Am rather stagnant in power dept and was wondering when you go out and do it, (Iknow there are plenty that don’t) is the session so strenuous that you need the next day off the bike or take a spin day, or would that be overdoing the session?

Every body is different, but I don't need to take a day off after a 1 hr HIIT session. After a big squat session/workout I typically can't ride the next day and I absolutely have to take a day, or two, after a 4 hr Z2 ride.

Yes. 100%.

I will do an active recovery ride, followed by a Z2 ride.

72 yo, definitely Yes to rest after hard or long days. Until I bought an eroadbike. Great active recovery machine.

Oh wait = ebikes not permitted on 50+ (crabhead) forum. Call it my un-bike, but still a great outdoor pedaling machine.

edit: Glad to be more of a cyclist than I used to be. Tough hills on every ride is a fact of life for me.

I should for sure but I am semi-retired so I can ride daily assuming otherwise, but I just go easy. Actually I am forced to go easy but might have to rethink this in future.

Here's a weird one: after really hard long rides I have a night of insomnia.

I believe poor sleep quality is actually quite a common sign of over-reaching. I’ve experienced it several times myself.

Yeah I would take it easy the day after a really hard interval session. But not necessarily a full rest day. I may do a recovery ride or even up to a 2 hour Z2 ride depending on what I was training for. I tend to take full rest days after long, hard 4+ hour rides rather than controlled interval sessions.

I get that too.

can relate

I'm 77 and doing 12-15 mi rides at a TT pace. That doesn't cause me to need a day off. But, I'm getting plenty of rest days thanks to rainy weather.

At our advanced age (and at any age, really), recovery is as important as the HIIT in order to maximize the benefit of the workout.

I ran a 50k ultra a couple of years back and the taper was incredibly important. I did not realize how much accumulated fatigue I had until the taper put some snap back into my legs.

I use heart rate variability, mood, and sleep quality to determine if a day off will yield better results than riding the day after HIIT session. I'm more inclined to take a rest day before the HIIT day with the thinking of having fresher legs to get the most from the workout. No idea if that is good or bad.

I ride every day. But after a hard ride I don't go as far or as fast or up any hills. Just fast enough to work up a sweat before I quit.

I rarely ride back-to-back days anyway, so yes, I take rest days after a HIIT or similar high intensity session. But more on point, if I've done a really hard session, I'll likely take it easy on the next ride (2 days later). Easier means zone 2 and a medium length ride for me, say 30-35 miles.

I've noticed, even if my legs feel fully recovered from a hard ride, they'll fatigue more quickly on the next ride. So, I plan accordingly.

No. This week I did 4 HIIT sessions. Saturday and today, on the smart trainer I did 2 sets of 4x(20"on 3'off) with complete recovery between sets. My best 20" average power on Saturday was 508 watts and today, it was 484 watts. Legs felt good both days.

One different between Saturday and Sunday was the I did lower cadence today. I find low cadence on the smart trainer much more difficult to produce power for the same level of effort. And I am about 150 watt lower on this type of effort on the trainer than at the track or on the road. YMMV.

This raises the question of how different HIIT sessions can vary in how much fatigue they cause. 20 sec intervals with 3 mins recovery are going to require a lot less recovery than say 3 min VO2 max intervals. For those who are familiar with Sufferfest, a workout like “9 Hammers” or any of their other hardcore HIIT sessions are not something you can repeat the next day. At least not at the prescribed intensity. But shorter micro-intervals are pretty easy to recover from. I often use them as activation sessions the day before a big event.

HIIT is a pretty broad brush when it comes to fatigue and recovery. I find some HIIT sessions pretty easy on recovery and others really do need some R&R the next day!

How much HIIT one can also depends on current fitness and load. I am currently cutting back my load from around a CTL of 100 down to about 70 and I can do HIIT workouts much more often than when carrying a negative training stress balance.

XERT takes a slightly different approach to assessing training readiness. There were some aspects of that package I liked and others I hated. The daily assessment I thought was on the right track back when I used it in 2016-2019

https://baronbiosys.com/assessing-readiness-to-train/

Speaking for myself, yeah, at 65 I usually need a recovery or full rest day after any HIIT session, unless we're talking a short 15-20 minute Tabata session at most. I do that kind of session only a couple of times a month now, and not always on the bike. I'll mix it up and do it as a running workout, maybe mixed with "cross-training" -- I don't mean the cultlike CrossFit thing, but a mix of sprints and calisthenics. If I do that kind of session, I can usually do an easy jog or ride the next day.

But usually my higher intensity bike sessions are 60-90 minute fartlek type sessions. I don't watch the clock but instead follow the terrain and wind to determine the untimed intervals of maximum effort.

It's been too hot here in Texas for hard efforts in daytime, and it stays ridiculously hot until after midnight. So I've been riding between midnight and dawn, depending on whether I'm still awake or up early.

Last night I tackled a familiar roller coaster route with a series of short, steep hills, each taking 30-90 seconds to climb depending on effort and conditions. Last night it was all into a 15 mph headwind, so it was harder than usual. Sometimes I'll spin 100+ rpm to get the heart rate up, other times I'll mash the hardest gear I can turn without stalling out. Last night I did the hard gear mashing thing. My quads felt it today. I walked a couple of miles at midday when it was 107+ degrees. I might do an easy indoor spin later to loosen up the legs. I don't "train" on indoor spins, I just set up a movie, TV shows or YouTube infotainment videos to watch for a couple of hours and just move the legs. If I feel like "training" I'd rather be outside.

73 and my joints and arthritis like (really demand) the rest day after. My hope is to keep the joints as a minimum or even a non-issue for as long as possible as I have detected things like a little roughness in a knee does seem to settle out on the rest day.

It's the time of year when I am in pretty good shape and every ride I do with my friends seems to be "epic." 2 days ago, 70 miles, 5800 feet of climbing. For a bunch of 68 year-olds this is "epic."

So today, instead of riding, I am taking the day off. My thighs still feel tired.

To answer your question, Yes.

Not sure I 'need' the rest day, but sure do prefer it.