Poor Agreement Between Cunningham Equation Using DXA Body Composition And Indirect Calorimetry In Female Athletes

Predicting female athletes’ resting energy expenditure (REE) is common practice to prescribe energy requirements. The Cunningham equation (CeREE) is used to predict REE using measured fat-free mass (FFM). Dual-energy x-ray absorptiometry (DXA) measures FFM, however, it is unknown the difference and agreement between CeREE values using DXA-measured FFM and measured REE (mREE) via indirect calorimetry. PURPOSE: Determine the difference and agreement between CeREE using DXA-measured FFM and mREE in collegiate female athletes. METHODS: 38 female athletes from a single Division 1-A University and 8 sports completed the study. Indirect calorimetry (ParvoMedics) mREE (kcal/d) and DXA (GE) were completed within 14 days of each other. Paired t-test was used to determine the difference between mREE and CeREE (REE [kcal/d] = 500 + 22 FFM[kg]) and agreement was assessed with Bland-Altman analysis. This analysis assessed the correlation between the mean of REE measures and the difference between CeREE and mREE values. Non-significant correlation indicates no bias in CeREE across the range of REE. Statistical significance was set at p ≤ 0.05. RESULTS: Mean body weight was 69.3 ± 9.2 kg [50.8-97.7 kg] and percent body fat percent was 25.6 ± 5.6% [12.8-39.4%]. CeREE (1624 ± 117 kcal/d) was not different (p = 0.892) from mREE (1617 ± 345 kcal/d). However, bias was detected (r = -0.842, p < 0.001) (see figure) and suggested CeREE overestimated REE at lower REE values and underestimated REE at higher REE values. CONCLUSIONS: While there was no difference between CeREE and mREE, bias indicates poor agreement and potentially clinically relevant differences across the range of REE in this sample of female athletes. Therefore, caution may be warranted when using CeREE with DXA-measured FFM on collegiate female athlete populations to prevent over-/under-prescribing energy requirements. However, further research with a larger sample size is needed to confirm preliminary findings.