Assessment of the range of energy availabilities and the prevalence of low energy availability among female endurance athletes

Research indicates that energy availability below 30 kcal•kg FFM-1•day-1 suppresses reproductive hormones and markers of bone formation while energy balance is hypothesized to occur at an energy availability of 45 kcal•kg FFM-1•day-1. Nonetheless, available evidence suggests that few female athletes achieve energy availabilities of 45 kcal•kg FFM-1•day-1 and little is known about the effects of energy availabilities between 30 and 45 kcal•kg FFM-1•day-1. This study examined the range of energy availabilities and the prevalence of low energy availability (currently defined as ? 30 kcal•kg-1 FFM•day-1) among female endurance athletes. Subjects were 40 female endurance athletes from the Salt Lake City area. Dietary patterns and eating behaviors were assessed by a health, weight, dieting, and eating patterns questionnaire. Energy availability was assessed via 3-day diet and activity records designed to capture three distinct training days (heavy, moderate and easy). Exercise energy expenditure was calculated using the Ainsworth Compendium For Physical Activity. Energy availability for the sample ranged from 7.6 to 54.1 kcal•kg-1 FFM•day-1 with a mean of 27.8 kcal•kg- 1 FFM•day-1. The majority of subjects (62.5%) (n=26) of subjects had an energy availability ? 30 kcal•kg-1 FFM•day-1, while only 5.0% (n=2) of subjects had an energy availability ? 45 kcal•kg-1 FFM•day-1. Those athletes with energy availabilities ? 30 kcal•kg-1 FFM•day-1 did not demonstrate a greater incidence of stress fractures or menstrual dysfunction. These preliminary data indicate that endurance athletes routinely demonstrate energy availabilities below the "optimal range", and that low energy availability is not predictive of menstrual function or bone health.