title: Relative heart rate, heart rate reserve, and VO2 during submaximal exercise in the elderly.
abstract: BACKGROUND
  The purpose of this study was to examine the relationships among relative maximal heart rate (%HRmax), maximal heart rate reserve (%HRmax reserve), and maximal oxygen uptake (%VO2max) during submaximal exercise by elderly subjects.
  
  
  METHODS
  VO2max and HRmax were determined on 36 women and 19 men, 60 to 80 yrs of age, by a maximal treadmill test to volitional exhaustion. On a separate day, subjects underwent a submaximal treadmill protocol consisting of three 6-min exercise stages at treadmill speeds and grades estimated to elicit 40%, 60%, and 80% of HRmax reserve. Cardiorespiratory responses were determined during mins 4-5 and 5-6 of each stage.
  
  
  RESULTS
  Measured exercise intensities expressed by the three methods were: %HRmax reserve = 36, 55, and 79%; %HRmax = 65, 75, and 88%; %VO2max = 53, 69, and 88%. %HRmax was greater (p < .05) than %VO2max at 53 and 69% of VO2max. %HRmax reserve was less (p < .05) than %VO2max for all three intensities. Slopes and intercepts for the linear regression equations relating %VO2max with %HRmax and with %HRmax reserve differed between men and women (p < .05). The regression equation relating %VO2max and %HRmax was y = -22.8 + 1.2 (%HRmax) -13.0 (Gender) + 0.2 (%HRmax x Gender): standard error of the estimate (SEE) = 9.7% and R2 = .71. The regression equation relating %VO2max and %HRmax reserve was y = 32.4 + 0.7 (%HRmax reserve) -10.9 (Gender) + 0.2 (%HRmax reserve x Gender): SEE = 9.8% and R2 = .70 (Gender: F = 0; M = 1).
  
  
  CONCLUSIONS
  The data indicate that there is considerable variability among methods of expressing exercise intensity and that %HRmax more closely represents %VO2max than does %HRmax reserve (p < .05) in older adults. These results are in contrast to what has been shown with younger subjects and with American College of Sports Medicine guidelines for exercise prescription.
authors.affiliation: Center for Exercise Science, University of Florida, Gainesville, USA.
authors.forename: L B
authors.initials: LB
authors.lastname: Panton
authors.forename: J E
authors.initials: JE
authors.lastname: Graves
authors.forename: M L
authors.initials: ML
authors.lastname: Pollock
authors.forename: L
authors.initials: L
authors.lastname: Garzarella
authors.forename: J F
authors.initials: JF
authors.lastname: Carroll
authors.forename: S H
authors.initials: SH
authors.lastname: Leggett
authors.forename: D T
authors.initials: DT
authors.lastname: Lowenthal
authors.forename: G J
authors.initials: GJ
authors.lastname: Guillen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D001794:Blood Pressure / Q000502:physiology; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006321:Heart / Q000502:physiology; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D016014:Linear Models; D008168:Lung / Q000502:physiology; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D010465:Perception; D005082:Physical Exertion / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012737:Sex Factors