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What did the rest of their training look like? It mentions low intensity, but how low & how much? Looks like Polarized training to me.

Joe Friel

kevbikemad--Unspecified in the study. They otherwise trained as they usually do so long as intensity was less than 88% MHR.

Bruce Wieand

Hi Joe, thanks for the interesting post. Did the study say anything about changes in economy after the 10 weeks? I'm thinking of two studies on VO2max I know of. From Jack Daniels "The Power of VDOT", I get the impression that VO2max and economy have somewhat of an inverse relationship; i.e., athletes with higher VO2max tend to have lower economy. And Veronique Billat "Interval training at VO2max: effects on aerobic performance and overtraining markers" indicates that VO2max training stimulates improvement in economy more that it does VO2max (4 week study). Thanks for your thoughts. --Bruce

Joe Friel

Bruce Wieand--No, economy wasn't measured in this study. And you're about economy and VO2max being contradictory in most research.

Mike E

This is apropos...Sufferfest is coming out with a new video this week, "Half is Easy", that is 2 sessions of (20 x :15 easy/:15 not easy).

Greg Hinrichsen

Joe, The study explains why I have had good results using a heart rate fartlek where I warm up for 30-40 minutes then hammer hard to zone 5a then pedal easy for recovery to Zone 3 and repeat again and again for 20-60 minutes total WI and RIs The work interval starts at around 2-3 minutes but quickly goes to about 45 seconds with about equal rest. I am competing in a 56 mile time trial in 6 weeks. If I read you correctly I should be doing longer time trials as the race approaches at projected 56 mile race effort. I am 55 years old. Thank you. Greg

Joe Friel

Greg Hinrichsen--Yes, I'd agree with your conclusion about your intervals. Good luck!

Greg Hinrichsen


John Daniel Teran

These short interval efforts remind me of the famous Billat 30-30 protocol. Briefly, the athlete spends 30 seconds at speed that elicits VO2max during a ramp test, then 30 seconds at roughly half that speed. The slow component of VO2 means that athletes spend considerable time at VO2max while in the recovery interval, causing total time at VO2max to be substantial, despite the short bouts.
Could something similar be going on here?

Joe Friel

John Daniel Teran--Yes, very similar.

Luiz Fernando Cambraia Gatti

Hi Joe.
13x30"(6.5')with 15"recovery and 3'recovery between de sets is not almost the same of 5'with 2.5'recovery because as you have mentioned this 15"recovery between the 30"efforts doesn't recover completely and it works like a full 6.5'interval?



8.7% improvement in V02max over 10 weeks in already well trained athletes seems huge, to me. How about you? I have read in a number of places recently that when doing very high intensity interval work (V02max into anaerobic) most of the improvement comes in the first 3 to 4 weeks and after 6 weeks it borders on a waste of time, meaning that for the effort put in and the fatigue acquired, there are more efficient ways to train. These articles mentioned that in the workouts made famous by Tabata, 80+% of the improvement came in the first 3 weeks. Do you have any thought on this?

Joe Friel

geocof2249--Yes, there are typically diminishing returns for high-intensity training after the first few weeks, depending on several variables such as the number of sessions per week and the athlete's starting fitness level.

Mitch Sonies

Joe - I've been doing the 30/15's for a month and have a few questions I haven't been able to find answers to. Maybe you can help.

1. Is the intensity of the WI I can maintain throughout the workout, by definition, my VO2 max? (I assume not, but am not sure.) I've noticed that I'm naturally doing the 30's at an average wattage that is 10-15% higher than when I started. So something good is happening, but I'm just not sure it's with my VO2 max.

I don't actually know my VO2 max. I'm just assuming it's 120% of my FTP, but I think my FTP has been moving around a bit as well.

FYI, I've modified the workout a bit. I'm doing 45 repeats of the 30/15 interval, with only a 1 min. recovery every 15 repeats besides the 15 sec RI. So it's roughly 30 straight minutes of 30/15s, which I find makes the workout seem easier to get through. (I'm getting a slight HR drift through the set, but I'm still only peaking at roughly my 60 min threshold HR by the end.)

2. Assuming I'm doing this workout with WIs above my VO2 max, is that counterproductive?

3. What should I be doing to maintain the VO2 max gains after the 10 weeks? Do you think I'd benefit from successive 10-week periodization blocks?

Joe Friel

Mitch Sonies - 1) Yes, It's about VO2max power which is very roughly 120% of FTP for most riders. But that does vary. 2) It's counterproductive if you find it hard to recover within and between the workouts. 3) You're likely to see a plateau at around 6 weeks. Doing this repeatedly is not going to keep increasing fitness non-stop. Once there is a plateau change the workout significantly or stop doing it for a while to focus on some other aspect of fitness.

Mitch Sonies

Joe -thanks for the response!

I just have a follow question regarding maintenance.

What do you guess we'd need to do to hold on to the uplift in VO2 max? Drop from doing the workout twice a a week to once a week? Or could we just shift back to threshold intervals and expect the VO2 max to hold steady? (I know from reading your books that aerobic fitness can decline pretty quickly.)

Ian Thomson

Hi Joe, I just came off the sofa to do a ride to conquer cancer, 2 days 240km. I trained for it using your Muscular Endurance work with Audio fuel. In the beginning I could not do it properly (really out of shape), so instead of the zone 4, I would do 30/30 at about 450watts (my ftp used to be 325). I did this 3 times a week for 3 months. I did the ride easy and was shocked.

I want to thank you for that audio fuel, it was easy to use, please do more. Thank you.

Joe Friel

Ian Thomson - Well done, Ian!

Joe Friel

Mitch Sonies - To maintain a training ability for a few weeks reduce the frequency of the workout by half while keeping the intensity the same.

Ian Thomson

I just tried the Run Cruize Intervals. Again excellent work. Thank you Joe for your great work in this field, and for being so generous with you knowledge and insight. I wish you good health.

Question: Zatopek did lots and lots of intervals, is it possible to do only intervals and be competitive in a marathon? In Italy he ran the Marathon for the first time and won. Or you still have to spend 70-80% of training the aerobic system?

Joe Friel

Ian Thomson--Zatopek was certainly an accomplished runner and well ahead his time when it came to training. You're right, he did a lot of intervals. Was that the _best_ way for him to train? Undoubtedly, given his many amazing accomplishments. Is it the best way for everyone to train when preparing for a marathon? Probably not. Some will respond much as he did while for others will make little or no progress. It comes down largely to one's unique limiters. That's the key to determining what _you_ hold do in training: Figure out what the race-specific weakness is that you are lacking and then go about improving it.

Elliot Power

Hi Joe,

I've re-read your triathletes training bible and am only confused on one thing. This post further confuses the matter.

Regarding anaerobic enduracne and VO2 max training, you mention in the training bible only front of the pack sprint and olympic distance athletes should train in zone 5b and above. Everyone else should focus on muscular endurance and limiting themselves to zone 4 and zone 5a below/at/just over lactate threshold level.

Prior to reading this article, I decided for my level of speed, that doing anaerobic endurance isn't worthwhile but now I'm not too sure.

Can you please elaborate on anaerobic endurance in terms of triathlon as this is the major confusion I'm having with you training methods.


Joe Friel

Elliot Power--I understand your dilemma, Elliot. My opinion on this has changed since I wrote the Tri Bible about 17 years ago. Considering rewriting the entire book because that is not the only thing. Change marches on. For long course tris I would have them do such intervals as described here in base 3 and then go back to what's described in the book for the build period. In build I would have them do a once weekly set of anaerobic endurance intervals blended into another workout to maintain VO2max. I've got another blog I want to write on a closely related topic as soon as my busy season (Sept-Oct) lets up. Stay tuned...


Hi Joe, thanks for all your great information. I have a question about the training surrounding the block of time for the hits workouts. I get pretty tired and don't want to injure myself from riding hard on my days off surrounding the two hard interval days. Is the surrounding Power zone for riding mostly power zone 1-2 or even 3 or can I even do some sweet spot training?
My A race is 1hr MTB race series.
I'm trying hard to keep from overtraining here and appreciate your guidance, thank you, Duane.

Joe Friel

Duane--If you find your recovery to be slow then I'd suggest either making all such easy rides z1 only or take a day off occasionally instead (combined with z1 other easy days).

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