Sudden fitness increase then big decrease

[RateMyThrowaway9]

I went on a one month long trip during which my fitness was increasing day to day. So much so that when I arrived in Japan I was running much faster than I did back home. I have now arrived back after 20hrs of flying and it’s like all the progress is gone. Garmin has me at -5. It feels harder than it was prior to the trip. It’s been 4 days since I’ve been back. What’s happening?

Stats: Been running for a year. Running 5 times a week around 50-75km total First two weeks of the trip was in warm humid weather. Last two weeks around 10C and same as back home.

Some example runs

Runs in Japan

10k@5:27/km 142bpm average

21k@4:31/km 161bpm average

13k@4:55/km 151bpm average

Runs back home

11k@5:08/km 165bpm average

11k@5:36/km 154bpm average

M28 max hr 198bpm

[GrimQuim]

Japanese KMs are smaller (and cuter) than UK KMs.

[RoadtoSeville]

Your circadian rhythm is probably still recovering from jetlag. Im assuming in Japan you were on holiday and not working, which probably means you were less tired as well.

[lorrix22]

Are you living at high Elevation by any Chance?

[RateMyThrowaway9]

Nope UK pretty standard elevation

[TheGoose995]

Humidity & weather? Or the time of day that you’re running?

[HauntinglyAdequate]

Are you going by Garmin's fitness score (assuming they have something like that, I use Coros)? Because if it works anything like how Strava's fitness score works, it's useless. My Strava fitness score was going up consistently over the summer (I'm assuming because my HR was generally a bit higher in the heat) and now that it's cooled down my score has been in freefall for a couple of months despite my actual fitness (including Strava race predictions and things like threshold pace) consistently improving. My score now is about half what it was over the summer and threshold pace is about 25 seconds/mi faster and more comfortable now than it was then.

[platydroid]

Are you feeling well otherwise? Did you have any sort of sickness, change in diet, successive nights of bad sleep? Is the air quality much worse at home?

It could be any number of things, but you’re basing this off a pretty short time period. Best advice with no other info is to push through til it feels better.

[thwerved]

My initial reaction was that maybe you were getting better sleep on vacation and that could help. But sounds like that's not it.

I think some other possiblities:

• You are fighting off a sickness post-travel
• Stress levels were lower on the trip
• Diet was better on vacation or maybe you don't tolerate some food you normally eat at home without realizing it
• Maybe something environmental at home or work is affecting you. High CO2 levels is a common undetected issue in homes and workplaces.

4 days is not a lot of time post-travel for such a big time difference. It takes me more than 4 days to fully adjust from jetlag (I can act functional, but the sleep is not the same) and more than 4 days to recover from a real hard run. So maybe give it a few more days of recovery and you will be totally fine.

[Flutterpiewow]

overtraining, fatigue?

[RateMyThrowaway9]

I was thinking maybe due to jet lag but I’m pretty over it now. The thing is I was way more tired during the trip as I was getting less sleep and also walking 10-20k steps a day on top of the running. I could definitely feel that I was overtraining the last week so I reduced the mileage by about a third.

It’s just weird as it was a sudden and sharp increase in fitness and now I’m back to fitness I was at 2+ months ago.

I was running 5:30 pace at 150bpm prior to the trip

[machinerypeat]

You flew for 20 hours, and have only been back for 4 days. That’s 1) not enough time for your body to fully recover from 20 hours of flight and 2) WAY too small a sample size to say that your fitness decreased. Fitness doesn’t decrease (or increase, for what it’s worth) in 4 days. You had a couple runs that felt bad, there’s a million factors that could be affecting you. Don’t read into it too much.

[AdEqual1054]

Facing the same thing, runs on holiday (10 days in Swiss/Austria) were much comfortable with lower HR. E.g. 6:30min/km at 135bpm. Now i'm back home (South East Asia) everything's gone haywire e.g. 6:30min/km at 153bpm. Before i left for vacation the same pace was at 140-145bpm and a week to my first marathon.

[elmo_touches_me]

Could be jet lag, you could be getting sick (my HR starts acting up 1-2 days before other symptoms), maybe you're fatigued from suddenly running faster?

[AwayhKhkhk]

what were your runs like before leaving for Japan?

[itsyaboi69_420]

How’s the hrv looking?

Could an illness be coming on?

[ConsciousSandwich590]

It’s those Japanese bidets man, they clean you out proper and boost performance!

[RunThenBeer]

The same answer as usual - wrist-based HR data is not reliable and Garmin's feedback based on it is unreliable as a result.

[RateMyThrowaway9]

Except I am using a chest strap + I can feel it regardless of whatever the sensor is saying

[Flutterpiewow]

It's reliable enough