title: Performance enhancement with maintenance of resting immune status after intensified cycle training.
abstract: BACKGROUND
  Unaccustomed intense endurance exercise is associated with short-term suppression of natural immunity. However, it is not established whether intensified endurance training alters resting immune status or increases the risk of upper respiratory infection (URI).
  
  
  OBJECTIVE
  This study examined the effect of intensified endurance training for performance enhancement on resting immune status in nine healthy, male competitive cyclists.
  
  
  METHODS
  Data were collected during 4 weeks of usual training (baseline), followed by prescribed cycle training that consisted of volume-building at customary training intensity (V phase, 6 weeks), unaccustomed very high intensity interval training at 100% maximal heart rate (I phase, 18 days), and an unloading taper (U phase, 10 days).
  
  
  METHODS
  The main performance criterion was a simulated 20 km time-trial. Aerobic capacity measures included power output at ventilatory threshold (POT(vent)) and maximal oxygen uptake (VO(2max)). Markers of immune status (lymphocyte subset counts, serum cytokine levels, and new URI cases) and physiological indicators of training stress (cycling economy, 24-hour urinary cortisol excretion, and serum testosterone concentration) were evaluated in the rested state, 36 to 44 hours postexercise, during baseline, and after each training phase.
  
  
  RESULTS
  Time-trial performance, POT9(vent), VO(2max), and cycling economy improved significantly (p < 0.001) after the V phase, and remained higher than baseline (p < 0.001) after the I and U phases. As compared with the V phase, performance time was faster after the U phase (p < 0.01). In contrast, lymphocyte counts, cytokine levels, incidence of URI, cortisol excretion, and serum testosterone concentration were not significantly different from baseline in any phase.
  
  
  CONCLUSIONS
  Cycling efficiency and performance improved while resting immune status was maintained throughout the 10-week training program. This study provides encouraging data in support of immunological robustness during intensified endurance training.
authors.affiliation: Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Canada.
authors.forename: Rudolph H
authors.initials: RH
authors.lastname: Dressendorfer
authors.forename: Stewart R
authors.initials: SR
authors.lastname: Petersen
authors.forename: Shona E
authors.initials: SE
authors.lastname: Moss Lovshin
authors.forename: Judith L
authors.initials: JL
authors.lastname: Hannon
authors.forename: Siow F
authors.initials: SF
authors.lastname: Lee
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: Bell
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology*; D003139:Common Cold / Q000209:etiology* / Q000276:immunology; D016207:Cytokines / Q000097:blood; D015444:Exercise / Q000502:physiology*; D017079:Exercise Tolerance / Q000276:immunology; D006339:Heart Rate; D006801:Humans; D006854:Hydrocortisone / Q000652:urine; D007108:Immune Tolerance / Q000276:immunology*; D007113:Immunity, Innate / Q000276:immunology*; D018655:Lymphocyte Count; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000276:immunology*; D011597:Psychomotor Performance / Q000502:physiology*; D012123:Pulmonary Ventilation; D012307:Risk Factors; D013739:Testosterone / Q000097:blood; D013997:Time Factors; D014891:Weight Lifting / Q000502:physiology
chemical_list: D016207:Cytokines; D013739:Testosterone; D006854:Hydrocortisone