2.3. Postpartum Exercise Intervention
Women in the intervention group participated in an ex- ercise program that provided exercise classes four times weekly for four weeks, 90 minutes each, at three months postpartum. In each class, approximately 10 women par- ticipated and two expert exercise instructors familiar with postpartum exercise ensured the validity of the exer- cise program. The exercise class included the following: 1) greeting and warm-up, (15 minutes); 2) aerobic exer-cise (50 - 60 minutes) where the participant sits and bounces on an exercise ball (Gymnic, Italy) measuring 55 cm or 65 cm in diameter; 3) rest, self-introduction or partner-up communication (5 minutes); and 4) muscular stretching and cool down (15 - 20 minutes).
The participants were able to attend the class either with or without their babies. If they attended the class with their babies, babies were laid down in the center of the circle formed by the participants, and the mothers were able to hold their babies, change their diaper or breast-fed the babies at any time. The exercise instructors regulated in a flexible manner the time allocated to the aerobic exercise and the stretching and cool down com- ponent varied in length according to abilities of the par- ticipants. During the exercise, each participant had a chance to communicate with other participants.