancient Greeks and Romans used olive oil, while Ethiopians and Somalis used frankincense.
  
  Section::::Terminology.
   Stretch marks (technically called "striae") are also a form of scarring. These are caused when the skin is stretched rapidly (for instance during pregnancy, significant weight gain, or adolescent growth spurts), or when skin is put under tension during the healing process, (usually near joints). This type of scar usually improves in appearance after a few years.
  
  Elevated corticosteroid levels are implicated in striae development.
  
  Section::::Types.:Umbilical.
   Stretch marks are caused by tearing of the dermis. This is often from the rapid stretching of the skin associated with rapid growth or rapid weight changes. Stretch marks may also be influenced by hormonal changes associated with puberty, pregnancy, bodybuilding, or hormone replacement therapy.
  
  There is no evidence that creams used during pregnancy prevent stretch marks. Once they have formed there is no clearly effective treatment, though various methods have been attempted and studied.
  
  Section::::Signs and symptoms.
   Striae gravidarum (pregnancy-related stretch marks) occur in 50% to 90% of women, and are caused both by the skin stretching and by the effects of hormonal changes on fibers in the skin. They are more common in younger women, women of color, women having larger babies and women who are overweight or obese, and they sometimes run in families. Stretch marks generally begin as red or purple stripes (striae rubra), fading to pale or flesh-color (striae alba) after pregnancy that will generally be permanent. They appear most commonly on the abdomen, breasts, buttocks, thighs, and arms, and may cause itching and discomfort. Although several kinds of multi-component creams are marketed and used, along with vitamin E cream, cocoa butter, almond oil and olive oil, none have been shown to prevent or reduce stretch marks in pregnancy. The safety for use in pregnancy of one herbal ingredient used in some products, Centella asiatica, has been questioned. Some treatments used to reduce scarring, such as topical tretinoin lasers, are sometimes used on stretch marks, but evidence on them is limited. Topical tretinoin has been shown to cause malformations in animals, without adequate human studies on safety in human pregnancies.
   Section::::Causes.:Pregnancy.
  
  Pregnancy stretch marks, also known as striae gravidarum, is a specific form of scarring of the skin of the abdominal area due to rapid expansion of the uterus as well as sudden weight gain during pregnancy. About 90% of women are affected.
   They were originally mapped by Iberall by drawing a series of circles over a portion of the body and then watching their deformations as the wearer walked around or performed various tasks. The circles deform into ellipses as the skin stretches over the moving musculature, and these deformations were recorded. After a huge number of such measurements the data is then examined to find all of the possible deformations of the circles, and more importantly, the non-moving points on them where the original circle and the deformed ellipse intersect (at four points per circle). By mapping these points over the entire body, a series of lines are produced.
   They can (but do not always) cause a burning and itching sensation, as well as emotional distress. They pose no health risk in and of themselves, and do not compromise the body's ability to function normally and repair itself, however, they are often considered a cosmetic nuisance. Young women are generally affected the most and often seek treatment for them from a dermatologist and following pregnancy.
  
  Section::::Causes.
  
  Stretch marks appear to be caused by stretching of the skin. This is especially true when there is an increase in cortisone.
   Section::::Non-specific stress indicators.:Skeletal non-specific stress indicators.:Harris lines.
  
  Harris lines form before adulthood, when bone growth is temporarily halted or slowed down due to some sort of stress (either disease or malnutrition). During this time, bone mineralization continues, but growth does not, or does so at very reduced levels. If and when the stressor is overcome, bone growth will resume, resulting in a line of increased mineral density that will be visible in a radiograph. If there is not recovery from the stressor, no line will be formed.
  
  Section::::Non-specific stress indicators.:Hair.
   Section::::Muscle expansion.
  
  Muscle tissue may also expand and grow, in a process known as stretch-induced myofibrillogenesis.
  
  Section::::Tissue inflammation.
   Lines of non-extension
  
  In the field of biomechanics, the lines of non-extension are notional lines running across the human body along which body movement causes neither stretching or contraction. Discovered by Arthur Iberall in work beginning in the 1940s, as part of research into space suit design, they have been further developed by Dava Newman in the development of the Space Activity Suit.
   In pretreatment samples, the zone of collagen shows a dense accumulation of elastin, but in posttreatment samples, this zone contains less dense elastin with significant, interlocking new collagen. Repeated low-energy PSR treatment is an effective modality for improving dyspigmentation, smoothness, and skin laxity associated with photoaging. Histologic analysis of posttreatment samples confirms the production of new collagen and remodeling of dermal architecture. Changes consist of erythema and superficial epidermal peeling without complete removal, generally complete by 4 to 5 days.
  
  Section::::Plasma medicine.
  
  Section::::Plasma medicine.:Dental treatments.
   Growth and remodeling have a major role in the cause of some common soft tissue diseases, like arterial stenosis and aneurisms and any soft tissue fibrosis. Other instance of tissue remodeling is the thickening of the cardiac muscle in response to the growth of blood pressure detected by the arterial wall.
  
  Section::::Imaging techniques.
   BULLET::::- Stage 2: Swelling is not reversible overnight, and does not disappear without proper management. The tissue now has a spongy consistency and is considered non-pitting: when pressed by the fingertips, the affected area bounces back without indentation. Fibrosis found in Stage 2 lymphedema marks the beginning of the hardening of the limbs and increasing size.
   Section::::Types.:Atrophic.
  
  An atrophic scar takes the form of a sunken recess in the skin, which has a pitted appearance. These are caused when underlying structures supporting the skin, such as fat or muscle, are lost. This type of scarring is often associated with acne, chickenpox, other diseases (especially "Staphylococcus" infection), surgery, certain insect and spider bites, or accidents. It can also be caused by a genetic connective tissue disorder, such as Ehlers–Danlos syndrome.
  
  Section::::Types.:Stretch marks.
   BULLET::::- Loeys–Dietz syndrome
  
  BULLET::::- Marfan syndrome
  
  BULLET::::- Occipital horn syndrome
  
  BULLET::::- Osteogenesis imperfecta (Lobstein syndrome)
  
  BULLET::::- Perforating calcific elastosis (localized acquired cutaneous pseudoxanthoma elasticum, perforating periumbilical calcific elastosis, periumbilical perforating pseudoxanthoma elasticum)
  
  BULLET::::- Pseudoxanthoma elasticum (Grönblad–Strandberg syndrome)
  
  BULLET::::- Reactive perforating collagenosis
  
  BULLET::::- Schweninger–Buzzi anetoderma
  
  BULLET::::- Sclerotic fibroma
  
  BULLET::::- Striae atrophicans
  
  BULLET::::- Striae distensae
  
  BULLET::::- Ullrich disease
  
  BULLET::::- Verrucous perforating collagenoma
  
  BULLET::::- Wrinkly skin syndrome
  
  Section::::Dermal and subcutaneous growths.
  
  Dermal and subcutaneous growths result from (1) reactive or neoplastic proliferation of cellular components of the dermis or subcutaneous tissue, or (2) neoplasms invading or aberrantly present in the dermis.
   Because it is used for so many movements and is in a shortened position when seated, the TFL becomes tight easily. TFL stretches lengthen this important muscle.
  
  Section::::Clinical significance.:Strain.
  
  A small case notes that “it seems possible that a sloped or banked surface could predispose an individual to a TFL strain.” In such a case, “treatment usually consists of rest, heat, and flexibility exercises”, such as lliotibial band stretching.
  
  Section::::Etymology.
   The reticular region lies deep in the papillary region and is usually much thicker. It is composed of dense irregular connective tissue, and receives its name from the dense concentration of collagenous, elastic, and reticular fibers that weave throughout it. These protein fibers give the dermis its properties of strength, extensibility, and elasticity.
  
  Also located within the reticular region are the roots of the hairs, sebaceous glands, sweat glands, receptors, nails, and blood vessels.
  
  Tattoo ink is held in the dermis. Stretch marks often from pregnancy and obesity, are also located in the dermis.
  
  Section::::Structure.:Subcutaneous tissue.
   In other words, an increase in cortisone levels can increase the probability or severity of stretch marks by reducing the skin's pliability; more specifically, it affects the dermis by preventing the fibroblasts from forming collagen and elastin fibers, necessary to keep rapidly growing skin taut. This can create a lack of supportive material as the skin is stretched, and lead to dermal and epidermal tearing, which in turn can produce scarring in the form of stretch marks. This is particularly the case when there is new tissue growth (which can interfere with the underlying physical support of the dermis or epidermis, by displacing the supportive tissue).
  
raw_presuppositions: Building muscle shouldn't cause stretch marks.
raw_corrections: Building muscle makes skin larger so it needs to stretch and have stretch marks. 