Direct and indirect impact of low energy availability on sports performance

Low  energy  availability  (LEA)  occurs  inadvertently  and  purposefully  in  many  athletes  across  numerous  sports;  and  well  planned,  supervised  periods  with  moderate  LEA  can  improve  body  composition  and  power  to  weight  ratio  possibly enhancing performance in some sports. LEA however has the potential to have negative effects on a multitude of physiological and psychological systems in female and male athletes. Systems such as the endocrine, cardiovascular, metabolism,  reproductive,  immune,  mental  perception,  and  motivation  as  well  as behaviours can  all  be  impacted  by  severe  (serious  and/or  prolonged  or  chronic)  LEA. Such widely diverse effects can influence the health status, training adaptation, and performance outcomes of athletes, leading to both direct changes (e.g., decreased  strength  and  endurance)  as  well  as  indirect  changes  (e.g.,  reduced  training response, increased risk of injury) in performance. To date, performance implications have not been well examined relative to LEA. Therefore, the intent of this narrative review is to characterize the effects of short- , medium- , and long- term  exposure  to  LEA  on  direct  and  indirect  sports  performance  outcomes.  In  doing so, we have focused both on laboratory settings as well as descriptive athletic case- study- type experiential evidence.