Completely agree with @DamonL on the fatigue. These intervals should not feel that hard on the legs, nor should they cause very hard breathing. Burning legs at this intensity would pop up a red flag for me, suggesting more rest is necessary. The other part about HR dropping very quickly also suggests that recovery is in order - HR does tend to drop off a cliff when the load is taken off at times like that. Sometimes it’s easy to mistake that drop in HR as improved fitness or recovery when in reality it’s fatigue, so it’s great that you’re paying attention to that and noticing those changes.
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Interesting - I’m in my recovery week at this point, so I’ll take a look at how things are going next week. Other signs of overtraining or overreaching aren’t present - resting hr is still at baseline (39), no excessive fatigue or soreness. On final graph hr did eventually come up, but only after increasing the work intensity. Also, I should have mentioned that I’ve been focusing on near meditative breathing during the recovery minute with the goal of seeing how rapidly I can make the HR drop. How would you judge increases in the work sets if not by an improving HR response?
Plan is 100% FTP based on a newly tested (and increased) FTP number. Will probably be quite tough I suspect. I will however do these using resistance rather than erg, so will be guided by how they feel rather than be fanatical about 100%. I usually do rest about 50%.
Hi @ben.grimmnitz, sorry I only have time for a quick reply, but I think Ryan covered it well. Just wanted to quickly address your two questions.
In terms of the first question, the focus is on the interval. I wouldn’t try to raise the wattage of the recovery or shorten it. The one minute recovery going easy is exactly what you want.
In terms of the low heart rate on the one set, yes, my immediate response is that you were fatigued. But the other thing I want to point out is that to do these intervals effectively you have to look at heart rate, power AND RPE. The fact that you said your legs were burning and you were struggling with the intervals tells me that your RPE was too high (i.e. you were aware you were going too hard but focusing on heart rate instead.) Some days heart rate is just low. It’s important to adjust based on feel and not try to force the heart (or power for that matter.)
Hope that helps!
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Great thread. Thank you to all of the contributors.
My question is around governors for these types of intervals. After a few weeks away from intervals, I did a 55 & a 64 (both 4 with minutes rest) back in late Jan. My HR peaked at 92% and lactate was 13.0 & 13.3mmol at the end of the second last interval in both workouts (my max lactate in ramp tests is about 21mmol). After a few weeks of doing 2 to 7 minute intervals 1-2 times a week, last night I did a 4x7 and held a higher power than I have during this block and RPE was down. 10.4mmol at the end of the second last interval & HR peaked at 93% at the end of the last interval.
Should one limit their power based on lactate (around 4-5mmol?) as well as HR during these intervals?
*Anticipating comments that my aerobic system is not developed…this was true but I have spent the last 2 years working almost exclusively on my low end power. Now, when doing long rides (6-8hrs) I have very little HR:Pwr decoupling and feel as strong in the last hour as the first. Also, for an example, a recent 3:45 hour ride on the trainer, 2% decoupling and lactate was 1.6mmol towards the end.
Thank you.
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Hi @trevor. The 5x5 has been a staple of mine for 25+ years, and I use different variations depending on the time of the season. Usually around this time of year heading into weekly training crits and fast Saturday Worlds rides, I like to use the approach of 5x5mx1m on one of my ‘hard’ days, but doing hard/max effort starts until my HR hits 90% maxHR (which is a few beats lower than my threshold HR) and then holding that HR for the remainder of the interval, pic is an example. My intent is to burn through some of my W’ and finish the interval with less anaerobic contribution. I know you like to use a cap of threshold HR +1, so I recently tried increasing my HR to just above my threshold HR with this approach only to find that the resulting power only changed a few watts. Therefore, for me, is the juice really worth the squeeze of those extra beats? I feel like that might only add unnecessary stress on my ANS. Would love to know your thoughts on my approach. I appreciate you, and the work all of you do!
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Does it make sense on the first set of 5x5s or any interval, to go harder and then back off toward the end to help to exhaust the glycolitic system and get to the aerobic part quicker.
If so, would that apply to say the first minute or so of each remaining set? To burn off more of the anaerobic aspect?
I wonder if that would apply for zone 1 of 3 endurance rides. Should the first half hour or so be done at some power above endurance power for the same reason?
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Hi @kc2738, impressive graph. Looks like you have the execution down. We actually have a podcast coming out next week where we address the question of doing the first 30 seconds harder. Our guest is my old coach, Houshang Amiri, who introduced me to the 5x5s. He’s a fan of going a little harder at the start of each interval.
In terms of your question about the higher heart rate, it’s important that you notice I say I cap the heart rate at threshold heart rate plus one. It’s a cap not a target. I don’t want my athletes to try to sit at that heart rate while doing the intervals. I just want them to back down if they do hit it.
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Thank you, Trevor, for the reminder. In this week’s 5x5 I got caught in forgetting it was a cap, not an HR average. I happen to have a copy of Dr. Sieler’s 2013 landmark study on the 4 x 8s and reread it.
It was based on isoeffort, or maximum sustainable effort. The HR numbers were a consequence, not used as a guide.
The 90% plus/minus 2% of max HR number was obtained from the last 2 minutes average of each 8-minute section (25%), not for the entire 8-minute session.
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I’m curious about execution of 4 X 8 min threshold intervals in relation to periodization. @trevor recommends a HR cap of 1-2 bpm above LT2 heart rate. Would it make sense to “bend” this rule closer to race season? I’m gearing up for a race mid June. My HR has recently been creeping 4-5 bpm over my estimated LT2 HR for the 3rd and 4th intervals. My RPE has been a bit higher, but I don’t feel like I’m crushing myself. I guess it’s also possible my LT2 HR is higher than at the start of the season. I’ve done 24 structured threshold interval sessions from November to April, and I’m planning some specific VO2/MAP in the two weeks before my first race. Would it make sense to be creeping into the over-threshold zone at this point?
Increasing intensity prior to a race and prior to a taper is a good plan, unless the race is very long distance.
If the intensity in your intervals feels less intense then before you have progressed and need to increase the stimulus: longer or harder intervals.
Hi @robertehall1, I would agree with that. I mostly only use that limit in the base season when I’m working on building the aerobic engine and not focused on race form. if I have an athlete continue five or eight minute intervals during the season, I’ll have them push the intensity and increase the rest period - anywhere from 1-to-0.5 up to 1-to-1. Good question!
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On the weeks I race (XC mtb), I usually keep interval intensity consistent with recent efforts as not to shock the system and incur soreness. On the off weeks, I will up the wattage if warranted.
After hearing this (and my own thinking), I added hard starts to my interval workouts. My thinking too is to burn through anaerobic power faster so I can get the HR up and work aerobically. I go hard until I see 81% HR and then go for target power and see, adjusting from there. I re-watched your 5x5 video @trevor and hear you say the power needs to be consistent. My first thought is why? With hard starts and a HR cap, my power can drop in the latter intervals. Below is a graph of a 4*8 workout from last week. You’ll see second interval has a 312w avg and last a 299w avg (hit HR cap and backed off).
Curious on your thoughts on this @trevor
Also, I am doing 5x5 and 4x8 over threshold. I was surprised to hear you say these are in the 90-100% range. Is going over (yet under a HR cap (92% Dr Seiler or your threshold +1)) going to be detrimental to aerobic adaptations? I think if I stayed at the 90-100% range my HR would be low. 100rpm might be a key change I need here though. I might give it a try and see.
Thank you.
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HI @DaveQB,
Revisiting your question in case that podcast didn’t answer it. But yes, I think when you’re getting into that question of a slightly harder start vs what I do which is to be steady throughout, you’re getting more into preference and style. I think both approaches are going to produce a quality workout. My old coach actually liked that harder first 30 seconds, but if he had athletes doing threshold intervals for 10 weeks, he’d wait until the final four or five weeks to add that harder start.
In terms of the percentages, you’ve probably heard my opinion which is not to get caught up in specific percentages. Honestly the best prescription for these intervals is do them as hard as you can that is still steady and is at a power you can hold across every interval. I give athletes that heart rate limiter so that they don’t go too hard - especially to start - but otherwise I tell them the power should be what you’re capable of that day.
Hope that helps!
Trevor
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Thanks @trevor
I guess this is the dilema. In order to get anywhere near 90% HR, I need to go really hard, but that’s too hard to sustain across intervals. I guess I need to pick 1 goal.
Side note, I started a threshold block. Did a 2*12 to start with and did it by feel as I wasn’t sure where I would land. Intervals were flat graphs and 5 watts apart. I surprised myself. I think I should rely on feel more.
HR GRAPHS
I re-watched your video on this. I was amazed at your heart graph; straight up and then steady. I didn’t think a human could do that. Then a mate showed me his and it is like yours 
. I thought I had developed a decent (relatively speaking, for me) aerobic system with a year spent focused almost exclusively on endurance and tempo. I guess it was THAT bad before 
.
I find this all very interesting 
Thanks for the reply @trevor
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@DaveQB glad this is helping! It can take years to get that sort of heart rate response and even then, your rider phenotype really needs to be a time trialist or all-arounder. If you’re seeing a quicker response and a flatter heart rate, then you’re doing great!
And yes, going by feel is a good approach. Find what your heart rate is when you do that and then you can use that as a guide. Everyone is different. For some 90% of Max is right on, for others, it’s too easy and for many it’s too hard.
Hope you’re doing well!
Trevor
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Thanks @trevor
That’s all making sense and answering my concerns. Thank you.
I think my phenotype is way different to you being that I am able to produce over 20mmol of lactate in ramp tests 
I think I’ll drop the 90% target for now and go more on feel and see how we end up. HR can vary based on fatigue, stress etc anyway. I think I finally have enough experience that I can trust my “feel”.
My feedback would be to include this last post from you on the 5x5 and 4x8 “Workout of the Month” pages to save getting more questions like I’ve asked, from others 
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Hi Trevor,
Like DaveQB, if I hold letting my HR rise in toward the end of the latter sets to 90% of max HR in the 5x5s, I see a noticeable drop-off in the 5th set average power compared to the 1st set.
Sometimes 5% or more % if I am not in good shape. You said that the 90% ideal would be different depending on the person.
Would you suggest that the priority be sustaining the same power throughout the 5 sets, and lowering HR% until we get to that point?
Experimenting to see what is the highest power we can maintain while below the 90% HR max, expecting that to rise as we do more of them?
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HI @micomico,
There’s a lot of debate on this, so I’m not going to say I have the monopoly on the right answer. In fact, I’d say there’s probably several right answers with slight variances in how they impact your physiology.
So, with that being said, the way I prescribe them is with a set wattage. All five intervals should be within about 10 watts in terms of their average wattages. The way I use heart rate in these intervals is to set a heart rate limit that’s one or two BPM above the athlete’s threshold heart rate. If the athlete is doing the intervals at the right wattage, they won’t be within 5 BPM of the heart rate limit on the first interval. But by the fourth and fifth, they’ll be riding the edge of that limit.
Here’s an example. The dotted red line is the athlete’s threshold heart rate:
This is where you’ll get a lot of debate. There are many coaches who feel not hitting that threshold heart rate in the first interval means the interval was a waste and they’ll throw in some anaerobic capacity work at the start to get the heart rate up. I don’t personally agree with that, but like I said, this isn’t a case where I can point to definitive research, so it’s as much opinion as anything.
Certainly if any of you have seen that definitive research, send it my way!
Hope that helps!
Trevor
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