ORIGINAL ARTICLE  EXERCISE AND SPORT CARDIOLOGY 

The Journal of Sports Medicine and Physical Fitness 2017 December;57(12):1702-10

DOI: 10.23736/S0022-4707.17.06998-5

Copyright © 2017 EDIZIONI MINERVA MEDICA

language: English

May a unitary autonomic index help assess autonomic cardiac regulation in elite athletes? Preliminary observations on the national Italian Olympic committee team

Roberto SALA ^{1, 2}, Mara MALACARNE ^{1, 2}, Fabio TOSI ^{1, 2}, Manuela BENZI ³, Nadia SOLARO ⁴, Stefano TAMORRI ³, Antonio SPATARO ³, Massimo PAGANI ¹, Daniela LUCINI ^{1, 2} ✉

¹ Department of Medical Biotechnology and Translational Medicine (BIOMETRA), University of Milan, Milan, Italy; ² Section of Exercise Medicine and Functional Conditions, Humanitas Clinical and Research Center, Rozzano, Milan, Italy; ³ Sports Medicine Institute CONI, Rome, Italy; ⁴ Department of Statistics and Quantitative Methods, University of Milano-Bicocca, Milan, Italy

BACKGROUND: Long term endurance training, as occurring in elite athletes, is associated to cardiac neural remodeling in favor of cardioprotective vagal mechanisms, resulting in resting bradycardia and augmented contribution of cardiac parasympathetic nerve activity. Autonomic assessment can be performed by way of heart rate variability. This technique however provides multiple indices, and there is not yet complete agreement on their specific significance. Purpose of the study was to assess whether a rank transformation and radar plot could provide a unitary autonomic index, capable to show a correlation between intensity of individual work and quality of autonomic regulation.
METHODS: We studied 711 (23.6±6.2 years) elite athletes that took part in the selection procedure for the 2016 Rio Olympic Games for the National Italian Olympic Committee (CONI). Indices from Heart Rate Variability HRV obtained at rest, during standing up and during recovery from an exercise test were used to compute a percent ranked unitary autonomic index for sport (ANSIs), taken as proxy of quality of autonomic regulation.
RESULTS: Within the observed wide range of energy expenditure, the unitary autonomic index ANSIs appears significantly correlated to individual and discipline specific training workloads (r=0.25, P<0.001 and r=0.78, P<0.001, respectively), correcting for possible age and gender bias. ANSIs also positively correlates to lipid profile.
CONCLUSIONS: Estimated intensity of physical activity correlates with quality of cardiac autonomic regulation, as expressed by a novel unitary index of cardiac autonomic regulation. ANSIs could provide a novel and convenient approach to individual autonomic evaluation in athletes.

KEY WORDS: Exercise - Heart rate - Sports - Athletes