Exercise load query

I am very much in doubt that all these stats are trustworthy. Yesterday I went for a super relaxed evening tour around town, 9km/h average, frequent stops, no effort at all

My watch tells me it was a Sprint effort with the highest load data I had in weeks. How is that possible?

You said ealier your MaxHR is similar to mine or 175.

Looking at your activity (2 hours at 70% MaxHR): your Exercise Load (158) and Aerobic Benedit (3.3) is what I would expect to get as well. As in same ball park.

I'm a bit surprised however by the 2.8 Anaerobic Benefit and this "Sprint" Primary Benefit which I had never heard of before. Looking at my records, I have never had it. Are you using a FR255 ?

With that said, looking at your HR chart: man it seems you have some sudden gaps in HR of like 20-30bpm, which perhaps the watch interpret as "sprints" hence the 2.8 Anaerobic Benefit ? Are you using a chest strap ? It looks like you don't.

no chest strap, as my tests in the past with running, cycling or rowing have not shown any significant difference in the data. Yesterday it seems though my 255 was completely off with the HR measurement. It was a super slow and relaxed evening bike rides with family and kids. No way I came anywhere close to 150 nor ever to 180. That is a very poor performance by the watch. 

The gaps of 20-30 beats are quite explainable: we stopped frequently and my heartrate dropped very quickly (or has never been really high before and the watch realized it once I stopped for a break)

still: really poor performance

Are you leaving the watch on after your activities, or are you taking it off? 

Who are you adressing ?

If me, I wear my watch 24/7, I never take it off.

I dont switch or take it off after workouts. I later take it off during the night

JRKingOfBeer

I was asking you, or anyone who is wondering about Exercise Load calculation! Exercise Load is a measurement that comes after the workout, so there are more factors taken into account besides the average heart rate during activities that were longer or shorter in comparison. Some factors may include the quality of your heart rate data during activities, or how your body reacted post-workout. If you were more tired or stressed the day of an activity, Exercise Load could be affected. Please see What is the Exercise Load Feature on My Garmin Device? for more information. Our EPOC article from our Garmin Terminology page is useful as well, and includes an video explanation regarding EPOC and Training Load. I hope this helps!

Garmin-Sierra thanks for the link. The information is unfortunately too vague to be able to answer the specific question I had. That's a little bit the problem with most Garmin's videos actually. They're slick,  professionnally shot etc... a lot of efforts goes into the production. But unfortunately, the actual content is generally too simplistic to be really helpful when you want to really dig into what the watch actually does. I don't mean to be ungrateful and I appreciate you took the time to provide an answer. It's just that it's too superficial to be really helpful.

ovekvam, I asked my question on a YouTube channel and the Youtuber gave me a more convincing answer:

"Hello! This is a good question - unfortunately I'm only hypothesizing. Without knowing your heart rate zones, I'm guessing that if you're doing 60-minutes on the rower at 140bpm this is low intensity exercise. So exercise load from Garmin I believe is based upon EPOC - being excess post-exercise oxygen consumption. Basically how much oxygen you use to return to baseline which is related to how much energy is expended. My belief would be that the oxygen requirement to get back to baseline after an hour on the rower is only slightly greater than that of doing 30-minutes on the rower as it's still low intensity exercise. It wouldn't be double the severity as the intensity is low and therefore energy usage is low-ish and therefore takes longer to reach a higher level of fatigue. My guess is that it isn't a directly linear process as given the intensity you're probably not going to be too fatigued. I hope that provides some clarity?"

Now, this explanation makes perfect sense to me. It is true that when doing my steady state sessions on the rowing machine at 130/140bpm, I do not feel that my recovery time is meaningfully different whether I row 30 minutes or an hour: in both cases, I recover super quickly. So in the context of EPOC, it makes sense that the load isn't meaningfully different either between 30 or 60'.

I still dont get how you receive 135 exercise load for such a low impact workout.

I did a 10x500m high intensity sprint workout with 10k distance and got only 84 and a Base cstegorization.

I dont know how much more intense I have to go on my rower than this and still it is only base

Your intervals are too short for the fact that you're not using a chest strap: your HR lags terribly and doesn't record the time (if any) you're spending above your lactate threshold. Since you are doing intervals, you obviously want some anaerobic benefit/improve VO2Max. But in order to achieve this, you need to spend enough time meaningfully above your lactate threshold. Which clearly here, as you can see, the IR sensor isn't recording.

Let me give you an example with my VO2Max rowing session this morning. It is a 15' warmup, followed by a few minutes rest, then followed by 5x750m(3'Rest). Because I am using a chest strap, my HR doesn't lag, and the watch is able to record some nice, smooth HR "waves" way above my lactate threshold. As a result, I got some excellent results and a whoping 293 Exercise Load.

As I said earlier: you need to get a chest strap. The situation you're in, as in those ugly lagging spikes, is what I had too before getting mine. $50 on Amazon to solve the problem.