CHAPTER ONE
INTRODUCTION
1.1     Background to Study
Exercise has become a vital part of many women’s lives. Although many women still prefer to engage in exercise during pregnancy, they are concerned about the possible adverse effects.
The concerns about exercising during pregnancy relate to the dual stresses of pregnancy and exercise that might create conflicting physiological demands on the mother-to-be (Wiswell, 1996; Sternfeld, 1997). In contrast to the adaptations that occur during pregnancy, which are intended to nurture and protect the foetus, those that occur during exercise serve to maintain maternal homeostasis. Excessive physical activity during pregnancy may thus create conflicting maternal and foetal needs and may pose potential risks for the outcome of the pregnancy. On the other hand, the adaptations may complement each other and offer potential benefits (Sternfeld, 1997).
The physiological changes that occur during exercise include: redistribution of cardiac output away from the visceral circulation to the exercising muscles and skin, depletion of energy stores and an increase in body temperature (Clapp, 1996). In addition, several other potential risks have been described, including teratogenic effects as a result of exercise-induced hyperthermia, decreased carbohydrate availability for the foetus, redistribution of uterine blood flow with subsequent foetal hypoxia, increaseduterine contractility with a possible increase in the risk for preterm labour, infertility, abortion, congenitalmalformation,cordentanglement,placental separation, premature membrane rupture, growth restriction, foetal trauma, foetal bradycardia, difficultlabour, as well as maternal musculoskeletal injury (Clapp, 1996; Sternfeld, 1997; Stevenson, 1997; Clapp, 2000; Borg-Stein, Dugan & Gruber, 2005).
Exercise recommendations during pregnancy have evolved over the last several decades (Borg-Stein et al., 2005). Until the 20th century physical activity during pregnancy had been discouraged primarily because of theoretical concerns of exercise-induced injury and adverse foetal and maternal outcomes (Dempsey, Butler & Williams, 2005). Consequently many saw pregnancy as a state of confinement in which women were not encouraged to engage in recreational physical activity (Dempsey et al., 2005). Results from animal studies published before the 1970’s clearly supported these concerns, which led to a variety of restrictive regulations regarding exercise(Clapp, 1996; Dempsey et al., 2005). Women were instructed to limit their involvement in exercise and non-exercisers were told not to initiate exercise when pregnant (Borg-Stein et al., 2005). In contrast, research findings published since the 1970’s do not support these concerns (Clapp, 2000; Dempsey et al., 2005). In fact, findings of studies completed since 1985 have demonstrated no adverse maternal or foetal effects in healthy women engaged in mild and moderate exercise activities (Clapp, 1996; Henriksson-Larsen, 1999; Riemann &Kanstrup-Hansen, 2000; Dempsey et al., 2005;), but rather, showed somewhatfavourable effects (Wiswell, 1996; Sternfeld, 1997; Clapp, 2000; Frey, 2002). The influence of the past 30 years of research can clearly be seen in the significant changes of the American College ofObstetriciansandGynaecologists (ACOG) guidelines, published in 2003 (Committee on patient education of the ACOG, 2003). These guidelines recommend moderate exercise, 30 minutes or more per day, on most, if not all days of the week for women with low risk pregnancies.