Original Article

European Journal of Applied Physiology

, Volume 108, Issue 3, pp 435-442

First online:

Can HRV be used to evaluate training load in constant load exercises?

  • Piia KaikkonenAffiliated withTampere Research Center of Sports Medicine Email author 
  • , Esa HynynenAffiliated withKIHU, Research Institute for Olympic Sports
  • , Theresa MannAffiliated withMRC/UCT Research Unit for Exercise Science and Sports Medicine, University of Cape Town
  • , Heikki RuskoAffiliated withDepartment of Biology of Physical Activity, University of JyväskyläKIHU, Research Institute for Olympic Sports
  • , Ari NummelaAffiliated withKIHU, Research Institute for Olympic Sports

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The overload principle of training states that training load (TL) must be sufficient to threaten the homeostasis of cells, tissues, organs, and/or body. However, there is no “golden standard” for TL measurement. The aim of this study was to examine if any post-exercise heart rate variability (HRV) indices could be used to evaluate TL in exercises with different intensities and durations. Thirteen endurance-trained males (35 ± 5 year) performed MODE (moderate intensity, 3 km at 60% of the maximal velocity of the graded maximal test (vVO2max)), HI (high intensity, 3 km at 85% vVO2max), and PRO (prolonged, 14 km at 60% vVO2max) exercises on a treadmill. HRV was analyzed with short-time Fourier-transform method during rest, exercise, and 15-min recovery. Rating of perceived exertion (RPE), blood lactate (BLa), and HFP120 (mean of 0–120 s post-exercise) described TL of these exercises similarly, being different for HI (P < 0.05) and PRO (P < 0.05) when compared with MODE. RPE and BLa also correlated negatively with HFP120 (r = −0.604, −0.401), LFP120 (−0.634, −0.601), and TP120 (−0.691, −0.569). HRV recovery dynamics were similar after each exercise, but the level of HRV was lower after HI than MODE. Increased intensity or duration of exercise decreased immediate HRV recovery, suggesting that post-exercise HRV may enable an objective evaluation of TL in field conditions. The first 2-min recovery seems to give enough information on HRV recovery for evaluating TL.


Autonomic nervous system Running exercise Recovery Short-time Fourier transform