title: Oxygen-uptake efficiency slope as a determinant of fitness in overweight adolescents.
abstract: OBJECTIVE
  Peak oxygen uptake (VO2peak) is frequently difficult to assess in overweight individuals; therefore, submaximal measures that predict VO2peak are proposed as substitutes. Oxygen uptake efficiency slope (OUES) has been suggested as a submaximal measurement of cardiorespiratory fitness that is independent of exercise intensity. There are few data examining its value as a predictor of V O2peak in severely overweight adolescents.
  
  
  METHODS
  One hundred seven severely overweight (BMI Z 2.50 +/- 0.34) and 43 nonoverweight (BMI Z 0.13 +/- 0.84) adolescents, performed a maximal cycle ergometer test with respiratory gas-exchange measurements. OUES was calculated through three exercise intensities: lactate inflection point (OUES LI), 150% of lactate inflection point (OUES 150), and VO2peak (OUES PEAK).
  
  
  RESULTS
  When adjusted for lean body mass, VO2peak and OUES at all exercise intensities were lower in overweight subjects (VO2peak: 35.3 +/- 6.4 vs 46.8 +/- 7.9 mL.kg(-1) LBM.min(-1), P < 0.001; OUES LI: 37.9 +/- 10.0 vs 43.7 +/- 9.2 mL.kg(-1) LBM.min(-1).logL(-1) P < 0.001; OUES 150: 41.6 +/- 9.0 vs 49.8 +/- 11.1 mL.kg(-1) LBM.min(-1).logL(-1) P < 0.001; and OUES PEAK: 45.1 +/- 8.7 vs 52.8 +/- 9.6 mL.kg(-1) LBM.min(-1).logL(-1) P < 0.001). There was a significant increase in OUES with increasing exercise intensity in both groups (P < 0.001). OUES at all exercise intensities was a significant predictor of VO2peak for both groups (r2 = 0.35-0.83, P < 0.0001). However, limits of agreement for predicted VO2peak relative to actual VO2peak were wide (+/- 478 to +/- 670 mL.min(-1)).
  
  
  CONCLUSIONS
  OUES differs significantly in overweight and nonoverweight adolescents. The wide interindividual variation and the exercise intensity dependence of OUES preclude its use in clinical practice as a predictor of VO2peak.
authors.affiliation: Rehabilitation Medicine Department, Mark O. Hatfield Clinical Research Center, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Bart
authors.initials: B
authors.lastname: Drinkard
authors.forename: Mary D
authors.initials: MD
authors.lastname: Roberts
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Ranzenhofer
authors.forename: Joan C
authors.initials: JC
authors.lastname: Han
authors.forename: Lisa B
authors.initials: LB
authors.lastname: Yanoff
authors.forename: Deborah P
authors.initials: DP
authors.lastname: Merke
authors.forename: David M
authors.initials: DM
authors.lastname: Savastano
authors.forename: Sheila
authors.initials: S
authors.lastname: Brady
authors.forename: Jack A
authors.initials: JA
authors.lastname: Yanovski
mesh_terms: D000293:Adolescent; D002648:Child; D004219:District of Columbia; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D050177:Overweight; D010101:Oxygen Consumption / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D012123:Pulmonary Ventilation / Q000502:physiology*