Relationship Between Heart Rate, Oxygen Consumption, and Energy Expenditure in Futsal

The primary aim of this study was to compare the measured oxygen consumption (Measured-VO₂) in a simulated futsal game (S-Game) with the estimated oxygen consumption (Estimated-VO₂) through a regression equation between heart rate (HR) and oxygen consumption (VO₂) (HR-VO₂) in treadmill running, and a secondary aim was to calculate the total energy expenditure (EE) in S-Game. Ten professional players (22.20 ± 3.22 years) were evaluated. HR-VO₂ was determined individually in the continuous test on the treadmill (Cont_Test). The Measured-VO₂ in S-Game was compared with the Estimated-VO₂ in the Cont_Test. Alactic and lactic pathways were estimated by VO₂. The Estimated-VO₂ presented no statistically significant difference with the Measured-VO₂, using the paired t-test (p = 0.38). However, the correlation between Estimated- and Measured-VO₂ was very weak (r = -0.05), and it presented poor agreement (concordance correlation coefficient = -0.04). In addition, a Bland-Altman plot presented bias of -2.8 ml/kg/min and individual difference as large as 19 ml/kg/min. The HR-VO₂ determined by the Cont_Test was not a good individual predictor of VO₂. The high intensity and intermittent nature of the futsal game possibly caused dissociation in the HR-VO₂ relationship. Cont_Test is not recommended for estimating VO₂ and calculating individual EE in the futsal game. This is recommended only for the group mean. The total EE in S-Game was 13.10 ± 1.25 kcal.min^-1 (10.81 ± 1.57 metabolic equivalents). The contributions from the metabolic pathways were as follows: aerobic (93%), alactic (5%), and lactic (2%).