title: Long-term high-intensity interval training associated with lifestyle modifications improves QT dispersion parameters in metabolic syndrome patients.
abstract: BACKGROUND
  QT dispersion (QTd) is a marker of myocardial electrical instability, and is increased in metabolic syndrome (MetS). Moderate intensity continuous exercise (MICE) training was shown to improve QTd in MetS patients.
  
  
  OBJECTIVE
  To describe long-term effects of MICE and high-intensity interval exercise training (HIIT) on QTd parameters in MetS.
  
  
  METHODS
  Sixty-five MetS patients (53 ± 9 years) were assigned to either a MICE (60% of peak power output [PPO]), or a HIIT program (alternating phases of 15-30 s at 80% of PPO interspersed by passive recovery phases of equal duration), twice weekly during 9 months. Ventricular repolarization indices (QT dispersion=QTd, standard deviation of QT = sdQT, relative dispersion of QT = rdQT, QT corrected dispersion = QTcd), metabolic, anthropometric and exercise parameters were measured before and after the intervention.
  
  
  RESULTS
  No adverse events were noted during exercise. QTd decreased significantly in both groups (51 vs 56 ms in MICE, P < 0.05; 34 vs 38 ms in HIIT, P < 0.05). Changes in QTd were correlated with changes in maximal heart rate (r = -0.69, P < 0.0001) and in heart rate recovery (r = -0.49, P < 0.01) in the HIIT group only. When compared to MICE, HIIT training induced a greater decrease in weight, BMI and waist circumference. Exercise capacity significantly improved by 0.82 and 1.25 METs in MICE and HIIT groups respectively (P < 0.0001). Lipid parameters also improved to the same degree in both groups.
  
  
  CONCLUSIONS
  In MetS, long-term HIIT and MICE training led to comparable effects on ventricular repolarization indices, and HIIT might be associated with greater improvements in certain cardiometabolic risk factors.
authors.affiliation: Montreal Heart Institute Cardiovascular and Prevention Center (ÉPIC) and Université de Montréal, 5055, St-Zotique Street East, Montreal, Quebec H1T 1N6, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Drigny
authors.forename: V
authors.initials: V
authors.lastname: Gremeaux
authors.forename: T
authors.initials: T
authors.lastname: Guiraud
authors.forename: M
authors.initials: M
authors.lastname: Gayda
authors.forename: M
authors.initials: M
authors.lastname: Juneau
authors.forename: A
authors.initials: A
authors.lastname: Nigam
mesh_terms: D000328:Adult; D015992:Body Mass Index; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D004562:Electrocardiography; D006321:Heart / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D008019:Life Style; D024821:Metabolic Syndrome / Q000097:blood / Q000503:physiopathology* / Q000534:rehabilitation*; D008875:Middle Aged; D064797:Physical Conditioning, Human / Q000379:methods / Q000502:physiology*; D012189:Retrospective Studies; D013997:Time Factors; D014280:Triglycerides / Q000097:blood; D055105:Waist Circumference; D015431:Weight Loss
chemical_list: D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D014280:Triglycerides
keywords: Cardiometabolic risk; Entraînement par intervalles; Exercice; Exercise; Interval exercise training; Metabolic syndrome; Repolarisation ventriculaire; Risque cardiométabolique; Syndrome métabolique; Ventricular repolarization