1 Disability & Rehabilitation, 2012; Early Online: 1–9 © 2012 Informa UK, Ltd. ISSN 0963-8288 print/ISSN 1464-5165 online DOI: 10.3109/09638288.2012.694575 Background: This study aimed to determine whether morbidly obese women have an alteration of heart rate (HR) kinetics and HR variability (HRV) during the 6-min walk test (6MWT) and if an aerobic exercise training can modify these indexes after gastric bypass surgery (GBS). Design and methods: Nineteen morbidly obese women were randomized to a trained (TG) or control group and 12 women of eutrophic group (EG) were also evaluated. The obese women were tested on two occasions: 1 week before and 4 months after GBS through record of HR and R-R intervals during 6MWT for analysis HR kinetics. The TG underwent an aerobic exercise training program on a treadmill (1-h session, totaling 36 sessions over 12-week). Results: Both obese groups demonstrated a significant reduction of rMSSD and slower HR kinetics during the 6MWT when compared to the EG. In addition, only the TG demonstrated a significant improvement in HRV indexes, walking distance, faster time constant and mean response time of HR during 6MWT after training (p < 0.05). Conclusion: Morbidly obese women have slower HR kinetics and altered cardiac modulation during submaximal exercise. However, aerobic exercise training can produce beneficial adaptations in HRV and faster HR kinetics following GBS. Keywords: bariatric surgery, autonomic nervous system, physical fitness, morbid obesity, body mass index Introduction Obesity is one of the most important threats to health in developed countries, increasing the risk of insulin resistance, type II diabetes, hypertension, dyslipidemia, sleep apnea syndrome, musculoskeletal complications [1], cardiovascular disease [2,3], alterations in the sympathetic nervous system [4,5] and reduced functional capacity [6]. Gastric bypass surgery (GBS) is an option for treatment of morbid obesity [7], and the best results in weight loss are achieved when this surgical procedure is followed with regular physical activity [8,9]. Besides the beneits of physical exercise as an aid to weight loss, a study previously conducted in our laboratory showed that the implementation of a 12-week exercise training program 1 month ater GBS improved functional capacity and cardiac autonomic modulation at rest, in which it was assessed by indexes RMSSD, NN50, pNN50, SD1 [which relect the extent of the activity of the parasympathetic autonomic nervous system (ANS)] and SDNN and SD2 (representative of the total variability in heart rate) the obese population when compared with GBS alone [10]. However, if autonomic nervous control of heart rate (HR) can be modiied during submaximal exercise remain to be investigated, that encouraged us to undertake this study. RESEARCH PAPER Effects of aerobic exercise training on variability and heart rate kinetic during submaximal exercise after gastric bypass surgery – a randomized controlled trial Viviane Castello-Simões 1 , Rodrigo Polaquini Simões 1 , Thomas Beltrame 1 , Daniela Bassi 1 , Aparecida Maria Catai 1 , Ross Arena 2 , Noé Carvalho Azambuja Jr 3 , João do Nascimento Ortega 3 & Audrey Borghi-Silva 1 1 Cardiopulmonary Physiotherapy Laboratory, Nucleus of Research in Physical Exercise, Federal University of São Carlos, São Carlos, São Paulo, Brazil, 2 Department of Physical Therapy of University of New Mexico, Albuquerque, New Mexico, United States, and 3 House Health and Maternity of São Carlos, São Carlos, São Paulo, Brazil Correspondence: Viviane Castello Simões, Rod. Washington Luis, km 235, 13565-905, São Carlos, São Paulo, Brazil. Phone:+55-16-33518952. Fax: +55-16-33612081. E-mail: vivica_castello@yahoo.com.br • he obesity is one of the most important threats to health in developed countries and bariatric surgery is an option for treatment of morbid obesity. • Exercise is an efective means of improving health ater this procedure due alterations of autonomic ner- vous system in this population. • his study showed that a program of aerobic physical training ater bariatric surgery was able to improve the kinetics of heart rate and the cardiac autonomic mod- ulation, both evaluated during submaximal exercise. Implications for Rehabilitation (Accepted May 2012) Disabil Rehabil Downloaded from informahealthcare.com by University of Waterloo on 10/09/12 For personal use only.