Winter Sport Athletes

Abstract

Introduction: Diets of athletes often provide sub-optimal levels of energy, nutrients, and fluids. Most data originate from summer sports, whereas only limited data are available from winter sports. Altitude and cold are environmental extremes that can prevail under winter sport-specific conditions, possibly altering daily nutrient requirement (1). In the first part of this project, we compared energy, macronutrient, and fluid intake of male and female winter sport athletes, training in two different environments: non-specific (dry-land) and specific (on-snow/on-ice). In addition, we assessed changes in iron status and supplement use. Female athletes who restrict energy intake may jeopardize performance and health (2). Severe forms of energy restriction, such as disordered eating, can lead to amenorrhea and increase the risk for stress fractures and osteoporosis. This combination of disorders is known as the Female Athlete Triad (3) and was the focus of the second part of the project. Negative effects on the skeleton are a primary concern of the Triad. However, it is possible that unique loading patterns and the high proportion of lean tissue in winter sport athletes may preserve bone mass. We investigated this hypothesis in the female athletes. In the third part of the project, we compared body composition and bone mineral density (BMD, g/m2) of female and male athletes to non-athletes. We hypothesized that athletes have greater BMD values compared to non-athletes. Methods: Eighty-one athletes involved in long track speed skating, snowboarding, biathlon, freestyle skiing, bobsleigh, skeleton, and luge were initially recruited for the study. All athletes were in preparation for the 2002 Olympic Winter Games. Thirty-four athletes qualified for the Olympics and 9 won medals. Of the initial subject pool, 34 females (age: 26.2 ± 6.0yrs; ht: 1.66 ± 0.07m; wt: 63.2 ± 7.3kg) and 23 males (age: 25.8 ± 4.2yrs; ht: 1.78 ± 0.07m; wt: 76.6 ± 7.5kg) volunteered to participate in the first part of the study. Athletes filled out 3-day, weighed dietary and 24-hour activity records during training in two environments (non-specific and specific). Mean altitude and temperature were 1614 ± 375m and 25 ± 2°C for non-specific and 1921 ± 442m and -1 ± 9°C for specific environment. To assess changes in iron status (serum ferritin, total iron binding capacity, serum iron, transferrin saturation, complete blood count), venous blood was drawn at the beginning and end of the study. Supplement use was assessed by dietary records and questionnaire. The Female Athlete Triad was examined on the sub-clinical level. Energy balance was calculated using 6-day averages of energy intake and energy expenditure. Restrained eating was evaluated using the Three-Factor Eating Questionnaire (4), menstrual dysfunction by questionnaires evaluating history and status, and osteoporosis (lumbar spine, proximal femur) by Dual Energy X-ray Absorptiometry, DXA (Hologic, QDR-1000/W). Differences in body composition (fat mass, lean tissue mass, % body fat) and BMD (whole body, lumbar spine, proximal femur) between athletes (N = 79) and non-athletes (N = 40) were assessed by DXA (Hologic, QDR-1000/W). Comparisons were made for energy, macronutrient, fluid intake, and iron profiles using a dependent t-test and for body composition and BMD using an independent t-test. Significance levels were corrected for multiple comparisons. The prevalence of the Female Athlete Triad was evaluated based on defined criteria for each component. Athletes who presented with one or more components were counted and prevalence was calculated. Preliminary results will be presented at the 2002 IOC World Congress.