MinnMan

After a glorious autumn of outdoor riding here in Minnesota, it's finally time to set up the trainer. I'll continue to ride outside when I can, but that won't be too many days/week. When I do ride outside in the winter, it's low intensity riding - building base, etc.,

So on the trainer I hope to do some briefer high intensity sessions. 1 hour is all I can stand on the trainer.

I've used the trainer in previous winters, but not with a HRM and cadence sensor.

The first indoor ride tonight, I did alternating 1 minute hard/4 minutes easy. Probably I was not totally consistent in my effort, but I was trying to hold about the same cadence in each part (about 105 RPM whilst spinning easily, and 90 RPM in the harder interval - I am generally an easy-gear spinner) and with each cycle, my HR drifted upwards (the high at the end of the hard period and the low at the end of the low period both increased by a few BPM each time).

Does that mean I'm doing it wrong? Should I be taking it easier in the easy parts? Or should I keep doing this until I don't see drift, and then up the difficulty?

I know that the easy portion of intervals is usually brief, but as you can see from this description, my HR recovery isn't so great, and I wouldn't be able to make consistent efforts for an hour with hard efforts spaced more frequently.

Thanks in advance for your perspectives.

Carbonfiberboy 

That HR increase is called "drift." Drift is a sign of not great aerobic conditioning. Ideally you shouldn't see drift during a one hour workout. That said, if you start of at one moderate power level or speed, then do an interval, when you come back to that moderate power level or speed you'll see that your HR at that level has increased. That's normal and I think hormonal. But it shouldn't keep increasing if you're in good shape.

I have a good riding buddy who's a PhD research physiologist. He says that no one knows what drives HR up. There are theories, but no one knows the answer, i.e. all the links in the chain of causation.

Be all that as it may, here's a CTS guide to getting started with trainer intervals:
The Proven CTS 9-Week Holiday Cycling Training Plan - CTS
I'm using it now.

chaadster

I don't know that I agree either with the conclusion that the OP's drift is anomalous or unusual, or the assertion that one should not, ideally, see drift over a 1hr ride.

I think drift is associated with constant effort, not interval or variable power output work. In other words, doing a continuous, low intensity, Z2 effort should not produce drift necessarily (given fitness), but doing mixed Z3/Z4 work should see a building of HR over an hour, which I don't understand to be "cardiac drift" per se, though HR is trending upwards over the duration.

is there some understanding I'm missing, or why should it be ideal to not see drift (irrespective of effort level)?

MinnMan

As the OP, I'm here to learn. But what if I were doing intervals to a particular target HR, and finding that at each interval my speed (or cadence or power) was diminishing? Wouldn't that be the same thing as finding that at each interval at a set effort, my HR increases?

I do agree with carbonfiberboy that my aerobic fitness is suboptimal. And I do appreciate the link to a training plan. I tend to make up my own training plans, which maybe isn't so smart. but it's because I have an opportunistic regimen (I'll ride outside when I can, inside when I have to, and the intensity of the outside rides is dictated in part by weather and road conditions)

maybe I'm not doing anything "wrong" - maybe this is exactly the workout I need? And and through repetition I can work towards doing that workout with no drift?

chaadster

I'm not clear if you're speculating, or saying you were in fact, performing to HR and maintaining your cadence through gear selection.

Either way, you said you were doing intervals of hard effort, in which case, and absent any knowledge of what the target HR was and where that put you on your effort scale, I would expect that cumulative hard efforts over an hour without sufficient recovery time to induce lower HR, would produce a steady rise in HR over the duration.

MinnMan

I didn't mean to be unclear. I was speculating about a different strategy - intervals at constant HR, but that's now what I was doing.

My strategy was constant effort - the same cadence (90 RPM) in the same hard gear. The effort was not all-out, but something I knew I could hold for a minute and that I would likely be able to do so repeatedly over the hour. In the first interval I got up to about 85% of MHR, but by the l last interval I was at 97% of MHR. There were 8 intervals over 40 minutes (10 minutes warm up and warm down, so an hour in the saddle) and each interval I went up approximately 2.5 BPM.

This was an experiment and maybe not the smartest one, but in advance I thought that the 4 minutes between intervals would be enough to recover so that I wouldn't feel blown out by the end of the hour. And I didn't feel so bad, except that, yeah, in the last couple of intervals i was counting the seconds.

From what I have read about CV drift (thanks to carbonfiberboy for giving me a key word to search), a lot of it relates to increased core temperature. Some of this seems inevitable to me as the hour goes by, even in my basement where the temperature is usually pretty cool. I guess it relates in part to the recovery - whether the 4 minutes of spinning is enough for me to cool down. Clearly it isn't.

chaadster

I would think that effort level is a key factor, esp. with regards to temp, as the harder one works, the hotter one gets. That's part of why I thought cardiac drift was a phenomenon particular to low intensity, steady-state efforts.

I suppose, though, if cardiac drift were defined as incorporating decoupling (as you describe, with corresponding loss of power/speed), making it distinct from a rising HR over time in response to hard efforts (but where power doesn't decrease), then I could understand that distinction. I'm not familiar enogh with the literature to know if that's actually the difference, though.

Carbonfiberboy 

When I'm in fair condition, like last week, only my 4th week back after being sick during a 6 week layoff, my hour of rollers went like this:
15' warmup, Z2
Interval:
2' at 90% LTHR
1' at full gas
2' at 90% LTHR
1' at full gas
2' at 90% LTHR
1' at full gas
6' easy spin
Repeat the interval twice more

During the "easy spin" I held a low power and HR steadily dropped. That was the same during both easy spins.
During the first two intervals I held my speed steady during each section. My HR was the same at the same speed during all those sections, that is once it came up to steady state.
During the last interval my 90% HR gave a slightly lower speed. My full gas speed however was the same though it felt harder. I could have held the same speed for the 90% sections of the last interval and let my HR go up, but I didn't want the extra stress so I went with the easier option.

When I'm in top shape and doing an hour of zone 2 (VT1 actually) on the rollers, my speed will climb very slightly at the same breathing rate and HR. This may be an effect of the tires warming, I don't know. It may be due to increasing efficiency as I warm up. If my speed goes down, I'm either tired from previous workouts or I'm not in top shape. In this latter case I could also hold the speed steady and see my HR and breathing go up, but that sort of defeats the idea of the VT1 workout, so I don't do that.
YMMV

Carbonfiberboy 

Yes, not enough recovery, but frequently we don't want full recovery, we want it to get harder. Depends on what systems you're trying to stimulate.

My workout space is usually at 50-55° and I have a 24" box fan blowing on my port forward quarter from about 6' away. Even so, sometimes I'll have to take my T-shirt off.

MinnMan

Right. I may invest in a box fan. But I listen to music when on the trainer, and the speakers are kind of puny. So maybe I'll also need some new speakers.

Just another example of how a cyclist always needs more gear.

gregf83 

That's perfectly normal when doing a set of hard intervals at constant power. If you're on Strava you can follow some top tier pros and see this same effect when they do intervals. The effect is probably amplified when training indoors due to inadequate cooling relative to riding outside.

Robert Gesink doing a set of intervals with roughly constant HR, notice that power drops:
https://www.strava.com/activities/379961895/analysis

Another set at constant power with increasing HR: https://www.strava.com/activities/378557749

These were in the middle training for the world championships earlier this year doing around 25 hrs/wk in top condition.

chasm54

Caridac drift is a pretty universal phenomenon as far as I know. It's one reason why training with HR alone is inferior to power. Almost invariably, one's heart rate drifts upward over the course of an effort relative to the power produced. Nothing to worry about, really, though as CFB says its onset may be later in the well trained.

Its interesting to speculate on the mechanisms. I'd always assumed, more or less unthinkingly, that it had something to do with rising core temperature, but given that increased HR is triggered by the difference in the oxygen concentration in venous and arterial blood, I guess it might be that the longer the effort goes on, the more O2 is required by the muscles to sustain a given output for some reason. No idea, really, just musing...

Carbonfiberboy 

Yes, anyone's HR is going to drift on a ride that long and an interval set that long and intense. It's remarkable how little his HR does drift!

It's also worth looking at his HR distribution for those rides. Does that look like our training ride distributions? Something like that distribution seems to be optimal down to ~8 hours/week.

kini62

Use BT headphones.

Subscribe to trainerroad and follow a plan. Winging it without a plan won't accomplish nearly as much as following a proven, structured plan.

chaadster

Yeah, both were intense, but he took lots of full recoveries after efforts in the first ride. The second ride was nuts, though! 3x 18min intervals at 350w w/ 500w surges before "dropping" back to 350w?? That's not possible for me to relate to! Just huge!


Here's one of my recent workouts which clearly exemplifies drift as I experience it. Even after dropping back to a 246w Tempo after those L6 efforts, my HR remains susbstantially higher than it was during the 240w Tempo segment leading into the intervals, despite dropping my cadence in an effort to get some recovery:


https://www.strava.com/activities/43...ysis/2823/3797


But that's an hour of solid, non-stop work at mostly Z2/3/4 HR and L3 power, so it's what I expect my HR to do.

Contrast that to the very more stable HR when effort level is held to Z2/3 HR, L2/3 power, and recovery is more complete. No drift over the same constant-effort hour:

https://www.strava.com/activities/429003213/analysis

gregf83 

His HR was steady in the first example but his power wasn't. First 2min interval was at 626W and the eighth interval was down to 508W.

MinnMan

Thanks for your various responses -I've learned some useful things. To those who say that the key is a disciplined training regimen, I'm sure you're right, but first I need to learn some things about riding the trainer. Though I used the trainer last winter and a little in the year previous, I never did disciplined workouts with any kind of data except time keeping. Now I have HR and cadence (but not power), and so before I start a program, I need to know what kind of cadences/gears I can hold for a given sequence over the course of an hour without blowing up.

I confess that the biggest motivation for becoming more disciplined on the trainer is that it passes the time better. Time crawls if I try to hold a constant effort. With intervals of any kind, the psychology is partially reversed - during the easier steps, I want time to pass slowly because I want to feel recovered before the next hard effort, and so, of course, it feels like that time goes by rather quickly.

Tonight I tried something different - 5 minutes moderately hard, 5 minutes moderately easy. There was again a lot of cardio drift, and I think it is more than my core temperature - my cardio fitness just isn't that great. But the hour passed relatively easily, and that's a big win.

chaadster

I don't think it's necessarily true you should wait to follow a plan, firstly because you can adjust your effort during a workout in order to complete it, and secondly because there is no shame or significant downside to failing; you learn and adapt when you overshoot.

There are lots of workouts that use RPE (i.e. Rating of Perceived Exertion) as effort guidelines, which following along with may do a lot to alleviate the irritation and boredom of watching time pass on the trainer. The aforementioned TrainerRoad offers programs like this, spec'ing RPE level and cadence range, and video workouts like those on Sufferfest also do the same, but added stimulating video and sound. Actually, I find Sufferfest music really annoying, but the effort prompts appear on-screen, so you could shut down the sound and supply your own, or just go without.

I'm one of those freaks (apparently) who can sit in silence just watching numbers and executing a written ride plan, but I also enjoy using Zwift, the online multiplayer virtual riding game, where your avatar is riding down the road (according to your effort) along with with other users' avatars. It's pretty fun, I think, and on Zwift, you can either execute your own ride program, use one of their Workout Mode plans, or just ride along and react to other riders' efforts, so there are several ways to use the game.

Zwift works by connecting your trainer and heart rate monitor to your computer via wireless, and relating your actual effort into the action on-screen. So, if you've got HR, speed, and cadence, Zwift will use that, along with a calculated a power curve for your specific make and model of trainer, and inputted weight, to determine your speed up and down the hills of virtual course. If you had a pwoermeter, it would use real power; if you had a "smart" trainer, it would automatically adjust resistance to match slope. All you really need is an ANT+ dongle to plug into your computer's USB port. Very cool stuff, and a really engaging way to spend trainer time.

EDIT: I should add that Zwift will allow you to capture your workout details and upload them to Strava where you can analyze them post-facto, keep a record of your workouts, and monitor fitness. You could do that without Zwift, of course, but you'll need a capture device like a Garmin head unit to aggregate your HR, speed and cadence, then move the data from the head unit to Strava. Are you now monitoring your data on a unit from which you can download your workout? If so, that'll work for Strava, TrainerRoad, and stuff like that.

TCR Rider

As far as Cardiac Drift is concerned I heard a theory years ago as to it's cause. It is directly connected to dehydration. As the length of the workout gets longer it becomes more difficult to maintain hydration. As a result the volume of blood in the body decreases when the amount of plasma decreases making the blood more viscous. This requires the heart to work harder in order to pump the thicker blood to the body.

BTW I agree that structured workouts on the trainer are a lot more tolerable, even enjoyable, than just putting in time aimlessly pedaling. I haven't tried Zwift yet but I just ordered a dongle to link to it and plan on signing up for the free trial through Strava.

Heathpack 

As you work longer & get dehydrated, your blood volume decreases. Cardiac output = stroke volume (the volume of blood pushed forward with each heart beat) x heart rate. When blood volume decreases, stroke volume decreases so therefore you must increase your heart rate in order to maintain cardiac output. There is a little more to it than this, but that's the gist.

As your body temperature rises, you also sends more blood to the surface of your body, for cooling. This means that your already reduced blood volume is now being delivered to a larger volume of blood vessels, effectively further reducing blood volume and as a result, heart rate.

There are other factors that contribute to HR- most notably hormonal/emotional/psychological factors. Basically, the more "stressed" or excited you are, the higher your heart rate.

qajaq

+1 Kini62 Great advise. Bluetooth headset & Trainer Road training programs. Running on a computer TR can be superimposed over youtube videos to alleviate the boredom. Indoors you will really benefit from the big box fan. Dealing with body temperature elevation during the course of a workout can increase your heart rate as you describe. Even at cool temperatures the fan made a big difference for me.

Qajaq