Hard start VO2max intervals

Ta. I’ve read the blog post but this is confusing:

  • A more ‘aerobic/slower-typology’ athlete can probably program the hard-start at a lower power target above their Threshold and/or for a shorter hard-start duration . Because they likely have faster VO2 onset kinetics and their Threshold is already at a higher percentage of their VO2max. Meaning they need less of a stimulus to get near VO2max.

I’m not sure if 55-90 seconds HR lag qualifies as “fast VO2 onset kinetics”

Maybe begin with 140% hard start dropping to 115% over 90 seconds then whatever length of hold. Star with workouts with 6x3, 5x4 and 4x5 sets. Sound about right?

1 Like

I realised last night after posting that I’d confused/conflated HR lag with VO2 kinetics. :roll_eyes: But then further thought that HR lag could well be an indicator of the latter since HR would need to increase to supply the extra oxygen to the muscles.

Another point about my attempt was that my cadence during the recovery intervals was pretty low. A bit of a habit I’ve got into . I’ll raise that by 15rpm or so and keep the effort aimed at the cardio-vascular system.

What about adding a third segment below FTP after the tapered power?
For example: 90sec. hard start (135% FTP) / 3min Tapered Power (110% FTP) / 90sec (95% FTP).

I tried this and for me, during the 90sec. @ 95% FTP, my HR only falls slowly which leads to high durations above 90% HR max. At the same time it´s something like a “VO2 max over/under” that may potentially help with lactate processing. Just a thought…

1 Like

Your second part here - the self-experimentation - is more important than the first part, IMO. Fast or slow is vague on purpose. It’s more about finding the balance of pacing for the interval that works best for you, given your goals for doing the workout and your physiological response.

Good question. I went down a brief rabbit hole to try and learn how HR kinetics correspond to VO2 kinetics. They are certainly related, but it seems to be that HR kinetics are more variable than VO2 kinetics. So the value of HR time response (say 55-90 sec) would not be a good predictor for VO2 time response. However a change in the former probably directionally indicates a change in the latter.

Good thought. Would definitely slow the recovery and maintain a higher VO2, HR, lactate, etc. metabolic flux for longer. Although taken to a logical end-point I think you’ve just re-invented continuous threshold training instead of interval training? :sweat_smile:

Ta. I’ve been going through most of the other posts on your blog :grinning:

I think that the “long” recovery after the initial warm-up anaerobic bursts/efforts and before the first main interval is too long for me, my HR is way down so there’s more work to get things going. If we assume that 90%MHR is enough for 90%VO2max then I’m a couple of bpm down at the end of the descending power portion of the interval for all the intervals. So I need more work prior to that without too much stress.

I’ve had a play with Workout Creator and made a version of the 6x3 of my own: the initial peak isn’t quite so high but I stay there for 30 seconds before dropping. Hopefully this will get my HR to rise quicker without overstressing my muscles. I’ll see next week when I do it!

1 Like

Don’t get what all the fuss is about. Go hard at the start. Do your best to hang on for the duration. Fin.

2 Likes

It would be closer to 85% of VO2max.

Or said another way: 90 ± 10% HRmax will be close to 90 ± 10% VO2max.

Related, but imprecisely so on any given day.

1 Like

Sorry, but that’s not correct. On average, the % of VO2max will be lower than the % of HRmax, at least until the two converge at 100%. That’s because at rest we’re at only 5-10% of VO2max, but are already at 20-33% (or more, if you’re chronotropically incompetent) of HRmax.

If you don’t believe me, ask Karvonen.

Tried this protocol for the first time tonight myself. Got through 3x5min, last full one power declined to FTP. Tried the fourth and was under threshold within 3min so I called it.

This was definitely more like VO2max work that I remember from my track days running 800s till I wanted to die, so I “like” it.

TR’s prescribed VO2max workouts never got me to the fish out of water breathing. These did, but it might just be having the power dialed for the longer duration.

All that said, my starts were obviously too hard. I peaked sub-600W so I wasn’t crazy with it, but too hard… probably should be closer to 400-450. Next set I may just start at my optimized interval power for 5min (320W) duration and try to sustain it for the full 4x5 and see if I get the same breathing sensation and RPE, then go from there.

1 Like

This is my experience too. Shorter intervals results in my legs blowing up and HR never really doing much (touching 90%, but not for any meaningful period). Longer ones (5-6mins) have enabled me to get to 95%+ HRM and maintain above 90% for 2mins+ each interval

2 Likes

Sounds like we had the same track coach…

Have wondered if my own fondness for 2-3 min “VO2” intervals on the bike comes from some sort of mental conditioning from doing those 800M workouts all through high school and college.

1 Like

I would aim for 1,5 min @ 5’ max power

There’s no way 90s at my 5min MMP would elicit the response I’m looking for. That would be 338W, and I’ve historically done 6x3 min intervals over 340W without much problem.

1 Like

Try to do 6 minute intervals.

But probably the difference in 5’ power and FTP is quite big (400 vs 300 watt)

My next set will be a hard start around 400W (instead of 600), and max effort from there for 5min, get through 4 of them completely on 5’ recovery. 20min TiZ, and then I’ll scale intervals and rest from there to get at least 4 more workouts at 20min TiZ over the next two weeks.

If that’s not what I want after I try it, I’ll try 4x5@320 (about 114% of FTP) without the hard start.

I think the right combination of “hard start” and “steady interval” varies by person to get the response you are looking for.

And also if intensity changes with successive intervals.

It does take some playing around to find what works best.

For me, 6 equal and steady intervals like Kaiser doesn’t work - meaning The first couple of intervals are easily doable, whereas the last two are “too hard”.

The hard starts I’ve landed on work pretty well. But I’m still tweaking.

1 Like

I got further in my own version of your Hard Start 6x3 - nearly got to the end of the third interval. :tada: My HR gets to 90% MHR about 15 seconds before the end of the descending ramp. I’ve not done any VO2max work with intervals over a minute for four months or so, so it’s getting the body back up to speed with them. I’m on a dumb trainer but I think for this type of workout you’d be better turning off ERG mode and just riding at whatever power to keep your HR high enough.

I’ve been listening to a few older podcasts over the last couple of days and there’s one where they are discussing long VO2max intervals with one study doing something very similar to the hard starts of @DaveWh but rather than a level steady state to complete the interval the riders just kept riding at the point where their HR was at or above 90%MHR, one got to 26 minutes :scream:

I agree - I definitely felt more of the stimulus I’m used to with vo2max work last season when I did 4x6min steady power intervals vs. the typical shorter intervals in most of TRs plans. This is also the first time I’ve done block-style periodization along with the hard-start, power-fading intervals, so I’m keen to see how it works.

My next problem to solve is how to recover from this block. Adaptation takes about six weeks, so rather than diving into more FTP work, I’m looking at more HVLI where I do a lot of zone 2 riding with a maintenance session every two weeks, and probably executing a four-week block of that before more SST/FTP work.

Just did my first set of hard start intervals.
6 x 2.5 min.
My heart rate only peaks into the last minute,
96%
95.5%
95.5%
94.4%
94.4%
92.6%
of maximum heart rate. To me this represents cardiac fatigue., or severe enough leg fatigue that the power I’m able to keep my cadence above 110 is too low to elicit a cardiac response.