“…Purposeful sampling was carried out, selecting participants for their capacity to provide relevant information in response to the research questions [26]. The inclusion criteria consisted of: (a) nursing students enrolled in the University of Huelva (https://enfe.acentoweb.com/) during the study period, (b) PD: who acknowledged experiencing menstrual pain for which no underlying cause had been diagnosed [7,31], (c) suffering from menstrual pain at least once in the last six months, with at least three periods per year [7][8][9][10][11][12][13][14][15][16][17][18][19], (d) moderate-severe pain intensity based on the visual analogue scale (VAS equal to or greater than 4 out of 10 [8,32,33], (e) for at least the three cycles prior to the study [34,35], (f) with normal menstrual characteristics in terms of cycle length, duration of menstruation, quantity and regularity. Normal menstrual characteristics were considered to be periods occurring every 24 to 38 days, on a regular basis, with bleeding that lasts 4.5 to 8 days, and 5 to 80 mL blood loss per cycle [36][37][38], and (g) not being a candidate for requesting diagnostic tests due to suspicion of suffering secondary dysmenorrhea or any other diagnosed pelvic or gynaecological problem based on the recommendations of the Primary Dysmenorrhea Consensus Guideline of the Society of Obstetricians and Gynaecologists of Canada and the Committee Opinion on Adolescent Health Care Dysmenorrhea and Endometriosis in the Adolescent developed by the American College of Obstetricians and Gynecologists [5,34,39].…”