The OwnZone determination in Polar heart rate
monitors is based on heart rate variability (R-R-interval) measurement during
exercise and it is a result of an extensive research co-operation between Polar
Electro Oy and international research groups. Heart rate variability (HRV) has
traditionally been referred only in medical research in patients. Polar got
interested in HRV in the beginning of 1990 when a Russian scientist presented
his findings to the Polar R&D department. In 1993 Polar started research
co-operation with the Merikoski Rehabilitation and Research Center, Oulu,
Finland, to find out if HRV could be useful also in healthy subjects at rest
and during exercise.
The first study projects were done with sedentary
subjects and with top athletes at rest. The athletes had higher HRV at rest
than the sedentary subjects (unpublished). Preliminary research was also done
during acute stress and anxiety on adults. Even though HRV was related to
stress, no notable results for the use of Polar Electro were found. HRV was
further investigated in athletes before and after resting (2 months) and
training (16 weeks) periods (Mäkikallio et al. 1996). In this phase of
co-operation, the division of Cardiology at the University of Oulu joined the
project to ensure experienced medical advice.
The next research
project was a 3 months training study with relatively sedentary subjects. The
results did not show any changes in the resting HRV after training
(unpublished). However, in this project the systematic repeatability in the HRV
decrease during graded exercise was found. A quantitative Poincaré plot
analysis method for HRV analysis was adopted (Huikuri et al. 1996). A large
bicycle exercise study with 110 men started (Tulppo et al. 1996a,b). An
additional trial with atropine medication (parasympathetic blockade) was
performed. It was shown that the Poincaré plot method can be used as a
reliable analysis method of HRV during exercise (Tulppo et al. 1996a,b). On the
average, the HRV "plateau" (Poincaré plot, SD1) was found at 50-55% of
maximal aerobic power (VO2max) or at about 61-65% of the maximum
heart rate (HRmax). In this phase Polar and Merikoski started
co-operation with the Cooper Institute for Aerobics Research in Dallas, Texas,
USA. Another large sample of 120 adult men and women was studied during
treadmill exercise to ensure the previous finding of HRV plateau during
exercise (Tulppo et al. 1996c, Wilkinson et al. 1996a,b, 1997, 1999). The
plateau occurred at somewhat higher percentage of the maximal aerobic power on
the least fit subjects (57%) compared to the most fit ones (53%) (Wilkinson et
al. 1996c). The HRV measures were shown to be independent of the absolute heart
rate (Thompson et al. 1997). Because all aforementioned studies concluded that
the HRV measures could serve as reliable markers of exercise intensity, Polar
adopted the method for technical development. This resulted in the OwnZone
After the basic research described above, several other
study projects have been carried out in co-operation with the Merikoski Center
from 1997 on. A large sample of 110 males was further analyzed and age was
shown to explain the HRV at rest and physical fitness during exercise (Tulppo
et al. 1997a,b, 1998a). One study has been conducted on the repeatability of
the HRV measures. In this work every subject was measured on four consecutive
days (two days between each) to detect possible day-to-day variation in HRV
during exercise (Tulppo et. al. 1998a). Another study has been done on bicycle
and on treadmill both at steady-state and during interval exercise to detect
possible differences between exercise modes. The results showed that the HRV
plateau, as expressed in percentages of maximal aerobic power, is well
repeatable, and the changes in the autonomic modulation of HR were comparable
during arm and leg exercise (Tulppo et al. 1999) Three of the aforementioned
studies (Tulppo et al. 1996b, 1998a, 1999) have been discussed also in the
doctoral dissertation by Mikko Tulppo on December 1998 (Tulppo 1998b).
In the early phase of the OwnZone development, a controlled trial with a
SmartEdge heart rate monitor simulator was done in the laboratory. The OwnZone
determination developed was consistent (unpublished). SmartEdge prototypes were
used in a field validation study on 50 adults to study if the field
determination of the OwnZone done by slow to fast walking-jogging warm-up
protocol is consistent with the HRV plateau measured in the laboratory. The
lower and the upper OwnZone target heart rate limits determined by SmartEdge
were (mean±SD) 121±8 and 154±9 bpm and corresponded to
64±4% and 82±5% of maximal heart rate, respectively (Laukkanen et
In a field study on ten adults, the OwnZone determination
test (incremental warm-up) was done twice a day for a month (unpublished). In
this group 90% of the subjects achieved the HRV-based OZ determination (OZV)
with an individual variation of 5-10 bpm. The OZ values tended to be 3-5 bpm
lower when the test was done in the morning (within 2 hours from waking up)
than those determined in the evening (after 6 p.m.). The lowest HR limits were
obtained in cycling, and the highest in cross-country skiing. The values in
walking-jogging were in between. A resting period (several days without
physical activity) as well as long-duration, low-intensity recovery-type
exercise seemed to increase the OZ heart rates slightly, whereas bad sleep and
stress feelings tended to decrease the heart rates.
reproducibility of individual training heart rate determined by Polar SmartEdge
HR monitor has proven to be good (Kinnunen et al. 1998). In this study on
healthy males the OwnZone determinations were repeated four times with four
days of recovery in between. In a study on 50 obese men and women (mean BMI 37
kg/m2) the lower and upper OwnZone HR limits determined by the
SmartEdge corresponded to 118 bpm (68% HRpeak) and 150 bpm (86%
HRpeak) on the average (Byrne et al. 1999). On 50 non-medicated
hypertensive males and females (mean age 45 years) the lower and upper HR
limits determined by the SmartEdge corresponded to 113 bpm (66%
HRpeak) and 147 bpm (85% HRpeak) on the average (Byrne et
al., submitted). On 58 keep-fit middle-aged marathon runners, men and women,
the OwnZone lower limit corresponded to 117 bpm (65% HRmax) and the
uppr limit to 147 bpm (83% HRmax) on the average (Virtanen et al.
The latest position stand of American College of Sports
Medicine (ACSM 1998) for the recommended quantity and quality of exercise for
developing and maintaining cardiorespiratory fitness in healthy adults
recommends 55/65-90 % of maximum heart rate for the intensity of training. The
results obtained on Polar OwnZone indicate that it can be used for feasible
target heart rate zone determination in adults.
American College of Sports Medicine. Position Stand: The
recommended quantity and quality of exercise for developing and maintaining
cardiorespiratory and muscular fitness, and flexibility in healthy adults. Med
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comparison of different determination methods. Submitted.
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Myerberg R. Abnormalities in beat-to-beat dynamics of heart rate before the
spontaneous onset of life-threatening ventricular tachyarrhythmias in patients
with prior myocardial infarction. Circulation 93, 1836-1844, 1996.
Kinnunen H, Tulppo M, Mäkikallio T, Hyyppä O, Nissilä S,
Laukkanen R. Reproducibility of individual training heart rate determined by
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Symposium, Kuopio, Finland, p. 63, 1998.
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The response of heart rate variability during graded treadmill exercise.
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Wilkinson J, Thompson R, Garcia M,
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variability to work intensity during graded maximal treadmill exercise.
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