title: Slower heart rate and oxygen consumption kinetic responses in the on- and off-transient during a discontinuous incremental exercise: effects of aging.
abstract: BACKGROUND
  The analysis of the kinetic responses of heart rate (HR) and oxygen consumption (VO(2)) are an important tool for the evaluation of exercise performance and health status.
  
  
  OBJECTIVE
  The purpose of this study was to investigate the effects of aging on the HR and VO(2) kinetics during the rest-exercise transition (on-transient) and the exercise-recovery transition (off-transient), in addition to investigating the influence of exercise intensity (mild and moderate) on these variables.
  
  
  METHODS
  A total of 14 young (23±3 years) and 14 elderly (70±4 years) healthy men performed an incremental exercise testing (ramp protocol) on a cycle-ergometer to determine the maximal power (MP). Discontinuous exercise testing was initiated at 10% of the MP with subsequent increases of 10% until exhaustion. The measurement of HR, ventilatory and metabolic variables and blood lactate were obtained at rest and during the discontinuous exercise.
  
  
  RESULTS
  The lactate threshold was determined in each subject and was similar between the groups (30±7% of MP in the young group and 29±5% of MP in the elderly group, p>0.05). The HR and VO(2) kinetics (on- and off-transient) were slower in the elderly group compared to the young group (p<0.05). Additionally, in the young group, the values of HR and VO(2) kinetics were higher in the moderate compared to the mild exercise intensity.
  
  
  CONCLUSIONS
  We concluded that the elderly group presented with slower HR and VO(2) kinetics in relation to the young group for both on- and off-transients of the dynamic exercise. Moreover, in the young group, the kinetic responses were slower in the moderate intensity in relation to the mild intensity.
authors.affiliation: Cardiopulmonary Physical Therapy Laboratory, Nucleus of Research in Physical Exercise, Universidade Federal de São Carlos (UFSCar), São Carlos, SP, Brazil. rpssimoes@yahoo.com.br
authors.forename: Rodrigo P
authors.initials: RP
authors.lastname: Simões
authors.forename: José C
authors.initials: JC
authors.lastname: Bonjorno
authors.forename: Thomas
authors.initials: T
authors.lastname: Beltrame
authors.forename: Aparecida M
authors.initials: AM
authors.lastname: Catai
authors.forename: Ross
authors.initials: R
authors.lastname: Arena
authors.forename: Audrey
authors.initials: A
authors.lastname: Borghi-Silva
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D003430:Cross-Sectional Studies; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D011446:Prospective Studies; D055815:Young Adult