IJCS | Volume 31, Nº4, July / August 2018

DOI: 10.5935/2359-4802.20180041 320 EDITORIAL International Journal of Cardiovascular Sciences. 2018;31(4)320-322 Mailing Address: Jari A. Laukkanen Seminaarinkatu 15. PO Box 35. FI-40014. University of Jyväskylä, Jyväskylä - Finland E-mail: jari.a.laukkanen@jyu.fi Is Cardiorespiratory Optimal Point Measured During the Maximal Cardiopulmonary Exercise Test a Relevant Indicator of Sports Performance? Jari A. Laukkanen Institute of Public Health and Clinical Nutrition - University of Eastern Finland, 1 Kuopio - Finland Faculty of Sport and Health Sciences, University of Jyväskylä, 2 Jyväskylä - Finland Central Finland Health Care District, Department of Medicine, 3 Jyväskylä - Finland Exercise; Respiratory Function Tests; Athletes; Cardiorespiratory Fitness; Athletic Performance. Keywords Cardiorespiratory fitness (CRF) is considered the gold standard for assessing aerobic performance among athletes and normal population and has recently been named as a clinical vital sign, being an essential indicator of cardiovascular and pulmonary function. 1 Cardiorespiratory fitness is associated with lower risk of non-fatal and fatal cardiovascular disease (CVD) events, with studies demonstrating a consistent, inverse association between CRF and mortality even after adjustment for the traditional risk factor burden. 2 Additionally, both maximal oxygen consumption (VO 2 max) and VO 2 at ventilatory threshold (VT) have been associated with a reduced risk of adverse health outcomes. 1,3-5 A literature-based meta-analysis of 33 observational cohort studies has better delineated the relationship of CRF with CVD and all-cause mortality outcomes. 2 However, VO 2 max and VT are often used to evaluate athletes’ performance and to monitor their training responses. During the cardiopulmonary exercise test (CPX), many variables could be used to assess specific training responses to the cardiovascular, respiratory and musculoskeletal systems based on the analysis of submaximal and maximal responses to a progressively incremental exercise. Modern CPX systems allow for the analysis of gas exchange at rest, during mild, moderate and maximal exercise levels, and during recovery and yield measures of VO 2 , carbon dioxide output (VCO 2 ), and ventilation (VE). 6 These advanced computerized systems provide both simple and complex analyses of these data that are easy to retrieve and store, which makes CPX widely available. Oxygen uptake at VT, often referred to as the anaerobic threshold, is a variable assessed at submaximal level of CPX. 6 For majority of healthy individuals, the anaerobic threshold lies at exercise intensities between 50% and 75% of VO 2 max, while in trained endurance athletes, it can reach intensities as high as 80% of VO 2 max. 6 Observing the oxygen ventilatory equivalents (the ratio between VE in l/min and VO 2 in l/min, VE/VO 2 ) in a given minute during CPX, it is possible to identify a U-shaped pattern with a clear minimal value. Ramos et al. 7 have named this minimal VE/VO 2 , a dimensionless variable, as cardiorespiratory optimal point (COP) with age- and sex-reference data and suggested that COP reflects circulation-respiration integration and the most economical use of ventilation to obtain oxygen for the active tissues during exercise. In this context, it is worthwhile to comment that VO 2 max depends on performing a truly maximal exercise test. Although VT can be assessed at the submaximal level, 5 it also requires a more intense exercise level compared to the assessment of COP, and VT measurement may be hindered by the existence of several distinct criteria for its identification and/or characterization, because it cannot be accurately defined in all cases, limiting its use in both clinical practice and sports performance. Applicability of the COP for the assessment of the athletes’ exercise performance is potentially interesting. 8 In addition to the fact that, as a submaximal variable of CPX, the use of COP is particularly interesting for people unable to achieve a maximal CPX because of functional limitations. In the sports scenario, where