https://dyrts.fr/en/ Recent content on Alg for Forerunner Hugo -- gohugo.io en dyrts@free.fr (Sébastien Dyrts) dyrts@free.fr (Sébastien Dyrts) Sébastien Dyrts Mon, 26 May 2025 00:00:00 +0000 https://dyrts.fr/en/posts/newzone/ Mon, 16 Sep 2024 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/newzone/ The use of zones is a simplified way of representing effort intensity. It has the advantage of providing a simplified reference point during the race and to define intensity ranges. Power Tool represents them in two ways: With a coloured progress bar in the screen’s background A number with two decimals It is also possible to create workouts via the Garmin Connect interface by specifying target power zones. The zones used, however, are those defined in Power Tool and not those defined on the Garmin’s platform. The zones are defined in the Garmin Connect IQ parameters. For example, in for the following configuration, we have chosen to specify only the threshold pace: Configuration the Zones in GarminIQ In fact, the only mandatory value is the critical power or threshold speed. If other values are omitted, they are determined according to Stryd’s formula. https://dyrts.fr/en/posts/trackdist/ Sun, 18 Feb 2024 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/trackdist/ One of Power Tool’s functions is to calculate the equivalent pace on the track. This corresponds to the speed on a flat road (in a windless situation) that the runner would have for a given power. In other words, if he runs at 300W at a pace of 4:00 on an athletics track, Power Tool will display 4:00 instead of the wattage. This is more intuitive, and makes it possible to use power-based training plans based on MAS (Maximal Aerobic Speed) When running a marathon, this pace is generally the same as the one measured. The wind can certainly influence it, but the difference in altitude is generally so insignificant as to be negligible on most courses. Trail running is a different matter, and the difference in altitude is such that it becomes equivalent to adding distance. A classic approximate formula is to consider that 100m of additional ascent is equivalent to 1km more. https://dyrts.fr/en/posts/powertool_stryd_workouts/ Sun, 14 Jan 2024 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/powertool_stryd_workouts/ Since 2023, Stryd’s Stryd+Zone data field has supported workouts created directly by Garmin Connect, and synchronizes PowerCenter workouts with the Garmin platform. The data field then reads steps directly from Garmin’s standard workouts and takes care of alerting when zones are exceeded. Power Tool and Power Workout support exactly the same functionality. As a result, the user ends up receiving alerts from two different applications for the same workout. Quite disturbing! A radical solution is to use only one of the fields. But this means losing a number of functions. If we remove the Stryd+Zone field, as a result we would have: No synchronization with PowerCenter No recording of advanced metrics such as LSS, ground contact time, form power… … If you remove Power Tool, you lose: the equivalent pace calculation on a track. the heart rate analysis for a given power. https://dyrts.fr/en/posts/powertool_new_hr_alg/ Wed, 16 Aug 2023 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/powertool_new_hr_alg/ Why change the mathematical model? The original idea was to use the same linear model which, in calculating heart rate, took into account the power of the last 15 seconds, the last 30 seconds and so on up to 4 minutes. The formula was then: $$ HR = a_0 + \sum_{i=1}^{5}{ a_{2i-1} \times P[-15 \times 2^{i-1}\ldots 0] + a_{2i} \times D[-15 \times 2^{i-1}\ldots 0] } $$ P[a…b] is the average power of the relative moment up to the moment b. P[-15…0], P[-30…0] and P[-60…0] are the average power of 15 seconds. D[a…b] is the standard deviation of power over the interval [a…b]. We therefore take into account the average power of 15, 30s, 60s, 1 minute, 2 minutes and 4 minutes and its average variations. The parameters a0 to a16 are determined in such a way as to minimize the error between the measured heart rate and that produced by the formula. https://dyrts.fr/en/posts/powerzone/ Thu, 18 May 2023 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/powerzone/ Zone numbers are a simplified way to represent the intensity of the effort. It has the advantage of providing a simple number, easy to interpret, during the race and for workouts, it permits to easily define the intensity ranges. Power Tool displays it in 2 ways: A progress bar in the background with a color that represents the zone A simple 2 digit zone number The zones are configured through the settings in ConnectIQ. For example, for the following configuration we have: Power zones configured in GarminIQ The zones are: Power Zone Color <150W 0 ⚪ transparent 150W-170W 1.x ⚫ gray 170W-190W 2.x :blue_circle: blue 190W-211W 3.x 🟢 green 211W-230W 4.x 🟠 orange 230W-250W 5.x 🔴 red >250W 6 🟣 purple To display the zone itself, it is necessary to select the value “Power Zone” for 3s, 5s, 10s or more for the fields: https://dyrts.fr/en/posts/tm_trail_training/ Fri, 20 Jan 2023 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/tm_trail_training/ Running on a treadmill is not the same as running on the road. And, this is not a detail because the effort required on the home trainer can be much higher than that of an outdoor run. I’m not an indoor runner, but I did a first try this winter and my heart rate was about 20 beats higher than normal: Heart Rate difference There are various reasons for this: The regulation of the body temperature is more difficult than outside. We run at room temperature and there is no wind and so no air flow due to the movement of the runner. But air is a thermal insulator, we find ourselves having difficulties to evacuate the heat induced by the effort in this environment. The speed being imposed, it is necessary to adjust permanently to the speed of the treadmill. https://dyrts.fr/en/posts/garmin_power_config/ Fri, 28 Oct 2022 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/garmin_power_config/ The problem With version 10 of the Fenix7 firmware1, Garmin offers native support for running power either: by the HRM-Pro chest strap or directly using the watch’s sensors. In both cases, this information takes precedence over the Stryd sensor because the footpod of Stryd requires an additional ConnectID field. This is particularly annoying because Stryd is more practical (a footpod is still more comfortable to wear than a chest strap) and more accurate. The solution for Fenix7 firmware 9 is to disable the advanced features of the HRM-Pro by connecting it only as a heart rate monitor. A bit restrictive to have to choose between having an accurate measured power and the running dynamics metrics of Garmin… The solution From version 10 of the Fenix7 firmware, it is possible to choose if the power comes from the HRM-Pro accessory or from the calculation of the integrated sensors of the watch. https://dyrts.fr/en/posts/power_workout_garmin_connect/ Mon, 22 Aug 2022 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/power_workout_garmin_connect/ Since 2022, Garmin has added support for running power but it is limited only to its own equipment. For the Stryd sensor, only two solutions officially exist: Either use the native Garmin running application and add the Stryd field. This configuration allows you to use only the power in an informative way. Structured training is not supported. Use the Stryd application and, in this case, structured training with the power sensor is possible but with losing many native functionalities like navigation or voice announcements. However, it is possible to add in the first configuration the Power Workout or Power Tool field which are handling the alerts of structured workouts created by Garmin Connect. Here’s how to do it. Watch configuration For the watch, it is only required to install the data field Power Workout or Power Tool in addition to Stryd’s own. https://dyrts.fr/en/posts/stryd_issue_with_walking/ Sat, 26 Mar 2022 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/stryd_issue_with_walking/ Recently, I discovered an issue with Stryd which produces completely weak results when walking. The pace and the distance were completely wrong and makes the foot pod completely unusable. With the support, we could identify the issue and find a proper solution which works well before a real fix in the firmware. Here it is. The issue itself Configuration: a standard Garmin walking activity, Power Tool is used as data field to view the power1 The Stryd foot pod is connected as accelerator to provide the speed and the distance. The ANT+ connection is used. The GPS is deactivated2 I was then walking during 10 minutes and after first 2 minutes, I was running during 15s. The expected distance for this test would be approximately 850m. Here is the result: Pace and Power issue with and Accelerator and Power Cycle ANT+ connection lap Duration Distance Pace 1 2:42. https://dyrts.fr/en/posts/vvo2max/ Mon, 24 Jan 2022 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/vvo2max/ The vVO2max (velocity at maximal oxygen uptake) is the threshold speed beyond which oxygen consumption stops increasing. It is certainly possible to run faster but the energy consumed is no longer provided by aerobic processes only but by the anaerobic process which generates lactic acid. It is therefore also known as the speed of running at maximum oxygen consumption. The acronym vVO2max describes it well: vVO2max is the “velocity at VO2max”, the speed at VO2max. vVO2max is interesting for three main reasons: It allows you to define the intensity of the training stages based on the pace. Classically, interval trainings are done between 100% and 105% of the vVO2max while endurance sessions are done between 65% and 70%. It allows a (very) rough estimation of your running time: Running Pace Marathon 80% vVO2max Half marathon 85% vVO2max 10 km 90% vVO2max This is the maximum speed that can be maintained for 4 to 8 minutes. https://dyrts.fr/en/posts/power2hr_calc/ Mon, 25 Oct 2021 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/power2hr_calc/ Power Tool now includes a heart rate calculator from the running power. It allows to visualize the heart rate of a power maintained during 4 minutes. 4 minutes corresponds to a prolonged effort and can be extrapolated over much longer periods. For shorter times, the heart rate for a certain power is difficult to represent. Indeed, a short acceleration creates a non-immediate variation (partly also caused by the sensor) and it depends in principle on: Power before acceleration The latency time of the organism The duration of the acceleration Its intensity All this complicates things… The calculation is made from a model whose parameters are determined during the running session. The model1 used is: $$ HR = a + b \times Power + c \times \log( Power + 1 ) + d \times Var( Power )$$ a, b, c, and d are calculated in such a way as to minimize the difference with the set of measurements made during the races. https://dyrts.fr/en/posts/powertool_screen/ Sat, 09 Oct 2021 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/powertool_screen/ The majority of Garmin’s data fields have a fixed layout with a single value displayed. “Power Tool” and “Power Based Workouts” offer further possibilities: The ability to display up to 3 data on the same screen An alternate view depending on the activity A progress bar representing the power or flat track pace zone Differences between “Power Tool” and “Power Based Workouts” “Power Based Workouts” is a feature-reduced version of “Power Tool”. Its main purpose is to provide the possibility of doing structured power-based workouts for watches with too little memory. It therefore does not include the calculation and display of the equivalent pace on a track and the dedicated configuration for the trail. For the rest, the possibilities described here are similar. As a reminder, the power and the pace on the track are identical: it is the power. The difference is in the unit used. https://dyrts.fr/en/posts/power_recording/ Sat, 24 Jul 2021 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/power_recording/ Power Tool et Power Based Workouts for Runner now log the power in the .FIT file. This eliminates the need to install also the Stryd’s data field to visualize the data after the race. This provides a bit more flexibility over Garmin watches as they limit often to two the number of Connect IQ fields. But, it also allows to visualize the power on the watch during the race without sharing the session with Power Center. We can find this idea a little absurd, but for my part, I don’t want my trail runs to be analyzed by Stryd algorithms (auto-CP and power curve). The solution until now was to manually delete or exclude the sessions on Power Center. Now it is simply possible not to download them. The platforms which permit the power analysis without Stryd’s native data field: https://dyrts.fr/en/posts/power_workout_garmin/ Sun, 13 Jun 2021 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/power_workout_garmin/ Here is a small comparison chart between the several possibilities to create and execute power-based workouts using Stryd (or Garmin’s own power device). It might not be exhaustive; if not, simply post a request at the end of the page to include it. Feature/Tool Stryd Zones Stryd Workout App Run Power Workout Power Tool for Runner Power-Based Workout for Runner Icon Author Stryd Stryd RunPowerWorkout Dyrts Dyrts Type Data Field Application Data Field Data Field Data Field Stryd’s Device Support :check_mark_button: :check_mark_button: :check_mark_button: :check_mark_button: :check_mark_button: Garmin’s Power Device Support1 :cross_mark: :cross_mark: :check_mark_button: :check_mark_button: :check_mark_button: Customization Connect IQ Menu on the Watch Connect IQ Connect IQ Connect IQ Power Zones Fetched from Power Center Models based on CP2 Table Table Work with Stryd Zones3 N/A N/A :check_mark_button: :check_mark_button: :check_mark_button: Actual watches Support4 :check_mark_button: :check_mark_button: :check_mark_button: Some :check_mark_button: Old watches Support5 :cross_mark: :check_mark_button: :cross_mark: :cross_mark: :cross_mark: Stryd Power Center’s Workouts Support :check_mark_button: :check_mark_button: :cross_mark: :cross_mark: :cross_mark: Training Peaks’s Workouts Support :check_mark_button: :check_mark_button: :check_mark_button: :check_mark_button: :check_mark_button: Final Surge’s Workouts Support :check_mark_button: :check_mark_button: :check_mark_button: :check_mark_button: :check_mark_button: Nolio’s Workouts Support :check_mark_button: :cross_mark: :check_mark_button: :check_mark_button: :check_mark_button: Tredict’s Workouts Support :check_mark_button: :cross_mark: :check_mark_button: :check_mark_button: :check_mark_button: Intervals. https://dyrts.fr/en/posts/workout_progress/ Sat, 12 Jun 2021 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/workout_progress/ Power Tool and Power Based Workouts for Runner display now the progress of the current workout step in form of a progress bar. It works for distance and time based steps and only for power or flat pace1 target ranges. It is simple and intuitive enough to avoids to switch the screen to the workout page just to check the remaining distance or time. Here is a small demonstration for a simple configuration of a warmup of 30s (without constrains) followed by a one minute run between 50W and 80W. The configuration: The result on the watch: Only for Power Tool ↩︎ https://dyrts.fr/en/posts/sensation/ Sat, 05 Jun 2021 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/sensation/ Recently, everyone seems to be interested in how to record their feeling for a session. Garmin has just released a version of the Forerunner watches that allow it to be informed at the end of it. Also, there is a set of new podcasts published about the sensation and the RPE. In a simplistic way, the RPE (Rating of Perceived Exertion) corresponds to the difficulty of the exercise noted from 1 to 10 (10 being the most difficult). The sensation describes the shape of the moment, rated from 1 to 5 (5 is the top of the form) and often represented by smileys. We will be focused here only on sensation. It is in general a good thing to include one’s sensations to enrich the measures of the races. It permits to establish a correlation between progressions with the shape of the moment. https://dyrts.fr/en/posts/workouts_tp/ Mon, 17 May 2021 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/workouts_tp/ Power Tool and Power Based Workouts for Runner are now supporting workouts with power constraints generated by Nolio, TrainingPeaks or Final Surge. To use it, just install the data field on a running activity and configure the notifications on the watch. That’s it! You will then get an out of range alert and see the power constraint for each programmed lap. https://dyrts.fr/en/posts/rowing_exit_explanation/ Sun, 02 May 2021 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/rowing_exit_explanation/ Exiting is only possible using the menu and not through the standard way using the back button. If you wonder why, it is simply to avoid that the recording gets stopped by inadvertence during a session. Procedure To access the menu, proceed as follows: on touch screen watches: long press of screen on other watches: long press to the menu button. Select the entry “Save & Exit” to save the session or “Discard” to ignore it. Video Tutorials Vivoactive 3 Forerunner 245 https://dyrts.fr/en/posts/pw2hr/ Sun, 21 Mar 2021 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/pw2hr/ In a simple way, we can compare the body to a car. The car, by the injection pump, supplies fuel and its energy allows us to move forward at a certain speed. The human body also has its pump, the heart, and its fuel is present in his blood. If you accelerate, the heart rate increases, to spend more energy to the muscles. The heart is our injection pump and our muscles are the engine. For an automobile, it is common to compare the consumed energy to the speed. It permits to determine the efficiency, the autonomy, the maximum speed, … Back to the running activity, we can ask ourselves the question of the relevance of the information provided by heart rate. There are two ways to answer this question: qualitatively, by analyzing how the power is influencing the heart rate and what is decorrelated to it. https://dyrts.fr/en/posts/power2pace_calc/ Thu, 15 Oct 2020 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/power2pace_calc/ Flat Pace integrates now a race calculator which computes the pace knowing the power. It is displayed just after the ‘pace vs power’ curve and permits to estimate the expected time for the standard races using the mean running power as input (or the power from Stryd’s race calculator). More about: Viewing the pace associated to the power. Click here to see an example. https://dyrts.fr/en/posts/power2pace/ Tue, 29 Sep 2020 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/power2pace/ Flat Pace can now display the correspondence curve between power and pace. This corresponds exactly to the following mathematical formula with the parameters learned during the races: $$ Speed = a \times Power + b + c \times Power \sqrt{Power} + d \times \sqrt{Power} $$ To view it, all you need to do is have the mobile connected to your watch and start the running activity which includes a Flat Pace data field. Garmin Connect will then display a notification like this: You just have to click on it to see the correspondence curve. Click here to see an example. Note: No data is stored online and it is not necessary to create an account to use this feature. Due to memory limitations, this functionality is disabled on: Approach® S60 Approach® S62 D2™ Air D2™ Charlie D2™ Delta D2™ Delta PX D2™ Delta S Descent™ Mk1 Descent™ Mk2 / Descent™ Mk2i fēnix® 5S fēnix® 5 fēnix® 5X fēnix® Chronos Forerunner® 735xt Forerunner® 935 Captain Marvel First Avenger Darth Vader™ Rey™ https://dyrts.fr/en/posts/stryd-allure-sur-piste/ Sat, 19 Sep 2020 00:00:00 +0000 dyrts@free.fr (Sébastien Dyrts) https://dyrts.fr/en/posts/stryd-allure-sur-piste/ Preamble This article is nor a presentation of the Stryd sensor, nor a description of its use. It is aimed at those who know the concept of running power and who own a Stryd sensor. It describes the inner algorithm of the Garmin watch app Flat Pace and a full-scale test. This is not a tutorial, nor a documentation of this data field. Why prefer speed? It may seem absurd to equip yourself with a power meter costing 200$ and use it only to measure the speed. Of course, it is true that the precision of the pace and the distance that this sensor gives are impressive1. And we can really pretend that it reduces the GPS only to navigation and we can completely ignore it for training analysis. But the main reason for choosing pace over power comes from the nature of the unit of measurement.