Metallifan33

I've noticed a few times that after a (relatively) long or hard day in the saddle, I tend to have some flu like symptoms the next day (runny nose, fatigue, what feels like a fever but is not).
This seems to happen when the training load is higher and I'm experiencing more stress and if I'm fasting (I do intermittent fasting as the primary goal right now is to lose weight as opposed to performance).
I feel perfectly fine the day after (i.e. two days after the ride).
Do any of you experience the same or similar thing?

WhyFi

Some fatigue and an RHR that's a couple ticks higher isn't unusual for me, but nope to the rest.

Iride01 

If I ride hard and don't hydrate correctly and replace enough spent carbs correctly during and just after the ride, then I will feel tired afterward and into the next day.

If I ride at any effort level for a time and don't hydrate correctly then I will also feel tired just after the ride and the next day.

CAT7RDR

What do you mean by a hard effort? Double Century with 20K of climb? Two hour loop 30 miles 1K of climb?

Dehydration and blood glucose would be my first considerations after a hard ride and fasting.

Metallifan33

Hard in relation to my usual effort of the previous month or so.
Yeah... I've been fasting the entire day and go for a fasted ride in the late afternoon for between 1.5 to 2 hrs. I guess it's time to change the diet. Oh well, fasting was the easiest diet for me, but I think I've reached the limit of efficiency for the method.

Andy Somnifac 

I've run into this after a really hard ride where I probably dehydrated myself pretty badly. I was busy holding on for dear life and seriously neglected proper hydration. I was down for a couple of days afterward. Wasn't fun.

popeye

Bonk.

Metallifan33

I always thought a bonk happened while you're riding, not the next day.

datlas 

Correct

Iride01 

If you want to ride fasted, then stay at a low level of effort so you don't use up any glycogen.

Some training methods say to do some long rides entirely in zone 2 or low zone 3.

rubiksoval

Nope. The day after a hard ride I'm usually okay, more of a deep-seeded fatigue. The second day after a hard ride has a bit more fatigue and is generally when I go easy/off.

Never had flu symptoms, though. That's not a good/normal thing.

Doomrider74

Id go with dehydration.

BCAC

I’d suggest getting blood work and a full physical, just to rule out anything more serious.

Living in Florida, it’s really easy to get dehydrated. And I go at it pretty hard. If I don’t drink enough or eat enough I can be pretty tired and out of sorts the rest of the day. But never the next.

samkl 

I sometimes feel like that after a long, hard brevet. Pretty common among randonneurs, though I can’t tell you the precise physiological reason. A cheeseburger and milkshake help. (Maybe not the best diet food.)

colnago62

Have tou been checked for allergies recently? Also, if ride in an area with air pollution, manufactured or organic, that can cause a lot of problems for your body.

SoSmellyAir

I don't know about the rest, but the runny nose may be due to riding in cold dry weather.

Kabuki12

I think maybe supplements in your water bottle could help. I started using Nuun a few years ago and it really helped. I usually do two to three hour rides , sometimes longer , but always take water with me. I found that sometimes in warmer weather I would fill my bottle two or three times . As I got older I started getting a let down or fatigue feeling so my daughter told me about this supplement and no more fatigue . I guess it could be psychological but it really works for me . The other thing I found is that if I stop every hour or so to stretch I get my strength back a bit. Repetitive motion can be bad when cycling if you don’t find a way to extend or stretch the legs back and neck.

sfrider 

I feel like that when I push my endurance envelope and have seen it referred to as endurance hangover. Just a "long" ride like last weekend's 4h tempo (62mi, 5600ft) won't do it - that just creates leg fatigue (legs feel stiff and like concrete the next day). It specifically has to push my endurance limit.

Airway irritation can follow hours of breathing hard in cold air. Nothing unusual.

Inusuit

I often have trouble sleeping the night after a hard ride, but never have any symptoms the next day other than being tired.

MinnMan

After a really hard ride (say, a full gas solo century with climbing), I may have issues with thermal regulation during that night's sleep. It feels like a fever but isn't. The next day I may feel fatigued, in part because of the ride and in part because the thermal regulation stuff inhibits a good night's sleep. No fever-like symptoms during the following day, though.

As to the running nose, in my mid 50s, I started having a very mild running nose pretty much all the time. I figure that' just part of being an old man.

Camilo

Dehydration and fatigue.

aliasfox

Especially with exercise and fasting, make sure you keep up with your electrolytes. No food means no salt, no salt means water will run through you faster than you want it to. That might mean switching to Gatorade or adding salt tablets. Not being able to keep in water will also reduce your blood volume - all of which will mess up thermal regulation and potentially give you headaches, lightheadedness, or worse.

After a long ride on a hot day, or even an hour on the treadmill a few degrees warmer than usual - I have no problem scarfing down half a frozen pizza with 2x recommended daily sodium intake. And instead of feeling like crap (like I often do after gorging on junk), I actually feel better.

But yes, if adding electrolytes doesn't solve your problem, might want to check with a doctor before pushing yourself any harder.

Rides4Beer

You've put yourself in a continually depleted state. You can't increase the training load and decrease caloric intake and expect to have any kind of decent results. Proper nutrition and recovery are absolutely key to improving, and to losing weight. Stop the fad diets, just work on balanced nutrition and with the increased workload, you'll lean out.

Freerojo

sounds like this https://www.healthline.com/health/vasomotor-rhinitis