The present study was designed as a prospective randomized clinical study with two parallel arms (Group I: AE, Group II: YE). Individuals without systemic or metabolic disease who were scanned using a 3-6 MHz transabdominal probe and a Mindray DC80 (USA) colour Doppler ultrasound device were included in this study. The primary outcome measure of our study was determined as the "Visual Analogue Scale (VAS)" score. Based on reference studies in the literature, the reduction in menstrual pain severity was predicted to be 2 units in one study group and 3 units in the other. Thus, in the two-way hypothesis test design, the sample size was calculated as 34 participants in total (17 participants per group), with 80% power and 5% type 1 margin of error. Considering a total 20% dropout rate, the final total sample size required was calculated as 44 individuals, with 22 individuals per study group.
Individuals were randomly assigned to 2 groups according to an online computer-generated (sealedenvelopeTM, Pocock 1983) block randomisation list. Menstrual pain, physical fitness parameters including cardiovascular fitness, muscle strength and endurance, and flexibility were evaluated with VAS, 6-minute walk test (6-MWT), quadriceps muscle strength ((Lafayette Instrument Company, Lafayette, Indiana), hand grip strength (Jamar® Plus, Paterson Medical, Green Bay, WI, USA), static and dynamic abdominal endurance test and sit-and-reach test, respectively.
All outcome measurements were performed before and after interventions (after the 2nd cycle). AE adjusted according to the Karvonen protocol (heart rate reserve percentage-% HRR) was applied to the first group for 8 weeks, 3 days a week, on a treadmill ergometer. Exercise intensity was adjusted according to weeks as follows: 30 min at 50% of HRR in weeks 0-2, 45 min at 50% of HRR in weeks 2-4, 45 min at 60% of HRR in weeks 4-6, and 60 min at 60% of KHR in weeks 6-8. YE including breathing and warming exercises, suryanamaskar, asanas, and various relaxation techniques was applied to the second group for 8 weeks, 3 days a week with the same duration as the first group. Since numerical characteristics did not show normal distribution, intergroup and intragroup differences were evaluated with nonparametric tests. For this purpose, aerobic and yoga groups were compared by Mann-Whitney U test. The Wilcoxon test was used in the analysis of within-group changes. A p-value less than 0.05 was considered to be statistically significant.