Validity of Recreational Marathon Runners' Self-Reported Anthropometric Data.

While studies on large samples of recreational runners have often relied on participants' self-reported height and body mass, the validity of these data have not been investigated for this population. Hence, this study sought to examine the validity of self-reported anthropometric measures among recreational marathon runners. Female (n = 32) and male (n = 135) recreational marathon runners were requested to estimate their body mass and height (and we calculated their self-reported body mass index [BMI]), after which we took actual measures of their body mass and height and calculated their actual BMI. Participants' self-reported values underestimated their actual body mass by 0.65 kg (p < .001, η2 = 0.222) and their actual BMI by 0.35 kg ⋅ m-2 (p < .001, η2 = 0.245). There was a significant Assessment Method × Sex Interaction for both body mass (p = .019, η2 = 0.033) and BMI (p = .017, η2 = 0.034), as women underestimated body mass values more than men. Participants overestimated their height by 0.44 cm (p < .001, η2 = 0.075), but the interaction of sex and assessment method for height was not statistically significant. Underestimates of body mass correlated with marathon racing speed (r = .24, p = .006) and body fat percentage (r = -.29, p = .001) in men, but not in women (p > .05). The disagreement between self-reported and measured anthropometric data in the present sample was lower than has been previously reported for the general population, suggesting that marathon runners may more accurately self-perceive and/or report their anthropometric characteristics. These findings are of practical value for health professionals and researchers (e.g., nutritionists and exercise physiologists) questionnaires to recreational marathon runners.