title: Fitness level impacts salivary antimicrobial protein responses to a single bout of cycling exercise.
abstract: OBJECTIVE
  Salivary antimicrobial proteins (sAMPs) protect the upper respiratory tract (URTI) from invading microorganisms and have been linked with URTI infection risk in athletes. While high training volume is associated with increased URTI risk, it is not known if fitness affects the sAMP response to acute exercise. This study compared the sAMP responses to various exercising workloads of highly fit experienced cyclists with those who were less fit.
  
  
  METHODS
  Seventeen experienced cyclists (nine highly fit; eight less fit) completed three 30-min exercise trials at workloads corresponding to -5, +5 and +15 % of the individual blood lactate threshold. Saliva samples were collected pre- and post-exercise to determine the concentration and secretion of α-amylase, human neutrophil proteins 1-3 (HNP1-3) lactoferrin, LL-37, lysozyme, and salivary SIgA.
  
  
  RESULTS
  The concentration and/or secretion of all sAMPs increased post-exercise, but only α-amylase was sensitive to exercise workload. Highly fit cyclists had lower baseline concentrations of α-amylase, HNP1-3, and lactoferrin, although secretion rates did not differ between the groups. Highly fit cyclists did, however, exhibit greater post-exercise increases in the concentration and/or secretion of a majority of measured sAMPs (percentage difference between highly fit and less fit in parentheses), including α-amylase concentration (+107 %) and secretion (+148 %), HNP1-3 concentration (+97 %) and secretion (+158 %), salivary SIgA concentration (+181 %), lactoferrin secretion (+209 %) and LL-37 secretion (+138 %).
  
  
  CONCLUSIONS
  We show for the first time that fitness level is a major determinant of exercise-induced changes in sAMPs. This might be due to training-induced alterations in parasympathetic and sympathetic nervous system activation.
authors.affiliation: Laboratory of Integrated Physiology, Department of Health and Human Performance, University of Houston, 3855 Holman St. Rm 104 Garrison, Houston, TX, 77204, USA.
authors.forename: Hawley
authors.initials: H
authors.lastname: Kunz
authors.forename: Nicolette C
authors.initials: NC
authors.lastname: Bishop
authors.forename: Guillaume
authors.initials: G
authors.lastname: Spielmann
authors.forename: Mira
authors.initials: M
authors.lastname: Pistillo
authors.forename: Justin
authors.initials: J
authors.lastname: Reed
authors.forename: Teja
authors.initials: T
authors.lastname: Ograjsek
authors.forename: Yoonjung
authors.initials: Y
authors.lastname: Park
authors.forename: Satish K
authors.initials: SK
authors.lastname: Mehta
authors.forename: Duane L
authors.initials: DL
authors.lastname: Pierson
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Simpson
mesh_terms: D000328:Adult; D056352:Athletes; D001642:Bicycling / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000032:analysis; D007781:Lactoferrin / Q000032:analysis; D008297:Male; D009113:Muramidase / Q000032:analysis; D010809:Physical Fitness / Q000502:physiology*; D012463:Saliva / Q000737:chemistry; D012471:Salivary Proteins and Peptides / Q000032:analysis*; D055291:Salivary alpha-Amylases / Q000032:analysis; D023084:alpha-Defensins / Q000032:analysis
chemical_list: D007071:Immunoglobulin A, Secretory; D012471:Salivary Proteins and Peptides; D023084:alpha-Defensins; C406413:human neutrophil peptide 1; C406416:human neutrophil peptide 2; C406427:human neutrophil peptide 3; D055291:Salivary alpha-Amylases; D009113:Muramidase; D007781:Lactoferrin