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Relationship between heart rate deflection point determined by Dmax method and 10-km running performance in endurance
D F Da Silva1, C S Peserico, F A Machado
1State University of Maringá, Maringá, Brazil - famachado_uem@hotmail.com.
Aim:
The aim of this paper was to verify the relationship between the speed at heart rate deflection point based on Dmax method (sHRDPDmax) with 10-km running performance and the speed at lactate threshold calculated with Dmax method (sLTDmax) in endurance recreationally-trained female runners. We also aim to examine the influence of exponential-plus-constant and third-order polynomial regression models and the influence of the heart rate points (model with initial HR points above 140 b·min(-1) versus model with all HR points) on the determination of the sHRDPDmax.
Methods:
Thirteen endurance recreationally-trained female runners were recruited. Participants performed a discontinuous incremental exercise tests initiating at 7 km·h(-1) with 1 km·h(-1) increments each 3 min to determine sHRDPDmax and sLTDmax according to two adjustments: 1) exponential-plus-constant regression model (sHRDPexp and sLTexp); 2) third-order polynomial regression model (sHRDPpol and sLTpol). The sHRDPDmax was also calculated based on HR points above 140 b·min(-1) (sHRDPexp>140 and sHRDPpol>140). Each participant performed a 10-km running performance (s10km).
Results:
Only the sHRDPexp and sHRDPexp>140 correlated with s10km (sHRDPexp, r=0.87; sHRDPexp>140, r=0.76) and showed higher correlations than the sHRDPpol and sHRDPpol>140 with sLTDmax. The sHRDPexp presented higher correlation with sLTexp than sHRDPexp>140, however sHRDPexp>140 better correlated with sLTpol than sHRDPexp. Furthermore, sHRDPpol>140 demonstrated higher correlations with sLTexp and sLTpol than sHRDPpol.
Conclusion:
The determination of sHRDPDmax according to different initial HR point and its correlation with sLTDmax is influenced by the regression model. Further, only sHRDPexp and sHRDPexp>140 were predictors of endurance performance. However, despite the high correlations, the deflection point very often occurred around the midpoint between initial and final speeds during the incremental test suggesting that the exponential-plus-constant may not be an appropriate regression curve.
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