Thursday, March 26, 2009

Interval Training and 40k TT

If you read my tweets at or in the right hand column on my blog home page you'll notice that I do a lot of intervals. What you're seeing there is similar to what I have many of the athletes I coach do in their training. This form of training has been around for a long time but was first mentioned and studied in the scientific literature in the late 1950s. Since then there have been many studies on the benefit of interval training. Most of these studies compared well-conditioned subjects doing high-intensity intervals with control athletes who trained with steady-state workouts only. This somewhat biased the results since several other studies have shown that for well-trained athletes high intensity training is more effective than simply training with high volume at a lower intensity. And you simply can't do the same amount of high-intensity training in a steady, non-interval workout. Intervals win hands down. So given the choice, if you want to improve your performance in endurance sport, intervals are the way to go.

I recently went back through my archives looking for what the research may say about the best way to train for a 40k time trial in cycling. A couple of the athletes I coach are focused on such events this season. I found four studies which suggested that with only 4 weeks of training race times for such a TT could improve 2% to 4%. So if you do a 40k in 60 minutes such an improvement would knock off 1 minute and 12 seconds to 2 minutes and 24 seconds. That's a lot of time reduction in a very short time frame.

Three of these studies (1,2,3) had similar workout protocols with 2 sessions a week with 6-8 intervals in a session and each interval lasting 5 minutes with 1 minute recoveries (this short recovery time is critical to the results you get--don't lengthen it). The power for these intervals was 80% of power at VO2max. If you find your average power from a 6-minute time trial using a power meter you can assume that is your power at VO2max and be pretty accurate. So if that power was 300 watts you'd do these intervals at 240 watts (6-8 x 5 minutes at 240 watts with 1 minute recoveries). That's probably just about your functional threshold power (the power you can hold for 1 hour). Basically that means you'd be doing intervals at about your 40k TT race power. Strange how that specificity thing works, isn't it?

The final study (4) I looked at used a much higher intensity, however. In this study highly trained cyclists and triathletes did intervals once a week for 4 weeks. Each of these sessions involved doing 8 intervals at power at VO2max with each interval lasting for 60% of the time the subjects could maintain power at VO2max. The recovery after each was twice as long as the work interval. So, let's go back to our example athlete from above. If when doing an all-out effort he could hold 300 watts for 6 minutes here's how his workout would look: 8 x 3 minutes and 36 seconds at 300 watts with 7 minutes and 12 seconds of recovery after each. That would be done once each week. That's a killer session so once a week is plenty.

It is possible, however, to combine these two workouts in a week. I often have riders do the first workout with 5 intervals early in the week and the second workout also with 5 intervals later in the week. In fact, if you track my workouts through Twitter you'll find I'm doing something similar to that right now (when travel allows). Most athletes would need 48 to 72 hours to recover from each of these before going hard again.

Just a side note here... Without a power meter you're just guessing as to what the intensity you should be using is for such workouts. A heart rate monitor doesn't improve that guesswork by much. Power meters are a necessity for such precise interval workouts.

1. Kubukeli ZN, TD Noakes, SC Dennis. 2002. Training techniques to improve endurance exercise performances. Sports Med 32(8): 489-509.
2. Lindsay FH, JA Hawley, KH Myburgh, et al. 1996. Improved athletic performance in highly trained cyclists aftyer interval training. Med Sci Sports Exerc 28: 1427-1434.
3. Weston AR, KH Myburgh, FH Lindsay, et al. 1997. Skeletal muscle buffering capacity and endurance performance after high-intensity interval training by well-trained cyclists. Eur J Appl Physiol 75(1): 7-13.
4. Laursen PB, CM Shing, JM Peake, JS Coombes, DG Jenkins. 2002. Interval training program optimization in highly trained endurance cyclists. Med Sci Sports Exerc 34(11): 1801-1807.


At March 27, 2009 6:36 AM , Anonymous Steve said...

Thanks Joe. I've found that a threshold and VO2 day midweek with racing on the weekend seem to be the most efficient use of time during my Build2 phase. Tough, but able to recover in time to race again. I'm either going hard or going easy as you talk about in the TrainingBible.

You mention a recovery interval 2x the length of the VO2 interval. Most sample workouts I see mention a 1:1 ratio (which have been very tough to complete).

How does a longer/shorter recovery period affect the benefits or training adaptations gained from a L5/VO2max workout? I'm guessing the longer recovery allows you to hold a higher percentage of Vo2 max while completing more intervals. This would mean more time in that range over the course of the workout and thus more improvements?

At March 27, 2009 6:59 AM , Anonymous Anonymous said...

Joe, super interesting, thanks!

Could this same protocol be used for a triathlete, training in 2 other sports? And for a 56mile TT (half-iron), would you recommend the same length intervals, or longer, lower-intensity ones.


At March 27, 2009 7:18 AM , Anonymous Mark said...

Hi Joe

The 8x5 workout at about FTP is the same amount of work 'on' as the classic 2x20, so basically an L4 workout.

What would you say is the better workout for L4? Would you agree that 5 minute intervals are better at L5?


At March 27, 2009 8:43 AM , Blogger Nate said...

Great post Joe.

I just posted a similar question on a forum a few days ago. I'm trying to figure out which workout would be better for me. My schedule consists of 3 HIMs and 1 IM with lots of little tris and road races sprinkled in.

My FTP is about 285 (haven't tested in a few weeks).

Workout 1
3x15 min with 6 min off
Set 1 - 290
Set 2 - 290
Set 3 - 300

Workout 2
1x43 min
Average Power 283

I have done both of these workouts in the last two weeks. I think I have a higher than normal AWC. Which workout do you think would be better? Maybe I should drop these and do those shorter intervals that this post talks about.


At March 27, 2009 1:58 PM , Blogger Joe Friel said...

Steve--As you get closer to the A race I believe the workout should becoming increasingly like the race. That means reducing the duration of the recoveries to less than 1:1 eventually.

At March 27, 2009 2:00 PM , Blogger Joe Friel said...

RC--Yes, it would work for a triathlete also. In the case of a HIM I'd suggest the first workout described is the most effective.

At March 27, 2009 2:04 PM , Blogger Joe Friel said...

Mark--As long as you can maintain a coupling between HR and power (i.e., no fade) for a long work interval then I believe that is better, especially as you get closer to the race. Again, specificity.

At March 27, 2009 2:06 PM , Blogger Joe Friel said...

Hi Nate--Depends on what your A races are. If the IM then I'd suggest much longer intervals done in the 3 zone. For HIM the 8 minute intervals at 4zone work well, I believe.

At March 28, 2009 12:31 PM , Anonymous Marshall Hance said...

My first question regarding the long recovery was already asked and answered. That makes sense and I suspect I now know the answer regarding how to best implement "two a day" workouts. Little more is mentioned in the new training bible than for intervals, two a day workouts are better.

Is the second workout a recovery session? Or does splitting these intervals in half allow for more quality work during an "hard" day?

Thank you,

-Marshall Hance
Asheville, NC

At March 28, 2009 1:42 PM , Blogger Joe Friel said...

Hi Marshall--I've never seen that question addressed in the literature. My guess is that to get the max benefit of VO2 max intervals that they need to be done in a single session. Spreading them out over 2 sessions in a day would not be as effective, I believe. The second workout is probably best as recovery. We--trained athletes recover best with light activity. Novices recover best by doing nothing.

At April 1, 2009 11:26 AM , Blogger vo2mike said...

Joe, are training for a 40k TT and training for MTB racing similar?

At the highest levels I anecdotally notice that good MTBers are good TTers on the road (eg. Cadel Evans, Floyd Landis)

Would you prescribe these intervals for an MTB XC racer?

At April 1, 2009 12:04 PM , Blogger Joe Friel said...

vo2mike--MTB training is very good for road racing. Requires excellent musc endur, climbing and pedaling skills. All of this makes for great road fitness too. Yes, I'd have MTBers do those intervals. Of course, there's a lot more to MTB racing than what these build.

At April 22, 2009 10:09 PM , Blogger Fixie Rider said...

Hi Joe,

I am working on improving my Time Trial abilities for Stage Races. Most of my TTs are in the 15k to 20k range. How could I adapt these workouts to the shorter distance?


At April 23, 2009 2:04 PM , Blogger Joe Friel said...

fixie rider--Thanks for your note. Just do the intervals at the goal intensity. The higher the intensity, the shorter the work intervals are. And as you get closer to the targeted race the recovery intervals also need to get shorter.


Post a Comment

<< Home