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High levels of cognitive dietary restraint are associated with stress fractures in women runners

University of British Columbia

Societal emphasis on body image and the 'ideal' body weight drives many women to make conscious efforts to limit their food intake in order to achieve or maintain a desired body weight. This attitude and eating behaviour is characterized by a preoccupation with food-related issues, and is referred to as dietary restraint or cognitive dietary restraint (CDR). The most commonly used instrument to measure and assess this dietary restraint is the restraint scale of the Three-Factor Eating Questionnaire (TFEQ). Female athletes are faced with body image challenges, as well as trying to achieve a body weight that is optimal for their performance. Many female athletes could therefore be experiencing these restrained eating patterns, to meet the combined pressures of an 'ideal body1 and enhanced performance. Most previous studies have generally found similar physical characteristics and energy intakes among women with differing restraint scores. However, CDR has been associated with subclinical menstrual cycle irregularities (MCI) and increased Cortisol levels, both of which can affect bone mineral density (BMD). Preliminary evidence has also reported an association between CDR and BMD or bone mineral content (BMC). Low BMD has been implicated in stress fracture risk, and runners are particularly at risk for lower extremity stress fractures. The purpose of this investigation was to assess CDR in female runners with a recent stress fracture (SF) and without a history of stress fracture (NSF). We recruited nulliparous normal-weight runners (running >20 km/wk) who were non-smokers, had regular menstrual cycles, were not currently dieting and had no history of an eating disorder. A sample of 79 runners (n = 38 SF, 29±5 yr; n = 41 NSF, 29±6 yr) completed a 3-day food record and questionnaire assessing physical activity, menstrual cycle history and perceived stress. The TFEQ was used to assess eating attitudes and behaviours, including CDR. SF and NSF runners had similar body mass index (21.2±1.8 vs 22.0±2.5 kg/m²), physical activity (35.7±13.5 vs 33.4±1.34 km/wk), perceived stress, and energy and macronutrient intakes. However, CDR was significantly higher in SF runners (11±5.4 vs 8.4±4.3, p<0.05). We conclude that women runners with a history of recent SF have higher levels of CDR. Subclinical MCI and increased Cortisol levels associated with high CDR may contribute to lowered BMD and increased risk for stress fracture. Prospective studies that include measurements of menstrual cycle characteristics, Cortisol levels and BMD are needed to determine if CDR is an independent risk factor for stress fractures, mediated by subclinical MCI and elevated Cortisol with subsequent bone loss.

Thesis/Dissertation

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2009-11-18

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http://hdl.handle.net/2429/15281

Human Nutrition

University of British Columbia

UBCV

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