title: Aerobic fitness impacts sympathoadrenal axis responses to concurrent challenges.
abstract: The combination of mental and physical challenges can elicit exacerbated cardiorespiratory (CR) and catecholamine responses above that of a single challenge alone.
  
  
  OBJECTIVE
  This study examined the effects of a combination of acute mental challenges and physical stress on cardiorespiratory and catecholamine responses.
  
  
  METHODS
  Eight below-average fitness (LF VO2max= 36.58 ± 3.36 ml-1kg-1min-1) and eight above-average fitness (HF VO2max= 51.18 ± 2.09 ml-1kg-1min-1) participants completed an exercise-alone condition (EAC) session consisting of moderate-intensity cycling at 60% VO2maxfor 37 min, and a dual-challenge condition (DCC) that included concurrent participation in mental challenges while cycling.
  
  
  RESULTS
  The DCC resulted in increases in perceived workload, CR, epinephrine, and norepinephrine responses overall. HF participants had greater absolute CR and catecholamine responses compared to LF participants and quicker HR recovery after the dual challenge.
  
  
  CONCLUSIONS
  These findings demonstrate that cardiorespiratory fitness does impact the effect of concurrent stressors on CR and catecholamine responses.
authors.affiliation: Department of Kinesiology, Texas A&M University Corpus Christi, 358 Island Hall, Corpus Christi, TX, 78412, USA. heather.webb@tamucc.edu.
authors.forename: Heather E
authors.initials: HE
authors.lastname: Webb
authors.affiliation: University of New South Wales, Sydney, Australia.
authors.forename: Deena A
authors.initials: DA
authors.lastname: Rosalky
authors.affiliation: Mississippi State University, Mississippi, MS, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: McAllister
authors.affiliation: Virginia Commonwealth University, Richmond, VA, USA.
authors.forename: Edmund O
authors.initials: EO
authors.lastname: Acevedo
authors.affiliation: Walter Reed Army Institute of Research, Silver Spring, MD, USA.
authors.forename: Gary H
authors.initials: GH
authors.lastname: Kamimori
mesh_terms: D000293:Adolescent; D000328:Adult; D002395:Catecholamines / Q000494:pharmacology; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects* / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*; D055815:Young Adult
chemical_list: D002395:Catecholamines
keywords: Cardiorespiratory fitness; Cardiovascular reactivity; Dual stress; Epinephrine; Norepinephrine; SA axis