title: Age differences in physiological responses to self-paced and incremental [Formula: see text] testing.
abstract: OBJECTIVE
  A self-paced maximal exercise protocol has demonstrated higher [Formula: see text] values when compared against traditional tests. The aim was to compare physiological responses to this self-paced [Formula: see text] protocol (SPV) in comparison to a traditional ramp [Formula: see text] (RAMP) protocol in young (18-30 years) and old (50-75 years) participants.
  
  
  METHODS
  Forty-four participants (22 young; 22 old) completed both protocols in a randomised, counter-balanced, crossover design. The SPV included 5 × 2 min stages, participants were able to self-regulate their power output (PO) by using incremental 'clamps' in ratings of perceived exertion. The RAMP consisted of either 15 or 20 W min-1.
  
  
  RESULTS
  Expired gases, cardiac output (Q), stroke volume (SV), muscular deoxyhaemoglobin (deoxyHb) and electromyography (EMG) at the vastus lateralis were recorded throughout. Results demonstrated significantly higher [Formula: see text] in the SPV (49.68 ± 10.26 ml kg-1min-1) vs. the RAMP (47.70 ± 9.98 ml kg-1min-1) in the young, but not in the old group (>0.05). Q and SV were significantly higher in the SPV vs. the RAMP in the young (<0.05) but not in the old group (>0.05). No differences seen in deoxyHb and EMG for either age groups (>0.05). Peak PO was significantly higher in the SPV vs. the RAMP in both age groups (<0.05).
  
  
  CONCLUSIONS
  Findings demonstrate that the SPV produces higher [Formula: see text], peak Q and SV values in the young group. However, older participants achieved similar [Formula: see text] values in both protocols, mostly likely due to age-related differences in cardiovascular responses to incremental exercise, despite them achieving a higher physiological workload in the SPV.
authors.affiliation: STRAPH Research Group, School of Sport and Exercise Sciences, University of Kent, Chatham Maritime, Kent, UK.
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Jenkins
authors.affiliation: STRAPH Research Group, School of Sport and Exercise Sciences, University of Kent, Chatham Maritime, Kent, UK.
authors.forename: Alexis R
authors.initials: AR
authors.lastname: Mauger
authors.affiliation: STRAPH Research Group, School of Sport and Exercise Sciences, University of Kent, Chatham Maritime, Kent, UK. J.G.Hopker@kent.ac.uk.
authors.forename: James G
authors.identifier: http://orcid.org/0000-0002-4786-7037
authors.initials: JG
authors.lastname: Hopker
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D002302:Cardiac Output; D015444:Exercise; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D010101:Oxygen Consumption
keywords: Cardiac output; Maximal exercise; Pacing; RPE