Straight from the source:
(American Academy of Dermatology)
http://www.aad.org/public/News/NewsReleases/stubborn.htm
Myth: Poor Hygiene Worsens Acne
The relationship between face washing and acne has always been greatly misunderstood, with most individuals believing that dirt and poor hygiene contribute to acne. In fact, a recent survey conducted at Stanford University asked participants about what they thought made acne worsen, and the majority, 91 percent, mentioned poor hygiene. ?If a patient believes that dirty skin causes acne, they logically conclude that washing their face more often will improve their acne,? said Dr. Boer Kimball. ?But dermatologists caution patients against washing too often, as the resulting irritation can exacerbate their acne.?
To determine the scientific validity of this myth, the effects of face washing on acne were recently studied at Stanford University. A group of twenty-four males washed their faces twice a day for two weeks using a mild over-the-counter facial cleanser. Then the participants were randomly selected to wash their faces either once, twice or four times a day for another six weeks. The study found that washing the face either once, twice or four times daily did not significantly change the appearance or condition of acne, and determined that the positive effects of increased facial cleansing are minimal at best. Dermatologists continue to recommend washing the face twice daily to maintain good overall skin health.
Myths: Exercise Can Clear Acne or Exercise Can Worsen Acne
The relationship between acne and exercise continues to show high levels of individual variability. Some believe that exercise and sweating can help clean out the pores, especially on the chest and back; while others note that their skin worsens when they exercise, especially those who use special equipment that rubs against their skin.
In another study conducted at Stanford University of patients with acne, it was determined that exercise-induced sweat does not have a significant positive or negative influence on acne of the chest and back. Twenty-three male participants were assigned to three groups: no exercise, regular exercise
followed by immediate showering and regular exercise followed by delayed showering. The number of acne lesions on the chest and back were counted over a two week period and no difference was noted between the three groups. ?Based on the finding of this study, regular exercise can be encouraged for patients with acne,? stated Dr. Boer Kimball. ?But they should avoid tight-fitting clothing and equipment. If tight-fitting equipment is required, it should be cleaned on a regular basis.?
Other Acne Myths
While misconceptions about facial hygiene and exercise are still the most commonly recognized acne beliefs, the Stanford survey also found that respondents believed that poor diet and decreased sleep can negatively affect acne. In addition, more than 80 percent of participants believed that increased stress, touching the face and popping pimples exacerbated the condition. Among male and female participants, the only differences noted were that more females believed that increased stress could worsen acne and that drinking more water would improve the quality of their skin. The study also found that some beliefs that were previously popular about acne were no longer viewed as true, including the idea that tanning improves the appearance of acne.