Parallel assessment of nutrition and activity in athletes: validation against doubly labelled water, 24-h urea excretion, and indirect calorimetry

J Sports Sci. 2010 Nov;28(13):1435-49. doi: 10.1080/02640414.2010.513482.


The assessment of nutrition and activity in athletes requires accurate and precise methods. The aim of this study was to validate a protocol for parallel assessment of diet and exercise against doubly labelled water, 24-h urea excretion, and respiratory gas exchange. The participants were 14 male triathletes under normal training conditions. Energy intake and doubly labelled water were weakly associated with each other (r = 0.69, standard error of estimate [SEE] = 304 kcal x day(-1)). Protein intake was strongly correlated with 24-h urea (r = 0.89) but showed considerable individual variation (SEE = 0.34 g kg(-1) x day(-1)). Total energy expenditure based on recorded activities was highly correlated with doubly labelled water (r = 0.95, SEE = 195 kcal x day(-1)) but was proportionally biased. During running and cycling, estimated exercise energy expenditure was highly correlated with gas exchange (running: r = 0.89, SEE = 1.6 kcal x min(-1); cycling: r = 0.95, SEE = 1.4 kcal x min(-1)). High exercise energy expenditure was slightly underestimated during running. For nutrition data, variations appear too large for precise measurements in individual athletes, which is a common problem of dietary assessment methods. Despite the high correlations of total energy expenditure and exercise energy expenditure with reference methods, a correction for systematic errors is necessary for the valid estimation of energetic requirements in individual athletes.

Publication types

  • Validation Study

MeSH terms

  • Adult
  • Athletes*
  • Bicycling / physiology
  • Biomarkers / urine
  • Body Water / physiology
  • Calorimetry, Indirect
  • Diet*
  • Dietary Proteins / administration & dosage
  • Energy Intake*
  • Energy Metabolism*
  • Exercise / physiology*
  • Humans
  • Male
  • Nutrition Assessment*
  • Pilot Projects
  • Running / physiology
  • Urea / urine
  • Young Adult


  • Biomarkers
  • Dietary Proteins
  • Urea