To analyze the effect of regular physical activities on the back pain of pregnants, a guasi - experimental and field method were used of all pregnants referring to the prenatal clinics of Qom province, 40 women (20 in the 2nd and also another 20 in the 3rd trimester) were selected and divided to test and control groups. At the beginning and at the end of the program, all participants completed the Quebec back pain questionnaire, while a special training program with a heart rate of 50-65% of maximal was applied for a period of 2 months for the test group. Analysis showed a significant reduction of back pain in test group of pregnants in the 2nd trimester (P<0.05).
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