TABLE 2. Group results
Intensity Apple Watch Fitbit Charge 2 ECG (bpm)
Very light 76.9 75.4 76.6
Light 102.6 100.2 104.2
Moderate 121.8 116.7 127.8
Vigorous 153.1 153.1 157.0
Very vigorous 177.0 157.5 179.9
Specific to each of the wrist-worn
devices, the Apple Watch had relative error
rates that ranged from 2.4% (overall) to 5.1%
(moderate). The Fitbit Charge 2 had relative
error rates that ranged from 4.9% (overall) to
13.4% (very vigorous). It should be noted that
the overall relative error rate increased in the
Fitbit Charge 2 as the intensity of exercise
increased (very light 4.9% to very vigorous
13.0%). The authors note that a relative error
rate of < 5% defines the acceptable limit.
The authors concluded that the Apple
Watch matched the ECG more accurately
for all exercise intensities overall, and for
each gender. Also, neither the apple Watch
or the Fitbit Charge 2 matched the actual
HR during the vigorous and very vigorous
intensity. The accuracy of the Apple Watch
and Fitbit Charge 2 was reduced as the
exercise intensity increased. As a clinician,
it is encouraging to note that wrist-worn
technology has made great improvements
THE QUICK READ
62 | NETWORK WINTER 2019
• Wearable technology continues to
evolve and to grow in popularity, with
a global revenue of around $34
billion
• Researchers determined the validity
of exercise heart rate at different
intensities for two popular wearable
devices
• Using a treadmill test, the data
collected by the Fitbit Charge and the
Apple Watch were compared to that
collected
by
medical-grade
electrocardiogram (ECG) monitoring
• The data collected by the wrist-worn
tech was understandably not as
accurate as that of the ECG, but
accuracy was noticeably improved
compared to earlier wearable
devices.
in accuracy over just 2 years. However, in
instances where a very accurate exercise
heart rate is required (i.e. exertional angina)
caution must be exercised (excuse the
pun) with regard to prescribing exercise,
particularly aerobic exercise, in individuals
where high exercise heart rates could
become life threatening.
Pros: We are impressed with this study, it
was well designed and conducted. Revenue
from wearable technology is predicted to
exceed $247 million dollars here in Australia
this year alone, with one in five Australians
owning a device. Worldwide, this market is
expected to exceed $34 billion by next year.
Clearly this is not a short-term trend and, as
we are seeing, the technology is improving
dramatically.
These devices are being used for more
than exercise heart rates. A friend from
Hawaii recently bought the new Apple Watch
for his dad, exclusively as it can monitor the
heart. Apple claims it captures the heart
rhythm (referred to as irregular rhythm
notification) when the wearer experiences
symptoms (rapid or skipped heart beats),
and it can provide this information to the
individual’s doctor. No doubt we will see
further improvements in this area over the
coming years.
Cons: It would have been an interesting
extension of this research if they also
investigated the accuracy during resistance
training.
REFERENCES
Thompson, E., Comstock, A., Reinwald, S., Blake,
S., Pimentel, R., Tracy, B., & Li, K. (2019). Heart rate
measures from the Apple Watch, Fitbit Charge HR
2, and electrocardiogram across different exercise
intensities. Journal of Sports Sciences. 37 (12):
1411-1419.
Climstein, M., & Walsh, J. (2016). Research
Reviews: Wrist-worn tech: Investment of waste of
Money? Australian Fitness Network. Spring: 44-45.
Pevnick, J., Birkeland, K., Zimmer, R., Elad, Y.,
& Kedan, I. (2019). Wearable Technology for
Cardiology: An Update and Framework for the
Future. Trends Cardiovascular Medicine. 28 (2):
144-150.
Dr Mike Climstein, PhD FASMF FACSM FAAESS
AEP
Dr Climstein is one of Australia’s leading Accredited
Exercise Physiologists. He is a faculty member
in Clinical Exercise Physiology, Sport & Exercise
Science at Southern Cross University (Gold Coast).
[email protected]
Dr Joe Walsh, PhD
Joe is a sport and exercise scientist. As well as
working for Charles Darwin and Bond Universities,
he is a director of Fitness Clinic in Five Dock,
Sydney. fitnessclinic.com.au