Abstract
Diet quality indices are a practical and inexpensive way to evaluate dietary patterns and adherence to nutrition guidelines. While the diet quality of athletes has been reported using population
indices, there is currently no reliable athlete-specific diet index.
PURPOSE: To assess the reliability of the recently developed Athlete Diet Index (ADI) in athletes.
METHODS: Eighty-three athletes (55 female; 18.9±4.2 years) from a state-based Australian sports institute consented to complete the ADI deployed using FileMakerTM Pro 16 (FileMaker Inc., 2017, Santa Clara, USA) on a portable device (iPad miniTM) on two occasions two weeks apart between June and December, 2019. Sixty-eight athletes completed the ADI on two occasions. Scoring (maximum=125) was based on population guidelines and international sports nutrition recommendations. Scored ADI items measured intake of core and discretionary foods, and markers of dietary habits relevant to athletes. Reliability was evaluated by comparing ADI scores of the first and second administrations using paired t-tests, intra-class correlation coefficients (ICC) and Bland-Altman plots (limits of agreement (LOA) set at mean±1.96SD, and bias determined via regression analysis) all conducted using SPSS Statistics version 26 (IBM Corp, Armonk, NY, USA).
RESULTS: In preliminary analyses, the mean ADI score was 84.1±15.2 (range 42.5-114.0, median 85.0). There was no difference between ADI scores on the two occasions of administration, mean difference 1.94 (95% CI: -0.49, 4.38, P=0.117) (paired t-test). The ICC was very good (ICC=0.80, 95% CI: 0.69, 0.87, P<0.0001). Bland-Altman analysis showed a mean difference of 1.94 (LOA -17.79, 21.60) and the regression line demonstrated no indication of systematic bias (y=4.57-0.03*x) (95% CI: -0.19, 0.13, P=0.701). There were no differences in serves of fruit, vegetables and grains between administrations; while differences were reported in serves of meat (1.69 vs 1.55, P=0.01) and discretionary foods (1.83 vs 1.86, P<0.0001).
CONCLUSIONS: The ADI is a novel athlete-specific diet index which has demonstrated very good reliability in athletes, providing practitioners with a promising measure of usual dietary intake. Further evaluation of the ADI, including validation compared to established dietary methodology, is warranted