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Reference devices:
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Timestamps:
00:00 Testing Background
01:28 Huawei Watch GT4 Improvements
05:35 Heart Rate Test 1 : Indoor Cycling
10:16 Heart Rate Test 2 : Outdoor Cycling
14:13 Heart Rate Test 3 : Running
16:29 Heart Rate Test 4 : Weight Lifting
20:45 Heart Rate Test 5 : Hiking
21:46 Sleep Test : Performance
30:02 Sleep Test : Comparison
32:39 GPS Test
39:40 Oxygen Saturation Test
44:04 Limitations
44:40 Heart Rate Test 6 : Theresa
46:52 Conclusions

The Huawei Watch GT4 comes in two sizes 46mm and 41mm, where the 46mm version is clearly aimed more at men and the 41mm version at women. The 46mm version comes in 4 colors: black, brown, green and gray, with different types of straps for each, though the green one might not release everywhere. The 41mm version comes in 3 colors: white, light gold and silver. In terms of design, the thing that stands out most is the octagonal bezel of the 46mm version. Personally I am not the biggest fan, but this is totally subjective of course. What I do like is the design of the 41mm version and the way the screen lays flush with the watch bezel.
In terms of heart rate tracking, the Huawei Watch GT 4 now comes with the newer TruSeen 5.5+ algorithm, whereas the GT3 launched with 5.0+. It is not publicly known what Huawei changed exactly about the algorithm, but they say that they use Artificial Intelligence algorithms to train an individualized model based on your historical data, that should improve the accuracy of the heart rate readings even under difficult conditions. They mention that it should for instance be better now during running for instance, and they also claim that the sensor should have improved accuracy in low-temperature environments, as well as faster blood oxygen readings and enhanced sleep reading accuracy. The GT4 can also take continuous measurements of your heart rate, oxygen saturation and stress levels throughout the day. Although I cannot test this, the GT4 has menstrual cycle management; version 3.0 keeps track of menstruation cycles and tries to estimate the ovulation date by analyzing things like your heart rate during sleep, body temperature, and breathing rate.
The GT4 uses version 3.0 of the TruSleep algorithm, which Huawei says has better sleep tracking accuracy; specifically Huawei says they estimate your sleep stages based on body movement, heart rate and HRV. Additionally, the GT4 now adds a new Sleep Breathing awareness feature that could help identify symptoms of Sleep Apnea. Similar to one of the biggest brands in the smartwatch world, the Huawei Watch GT4 also shows your daily activity in a ringed format. These rings are now slightly changed.