Background:The relationship between heart rate (HR) and oxygen consumption (VO2),(HR-VO2) shows linearity in the continuous exercise. From this linear relationship between HR-VO2, HR
has been used to estimate VO2 and calculate the caloric expenditure in intermittent exercise, as in soccer and futsal. Although the VO2 can be estimated by the HR in continuous exercise by the linear
relationship obtained in treadmill running, this relationship is not well understood in intermittent exercise. It is likely that the estimated VO2 in exercises or intermittent sports, from the HR-VO2
relationship of continuous exercise may overestimate the real VO2, since which occur accelerations, decelerations, changes of direction and other intense activities that may interfere with HR-VO2
linear relationship. The aim of this study was to determine whether the equations obtained by the HR-VO2 relationship in a continuous test (CT) on a treadmill and an intermittent test with recovery on
the court (ITR) are able to estimate the VO2 at different intensities.
Methods:Eight professional futsal players, from team of the National League of Brazil (25.0 ± 4.3 years, 179 ± 6 cm; 76.4 ± 5.7 kg and 17.2 ± 3.0% fat) were evaluated. The players
underwent two maximal tests (CT and ITR), for determination of maximal oxygen consumption (VO2max) with initial intensity of 8 km/h until exhaustion. HR-VO2 relationship was obtained by linear
regression of each subject individually for each test. Based on HR-VO2 regression equation of each test, VO2 was calculated for each intensity in both tests, VO2 estimated in continuous test (VO2c)
and VO2 estimated in ITR test (VO2i) and compared with the real VO2 (VO2r) of ITR test. VO2 and HR were used by the calculations of the average at the final 30 seconds of each test stage. Pearson
correlation was used to verify the relationship between FC-VO2 of the two tests. ANOVA by repeated measures was used and post-hoc Newman-Keuls (P <0.05).
Results:VO2max was higher in the TC when compared to the ITR (50.78 ± 2.67 and 47.06 ± 4.73 mL/Kg/min, respectively) as opposed to the maximum heart rate, which was higher in the ITR
(178 ± 8:58) compared to CT (184 ± 7.92). There was no difference between the speed that was reached at VO2 tests (p> 0.05). Both tests showed significant correlation between HR-VO2 (TC: 0.94 ± 0.02
to ITR: 0.86 ± 0.07). Only the intensity of 8 km/h the results did not differ. In all other intensities (9-16 km/h) VO2c, estimated by the equation in continuous test differed significantly from VO2r
and VO2i. Considering the mean of all the intensities, the use of CT regression equation overestimated VO2r by 15%, whereas the equation obtained by ITR test underestimated by only 0.4%.
Conclusions:The VO2c estimated by HR based on the regression equation in the CT test differed from VO2r, while with the equation in the ITR test did not. The use of HR-VO2