[Closed] Legs frequently tired, any ideas why?

More cycling.

Like any form of exercise, the more you do, the easier it becomes.

After my first jab in April and my second jab in June, my legs have often complained on the bike if I try to ride above z3. Sometimes they're fine, rarely they are even great, but I've no idea what my legs are going to feel like on a day to day basis regardless of what I've done recently on a bike or my postie job on foot. I did have side effects after each jab, more pronounced and longer lasting after the first.

Strangely, z5+ doesn't feel that much weaker than normal, but z4 is where I really notice the struggle on these regular tough days.

I'd guess the lack of stretching isn't helping and it is a fact that as you get older, it takes a bit longer to recover, so you may not be recovering as much as you had hoped.

I'm guessing, but I think there is also some sense in the do more - my legs seem to take the whole ride to get going these days, but if I can get 3 rides in in 3 days, my legs feel ok on the 4th day...

Rest days? Same age, slightly lighter, slightly shorter also tired legs (feeling but no real loss of power still happily race the 26yos up the hill last night after an hour on the turbo) legs tired today so no run no ride. They'll be better tomorrow.

Slow down a little on your ride? 2kph slower requires significantly less power and thus has less fatigue.

Long term effects from the covid you had in February?

I had covid in February this year and have no top end power. I was off the bike 2 months then slowly carefully got back on. If HR gets up high then the legs don’t like it.

Exactly my issue - though I got COVID in November and still have some breathing issues. Research has showed that COVID can cause microscopic damage to gas exchange efficiency between the lungs and blood. Therefore when working under load, your legs are probably not getting enough oxygen and in anaerobic state sooner than normal.

Academic paper here https://pubs.rsna.org/doi/10.1148/radiol.2021210033

This group has been funded as part of the recent round of long COVID funding to look at this in non hospitalised patients, where similar is expected.

malnutrition?

It sounds like overtraining/overuse/lack of recovery. I would say change one thing for a few months and see what happens. E.g. sit down more (if you can - maybe go on hol/throw a sickie!). Change your diet, increase calories, start road biking, do more/less miles. Try and keep everything else constant and evaluate the effects. If nothing happens, change 2x things, but start with more rest for the legs.

It's all relative, and I'd be pretty happy with your 80k and 2k ascent in 5hrs, but if you're feeling the shortfall that's frustrating.

You could try and look at your effort over those 80k and 2k of climbing, and take it a bit easier while you're doing it to build back to where you were. Trying to keep your HR in zone 2 or 3 for longer, and managing the effort while climbing can help your CV system build back, and allow the legs to catch up as well as less lactate to cope with.

How do you mean "leg don't like it"?
Pain or lack of power? (or both?)
Couple of times recently I've felt like my legs were empty climbing in v high temperatures, recovered in seconds once we reached shade.

How's your diet? Getting enough protein / vits / minerals?

I don't compete and I'm not on any kind of diet regime but I aim for 100k a week (XC miles) for personal fitness goals and I'll always down a homemade recovery shake when I get home after a longer ride. Fresh banana, oat flour, electrolyte powder and 15gs of unflavoured whey protein.

On the recommendation of a friend who does race XC, I've also started taking magnesium supplements and I haven't had a single case of cramping or leg pain since. That's before, during and after a ride. I also sleep better. Half a year's supply of capsules cost around a tenner.

Thanks for all the tips so far.
Have now done 5 rides in 5 days because I'm enjoying it being so dry on the trails. Each about 90mins and 20k with 500m ascent in South Shropshire hills. Have been spinning lower gears, going more slowly and definitely helping.
I am still getting aches in the legs. Calves and quads mostly. What's helping more than anything is stretching and using a foam roller either in the early morning the day after, or before bed the same day. After this, the legs and lower back feel loose and strong.
Why are my legs developing that level of aches and pains? If I don't stretch or roll, the pain just stays.
Is it position on the bike?
Still spinning gears that are too big?
Still pushing too hard?

Stop riding so much.