title: The effect of acute magnesium loading on the maximal exercise performance of stable chronic obstructive pulmonary disease patients.
abstract: OBJECTIVE
  The potential influence of magnesium on exercise performance is a subject of increasing interest. Magnesium has been shown to have bronchodilatatory properties in asthma and chronic obstructive pulmonary disease patients. The aim of this study was to investigate the effects of acute magnesium IV loading on the aerobic exercise performance of stable chronic obstructive pulmonary disease patients.
  
  
  METHODS
  Twenty male chronic obstructive pulmonary disease patients (66.2 + 8.3 years old, FEV1: 49.3+19.8%) received an IV infusion of 2 g of either magnesium sulfate or saline on two randomly assigned occasions approximately two days apart. Spirometry was performed both before and 45 minutes after the infusions. A symptom-limited incremental maximal cardiopulmonary test was performed on a cycle ergometer at approximately 100 minutes after the end of the infusion.
  
  
  RESULTS
  Magnesium infusion was associated with significant reductions in the functional residual capacity (-0.41 l) and residual volume (-0.47 l), the mean arterial blood pressure (-5.6 mmHg) and the cardiac double product (734.8 mmHg.bpm) at rest. Magnesium treatment led to significant increases in the maximal load reached (+8 w) and the respiratory exchange ratio (0.06) at peak exercise. The subgroup of patients who showed increases in the work load equal to or greater than 5 w also exhibited significantly greater improvements in inspiratory capacity (0.29 l).
  
  
  CONCLUSIONS
  The acute IV loading of magnesium promotes a reduction in static lung hyperinflation and improves the exercise performance in stable chronic obstructive pulmonary disease patients. Improvements in respiratory mechanics appear to be responsible for the latter finding.
authors: Internal Medicine Department, Medical School of Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
authors: Angélica Florípedes do
authors: AF
authors: Amaral
authors: Lourenco
authors: L
authors: Gallo
authors: Hélio
authors: H
authors: Vannucchi
authors: Júlio César
authors: JC
authors: Crescêncio
authors: Elcio Oliveira
authors: EO
authors: Vianna
authors: José Antônio Baddini
authors: JA
authors: Martinez
mesh_terms: D000368:Aged; D001993:Bronchodilator Agents / Q000008:administration & dosage; D015444:Exercise / Q000502:physiology; D005080:Exercise Test / Q000187:drug effects*; D005260:Female; D006801:Humans; D008274:Magnesium / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000187:drug effects; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy*; D012129:Respiratory Function Tests; D013990:Tidal Volume / Q000187:drug effects; D016896:Treatment Outcome; D055986:Vital Signs / Q000187:drug effects
chemical_list: D001993:Bronchodilator Agents; D008274:Magnesium