Rate Monitoring is State of the Art
Heart rate is a useful indicator of
physiological adaptation and intensity of effort. Therefore, heart rate
monitoring is an important component of cardiovascular fitness assessment and
training programmes. The electrocardiogram (ECG) and Holter monitoring devices
are accurate, but not feasible for use in field settings due to cost, size and
complexity of operation. Light-weight telemetric heart rate monitors equipped
with conventional electrodes have been available since 1983 and have proved to
be accurate and valid tools for heart rate monitoring and registering in field
measurements. Polar Electro Oy has been a leading company in producing
ambulatory heart rate monitors for fifteen years. This article reviews the
development history of Polar Heart Rate Monitors and their measurement accuracy
compared to Holter ECG devices at rest and during exercise both in adults and
Accurate heart rate monitoring is essential in fitness training
and testing. Manual pulse palpation provides inaccurate results (Clapp and
Little 1994). The use of ECG or Holter monitoring is too costly and complex for
exercisers to use in the field. The first wireless heart rate monitor was
introduced in 1983. It was a portable Polar PE 2000 heart rate monitor which
consisted of a transmitter and a receiver. The transmitter could be attached to
the chest using either disposable electrodes or an elastic electrode belt. The
receiver was a watch like monitor worn on the wrist. The wireless Polar heart
rate monitoring method was developed at the University of Oulu, Department of
Electronics. In the beginning the heart rate monitors were targeted for coaches
and sportsmen to optimize the quality and efficiency of training. Soon exercise
scientists started to research the monitors and use them in their work. The
first issue of Polar Research Index (1995) includes altogether 200
physiological and medical studies on humans and animals involving Polar heart
rate monitors. Today the selection of heart rate monitors includes easy-to-use
products for everyone interested in wellness, fitness and health.
Heart rate monitors and their accuracy
Polar Electro Oy introduced it's first retail monitor, Tunturi
Pulser, in 1978. This was a heart rate monitor with optional cable-connected
chest belt. Five years later, in 1983, the first wireless heart rate monitor
using electric field data transfer was introduced. This microcomputer was
called Sport Tester PE 2000 (Figure 1). Karvonen et al. (1984) compared heart
rates measured by Holter and PE 2000. The results showed that the mean heart
rates obtained by ECG and PE 2000 differed from each other at most by 5 beats
min-1 and in single measurements by 0-10 beats min-1 at every work load. The
differences were caused mainly by the different methods of calculation using
either ECG ruler or microcomputer display reading. It was concluded that both
methods can be regarded as equally valuable for measuring heart rate during
In 1984 Polar Electro Oy introduced the world's first heart
rate monitor equipped with computer interface and transmission by magnetic
field. This was called Sport Tester PE 3000 (Figure 2). Vogelaere et al. (1986)
compared the heart rate readings of PE 3000 with Holter ECG reference values on
twenty subjects during exercise. The results showed that PE 3000 is a valid
alternative for measuring heart rate in the field and for laboratory research
purposes compared with the fragile and unwieldy Holter apparatus.
Leger and Thivierge (1988) compared the validity, stability and
functionality of thirteen different heart rate monitors. The monitors were
divided into three categories according to the correlation of the heart rate
readings with those of the Holter. The monitors were regarded as excellent if
the correlation coefficient (r) was 0.93 and standard error of estimate
(SEE) less than 6.8%; good if 0.93>r0.65 (SEE 6.8%-15%); and inadequate
with r<0.65 (SEE >15%). Based on this classification the heart rate
monitors using conventional chest electrodes to measure electrical activity of
the heart namely Exersentry (Respironics Ltd, Hong Kong), PE 3000 (Polar
Electro, Finland), Pacer 2000 H (Sportronic AG, Switzerland) and Monark 1
(Monark-Crescent, Sweden) resulted in excellent readings. Seiko 1 (Seiko,
Japan) achieved good validity and several others using other types of
electrodes or earlobe photocell to measure the opacity of the blood flow, were
inadequate. In a study by Seaward et al. (1990) the precision and accuracy of a
portable PE 3000 proved to be equal to that of ECG. The 250 data sets obtained
at rest and during variable-intensity exercise resulted a correlation
coefficient of 0.9979 over the heart rate range of 55 -177 beats min-1.
Thivierge and Leger (1989) also published a review about the operation
principles, validity, stability and functional characteristics of heart rate
monitors. In this paper the results were consistent with their previous work
(Leger and Thivierge 1988); the heart rate monitors with conventional
electrodes gave more valid results and the use was more feasible compared with
those using non-conventional electrodes or photo-electric sensors placed either
on finger or ear.
Treiber et al. (1989) studied heart rate monitoring
with children in the laboratory and in field settings during six different
exercise activities and recovery. They reported correlation coefficients of at
least 0.93 (SEE 1.1-4.3 beats min-1) between the Sport Tester PE 3000 and ECG
derived heart rates. The interface and software package (Sport Tester Training
System) proved to be an efficient tool for heart rate analysis. This was the
first computerized training system for measuring, registering and printing
heart rate information.
Polar Sport Tester, also known as Polar
Vantage XLâ , came out in 1989 (Figure 3). This was a water resistant
heart rate monitor with contactless (magnetic field) computer interfacing and a
large memory in watch size. The accuracy of this monitor was studied by Godsen
et al. (1991). They compared 2633 heart rate readings during treadmill running,
rowing, arm-leg cycle ergometry and weight training. As a result, the Sport
Tester yielded heart rate values within ± 6 beats min-1 from ECG values
about 95% of the time. Their conclusion stated that arrhythmias, anticipatory
heart rate rises and rapid adaptation to or recovery from exercise explained
most of the errors. Wajciechowski et al. (1991) published a study about the
accuracy of two Polar heart rate monitors (most probably Polar Vantage
XLâ) compared with ECG readings during walking, jogging and aerobic dance
in women. When the monitor values were averaged for 10-s readings (400 cases),
the correlation coefficient between the monitor and ECG values was 0.99. Ninety
percent of all measured errors were within ± 8 beats min-1.
During 1990-1993 Polar Electro introduced many new innovations. Polar
CycloVantage was the world's first cycle-computer with a computer interface
measuring speed, time, distance and pedalling rate. Polar Accurex IITM heart
rate monitor had sport watch functions and an average heart rate,
Windowsâ based analysis software and an integrated, lightweight, water
resistant one-piece transmitter (T40, Figure 4). Easy-to-use consumer-friendly
products including buttonless FavorTM and BeatTM heart rate monitors were
introduced during 1991-93.
Lewis (1992) compared Polar Favor and Edge
heart rate monitors in his work on 24 subjects during light to maximal
intensity endurance activities. The correlation coefficient and standard
deviation (S.D.) of the heart rates registered by the monitors were 0.97
(± 3-4 beats min-1) when compared to ECG measurements.
Polar introduced the Vantage NVTM heart rate monitor (Figure 5) including for
the first time coded transmission (one signal from each transmitter to
receiver) and R-R recording (beat to beat) and analysis system (Polar Advantage
Interface SystemTM and Precision Performance SoftwareTM for Windowsâ).
This innovative monitor was used in the study of Kaikkonen et al. (1997) for
the detection of recovery and overtraining in male orienteers. They reported
that the measurements were easy to perform and analyse by the sportsmen at home
and during a training camp with the Vantage NVTM and a Precision Performance
SoftwareTM. Kinnunen and Heikkilä (1997; also see abstract in this
journal) evaluated the timing accuracy of the Polar Vantage NVTM heart rate
monitor in the measurement of R-R intervals. Their results showed that in 99.9%
of the R-R intervals the difference between Polar Vantage NVTM and Polar R-R
RecorderTM (Ruha et al., 1997) was within ± 5 ms.
In 1997 Polar
launched the Xtrainer PlusTM, which is a heart rate monitor and a
cycle-computer in one unit. This device is able to measure heart rate,
distance, time, speed, cadence and altitude during performance.
very latest innovation, Polar SmartEdgeTM (Figure 6), is a heart rate monitor
with an automatic intensity guidance feature (called the "OwnZone"), and is
also capable of estimating energy expenditure during exercise (the "OwnCal").
Both features are based on R-R recording and equations derived from extensive
physiological research conducted in several research units.
research group has evaluated Polar SmartEdgeTM "OwnZone" and "OwnCal" features
(unpublished observations). The lower heart rate limits determined by the Polar
SmartEdgeTM heart rate monitor correspond to 62 ± 4% and 65 ± 3%
and the upper limits to 80 ± 5 and 84 ± 3% of the maximum heart
rate in men and women, respectively. The energy expenditure predicted by
SmartEdgeTM was compared with that measured by Cosmed (K4, Italy). In two
thirds of the subjects, the difference between the values of the two pieces of
apparatus was less than 15% during cycling and walking, which was considered
Polar Heart Rate Monitors have for fifteen years been recognized
as the most accurate tools for heart rate monitoring and registering in the
field. Extensive research and development work has also resulted in top quality
devices for the analysis of heart rate data. Table 1 summarizes the most
notable innovations of Polar Electro Oy since 1977. In the future the heart
rate monitors and analysis tools will increasingly develop in the direction of
interpretation of heart rate information.
Table 1. "Firsts" in heart rate monitoring (HRM) by Polar
|Battery operated fingertip pulse meter
|Polar's first retail monitor Tunturi
|Wireless heart rate monitor Sport
Tester PE 2000
|HRM with computer interface Sport
Tester PE 3000
|Computerized Sport Tester Training
|HR analysis Software for IBM PC
|Sport Tester PE 300 (target zone time
|Contactless computer interface HRM
Polar Sport Tester
|Cyclecomputer with wireless HRM Polar
|Windows based Analysis Software
|Intergrated one piece transmitter T40
|Consumer product family
|NightVision feature in HRM Accurex NVTM
|Coded transmission in HRM Vantage NVTM
|R-R recording and analysis in HRM
|HRM and cyclecomputer in one unit Polar
|Polar SmartEdgeTM HRM with OwnZone and
Clapp III, J. and Little, K. (1994). The physiological response
of instructors and participants to three aerobics regimens. Medicine and
Science in Sports and Exercise, 26(8), 1041-1046.
Godsen, R., Carroll,
T. and Stone, S. (1991). How well does Polar Vantage XL Heart Rate Monitor
estimate actual heart rate? Medicine and Science in Sports and Exercise, 23(4),
Kaikkonen, H., Karppinen, T. and Laukkanen, R. (1997).
Recovery and overtraining detection in male orienteers before, during and after
intensive training period. Abstract in 6th International Scientific Symposium
on Orienteering, Oslo, Norway, 18-19 August.
Chwalbinska-Moneta, J. and Säynäjäkangas, S. (1984). Comparison
of heart rates measured by ECG and Microcomputer. The Physician and
Sportsmedicine, 12(6), 65-69.
Kinnunen, H. and Heikkilä, I.
(1997). The timing accuracy of Polar Vantage NV heart rate monitor. Journal of
Sports Sciences (present issue).
Leger, L. and Thivierge, M. (1988).
Heart rate monitors: validity, stability and functionality. The Physician and
Sportsmedicine, 16(5), 143-151.
Lewis, D. (1992). An investigation
into the accuracy of the Polar Favor and the Polar Edge heart rate monitors
compared with direct ECG measurements. Newcastle Polytechnic, Newcastle, UK,
Polar Research Index (1998). Polar Electro Oy,
Ruha, A., Sallinen, S. and Nissilä, S. (1997).
A real-time microprocessor QRS detector system with a 1 ms timing accuracy for
the measurement of ambulatory HRV, IEEE Transactions on Biomedical Engineering,
Seaward, B., Sleamaker, R., McAuliffe, T. and Clapp, J.
(1990). The Precision and Accuracy of a portable heart rate monitor. Biomedical
Instrumentation & Technology, 24(1), 37-41.
Thivierge, M. and
Leger, L. (1989). Critical review of heart rate monitors. Canadian Association
for Health, Physical Education and Recreation Journal, 55(3), 26-31.
Treiber, F., Musante, L., Hartdagan, S., Davis, H., Levy, M. and Strong, W.
(1989). Validation of a heart rate monitor with children in laboratory and
field settings. Medicine and Science in Sports and Exercise, 21(3), 338-342.
Vogelaere, P., De Meyer, F., Duquet, W. and Vandevelde, P. (1986).
Vergleich zwischen "Sport Tester PE 3000" und Holter-EKG zur Messung der
Herzfrequenz (Sport Tester PE 3000 vs Holter ECG for the measurement of heart
frequency). Science and Sports, 1(4), 321-329.
Gayle, R., Andrews, R. and Dintiman, G. (1991). The accuracy of radio telemetry
heart rate monitor during exercise. Clinical Kinesiology, 45, 9-12.