title: Relation between heart rate recovery after exercise testing and body mass index.
abstract: BACKGROUND
  Impaired heart rate (HR) recovery after exercise testing is considered a predictor of cardiovascular mortality as it reflects vagus nerve dysfunction.
  
  
  OBJECTIVE
  To assess the relationship between body mass index (BMI) and HR recovery after exercise.
  
  
  METHODS
  We analyzed the records of 2443 patients of both sexes, aged between 20 and 59 years, in sinus rhythm, not using negative chronotropic agents and with no myocardial ischemic response to exercise testing carried out at a specialist clinic, between 2005 and 2011. BMI was categorized as normal (18.5-<25 kg/m(2)), overweight (25-≤30 kg/m(2)) or obese (>30 kg/m(2)). The different BMI groups were compared in terms of HR recovery after exercise, which was calculated as the difference between maximum HR during exercise and in the first minute of recovery. Recovery was considered impaired when the difference was ≤12 bpm.
  
  
  RESULTS
  Eighty-seven (3.6%) patients presented impaired recovery, which was three times more prevalent in the obese group and twice as prevalent in the overweight group compared with the normal group (p<0.001 and p=0.010, respectively). Obese patients presented higher basal HR and lower maximum HR, as well as reduced chronotropic reserve (p<0.001). In multivariate analysis, impaired HR recovery was associated with overweight (relative risk [RR]=1.8; p=0.035), obesity (RR=2; p=0.016), number of metabolic equivalents (RR=0.82; p<0.001) and resting HR (RR=1.05; p<0.001). The hazard ratio for hypertension was 2 (p=0.083, NS).
  
  
  CONCLUSIONS
  Impaired HR recovery was associated with higher BMI, demonstrating that obese individuals present vagus nerve dysfunction.
authors.affiliation: Departamento de Pós-Graduação em Ciências da Saúde, Universidade Federal de Pernambuco, Recife, Pernambuco, Brasil. Electronic address: tereza.lins@gmail.com.
authors.forename: Tereza Cristina
authors.initials: TC
authors.lastname: Barbosa Lins
authors.affiliation: Departamento de Pós-Graduação em Ciências da Saúde, Universidade Federal de Pernambuco, Recife, Pernambuco, Brasil.
authors.forename: Lucila Maria
authors.initials: LM
authors.lastname: Valente
authors.affiliation: Departamento de Pós-Graduação em Ciências da Saúde, Universidade Federal de Pernambuco, Recife, Pernambuco, Brasil.
authors.forename: Dário Celestino
authors.initials: DC
authors.lastname: Sobral Filho
authors.affiliation: Departamento de Pós-Graduação em Ciências da Saúde, Universidade Federal de Pernambuco, Recife, Pernambuco, Brasil.
authors.forename: Odwaldo
authors.initials: O
authors.lastname: Barbosa e Silva
mesh_terms: D000328:Adult; D015992:Body Mass Index; D005080:Exercise Test; D005260:Female; D006339:Heart Rate; D006801:Humans; D006973:Hypertension; D008297:Male; D008875:Middle Aged; D050177:Overweight; D055815:Young Adult
keywords: Autonomic nervous system; Exercise test; Frequência cardíaca/recuperação; Heart rate/recovery; Obesidade; Obesity; Sistema nervoso autônomo; Teste de exercício