How to properly do anaerobic interval runs?

5133430 11 days ago

Yesterday I tried my first suggested sprint interval run, and I would like to get some feedback on what I'm doing right and wrong and how to best perform these types of workouts using my Garmin.

For the first intervals, I tried to sprint at once the timer started, but it seems the numbers on the watch are slow to update and took about 10-15 seconds before I hit the zone. For the later intervals, I tried picking up speed before beginning to be close to the speed before the interval began and then slowing down about 5-10 seconds before it finishes to compensate. Is this the right way to do it? I still seem to be missing the zone quite a bit. Also, I found it really difficult to keep in the interval zone during the sprints because I'm running hard, making it difficult to check the watch to see my progress.

My execution score was only 63%, which is terrible compared to all my other workouts so far (base and tempo) that have been above 90. Is this just a limitation of the watch not being able to pick up the speed changes or is there something I can do to fix this?

Also, despite being an anerobic run, I only got 2.1 TE for anerobic. I got 3.5 for aerobic, which seems to imply I wasn't pushing hard enough in the sprints? I also noticed that some intervals didn't seem to push the heart rate up much at all.

I'd really appreciate any feedback from more experienced Garmin users on how to improve this kind of workout in the future.

(Sorry, this should be for the 965, not 955. Maybe the mods could move it? Thanks!)

Top Replies

All Replies

0 ronand 11 days ago

Are you using a HRM strap? Wrist HRM is not good enough for anaerobic intervals as there is too much lag

0 DaKo 11 days ago

Tempo measurements are a bit slow, because Garmin is using an average of about 5 secs or so. I usually start these kind of short sprints 5 secs before the watch tells me to do. It gives better results. You should stop the sprint also 5 sec earlier than. But it is al peanuts if you ask me. Most important is the repeating sprint you do, not the exact time.

+1 ZombieSloth 10 days ago

First, as ronand mentioned, it will be hard to get good HR measurements with the optical sensor on the watch. especially if sprinting since you are gonna be flailing your arm around a good amount. Heck, with the HR strap I have found that sometimes I get measurement drops if I am really going all-out because extending my arms forward can cause the contact pads to lift off of my chest.

Anyway, having had the FR955 for a few years now and using the daily workouts on and off with varying levels of compliance, here are some thoughts.

1. Anaerobic TE is going to be based on short bursts of high intensity output, and by definition they cannot be sustained very long. The general consensus here is that you need to have several large swings in HR (short bursts up to high values, followed by a recovery period down at a lower value). That is mostly accurate, although I think that accelerometer and GPS values also play into it via estimates of your running power.

2. Sprints. Strictly speaking, a sprint is an all-out effort. I just ignore the pace targets entirely and hit the intervals as hard as I can, at least in cases of 15 second long intervals. If you are still getting your body used to it all, then stick with the suggested number of intervals and only go all-out if you are confident enough in your fitness to not get hurt. Also, the number of intervals is usually too small for me to get a good (>3) anaerobic TE. I typically make my own sprint workout in Connect which is the same time intervals as the suggest one, but with more reps.

3. Anaerobic workout. If you want to shoot for a >4 TE, then you are gonna suffer lol. I generally find that I have to do something like this, where each of the intervals are at the maximum effort that I can sustain for that interval. 6x800m + 5x400m + 4x200m. After each interval at high effort, I walk/slow jog an interval of the same distance to recover. The 800m ones are the worst, and I am solidly questioning my decisions after the second one lol.

4. Execution score is not that big of a deal really. It always feels nice to be >90%, but sometimes is is not realistic to hit that. Sprint intervals are one good example. The execution score is just time-at-specified-value divided by total time. It can take a minute or more for heart rate to get back into a recovery zone after an interval, and it takes time to get up to full speed. And ultimately, a low execution score is not necessarily indicative that you did not get a good or effective workout in.

A common mistake people make (I was there myself at one time) is to assume that high HR = anaerobic. So they go run in zone4/5 non-stop for 30-120 minutes, and then get mad at the end when the run gets labeled as VO2Max or Threshold with zero anaerobic TE. But, that is how it works, nothing you can do non-stop for a half an hour or more is anaerobic! It's gonna all go into the "high aerobic" bucket in your training status.

In the end, do the workouts and be consistent. They are generally pretty good, and you can learn a lot about how to train as you spend time doing them and paying attention to your fitness / performance level. Once you have a solid feel (maybe after 6-12 months of using them consistently) you can start to layer in your own workouts if you are feeling like the suggestions are not pushing you enough or you want to focus more on something. The DSWs, at least for me, were sort of limiting in that they seemed to stay pretty conservative. After using them for 9 months or so, I started going out for long (like 3-5 hours) trail runs, and as those efforts started pushing up all of my performance metrics, the daily suggestions started getting a lot harder lol. IIRC, my long DSW runs started being >2 hours, whereas they were often ~1 hour before I started doing my own thing. Now I rarely use them directly, but I'll see what is in the queue and do my own harder variations of the suggestions. The DSWs can help you improve your baseline performance and avoid injuries, but they are not a coach for maximum performance!

0 5133430 9 days ago in reply to ZombieSloth

Wow, thanks for a really detailed reply here. I'm used to doing training like fartleks and hills, but this is my first time with an expensive watch guiding me, so it's a learning process as well. I guess I need to make sure I listen to my body more than trusting the technology 100% though. It's quite impressive, but it's not perfect (yet).

I'm aware that anaerobic is supposed to be short bursts of unsustainable exercise. I guess it makes sense that this would be calculated as extremely high heart rate, and if everything is set up right, I wouldn't be able to sustain this for more than a minute at most. What I'm finding difficult is how to not overshoot/undershoot the pace for the 1 minute bursts, especially with the lagginess of the GPS.

I don't have a heart rate monitor. It's on my wish list and I hope to pick one up soon to improve these anaerobic workouts.

I thought the anaerobic suggestion was the only anaerobic workout the watch would suggest, but now it seems the suggested workout for today is proper sprints (10 second bursts). I will try to see if I can get this one up into anaerobic, probably starting 5 and ending 5 seconds early so that it picks up my speed more in range. If I still feel good after the workout, I may throw in an extra few sprints to push myself to the limit, as you suggest.

I'm still in my first month with the watch, so I'm just going to stick with the suggested workouts, kinda as an experiment to see what it tells me, as I generally trust Garmin's sport science here. It's slowly been increasing my long workouts, and I hope it will keep pushing it up every week and not cap at an hour. I don't know how far it will go on its own though, so I may have to trick it with a long workout or two just to bump up the distances.

0 ronand 9 days ago

I just did an interval session using my 255 and HRM strap. I got a 100% execution score. The intervals were 10 x 1 minute "Very Hard" - I'm using 23.13 beta firmware which doesn't specify a target heart rate. The anaerobic effect was 3.6 (estimate was 3.3)

https://connect.garmin.com/modern/activity/18852210738

0 5133430 9 days ago in reply to ronand

Impressive! I suppose it gives me something to strive for!

Do you start ramping up before the intervals? It seems like your speed immediately jumps up, whereas mine felt like it lagged for a few seconds.

Other than that, how do you know what "very hard" is? How do you ensure you don't overshoot or undershoot that zone? And then how do you so quickly return to recovery pace after the interval?

0 ronand 9 days ago in reply to 5133430

I usually just begin to speed up 2 or 3 seconds before the interval starts. Very hard is exactly that! When I first got the watch I tried without the hrm and got poor execution scores and very little anaerobic effect so I always use the chest hrm for these kind of activities. For zone 2 easy runs the wrist hrm is OK.

0 global_local 8 days ago

See my experience with the same problem here. You need an external chest strap to get right HR data and an inertial sensor aka stryd to get instant pace (you can choose from rt, 3, 5, 10 sec average). IMHO garmin displayed only a strong averaged pace with a base about 20-30 sec, not a 5 (that would be great) it has no sense on intervals...

0 B1nny 6 days ago in reply to global_local

How did you set-up a data field to view AnTE per interval?

0 global_local 4 days ago in reply to B1nny

I've made a new data screen with a AeTE and AnTE, they are standard datafields. It's not lap based, only cumulative. But i can hold in mind 4-6 digits till I get back home.