Supplementary Information

Table 3: Schema of the various HRV measurement and analysis techniques used for frequency-domain analysis in horses

Source / Quantity / IBI measurement / Spectral analysis / HRV parameter / Objectve
Oel et al. 2014 / n=16 / Televet 100® (Fa.Kruuse, Marslev, Denmark) und Televet 100-Software Version 4.1.3 (Company Rösch & Associates Information Engineering GmbH, Frankfurt,
Germany) / HRV Analysis Software 1.1 (Biomedical Signal Analysis Group, Department of Applied Physics, University of Kuopio, Finland);
5x 5 min. intervals,
FFT / LF and HF normalized, LF/HF ratio / Eye enucleation, oculocardiac reflex ,
retrobulbar block
Christensen et al. 2014 / n=15 / Polar® Equine RS800CX (Polar Electro Oy, Kempele, Finland), Polar® ProTrainer Equine Edition 5TM Software; / ? / RMSSD,
LF/HF ratio / Different head-neck positions in ridden horses
Munsters et al. 2013 / n=9 / Polar® Equine RS800CX (Polar Electro Oy, Kempele, Finland), Polar® ProTrainer Equine Edition Software; / Kubios HRV software (Biosignal Analysis and Medical Imaging Group),
512 IBIs, artefact correction, detrended, smoothness parameter 500 ms,
FFT / SDNN, RMSSD,
LF, HF,
LF/HF ratio / Air transport
Vitale et al. 2013 / n=10 / ECG telemetry system (Life Scope 8, Nihon Kohden, Tokyo, Japan), sampling frequency 1000Hz, NI/USB-6009 acquisition board with Signal Express software (National Instruments, Austin, TX, USA) / Kubios HRV software (Department of Applied Physics, University of Kuopio, Finland);
comparison of 5 min. and 15min. intervals / SDRR,
RMSSD;
LF and HF normalized
LF/HF ratio,
SD1, SD2 / Effects of restriction of movement
Zebisch et al. 2013 / n=18 / Televet 100® (Engel Engineering Services GmbH, Offenbach, Germany) und Televet 100® Software Version 4.1.3 / Kubios HRV software (Biosignal Analysis and Medical Imaging Group),
120 sec,
Interpolation, FFT / LF and HF
normalized, LF/HF ratio / Different head-neck positions in ridden horses
Ohmura et al. 2012a / n=5 / Holter-ECG (SM-60, Fukuda Denshi Co Ltd., Tokyo) / 512 IBIs,
FFT, Hamming Window / LF, HF, LF/HF ratio / Withholding of food, stress, circadian rhythm
Ohmura et al. 2012b / n=6 / Holter-ECG (SM-60, Fukuda Denshi Co Ltd., Tokyo) / 512 IBIs,
FFT, Hamming Window / LF, HF, LF/HF ratio / Road/air transport, stress
Peters et al. 2012 / n=7 / Polar® RR Monitor S810i (Polar Electro Oy, Kempele Finland) / Polar Equine Software 4.04.043H;
no further details / RMSSD, pNN50;
LF, HF, LF/HF ratio / Anticipatory behavior, animal welfare indicator
Sundra et al. 2012 / n=5 / Powerlab data recorder (ADInstruments, Sydney, Australia), Chart Software (v 5.5.1 ADInstruments) / ChartPro version 5.5.6 Heart Rate Variability Module (ADInstruments),
FFT / SDNN, RMSSD;
Total Power, LF, HF, LF/HF ratio / Influence of spasmolytic agents (hyoscine, propantheline)on heart rate variability
Werhahn et al. 2012 / n=6 / Polar® Equine RS800CX (Polar Electro Oy, Kempele, Finland), Polar® ProTrainer Equine Edition Software;
measurement at rest at night in recumbency / Kubios HRV software (Biosignal Analysis and Medical Imaging Group, Kuopio, Finland);
4x 5-minute intervals; artefact correction adjusted at 0,5 sec (intervals deviating >50%), interpolation rate 2 Hz / SDNN, RMSSD;
LF/HF ratio / Effects of free exercise on the behavior of horses single housed in loose-boxes
Gehrke et al. 2011 / n=9 / Holter-ECG (Del Mar Avionics) und Holter Monitoring Software HeartMath, Impresario (Delmar-Reynolds/Spacelabs, L.A., California); contact electrodes used on shaved, iodized skin with superglue to attach;
Holter-ECG measurement 24 h / 5 min. segments analysed by HeartMath Research Insitute, (Boulder Creek, California) with DADiSP® (Newton, MA) / SDNN, SDNN index RMSSD;
ULF, VLF, LF and HF normalized / Comparison of HRV on the basis of Holter-ECG measurements at rest of horses engaged in equine-assisted activities with those from trained Thoroughbred (Kuwahara et al., 1999)
König von Borstel et al. 2011 / n=36 / Polar® 800XS (Polar Electro Oy, Kempele Finland) / Kubios HRV software (Kuopio, Finland),
no further details / RMSSD;
LF/HF ratio / Assessment of equine personality
Matsuura et al. 2010 / n=6 / FM-180 Fukuda Denshi (Tokyo, Japan), adhesive electrodes;
HRV measurement 30, 60 and 90 min. after trekking / 5 min. intervals,
ECG processor analyzing system (SCM-5000, Fukuda Denshi), maximum entropy method (MemCalc/Chiram: Suwa Trust, Sapporo, Japan) / LF, HF, LF/HF ratio / Stress in leading and following horses after horse trekking
Oel et al. 2010 / n=20 / Televet 100® (Engel Engineering Services GmbH, Offenbach, Germany) und Televet 100® Software Version 4.1.3 / 5x 5 min. (300 sec) intervals,
HRV Analysis Software 1.1 (Biomedical Signal Analysis Group, Department of Applied Physics, University of Kuopio, Finland)
FFT / SDNN
LF and HF normalized LF/HF ratio / Pain assessment in equine general anesthesia
Parker et al. 2010 / n=6 cross-over design / ECG (Nihon Kohden, Brentford Middlesex, UK) with C220 ECG electrodes (Cardicare, Essex, UK) and
Polar®Equine S810i R-R Recorder (Polar Electro Oy, Kempele Finland) with Polar HorseTrainer software / HRV analysis software (Biomedical Signal Analysis Group, Department of Applied Physics, University of Kuopio, Finland),
512 IBIs,
FFT / RMSSD, pNN50;
VLF, LF, HF, TOTAL; PNSI, SNSI / Comparison of Polar RR-interval data and IBIs calculated from recorded ECG
Nagy et al. 2009 / n=40 / Polar®Equine S810i heart rate monitor and Polar®HorseTrainer 3.0 software (Polar Electro Oy, Kempele Finland), automatic error correction (moderate filter power with minimum protection zone set at 6 bmp/min) / HRV-analysis software (Biomedical Signal Analysis Group, Department of Applied Physics, University of Kuopio, Finland),
detrending (smoothness priors method)
AR / LF, HF, LF/HF ratio / Feeding stress-test, control and crib-biting horses (with or without inhibition), coping with stress, oral activity
Uhlendorf 2009 / n=100 / Televet®100 (Engel Engineering Services GmbH, Offenbach, Germany), adhesive electrodes (Megro GmbH & Co.KG, Wesel, Germany),
Holter-ECG 24 h / HRV analysis software 1.1 (Biomedical Signal Analysis Group, Department of Applied Physics, University of Kuopio, Finland),
2x/day 3 segments of 5 min.
FFT / RMSSD;
LF, HF, LF/HF ratio / Echocardiographic findings and Holter-ECG as well as exercise ECG
Hoffmann 2008 / n=24
cross-over design / Polar® S810 (Polar Electro Oy, Kempele Finland) / 5 min intervals,
Interpolation 2 Hz, FFT
normalization: HFn.u.=HF/(TOTAL-VLF) / HF n.u.;
Poincaré Plot: SD2 / Assessment of horse housing systems
Cottin et al. 2006 / n=7 / Polar® S-810 heart rate monitor and Polar® precision performance SW, 4.00.020 (Polar Electro Oy, Kempele Finland) / 256 IBIs resampled,
Blackman window, FFT, see Cottin et al. (2005) / SDNN, RMSSD;
LF, HF, LF/HF ratio;
Poincaré Plot: SD1, SD2 / High intensity interval training, trotting horses, recovery
Hada et al. 2006 / n=7 / Holter-type electrocardiograph SM-60 (Fukuda Denshi, Tokyo, Japan) and Polar®S810 heart rate monitor (Polar Electro Oy, Kempele, Finland) / ECG analysis system (Softron, Tokyo, Japan)
FFT, Hamming window / LF, HF, LF/HF ratio / Exercise, heart rate recovery time versus high frequency power
Minero et al. 2006 / n=8 / Polar®Vantage NV (Polar Electro Oy, Kempele, Finland) / 5 min. / 512 IBIs,
FFT, Hanning window / SDNN, RMSSD, RR min, RR max;
LF, HF, LF/HF ratio / Stress test, therapeutic riding horses in comparison to jumping horses
Ohmura et al. 2006a / n=5 / Holter-type electrocardiograph SM-60 (Fukuda Denshi, Tokyo, Japan) / HRV analysis software (Softron, Tokyo, Japan)
FFT / LF, HF, LF/HF ratio / Effects of sympathomimetics on HRV
Ohmura et al. 2006b / n=5 / Holter-type electrocardiograph SM-60 (Fukuda Denshi, Tokyo, Japan) / HRV analysis software (Softron, Tokyo, Japan)
512 IBIs,
FFT, Hamming window / LF, HF, LF/HF ratio / Long distance road transportation (21 h)
van Breda 2006 / n=12 / Polar electrodes and Con2trol device (Badhoeverdorp, The Netherlands) / HRV analysis software (Biomedical Signal Analysis Group, Dept. of Applied Physics, University of Kuopio, Finland);
no further details; / RMSSD;
LF, HF, LF/HF ratio / Riding horses, stress, “Rollkur”
Cottin et al. 2005 / n=10 / Polar® S-810 heart rate monitor (Polar Electro Oy, Kempele Finland) / 256 IBIs
time-domain analysis: Smoothed Pseudo Wigner Ville Distribution (SPWVD);
LARY_CR, INRIA software (SCICOS-SCILAB); Hilbert Transform, Finite Impulse Response (FIR), definition frequency bands;
frequency-domain analysis: Blackman window, FFT
Matlab software, 6.5.1 (Mathworks Inc., Natick, Massachusetts, USA) / LF, HF, LF/HF ratio;
normalization: LFn.u.=100*LF/(LF+HF); HF dito / Exercise intensity, repetition, trotting horses
Norman et al. 2005 / n=6 / ECG electrodes (C220, Cardiacare, Essex, UK), telemetry transmitter (ZB_822PK, Nihon Kohden, Brentford, Middlesex, UK), receiver unit with oscilloscope display (Lifescope 8, Nihon Kohden), digitalization, Po-Ne-Mah Physiology Platform, Gould Instrument Systems) and ECG MiniDisc Recorder (MZ-N710, Sony) / Microsoft Excel, Dplot 1.8.2 (HydeSoft Computing, Vicksburg, MS, USA)
512 IBIs,
FFT, Hamming window / SDNN, RMSSD, pNN50;
LF, HF, TOTAL;
PNSI, SNSI / ECG signals recorded onto a MiniDisc
Rietmann et al. 2004a / n=19 / Polar®R-R Recorder (Polar Electro Oy, Kempele, Finland),
RR-intervals / ProBeat® (Bellinzona, CH), ProFit® (Quantum Soft, Zürich, CH),
256 IBIs or less,
AR (Bernasconi et al., 1998) / SDNN;
LF, HF, LF/HF ratio / Pain, laminitis
Rietmann et al. 2004b / n=20 / Polar®R-R Recorder (Polar Electro Oy, Kempele, Finland),
RR-intervals / ProBeat® (Bellinzona, CH), ProFit® (Quantum Soft, Zürich, CH),
256 IBIs or less,
AR (Bernasconi et al., 1998) / SDNN;
LF, HF, LF/HF ratio / Exercise, mental stress (walk backwards)
Eager et al. 2004 / n=6 / ECG / 512 IBIs,
no further details / LF, HF,
TOTAL / Temperament test (water spray), circadian rhythm
Bachmann et al. 2003 / n=22 / Polar®R-R Recorder (Polar Electro Oy, Kempele, Finland),
RR-intervals / ProBeat® (Bellinzona, CH), ProFit® (Quantum Soft, Zürich, CH),
170 IBIs,
AR (Bernasconi et al., 1998) / LF, HF, LF/HF ratio / Feeding stress test, crib-biting and control horses
Kato et al. 2003 / n=10 / Holter-type electrocardiograph SM-60 (Fukuda Denshi Co Ltd., Tokyo, Japan) / ECG processor analyzing system (Softron Co Ltd, Tokyo, Japan)
512 IBIs: resampled 200ms,
FFT, Hamming window / LF, HF, LF/HF ratio / Immersion in warm springwater
Voss et al. 2002 / n=7 / ECG (Par-Port/M, PAR Elektronik, Berlin, Germany) / software program RQA 5.2
5 min.,
FFT
normalization: LFn.u.=100*LF/(LF+HF); HFn.u.=100*HF/(LF+HF); / SDNN;
LF and HF normalized
Recurrence Plot / Aqua-treadmill exercise
Ohmura et al. 2001 / n=7 / Holter-ECG (SM-60, Fukuda Denshi Co Ltd., Tokyo) / ECG processor analyzing system (Softron, Tokyo, Japan),
512 IBIs, resampled 200ms, FFT, Hamming window / LF, HF, LF/HF ratio / Effects of repeated atropine injection
Witte 2001 / n=25 / ECG (PAR-PORT/M, PAR Elektronik, Berlin, Germany) / Paron Software,
512 IBIs / 300 sec,
FFT / SDNN, SDANN, RMSSD;
LF, HF normalized LF/HF ratio;
Recurrence Plot / Applying HRV in horses: in a resting position and after exercise
Physick-Sheard et al. 2000 / n=6 / ECG telemetry transmitter (Model 8121) with oscilloscope monitor (Model 8091) from S & W Medico Teknik A/S, (Albertslund, Denmark), / QRS recognition algorithm (APL*PLUS III, Manugistics, Inc., Rockville, Maryland, USA)
512 IBIs,
FFT, Hanning window / VLF, LF, HF;
TOTAL=VLF+LF+HF;
SNSI=LF/HF,
PNSI=HF/TOTAL / HRV at rest and during treadmill exercise
Mohr et al. 2000 / n=25 / ECG (PAR-PORT/M, PAR Elektronik, Berlin, Germany) / Paron Software,
5 min.,
FFT / SDANN, RMSSD;
LF, HF;
Recurrence Plot / Mental stress, exercise
Kuwahara et al. 1999 / n=24 / Holter-ECG (Fukuda Denshi, Tokyo, Japan) 24h / ECG processor analysing system (Softron, Tokyo, Japan)
512 IBIs, resampled 400 ms
FFT, Hamming window / LF, HF, LF/HF ratio / Influence of training, circadian rhythm
Thayer et al. 1998 / ? / ECG with AMD (amulatory monitoring device), see (Thayer et al., 1997) / 3-5 min.,
FFT / MSD (mean successive differences), frequency-domain parameter ? / HRV during treadmill exercise
Kuwahara et al. 1998 / n=1 / Holter-ECG (Fukuda Denshi, Tokyo, Japan),
14 h / ECG processor analysing system (Softron, Tokyp, Japan),
512 IBIs,
FFT, Hamming window / LF, HF, LF/HF ratio / Atrial fibrillation
Bowen and Marr 1998 / n=4 / ECG / 5 min. / LF, HF / Effects of glycopyrolate and propanolol on frequency domain analysis, threshold set for frequency bands
Thayer et al. 1997 / n=4 / microprocessor controlled Ambulatory Monitoring System (AMS) (LvD, University of Amsterdam, The Netherlands) / 3-5 min.,
FFT / MSD (mean successive differences), frequency-domain parameter? / heart rate variability for spectral analysis in horses with AMS
Kuwahara et al. 1996 / n=10 / ECG two-channel recorder (Fukuda Denshi, Tokyo, Japan) / ECG processor analyzing system (Softron, Tokyo, Japan),
512 IBIs,
FFT, Hamming window / LF, HF / Power spectral analysis of HRV in horses, effects of atropine, propranolol, thresholds frequency bands horse
Clément and Barrey 1995a / n=1 / RR-Recorder (BHL 5000, Baumann & Haldi SA, Fleurier, Switzerland) / 1024 IBIs,
FFT with autocorrelation / LF
(LF range <0,056 Hz Eq) / Heart rate variability in horses at rest, effects of atropine and adrenalin
Clément and Barrey 1995b / n=30 / RR-Recorder (BHL 5000, Baumann & Haldi SA, Fleurier, Switzerland) / 1024 IBIs,
FFT with autocorrelation / LF / Effects of age, gender and breed on HRV in horses

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