title: Effects of beta-blockade on exercise performance at high altitude: a randomized, placebo-controlled trial comparing the efficacy of nebivolol versus carvedilol in healthy subjects.
abstract: OBJECTIVE
  Exposure to high altitude (HA) hypoxia decreases exercise performance in healthy subjects. Although β-blockers are known to affect exercise capacity in normoxia, no data are available comparing selective and nonselective β-adrenergic blockade on exercise performance in healthy subjects acutely exposed to HA hypoxia. We compared the impact of nebivolol and carvedilol on exercise capacity in healthy subjects acutely exposed to HA hypobaric hypoxia.
  
  
  METHODS
  In this double-blind, placebo-controlled trial, 27 healthy untrained sea-level (SL) residents (15 males, age 38.3 ± 12.8 years) were randomized to placebo (n = 9), carvedilol 25 mg b.i.d. (n = 9), or nebivolol 5 mg o.d. (n = 9). Primary endpoints were measures of exercise performance evaluated by cardiopulmonary exercise testing at sea level without treatment, and after at least 3 weeks of treatment, both at SL and shortly after arrival at HA (4559 m).
  
  
  RESULTS
  HA hypoxia significantly decreased resting and peak oxygen saturation, peak workload, VO(2) , and heart rate (HR) (P < 0.01). Changes from SL (no treatment) differed among treatments: (1) peak VO(2)  was better preserved with nebivolol (-22.5%) than with carvedilol (-37.6%) (P < 0.01); (2) peak HR decreased with carvedilol (-43.9 ± 11.9 beats/min) more than with nebivolol (-24.8 ± 13.6 beats/min) (P < 0.05); (3) peak minute ventilation (VE) decreased with carvedilol (-9.3%) and increased with nebivolol (+15.2%) (P= 0.053). Only peak VE changes independently predicted changes in peak VO(2)  at multivariate analysis (R= 0.62, P < 0.01).
  
  
  CONCLUSIONS
  Exercise performance is better preserved with nebivolol than with carvedilol under acute exposure to HA hypoxia in healthy subjects.
authors: Department of Cardiology, S. Luca Hospital, IRCCS, Istituto Auxologico Italiano, Milan, Italy.
authors: Mariaconsuelo
authors: M
authors: Valentini
authors: Miriam
authors: M
authors: Revera
authors: Grzegorz
authors: G
authors: Bilo
authors: Gianluca
authors: G
authors: Caldara
authors: Giulio
authors: G
authors: Savia
authors: Katarzyna
authors: K
authors: Styczkiewicz
authors: Sara
authors: S
authors: Parati
authors: Francesca
authors: F
authors: Gregorini
authors: Andrea
authors: A
authors: Faini
authors: Giovanna
authors: G
authors: Branzi
authors: Gabriella
authors: G
authors: Malfatto
authors: Damiano
authors: D
authors: Magrì
authors: Piergiuseppe
authors: P
authors: Agostoni
authors: Gianfranco
authors: G
authors: Parati
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage*; D000328:Adult; D000531:Altitude; D001578:Benzopyrans / Q000008:administration & dosage*; D002227:Carbazoles / Q000008:administration & dosage*; D000077261:Carvedilol; D004311:Double-Blind Method; D015150:Echocardiography, Doppler; D004983:Ethanolamines / Q000008:administration & dosage*; D005080:Exercise Test; D017079:Exercise Tolerance / Q000187:drug effects*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D000860:Hypoxia / Q000000981:diagnostic imaging / Q000503:physiopathology*; D007558:Italy; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D000068577:Nebivolol; D010101:Oxygen Consumption / Q000187:drug effects; D010919:Placebos; D011412:Propanolamines / Q000008:administration & dosage*; D015656:Respiratory Mechanics / Q000187:drug effects; D013997:Time Factors
chemical_list: D000319:Adrenergic beta-Antagonists; D001578:Benzopyrans; D002227:Carbazoles; D004983:Ethanolamines; D010919:Placebos; D011412:Propanolamines; D000068577:Nebivolol; D000077261:Carvedilol