Relationship between energy deficits and body composition in elite female gymnasts and runners

Purpose: The purpose of this study was to evaluate energy balance and body composition in 42 gymnasts ((X) over bar age = 15.5 yr) and 20 runners ((X) over bar age = 26.6 yr), all of whom were on national teams or were nation ally ranked. Methods: Athletes were assessed for body composition using DEX A and skinfolds, and energy balance was determined with a Computerized Time -Line Energy Analysis (CTLEA) procedure. Results: Results from the CTLEA we re assessed as the number of within-day energy deficits (largest and freque ncy) and within-day energy surpluses (largest and frequency). There was a s ignificant difference (P = 0.000) in the (X) over bar number of hourly ener gy deficits > 300 kcal experienced by gymnasts (9.45 +/- 6.00) and runners (3.70 +/- 5.34). There was also a significant difference (P = 0.001) in the (X) over bar number of hourly energy surpluses > 300 kcal experienced by g ymnasts (1.40 +/- 3.04) and runners (6.20 +/- 5.50). The (X) over bar large st daily energy deficit was 743 (+/- 392) kcal for gymnasts and 435 (+/- 34 0) kcal for runners. The (X) over bar largest daily energy surplus was 239 (+/- 219) kcal for gymnasts, and 536 (+/- 340) kcal for runners. There was a significant relationship between the number of daily energy deficits > 30 0 kcal and DEXA-derived body fat percent for gymnasts (r = 0.508; P = 0.001 ) and for runners (r = 0.461; P = 0.041). There was also a negative relatio nship between the largest daily energy surplus and DEXA-derived body fat pe rcentage for gymnasts (r = -0.418; P = 0.003). Using the energy balance var iables, age, and athlete type (artistic gymnast, rhythmic gymnast, middle-d istance runner, long-distance runner) as independent variables in a forward stepwise regression analysis, a small but significant amount of variance w as explained in DEXA-derived (P = 0.000; R-2 = 0.309) and skinfold-derived (P = 0.000; R-2 = 0.298) body fat percent by the number of energy deficits > 300 kcal and age. Conclusions: These data suggest that within-day energy deficits (measured by frequency and/or magnitude of deficit) are associated with higher body fat percentage in both anaerobic and aerobic elite athlet es, possibly from an adaptive reduction in the REE. These data should disco urage athletes from following restrained or delayed eating patterns to achi eve a desired body composition.