Accuracy of the Suunto system for heart rate variability analysis during a tilt-test

RBCDH DOI: http://dx.doi.org/10.5007/1980-0037.2015v17n4p409 original article Accuracy of the Suunto system for heart rate variability analysis during a tilt-test Acurácia do sistema Suunto para a análise da variabilidade da frequência cardíaca durante um teste de inclinação Anthony Bouillod1 Johan Cassirame1 Jean Marc Bousson2 Yoshimasa Sagawa Jr3,4 Nicolas Tordi 2,4 Abstract – The aim of this study was to assess the accuracy of the Suunto Memory Belt (SMB) heart rate (HR) recorder compared with that of a standard electrocardiogram system (ECG) and compared the heart rate variability (HRV) analyses conducted with each dataset. Heart rate was simultaneously recorded using ECG and SMB in fifteen participants [mean (SD) age 27.3 (13.9) years, height 177.4 (10.2) cm and body mass 66.8 (15.3) kg] during an orthostatic tilt test. The two datasets were analysed to compare the number and type of R-R interval artefacts and indices from HRV (RMSSD, pNN50, HF, LF, SD1, and SD2). For artefact detection, 16,742 R-R intervals were analysed during all recordings. Only 18 artefacts, 9 type 1 (long R-R interval) and 9 type 2 (short R-R interval), were identified with the SMB. Bland-Altman analysis indicated excellent accuracy for the SMB, with limits of agreement of -2.00 and +1.94 ms. Further, the reference and SMB systems were strongly correlated. The similarity between each device indicated that the SMB could reliably record R-R intervals. Key words: Heart rate; Physiology; Validation studies. Resumo – Este estudo foi realizado com o objetivo de avaliar a precisão das medidas de Frequencia cardíaca (FC) e da variabilidade da FC (VFC) obtidas através de um cardiofrequencímetro Suunto Memory Belt, em comparação com um sistema de eletrocardiograma (ECG) de referência. Quinze participantes [média (desvio padrão), idade de 27,3 (13,9) anos, estatura de 177,4 (10,2) cm e massa corporal de 66,8 (15,3) kg] foram equipados para o registro simultâneo da FC através do ECG de referência e do cardiofrequencímetro Suunto Memory Belt durante um teste de inclinação ortostático. Os dados obtidos pelos dois sistemas foram analisados para comparar o número e tipo de artefatos dos interavalos R-R e também comparar diversos indices de VFC (RMSSD, pNN50, HF, LF, SD1 e SD2). Para todos os participantes, foram analisados 16.742 intervalos R-R e comparados entre os dois sistemas. Somente 18 artefatos foram encontrados para o Suunto Memory Belt em relação o ECG de referência: 9 foram do tipo 1 (intervalos RR longos) e 9 do tipo 2 (intervalos RR curtos). A análise de Bland-Altman mostrou excelente precisão do sistema Suunto Memory Belt com limites de concordância entre -2.00 e +1.94 ms. O sistema Suunto Memory Belt também mostrou uma forte correlação com o sistema ECG de referência. De acordo com os testes realizados, e a similaridade com o ECG de refêrencia conclui-se que o Suunto Memory Belt é capaz de registrar de forma precisa os intervalos R-R. Palavras-chave: Fisiologia; Frequência cardíaca; Estudos de validação. 1 University Bourgogne Franche-Comte. EA 4660 Culture Sport Health Society. Plateforme EPSI. Besancon, France. 2 University Bourgogne Franche-Comte. FDE EA4267, (FHU INCREASE ou Labex LipSTIC ou autre), Service ou lab. hospitalier. Besancon, France. 3 University Hospital of Besancon. Laboratoire d’exploration fonctionnelle clinique du mouvement. Besancon, France. 4 University Hospital of Besancon. Centre d’Investigation Clinique. Besancon, France. Received: 20 August 2014 Accepted: 11 March 2015 CC BY Licence Creative Commom Accuracy of the Suunto system Bouillod et al. INTRODUCTION The variability of R-R intervals, the period between 2 successive R-peaks of the QRS complex, is the basis for calculating heart rate variability (HRV). HRV analysis is a non-invasive tool used to assess the impact of the parasympathetic and sympathetic systems on the heart. Since the studies of Sayers1, 40 years ago, HRV has been used in sports science to prevent or detect overtraining2-4. The basic principle of HRV monitoring is to infer possible changes in cardiac autonomic nervous system (ANS) status with training with repeated HRV assessments over the time. ANS status can be explored via HRV assessments in various situations (at rest, awake, asleep, during or after exercise). The physiological determinants of resting HRV are related to genetics, plasma volume, autonomic activity and body position5-8. Moving from the supine to standing posture results in the translocation of 300-800 ml of blood from the central intravascular compartment to dependent regions in the legs, buttocks, pelvis and splanchnic circulation. This orthostatic stress evokes a sequence of compensatory cardiovascular responses to maintain homeostasis. The sympathetic nervous system, parasympathetic nervous system and baroreflex play a role in this homeostatic response9. Because an HRV test is very simple to perform, it can easily be used for advanced detection of an acute tiredness state or indicate an overtraining state10. During the last 2 decades, technological advances produced a number of portable devices that may reliably, accurately, and easily record R-R intervals. The use of HRV requires accurate measuring devices and a rigorous method of treatment and analysis as defined by the Task Force of European Society of Cardiology and the North American Society of Pacing and Electrophysiology11. To ensure the validity of HRV analysis, these portable devices are usually compared with traditional electrocardiogram (ECG) systems12-13. However, in many situations, these conditions and recommendations are not followed. The quality of heart rate recording and subject activity during the recording may compromise the interpretation of the HRV analysis due to body motions or other external electronic or mechanical stimuli. The poor quality of the signal may in turn affect HRV parameters14-16. The Suunto Memory Belt (Suunto, Vantaa, Finland) is a unique simple system that enables R-R interval recording in a chest belt without transmission to a receiver. Transmission could be an element of disturbance; the distance between the emitter and transmitter and items of clothing between the two can affect the signal. Recording several people in the same area can also cause interference between nearby emitters and transmitters. The Suunto Memory Belt (SMB) does not have this limitation because the recording is made directly on the thorax with no transmission. In addition, transmission to the receiver may disturb athletes during their practice. A comparable tool has already been validated17. However, whether SMB can be used to accurately analyse HRV 410 has not been confirmed. Our objective was to assess the accuracy of the SMB recorder compared with that of a standard ECG system (BioAmp, Powerlab, ADInstruments, Castell Hill, Australia) during an active orthostatic tilt-test and to verify the consistency of HRV data obtained with the SMB system (...truncated)