Development and content validity of Diet Quality Index for Athletes (DQI-Athletes)

Dietary recommendations for athletes vary according to the type of sport, and the use of uniform assessment criteria may not accurately capture diet quality of athletes from different sport disciplines and weight categories. For example, applying the same guidelines to power and skill sport athletes may lead to inaccurate scoring, similar to the limitations observed with population-based diet quality indices. Therefore, this study aimed to develop a Diet Quality Index for Athletes(DQI-Athletes) and establish its content validity for the Indian athletic population.

DQI-Athletes included four component types: adequacy,moderation, ratio, and dietary behaviours. Total score of DQI-Athletes ranged from 0 to 100. A total of 108 athletes(≥ 18 years; 52 females), currently in the training phase and representing diverse sports disciplines, were purposively selected. Dietary intake and anthropometric measurements were assessed using standardized protocols. Content validity was evaluated by a panel of ten experts through qualitative review and quantitative assessment through Lawshe's Content Validity Ratio(CVR).

Adequacy components assessed the intake of cereals and grains, fruits, vegetables, dairy, total protein-rich foods, and micronutrients. Moderation components evaluated consumption of processed meat, processed fruit products, roots and tubers, cooking oil, solid fats, and added sugars. Scoring for adequacy and moderation components was based on an energy-density approach to account for variations in total energy intake of athletes from different sports. For adequacy components, scores ranged from zero(no intake) to maximum points (when intake met or exceeded the recommended cut-off), with intermediate values scored linearly. For moderation components, maximum points were assigned for intake at or below the cut-off, and zero points were assigned for intake at or above the threshold, with linear scoring in between. Thresholds for moderation components were determined based on the 85th percentile of intake observed in the study population. The ratio component was the ratio of whole grains to total grains intake. A ratio at or below the threshold ( ≤ 0.5) was assigned zero points. Behavioural components included abstinence from alcohol, adequate fluid intake, and consumption of pre- and post-training meals, which were assessed using a Likert scale. CVR for DQI-Athletes was 0.9.

DQI-Athletes integrates adequacy, moderation, ratio, and behavioural components to evaluate the overall diet quality of athletes of different sports. High CVR confirmed the content validity of the tool.