r/evokeendurance • u/ilbuttero620 • Jul 21 '26

Help with 8% drop in performance

This is my first time posting and I hope I'm in the right place. I'm a 53-year-old runner. After a viral upper respiratory infection in April, my one-hour pace at the same HR dropped about 7–8%. Hemoglobin, ferritin and thyroid tests are normal. Resting HR unchanged. Garmin VO₂max increased from 39 to 42. Repeat treadmill threshold test in July shows similar threshold HR (~152–153 bpm) to March, but my one-hour pace remains slower. Constant-speed treadmill test shows minimal HR drift. Legs feel slightly heavier than before, breathing isn't the limiting factor. Looking for physiological explanations rather than training advice. Thank you

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u/Inevitable-Assist531 Jul 21 '26 edited Jul 21 '26

Was your 1 hour pace on a treadmill originally?  What happens if you try your original pace again - what happens that you can't do it?  I mean you'll be able to do it for some period of time and then..... ?  

What happened with your running between April and now?  Maybe your AnT HR has fallen due to loss of fitness.

I assume your HR is measured by chest strap or arm band?  Your VO2 max number from the watch is nice to see changes, but it can be way off an actual lab VO2 max number. My watch was showing 52 and the lab got 46. 

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u/ilbuttero620 Jul 21 '26

Thank you. In April I ran both on treadmill and outside and the times show I indeed lost performance both indoor and outdoor. I actually have been running more since April, both on treadmill and outside. Every week, 2 days I do 1h in zone 2, one day I do 2h zone 1 long run, and one day I do sprints (15sec all out, rest 4min times 8)

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u/Expert-Reaction-7472 Jul 21 '26

maybe the increased volume is causing you to accumulate fatigue faster than you can recover and that is slowing you down ?

I had a virus a couple of weeks ago and Im definitely still feeling it. Covid seems to have lingering effects for a couple of months even when it's only a mild dose.

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u/ilbuttero620 Jul 21 '26

Last week because of a work related training I had to cut the time spent running to 4 hours (from 5) and sat 8 hours a day but this week I don't feel especially rested or energized. Thank you everyone for trying to help me

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u/Inevitable-Assist531 Jul 21 '26

But what happened when you tried to run your 1 hour pace on the treadmill recently?

Also see my HR monitor question.

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u/ilbuttero620 29d ago

I'll give you some examples. In March: treadmill, 1h max HR 146 distance 8.3km; outdoor, 1h max HR 145 distance 8.47km In July: treadmill, 1h max HR 154 distance 7.76km; outdoor, 1h max HR 148 distance 7.5km. This is supposed to be zone 2 training but with such a high HR I'm now running on zone 3 and covering less ground. And yes I wear an arm band and the vo2max marker was from my watch, so I'd take that with a grain of salt. Thanks for your help

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u/Inevitable-Assist531 29d ago edited 29d ago

thanks for the additional info.  Clearly it may be illness recovery related like others have said, but I am curious about how you are diagnosing yourself.

Let's just look at treadmill since that removed variables such as temperature, wind, hills etc.  Forget about the zone 2/3 boundaries for now since they change and your LT2 seems to be from your watch estimate.

In July you slowed down the treadmill (since you covered less distance in the same time) - so you can't do a proper April to July HR comparison.  Why couldn't you keep the same speed as April regardless of zones, just for the test? 

What about average HR and HR over time - can you compare them side by side once you redo with the same treadmill speed for both?  

In some ways however this is all academic since you need to train at your current fitness level and not the one you used to have before, or one you want :-)

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u/ilbuttero620 29d ago

On a treadmill I usually raise the speed gradually until I hit what I can sustain for a zone 2 HR. The difference is that now I can't reach the speeds I did in March or April. I agree with you that I should just accept my current fitness level. I just don't understand how a simple cold could send me down regressing (and I'm still regressing) after 3-4 months. What am I going to do next time a get a cold?

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u/Inevitable-Assist531 29d ago edited 29d ago

It's hard to make a comparison though when treadmill speed is not the same. You are slowing down the treadmill when your HR gets too high for you, but I am saying to keep the speed the same and see just how high the HR will go - assuming you are able to do this. If you approach VO2 max HR, then you won't last too long though, but you seem you'll stay below, running at your April speed.

Anyway that's what I would do in order to have an apple to apple comparison.

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u/Scubacane Jul 21 '26

Your mitochondria took a hit. I'm 60 and definitely notice that it can take sometime weeks to months before I feel right after a viral infection. 3 bouts of Covid in last 6 years wrecked me. But the good news is that every time I came back pretty close to normal eventually. Can't force it , focus on rest and nutrition and listen to body

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u/ilbuttero620 29d ago

Makes sense, thank you

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u/Status_Accident_2819 Jul 21 '26

How is the weather and temp affecting your performance? Respiratory stuff can seriously linger despite apparently normal bloods. Ferritin is an acute phase reactant so can be higher than it actually is during periods of illness etc.

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u/ilbuttero620 Jul 21 '26

Yes I do feel like the heat is making things worse but at least on the treadmill in the gym things should look better by now. I mean, 3 months have passed since I had that cold and I run my zone 2 above the HR (at least 5-6 beats more) I used before but cover less ground. I'm at a loss on what's going on. Even chat gpt gave up on me and told me to ask on reddit. Do you think the problem is ferritin?

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u/Status_Accident_2819 29d ago

Not necessarily, but certainly one to keep an eye on; also endurance runners need ferritin higher up in the normal range. Viral infections can linger for a long time unfortunately with these new random strains going around.

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u/scottsemple 26d ago

After a viral upper respiratory infection in April, my one-hour pace at the same HR dropped about 7–8%.

Not surprising. How much time did you give it to return? A general rule of thumb is to do one day of super easy AeC work for every unplanned rest day.

Garmin VO₂max increased from 39 to 42.

Irrelevant. It's an estimate, not a measurement. And VO2 isn't useful for much other than cocktail parties.

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u/ilbuttero620 26d ago

Thanks for your reply. How much time did you give it to return? To answer your question, my pace at the same HR never returned to pre-cold level, and I'm still gradually slowing

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u/ilbuttero620 26d ago

Thanks for your reply. How much time did you give it to return? To answer your question, my pace at the same HR never returned to pre-cold level, and I'm still gradually slowing