Dayanıklılık Sporcularında Oksijen Tüketimi ve Enerji Harcamasının Kalp Atım Hızı İndeks Yöntemi ile Değerlendirilmesi

Abstract

The purpose of this study is to validate heart rate index method (HRindex) in assessment of VO2max and energy expenditure at diverse intensities in endurance athletes. 22 male athletes, who were involved in middle and long distance running and orienteering and participated in the competitions for at least 3 years, voluntarily participated in the study. After the measurement of resting HR (HRrest), submaximal and maximal oxygen consumption was measured on a treadmill with indirect calorimetric method (IC) with a graded exercises test protocol. During the test, oxygen consumption (VO2) and HR values of participants were recorded at each workload. HRindex was calculated from HRexercise /HRrest ratio. By using HRindex values, maximal oxygen consumption and energy expenditure at intensities corresponding to <72%, 72-88% and >88% of reserve HR (HRR) were estimated. Regression analysis was performed to assess the relationship between HRindex calculated at each rate for each participant, and VO2 values as MET. The difference between measured and estimated VO2max and energy expenditure at three different intensities (< 72% HRR, 72-88% HRR and >88% HRR) were determined by paired t test. The bias between measured and estimated VO2max and energy expenditure and lower and upper limits of agreement were determined by Bland-Altman plot. At the same time, agreement between measured and estimated variables was determined by Information-Based Measure of Disagreement (IBMD) method. There is a moderate positive relationship between METs (VO2) and HRindex values (r = 0.601; p = 0.000). VO2max estimated with using HRindex method was significantly lower (11.3%) (p = 0.013). Similarly, the energy expenditure estimated with HRindex method at each intensity was significantly lower than IC method (at < 72% HRR t = 0.326; p = 0.002, at 72-88% HRR t = 2.09; p = 0.04 and at >88% HRR t = 5.01; p = 0.000). Bland-Altman plots showed that agreement interval between lower and upper limits of agreement for VO2max was wide. For the agreement between IC and HRindex method, IBMD values were statistically different from zero (for VO2max t = 8.992; p= 0.000, for < 72% HRR t = 18.578; p = 0.000, for 72-88% HRR t = 18.342; p = 0.000, for >88% HRR t = 19.769; p = 0.000). The findings of this study showed that the HRindex method cannot be used to estimate VO2max in endurance athletes, but it can be used to assess energy expenditure at different intensities.