title: High prevalence of false-positive plateau phenomena during VO2max testing in adolescents.
abstract: OBJECTIVE
  It is believed that a plateau in oxygen consumption (VO2) at the end of an incremental exercise test identifies the upper limits of cardiovascular capacity. We investigated how different criteria influence the frequency with which the "plateau phenomenon" is detected and the prevalence at which "false" plateau phenomena occurs during sub-maximal exercise.
  
  
  METHODS
  Cross-sectional.
  
  
  METHODS
  Six different criteria with 3 different sampling intervals each were used to identify the "plateau phenomenon" from a single data set comprising 63 incremental exercise tests along with secondary criteria based on target heart rate (HR) and respiratory exchange ratio (RER). A single criterion from the original 18 (HALF) was also used to detect the incidence of any plateau phenomena during each test.
  
  
  RESULTS
  The plateau phenomenon was detected in 16-82% of the tests depending on the criteria used, mostly as a result of the different sampling intervals. HALF identified 103 "plateau phenomena" but 73 (70.9%) of these occurred during sub-maximal exercise and so were "false". "False" plateaus were verified by at least one secondary criterion in 27% of cases. Participants reached the HR and RER targets after 83.6 ± 11.7% and 81.9 ± 18.1% of total test duration, respectively.
  
  
  CONCLUSIONS
  The wide range in the percentage of plateau phenomena detected by different criteria plus the high rate (71%) of "false" plateau during sub-maximal exercise could indicate that this phenomenon is a calculation artifact rather than an indicator of true physiological events. Secondary criteria can be reached early in exercise and often identify "false" plateau phenomena as "true".
authors.affiliation: Department of Human Biology, University of Cape Town and Sports Science Institute of South Africa, South Africa. Electronic address: fernando.beltrami@uct.ac.za.
authors.forename: Fernando G
authors.initials: FG
authors.lastname: Beltrami
authors.affiliation: Human Performance Laboratory, Technological and Higher Education Institute of Hong Kong, Hong Kong. Electronic address: delwong@alumni.cuhk.net.
authors.forename: Del P
authors.initials: del P
authors.lastname: Wong
authors.affiliation: Department of Human Biology, University of Cape Town and Sports Science Institute of South Africa, South Africa. Electronic address: timothy.noakes@uct.ac.za.
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Noakes
mesh_terms: D000293:Adolescent; D003430:Cross-Sectional Studies; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology; D012916:Soccer / Q000502:physiology
keywords: Aerobic power; Aerobic test; Cardiorespiratory endurance; Maximal oxygen consumption