1.1 BACKGROUND TO THE STUDY
In recent years, there has been a great increase of knowledge derived from scientific studies regarding physical exercise during pregnancy (Mason et al, 2010). This reflects the need to clarify their effects for mother and fetus, as some women of childbearing age report exercising and may continue their exercise practice during pregnancy, whereas other sedentary women may start this practice only during pregnancy. As the effects of healthy lifestyle are well known and supported by studies that show it is safe for both mother and fetus, physical exercise is recommended activity for pregnant women. The American College of Obstetricians and Gynecologists recommends that all healthy pregnant women follow the American College of Sports Medicine-Centers for Disease Control and Prevention’s general guidelines for physical exercise by engaging in 30 min or more of moderate physical activity per day in the majority or preferably all days of the week.Women who were active before pregnancy may continue their activities, but change intensity and frequency over the course of pregnancy.Other guidelines for physical exercise during pregnancy and the postpartum period have been published, such as the Canadian guidelines for exercise during pregnancy in 2003, and the recommendations of the Royal College of Obstetricians and Gynaecologists in 2006. Some researchers argue for the necessity of incorporating strength training and muscle conditioning, revising the definition of moderate exercise, and increasing the amount of vigorous intensity exercises and weekly physical activity expenditure. Aerobic exercise is recommended to maintain cardiovascular fitness and to help prevent chronic diseases, apart from avoiding excessive weight gain (Valim et al, 2011). They should involve large muscle groups in activities such as when walking or jogging, using stationary bicycle, treadmill, swimming, water aerobics exercises, aerobic dance, or low-impact aerobics. Regardless of the choice of activity, it is important that women find a modality of exercise to which they will adhere over the long term. Those exercises that increase the risk of falling, abdominal traumas and contacts sports should be contraindicated (Valim et al, 2011).
Recent recommendations add strength training to the routine exercise of pregnant women. They suggest that light strength training during second and third trimesters does not affect newborn size or overall health. These effects have been rarely studied, although many women looking for muscle conditioning during pregnancy think that practices such as Pilates and yoga, circuit-type resistance training, and weight training could be beneficial (Artal&O’Tolle, 2003). The possible benefits of increasing strength and stretching training are improvement in overall body strength, good posture and body core strengthening that may contribute in labor, birth, and prevent musculoskeletal discomforts. In addition, pelvic floor muscle strengthening is also an important component in pregnant women’s exercise. Routine exercise is required to reduce the prevalence of urinary incontinence. Nevertheless, there is little evidence-based literature concerning these practices, so it should be recommended to be careful when women plan to be engaged in these activities,mainly when starting only during pregnancy.
Attention should also be paid in avoiding exercise in supine position during the second half of pregnancy in order to prevent hypo-tension and avoid the Valsalva maneuver throughout the pregnancy. Previously, sedentary women should start with 15 min of exercise three times a week and gradually increase to 30 min four times a week at low-to moderate intensity. Active women may keep their routine exercise or perform at least moderate-to vigorous exercise four times a week in sessions of 30 min or more. Athletes or women who have higher fitness status should be evaluated individually. Some high impact activities or sports with fall or trauma risks should be avoided, and the intensity of exercise like running should be reduced. For all, brief warm-up and cool-down periods should be incorporated to each session of exercise.