Body metrics when doing mainly indoor sports

You can have both training effect and anaerobic training effect on a data screen. I use these figures to keep track of my sessions as I do them. It works fine for all types of training, with the exception of rowing, for some odd reason.

I also use pulse zone and times in zone, and in combination with the training effect, this helps me push a bit extra when doing interval or threshold sessions. Or keeping the effort down, when doing endurance or recovery sessions.

I also have the Ambit (3), to compare with.

To get the training status, you need to get a VO2max from your device, and the only way to get it, is from running regularly (at least once every two weeks, minimum) or biking with a power meeter. I would have preferred to be able to set my VO2max (since I have it from a lab test), but this is not possible. I have set my threshold manually.

For me, the VO2max estimate is a couple of points below the tested, but that seems reasonable, since running outdoors adds wind and weather impacting speed.

For me, the F5 offers more useful functionalities, but the Ambit 3 was (is) very good too. On that model you also can have training effect on a data screen, but not anaerobic training effect.

edit: if you use a HR strap, you do not need to wear the watch whilst logging. You can strap the watch to the elliptical, or bike, or stair stepper.

As nyqand says - you need to have HR recording in order to get any training values, and you can only get VO2max by running or cycling with a power meter. Both TE scores and VO2max scores are device specific too - so if you had two garmin watches for example they would both need to measure and calculate your metrics.

I would be wary of using a Fenix 5S or 5 in the manner you're describing, as you'll need to use a heart rate strap and both the 5S and 5 have connectivity issues (which aren't present in the much larger 5X or the plastic 935). I use my 5 for a lot of indoor training (mostly crossfit or other HIIT routines) and although I still wear the watch on my wrist I use a strap and will often have data drop-outs when my arms are extended away from my body (like during a burpee or pull-ups). So not wearing the watch may well put you out range and result in drop-outs. The drop-outs in turn will then affect your TE scores etc.

It's possible Garmin have done a hardware revision and rectified the bluetooth/ant+ connectivity problems but they've been very quiet on the situation.

Training Effect requires only HR data (and a V02Max figure to give it a baseline), and is applicable to nearly all sports. It doesn't require accelerometer or GPS data. Training Load also requires HR data only. These metrics only require an initial V02Max figure - once you have that, you will continue to get the TE and Load metrics, even if the V02Max data is months old.

Training Status effectively compares changes in your VO2Max figures with changes in training load, and has an educated guess at what's going on. This is the one metric that requires regular outside running or cycling with a power meter. If it doesn't have VO2Max data from the last 2 weeks, it will drop to No Status, but the watch will continue to generate TE and Load.

I totally get that you have little interest in running compared with your existing indoor workouts. The question is whether you see 2 x 10 minutes of running outside when you get the watch as an INITIAL investment in getting quality data. Once you have got that, you don't need to run again if you are just interested in TE and Load.

While there are some issues with connectivity with SOME 3rd PARTY footpods and power meters (obviously located further away from the watch, with some interference from the body), there are fewer problems with HR monitors. I cycle regularly with my F5 strapped to the handlebars, and have seen no dropouts with my Garmin HRM-Run. I also saw no dropouts when I experimented with my old Suunto Smart HR belt. With clear line-of-sight between a chest strap and the watch on a crosstrainer in front of you, I can't foresee too many problems. The Forerunner 935 has the same functionality as the Fenix 5, but the plastic case seems to avoid these connectivity issues.

While there are some issues with connectivity with SOME 3rd PARTY footpods and power meters (obviously located further away from the watch, with some interference from the body), there are fewer problems with HR monitors.

I guess it will be a "your mileage may vary" type of situation, but I have consistent drop-outs with both my two Garmin HRM chest straps (one Run4 and one Tri) plus dropouts with both my Polar H7 and Wahoo TICKR Run.
However if you read these forums you will see there is a consistent pattern of connectivity issues with a range of products - the connectivity range of the Fenix 5 and 5S is terrible, but yes I guess as mcalista says if you have the watch sitting on the cross trainer directly in front of you or on the handle bars of your bike you shouldn't have issues with a HR strap.

Thanks a lot for your helpful answers!

Just a couple more things to make sure:

1. Am I right that once I've got the VO2 max registered, Fenix 5 can be set to NOT update the value automatically? I don't mind the initial setup as long as it stays there.

2. Why is running required specifically to get the VO2 max? Does it somehow incorporate arm movement into the calculation? I'm thinking of kickbiking as an alternative here.

3. I am indeed going to be using a HR belt. The connectivity problems are with specific Ant+ belts and NOT with Bluetooth, right? I'd be getting a Wahoo Tickr HR belt connected over Bluetooth.

EDIT: 4. This would seem to imply Anaerobic TE will be useless/unreliable when training indoors: "Anaerobic Training Effect uses heart rate and speed (or power) to determine how a workout affects your ability to perform at very high intensity" (from the manual). I don't know if that means GPS or arm movement data. If the latter, I guess I could wear the watch on my wrist while doing intervals on the crosstrainer, instead of attaching it on the handlebar (I could use the Wahoo Android app to show me my real-time HR data).

1. There's no setting for this. No running with GPS/Cycling with power meter = no new VO2Max figure. The watch will just use the most recent VO2Max data it has, even if that is months old.

2. Running is an extremely well studied activity in hundreds of sports labs around the world. And researchers have a very good idea of how much effort is required to run at any specific pace and gradient. GPS and the barometer tells the watch your speed and elevation gain in a reasonably reliable manner , and by comparing this "output" to your "input" (ie. HR as a % of HRMax), the watch can work out your fitness level/Vo2Max. Calibration differences between treadmills means this data is not reliable for treadmill running.

Cycling is also well studied but road surface, wind speed and direction and bike aerodynamics mean speed and gradient are not reliable ways of measuring output. However the existence of Direct Force Power Meters (strain gauges in the pedals, cranks, etc) means output can be directly measured - not just implied as with running.

Other sports (including kickbiking) are not as well studied, and there aren't reliable ways of comparing input to output.

3. The general sensor advice is to try ANT+ before BLE. And the beauty of the TICKR HR is that it allows you to do either. But if you are concerned, I would seriously advise looking at the Forerunner 935, which is essentially the Fenix 5 in a plastic case which avoids the connectivity issues associated with the Fenix's metal case.

4. Heart rate is a lagging indicator of effort - it can take 20-30 seconds for your HR to increase after you increase your level of effort (and a similarly delayed response when you decrease your effort). This is not a huge issue for longer intervals, but anaerobic training is typically done through a series of quite short intervals. Using speed from GPS allows the watch to better identify the start of the interval (a cycling power meter is better still, as it picks up the increase in effort almost immediately, even before you have started accelerating). But the watch will still generate Anaerobic TE from HR data, if that is what is available. I don't think watch movement comes into it.

All these connectivity issues make me regret not having returned my F5 in favor of the less expensive Forerunner 935 when that later was released. Yes, the F5 looks much nicer but, well, it needs to work.