Amazfit GTS 4 : Full Scientific Review ( Form over Function… )

Testing the GTS 4: A Comprehensive Review

Introduction to the GTS 4

• The video introduces a systematic review of the GTS 4's capabilities in sports and health tracking, contrasting it with the previously reviewed GT-R4.

• The GTS 4 is described as a lighter and smaller version of the GT-R4, featuring a square screen which may enhance its performance.

• Data collected includes metrics from 29 workouts, 11 nights of sleep, and 13 GPS tracks for comparison against reference devices.

Health and Sports Tracking Features

Heart Rate Tracking Accuracy

• The review focuses on three key features: heart rate tracking accuracy, sleep stage tracking performance, and GPS tracking.

• Heart rate measurements from the GTS 4 are compared to those from a Polar H10 ECG chest strap for accuracy during indoor cycling sessions.

Analysis of Heart Rate Data

• An overview graph shows heart rate measurements; points closer to the blue line indicate better agreement between devices.

• A significant number of data points fall below this line, indicating instances where the GTS 4 recorded half of the actual heart rate due to noisy signals.

Correlation Metrics

• The correlation value (R = 0.67) indicates moderate agreement but suggests room for improvement in heart rate detection accuracy.

Individual Training Session Insights

• Specific training sessions reveal inconsistencies; some show poor agreement while others perform adequately in detecting heart rates.

• In one session, the GTS 4 consistently underreported heart rates during intervals but showed improvement in another session.

Performance Comparison with Other Devices

Overall Performance Context

• The analysis highlights variability across different training sessions; some performed well while others did not meet expectations.

• Comparisons with other tested watches illustrate that while some sessions were satisfactory, overall consistency remains an issue.

Conclusion on Heart Rate Tracking

• Despite occasional successes in detecting peaks accurately, many sessions exhibited significant discrepancies in heart rate readings.

GTS4 Performance Analysis

Comparison with Other Smartwatches

• The GTS4 does not perform well compared to many other smartwatches, particularly in the lower region of performance plots.

• Notable devices with high correlation scores include various Apple watches, some Huawei models, Galaxy Watch 4, and Google Pixel Watch. The GTS4 is not favored by the reviewer.

Running Performance Evaluation

• During outdoor running tests, the GTS4 struggled to accurately track heart rate peaks; it often recorded lower than actual peak heart rates.

• Although there was slight improvement in tracking during a second run, overall accuracy remained questionable for heart rate monitoring while running.

Cycling Heart Rate Tracking

• Cycling presents additional challenges for accurate heart rate readings due to wrist movement; the GTS4 was tested over 13 bike rides.

• The review notes that all tests were conducted at the end of 2022 and acknowledges potential software updates that may have occurred since then.

Data Analysis from Cycling Tests

• A plot shows significant spread in data points for cycling heart rates; many readings indicated lower than actual heart rates.

• Specific bike ride analyses reveal discrepancies between GTS4 readings and ECG chest strap data, with several instances of incorrect low heart rate detection.

Weightlifting Performance Insights

• The new Bio Tracker 4.0 sensor used in the GTS4 does not show significant improvements over previous sensors based on weightlifting performance evaluations.

Heart Rate Tracking Performance of the GTS 4

Overview of Heart Rate Detection

• The performance of the GTS 4 in heart rate detection is mediocre, with a correlation value of 0.69 indicating inconsistent results.

• During training sessions, the GTS 4 struggles to detect peak heart rates, particularly when tension increases on the arm during sets.

• Compared to other watches tested, the GTS 4 ranks in the middle for consistency; it performs similarly to the Amaze GT-R4 but is not ideal for weightlifting.

Recommendations and Ratings

• For accurate heart rate tracking during weightlifting, an ECG chest strap is recommended over the GTS 4.

• Overall reliability for exercise heart rate tracking with the GTS 4 is low; it receives a rating of 2 out of 5 stars.

Sleep Stage Tracking Capabilities

Comparison with EEG Device

• To evaluate sleep stage tracking accuracy, comparisons are made between the GTS 4 and an EEG device called The Dream 2.

• The study spans over eleven nights to assess how well the GTS 4 predicts sleep stages compared to EEG readings.

Sleep Stage Agreement Analysis

• Only about 43% of deep sleep detected by EEG was also identified as deep sleep by the GTS 4, which is considered low compared to other devices that achieve up to 80% agreement.

• A significant portion (56%) of what was recorded as deep sleep by EEG was misclassified as light sleep by the GTS 4.

Individual Night Observations

• On specific nights, there were instances where no agreement existed between deep sleep recordings from both devices; this indicates poor performance from the GTS 4.

• Light sleep detection showed better agreement at around 67%, but discrepancies still occurred where light sleep was often classified incorrectly as REM or deep sleep.

REM Sleep Tracking Issues

• The agreement for REM sleep detection was notably poor at approximately only 35%, suggesting significant inaccuracies in identifying this stage.

• Similar patterns emerged across individual nights where most detected REM sleep was instead categorized as light or deep sleep by the GTS 4.

Conclusion on Sleep Tracking Performance

Sleep Tracking Performance of the GTS 4

Overview of Sleep Data Analysis

• The GTS 4 shows poor REM sleep detection, with almost no REM recorded during one night, which is unlikely based on typical sleep patterns.

• The analysis indicates that the GTS 4 fails to accurately reflect sleep cycles; typically, four to six cycles should be visible but are not detected.

• There is a significant discrepancy in wake detection; only 40% of awake time was captured by the GTS 4 compared to EEG data.

• The GTS 4 misclassifies some awake moments as light sleep, indicating lower sensitivity than EEG devices in detecting wakefulness.

• Overall, the performance pattern suggests that while longer awake periods are sometimes detected, shorter ones often go unnoticed.

Comparative Performance Against Other Devices

• A comparison graph shows that various Apple Watches outperform the GTS 4 significantly in terms of agreement with EEG data across different sleep stages.

• Notable high-performing devices include Apple Watch Series 7 and Series 8, along with Fitbit and Google Pixel Watch for accurate sleep tracking.

• The GTS 4's performance is closely aligned with its predecessor (GTR 4), suggesting similar algorithms may be used across these models.

• In terms of average agreement over four sleep stages, the GTS 4 ranks among the worst alongside some Huawei and Garmin devices.

• Due to its inadequate tracking capabilities, a rating of only two out of five stars is given for the GTS 4’s sleep stage tracking.

GPS Tracking Evaluation

• The GPS functionality was tested during ten bike rides to assess signal acquisition speed and accuracy over repeated routes.

• Signal acquisition was generally quick; three out of five rides had accurate initial location detection without additional waiting time for signal lock.

• However, there were inconsistencies in signal overlap across rides; signals did not align well when comparing multiple trips on the same route.

GPS Tracking Performance of the Amazfit GTS 4

Initial Observations on Signal Quality

• The initial signal quality for the Amazfit GTS 4 appears poor, with signals spread apart during rides.

• Upon cycling back from work, the GPS acquisition moments are closely grouped, indicating some improvement in signal acquisition.

Analysis of Signal Consistency

• Despite initial improvements, later signals show significant inconsistency; some signals appear to go through buildings or parks where no riding occurred.

• Notable deviations in signal paths are observed, particularly where two rides diverge significantly from others and do not align with actual routes taken.

Overall Evaluation of GPS Accuracy

• The overall performance is disappointing; large deviations between signals raise concerns about the accuracy of route tracking by the GTS 4.

• While it can provide a rough estimate of distance for casual use, it may not be reliable for precise tracking needs. A rating of 2.5 out of 5 stars is given for GPS tracking performance.

Health and Sports Tracking Assessment

• The health and sports tracking capabilities also receive a low rating of 2 out of 5 stars due to poor measurement accuracy despite appealing design features.

• For users primarily interested in health metrics, alternative options like Apple Watches are recommended for better heart rate and sleep stage tracking.

Recommendations for Alternative Devices

• The speaker suggests considering an Apple Watch SE for superior health metrics but notes that it requires an iPhone to function effectively.