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. 2017;28(3):99-103.
doi: 10.1294/jes.28.99. Epub 2017 Sep 20.

Changes in Heart Rate and Heart Rate Variability as a Function of Age in Thoroughbred Horses

Free PMC article

Changes in Heart Rate and Heart Rate Variability as a Function of Age in Thoroughbred Horses

Hajime Ohmura et al. J Equine Sci. .
Free PMC article


We investigated changes in heart rate (HR) and HR variability as a function of age in newborn foals to old Thoroughbred horses. Experiments were performed on a total of 83 healthy and clinically normal Thoroughbred horses. Resting HR decreased with age from birth. The relationship between age and HR fit the equation Y=48.2X-0.129(R2=0.705); the relationship between age and HR for horses 0-7 years old fit the equation Y=44.1X-0.179(R2=0.882). Seven-day-old horses had the highest HR values (106 ± 10.3 beat/min). The low frequency (LF) and high frequency (HF) powers increased with age in newborn to old horses. These changes in HR and HR variability appear to result from the effects of ageing. Three- to seven-year-old race horses had the lowest HR values (32.9 ± 3.5 beat/min) and the highest LF and HF powers except for the HF powers in the oldest horses. Race training may have contributed to these changes. Horses of ages greater than 25 years old had the highest HF powers and the lowest LF/HF ratios. In individual horses, 8 of the 15 horses over 25 years old had LF/HF ratios of less than 1.0; their HR variability appears to be unique, and they may have a different autonomic balance than horses of younger age.

Keywords: autonomic nervous activity; foal; old Thoroughbred.


Fig. 1.
Fig. 1.
(Top) The relationship between age and HR fit the equation Y=48.2X–0.129 (R2=0.705). (Bottom) The relationship between age and HR from 0–7 years of age fit the equation Y=44.1X–0.179 (R2=0.882).

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    1. Akselrod S., Gordon D., Ubel F.A., Shannon D.C., Berger A.C., Cohen R.J. 1981. Power spectrum analysis of heart rate fluctuation: a quantitative probe of beat-to-beat cardiovascular control. Science 213: 220–222. - PubMed
    1. Blackburn M.W., Calloway D.H. 1985. Heart rate and energy expenditure of pregnant and lactating women. Am. J. Clin. Nutr. 42: 1161–1169. - PubMed
    1. Brosh A., Aharoni Y., Degen A.A., Wright D., Young B. 1998. Estimation of energy expenditure from heart rate measurements in cattle maintained under different conditions. J. Anim. Sci. 76: 3054–3064. - PubMed
    1. Ceesay S.M., Prentice A.M., Day K.C., Murgatroyd P.R., Goldberg G.R., Scott W., Spurr G.B. 1989. The use of heart rate monitoring in the estimation of energy expenditure: a validation study using indirect whole-body calorimetry. Br. J. Nutr. 61: 175–186. - PubMed
    1. Hebestreit H., Bar-Or O., McKinty C., Riddell M., Zehr P. 1995. Climate-related corrections for improved estimation of energy expenditure from heart rate in children. J. Appl. Physiol. 79: 47–54. - PubMed