Exercise does not help to alleviate period pain, despite it being commonly recommended for women with monthly symptoms, say researchers.
A study of more than 650 university students reported in BJOG found 28% had moderate to severe period pain.
But Birmingham University researchers said they found no link with the amount of exercise the participants did.
GPs said women should be encouraged to do exercise regardless but drugs are available for those with period pain.
The study authors said beliefs about exercise being an effective treatment for bad period pain had persisted for years.
It is a common problem and people usually self-medicate
Professor Steve Field, Royal College of GPs
They carried out a questionnaire among 18 to 25-year-olds to find out what age they started their period, how often they had periods, what contraception they used, and whether they had children or had any conditions such as endometriosis or fibroids.
The students were also asked what type of exercise they did and how often as well as other general lifestyle questions.
Responses showed that 72% had no or very little period pain but 28% had moderate to severe pain with their monthly cycle.
After taking into account mood, ethnicity, weight, smoking, and use of the contraceptive pill, they found no link with how much exercise a woman did and whether she suffered from period pain, or how bad her pain was.
'Anecdotal beliefs'
Researcher, Dr Amanda Daley concluded that more research was needed before women are told that exercise will reduce of alleviate period pain.
"Anecdotal beliefs that exercise is an effective treatment have prevailed for many years and while it might seem intuitively appealing to promote exercise as a treatment for menstrual disorders, the findings from this study, along with many others, would not support such a view.
"Of course there are many other important health reasons for encouraging women to be physically active and exercise performed in moderation is unlikely to be harmful."
Royal College of GPs chairman Professor Steve Field said women with period pain should do what works for them and exercise might make them feel better in general.
"It is a common problem and people usually self-medicate.
"Some exercise is good for you of course but the main treatment for period pain is the contraceptive pill."
盡管建議有痛經的婦女做鍛煉,但是它對緩解痛經沒有幫助,研究人員說。
650多所大學學生的調查研究在BJOG上報告,發現28%的學生有中到重度的痛經。
但是伯明翰大學研究員說,他們發現參加者的痛經與所做的運動量沒有關聯。
醫生說,要不是經期疼痛,不管是否使用藥物,應該鼓勵婦女做鍛煉。
這項研究的創始人說,鍛煉是重度經期疼痛婦女有效治療的說法持續了數年。
他們完成了在1-25歲女孩中 "那是一個常見的問題做的一次問卷調查發現她們 而且人們通常自己月經的初潮年齡,月經 治療"
間隔時間,她們使用的避孕 皇家醫科醫師學院史蒂方法,以及她們是有孩子還 夫菲爾德教授
是處于像子宮內膜異位或子宮平滑肌瘤狀態。
學生們還被提問了她們所做鍛煉的方式以及多長時間鍛煉一次和其它的生活方式問題。
調查顯示,72%的學生沒有痛經或僅有輕微疼痛,但是28%的學生在經期,有中到重度疼痛。
把情緒,種族,體重,吸煙,和避孕藥的使用考慮在內之后,他們發現女性患痛經或她的疼痛的嚴重性與她們的運動量沒有關聯。
'軼事信仰'
研究員阿曼達達類做出結論,在通知女性運動將減少緩解經期疼痛之前,我們需要作更多的研究。
運動是一種有效的治療的軼事信仰已經盛行很多年,而且似乎是直觀地呼吁增加運動,作為一種月經不調治療,這種研究的調查結果以及其它的研究結果不支持這種觀點。
"當然還有許多其它重要的健康原因,鼓勵婦女進行中等量的體育體操活動對身體是不會有害的。"
皇家醫科醫師學院主任教授史蒂夫菲爾德說,經期疼痛的婦女應該做使她們總體上感到舒服的工作和運動。
"那是個常見問題而且人們通常自己治療。"
"當然有些運動有益于健康,但是痛經的主要治療是使用避孕藥。"