Metrics like pace, hr, cadence etc. are measurements. Other things, like load, for example, are algorithmically estimated values. When I see a load value on here, whose algorithm is that from? The originator of the data (in my case Garmin), or is that intervals.icu’s algo taking my Garmin metrics and doing the further calculations?
Most of the algorithms used by platforms like Intervals, are based on the Power Management Chart, like it is used in TrainingPeaks.
Andy Coggan invented the power based algorithms on earlier work by Bannister (heart rate based).
If you want to understand the science and art of using power metrics and charts, go buy and study Training and Racing With a Power Meter (3rd edition is current). Book is full of examples and info.
Garmin uses EPOC as Load (their own way of calculating load with some impact of your hr and respiration)
intervals.icu is using TSS similar to that of Training peaks (but the name is copyrighted) it is just a very simple calculation where 1h@threshold is 100 points
TSS was intended to visualise very roughly your future load when planning a season and not assesing your current load on a daily basis
if you look at activity info in your Garmin connect app or web, you will find there EPOC=Load and TSS (but garmin uses only epoc for its own inside other calcs like training fatigue etc.)
you can create a custom fitness graps in intervals.icu using epoc instead of tss
Thank you. So, if I understand correctly, the short answer is that, for calculated metrics (as opposed to directly measured metrics), intervals.icu is doing its own calculation, rather than just taking over whatever is coming from whatever platform (in my case Garmin Connect) that I have connected to it, is that right?
Yes. Power and HR and other sensor data is synced from Garmin/Wahoo/Hammerhead, and then Intervals uses established algorithms for the derived metrics.
Yes, but there are Custom fields in Intervals that allow you to get more ´hidden´ data in the FIT file from Garmin.
Like detected VO2max, Aerobic and Anaerobic training effect…
Yeah but keep in mind. that most of those calculated metrics are golden standards used very often by many other brands and platforms (like the fitness graph in Strava). TSS - training stress score is a very popular metric and even Garmin uses it as a backup for activities imported to Garmin from other sources, without hr recorded by a Garmin watch.
Intervals.icu is using those calculated metrics so you can plan the future of your training. You can create/import your planned workouts, put them all into your calendar months ahead and intervls.icu will give you load for those workouts and draw your fitness graph months into the future so you can toughly check your fatigue levels, load ramp etc. IT is a great way to schedule a correct training progression.
If you use a Garmin watch or a bike computer, you get there Garmin metrics for load=epoc and othre stuff, meaning garmins own way to asses your load during a workout. It does not work into a future, you can’t plan using it, you can use it to check/compare with other previous workouts done by you. You can import those metrics into intervals.icu and use them alongside tss etc.
From my experience, load graphs for tss and garmins epoc overlap almost completely as long as you build base and keep yourself below a threshold but there is a big difference with workouts over a threshold. Garmins epoc for me is giving numbers much more closer to my RPE and in a way much closer to reality I think. Classic example would be a set of 5x4min vo2max intervals at 105%+ (95 tss), where if done correctly my percieved fatigue for after the workout and next day is very similar to a 120km z2 ride (215 tss). Garmin gives me epoc close to that from such a ride and tss ofc is a much much lower number. So you can schedule vo2max intervals using tss just keep in mind your epoc score will be probably much higher (and real fatigue probably too)
PS. all those metrics are based on your hr and power from a workout so in some sense they all are based on your garmin, just those “calculated” use hr, and garmin uses some gimmicks on top of that (like hrv and current vo2max) to further recalculate those metrics.