Effect of acute exercise-induced fatigue on maximal rate of heart rate increase during submaximal cycling

Abstract

Different mathematical models were used to evaluate if the maximal rate of heart rate (HR) increase (rHRI) was related to reductions in exercise performance resulting from acute fatigue. Fourteen triathletes completed testing before and after a 2-h run. rHRI was assessed during 5 min of 100-W cycling and a sigmoidal (rHRI_sig) and exponential (rHRI_exp) model were applied. Exercise performance was assessed using a 5-min cycling time-trial. The run elicited reductions in time-trial performance (1.34 ± 0.19 to 1.25 ± 0.18 kJ · kg⁻¹, P < 0.001), rHRI_sig (2.25 ± 1.0 to 1.14 ± 0.7 beats · min⁻¹ · s⁻¹, P < 0.001) and rHRI_exp (3.79 ± 2.07 to 1.98 ± 1.05 beats · min⁻¹ · s⁻¹, P = 0.001), and increased pre-exercise HR (73.0 ± 8.4 to 90.5 ± 11.4 beats · min⁻¹, P < 0.001). Pre-post run difference in time-trial performance was related to difference in rHRI_sig (r = 0.58, P = 0.04 and r = 0.75, P = 0.003) but not rHRI_exp (r = −0.04, P = 0.9 and r = 0.27, P = 0.4) when controlling for differences in pre-exercise and steady-state HR. rHRI_sig was reduced following acute exercise-induced fatigue, and correlated with difference in performance.

KEYWORDS:

• heart rate kinetics
• athletic performance
• exercise-induced fatigue
• heart rate response
• exercise onset

ACKNOWLEDGEMENTS

The technology described in this publication is the subject of provisional patent PCT/AU2011/000804 filed by the University of South Australia. RLT and JDB are employees of the University of South Australia.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was funded by a Catalyst Grant from ITEK Pty Ltd, which is the commercialization arm of the University of South Australia.