The relationship between body composition components, risk for disordered eating and irregular menstrual patterns among long-distance athletes
Prinsloo, Judith Cecilia
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In distance running specifically, a lean body appearance is emphasized as optimum for performance (Greydanus & Patel, 2002). In order to obtain or keep this leaner body, many athletes lower their energy intake and which, in addition to a demanding exercise schedule, consequently creates an energy deficit (Byrne & Mclean, 2001; Warren & Perloth, 2001; Goodman & Warren, 2005; Waldrop, 2005). Energy deficiency ultimately leads to amenorrhea and lowered bone density (Loucks & Heath, 1994; Van de Loo & Johnson, 1995; Sanborn et a/., 2000). Recently, however, the American College of Sports Medicine Position Stand accentuated that low energy availability with or without an eating disorder disrupts normal menstrual function (ACSM, 2007:1868). Thus low energy availability may be inadvertent, intentional or psychopathological (ACSM; 2007:1867). Studies have made contributions to the field of physical science by studying the prevalence of menstrual irregularities and disordered eating amongst athletes, but none have focused on the black South African female athlete, which makes this study unique, Consequently the first purpose of this study was to determine the prevalence of energy availability, menstrual irregularity and risk for disordered eating in a group of black South African runners. Descriptive measures were calculated. Effect sizes were also determined (Ellis & Steyn, 2003); where practical significance can be understood as a large enough difference to have an effect in practice. Mean energy availability for the group was 124.16 ± 94.93 kJ/kgLBM/day. Four of the thirty-two athletes (12.5%) reported menstrual irregularities. 40.6% reported risk for disordered eating. It was found that mean energy availability is not low in this group of athletes, but both menstrual irregularity and risk for disordered eating was prevalent. The second purpose of this study was to assess menstrual status and its association with body composition and energy availability among this group of black South African runners. Subjects were grouped in terms of energy intake, energy output, energy availability, menstrual status and risk for disordered eating, where descriptive measures were calculated. Because this was an availability study, p-values were not applicable and effect sizes were calculated to determine whether any of the differences were practically significant. Percentage body fat and energy expenditure had a visible effect (both effect sizes = 0.46) on menstrual regularity, but a practically significant relationship emerged between energy intake and energy availability (effect sizes = 0.84 and 1.01 respectively) and menstrual regularity. Energy intake differed significantly between the regular (9793 ± 3504) and irregular groups (6862 ± 1906) with an effect size of 0.84. The energy availability differed significantly between the regular (146 ± 93 kJ/kgLBM/day) and irregular (44 ± 60 kJ/kgLBM/day) groups (effect size = 1.01). It was found that menstrual regularity had a significant relationship with both energy intake and energy availability.
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