IJCS | Volume 31, Nº4, July / August 2018

DOI: 10.5935/2359-4802.20180030 323 ORIGINAL ARTICLE International Journal of Cardiovascular Sciences. 2018;31(4)323-332 Mailing Address: Christina Grüne de Souza e Silva Rua Professor Rodolpho Paulo Rocco, 255 - 8º andar - Cidade Universitária, Campus do Fundão. Postal Code: 21941-913, Rio de Janeiro, RJ - Brazil. E-mail: christina.g.dss@gmail.com Cardiorespiratory Optimal Point in Professional Soccer Players: A Novel Submaximal Variable During Exercise Christina Grüne de Souza e Silva, 1,2 Claudia Lucia Barros de Castro, 3 João Felipe Franca, 3 Altamiro Bottino, 4 Jonathan Myers, 2 Claudio Gil Soares de Araújo 3 Instituto do Coração Edson Saad, Universidade Federal do Rio de Janeiro, 1 Rio de Janeiro, RJ - Brazil Veterans Affairs Palo Alto Health Care System/Stanford University, 2 Palo Alto, California - USA Clínica de Medicina do Exercício, CLINIMEX, 3 Rio de Janeiro, RJ - Brazil São Paulo Futebol Clube, 4 São Paulo, SP - Brazil Manuscript received January 26, 2018; revised manuscript April 09, 2018; accepted April 22, 2018. Abstract Background: Maximal oxygen consumption (VO 2 max) and ventilatory threshold (VT) obtained during a cardiopulmonary exercise test (CPX) are used in the evaluation of athletes. However, the identification of these variables may sometimes be unreliable, which limits their use. In contrast, the cardiorespiratory optimal point (COP) is a submaximal variable derived from CPX with objective measurement and prognostic significance. However, its behavior in athletes is unknown. Objective: To describe the behavior of COP in professional soccer players and its association with VO 2 max and VT. Methods: VO 2 max, VT and COP were obtained retrospectively from 198 soccer players undergoing maximal treadmill CPX using ramp protocol. COP was defined as the lowest value of the ventilation/oxygen consumption ratio in a given minute of the CPX. The soccer players were stratified according to their field position: goalkeeper, center-defender, left/right-back, midfielder and forwarder. Continuous variables were compared using unpaired Student t test or ANOVA, or Mann-Whitney test or Kruskal-Wallis test depending on their distribution, and categorical variables were compared using chi-square test. Pearson correlation was used to test the association between COP and other ventilatory variables. A level of 5% was used for statistical significance. Results: COP (mean ± SD) was 18.2 ± 2.1 and was achieved at a speed 4.3 ± 1.4 km.h -1 lower than that achieved at the VT. While VO 2 max (62.1 ± 6.2 mL.kg -1 .min -1 ) tended to be lower in goalkeepers (p < 0.05), the COP did not vary according to field position (p = 0.41). No significant association was observed between COP and VO 2 max (r = 0.032, p = 0.65) or between COP and VT (r = -0.003, p = 0.96). Conclusion: COP can be easily determined during submaximal exercise performed with incremental speed in soccer players and does not vary according to the athlete’s field position. The absence of association with VO 2 max and VT indicates that COP provides distinct and complementary information to these variables. Future studies are needed to determine the practical implications of COP in assessing athletes. (Int J Cardiovasc Sci. 2018;31(4)323-332) Keywords: Exercise; Football / trends; Spirometry /methods; Bronchospirometry /methods; Athletic Performance. Introduction The cardiopulmonary exercise test (CPX) is a functional and noninvasive procedure used to assess the integration of the cardiovascular, respiratory and musculoskeletal systems based on the analysis of submaximal and maximal responses to exercise. 1 The information obtained from CPX is important to the prognostic assessment of healthy and unhealthy individuals, 2,3 and themeasures of maximal aerobic power, represented bymaximal oxygen consumption (VO 2 max), and of ventilatory threshold (VT) are often used to assess and monitor athletes’