title: PWC 75%/kg, a fitness index not linked to resting heart rate: testing procedure and reference values.
abstract: OBJECTIVE
  To develop a fitness index unlinked to resting heart rate and suitable for clinical use, and to obtain reference values of this new index for healthy subjects.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Research laboratory.
  
  
  METHODS
  A volunteer sample of healthy subjects (N=100; 50 men; age range, 20-70y) randomly recruited from the general community.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Participants performed a submaximal, multistage cycle ergometer test. A new fitness index, the physical working capacity at 75% of the predicted maximal heart rate per kilogram of body weight (PWC(75%)/kg), was calculated. Its concordance with a previously described fitness index and its relationship with age were examined, as well as differences attributable to sex and lifestyle. Reference values of the PWC(75%)/kg (mean ± SD and 95% confidence interval) were calculated and categorized by age classes of 10 years and by sex.
  
  
  RESULTS
  The intraclass correlation coefficient (ICC) between PWC(75%)/kg and the working capacity index at 65% of the heart rate reserve per kilogram of body weight (WCI(65%HRreserve)/kg) was very high (ICC=.96, P<.001), indicating that the fitness index can be estimated without measuring the resting heart rate. PWC(75%)/kg decreased as age increased. The average PWC(75%)/kg was significantly higher in men than in women (P<.001), and in active than in inactive subjects (P<.01).
  
  
  CONCLUSIONS
  This study presents a new fitness index, the PWC(75%)/kg, which is suitable for measuring fitness in active and sedentary people aged 20 to 70 years. It may also be a suitable fitness index for selected chronically ill individuals. This study also provides reference values of the PWC(75%)/kg obtained from healthy men and women.
authors.affiliation: Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium.
authors.forename: Charles Sebiyo
authors.initials: CS
authors.lastname: Batcho
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Thonnard
authors.forename: Henri
authors.initials: H
authors.lastname: Nielens
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000886:Anthropometry; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D016552:Ergometry; D005080:Exercise Test / Q000379:methods*; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010807:Physical Endurance / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D012016:Reference Values; D015203:Reproducibility of Results; D012146:Rest; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012737:Sex Factors; D055815:Young Adult