How do intervals work?
 

I do them, and I know they make you fitter, increase your LT, train your body to buffer lactic acid, but I don't really know how they do it.

For example, why not 2x20 instead 6x6 LT intervals? Why wait until your HR gets down to 60% before starting up that hill again?

i'm not sure what 6x6 or 2x20 means... can you explain? i'm just getting into training, and someone told me i should start doing interval training

does it require you to monitor your heart rate exactly?

The different durations are meant to target different energy systems. The longer intervals are designed to work on your threshold power, whereas shorter durations are meant to work on your anaerobic capacity, or vo2 max capacity.

But, you need to key the intensity to the duration. 6 minute intervals at threshold aren't very useful. It's when you stretch it out to 15-30 minutes that you start to force adaptations. At 6 minutes, you want to go harder than threshold.

So to answer your question, different lengths of intervals for different energy systems. Which one you want to train depends on where you are in terms of fitness, as well as your short and long term goals.

6x6 is 6 repetitions for 6 minutes each. 2X20 is 2 for 20 mins each.

you don't need a heart rate monitor to get benefit out of intervals, however it is useful if you want to target a certain heart rate. for example, this time of year i'm riding 30 minute intervals at tempo, which for me is 152 -158 beats per minute. it would be very difficult to stay in that slim margin without a monitor. for max effort intervals, you can pretty much just pedal as fast as possible, and the HR isn't as important.

i'm of the old school thought that you should try to train for the situations that occur in your competitions. for example, shorter faster intervals are great for getting you used to the efforts in a crit. longer, steadier efforts are usually seen in road races. a large part of this is training your mind to tolerate the pain that these different efforts cause. 2x20 is mentally difficult to do....but so is trying to do a solo breakaway for 15k.

thanks. so if i'm training for both a crit and a RR for mid march, how many hours a week should i be doing intervals? or how much would you be doing?

Typically, time-based Intermittent Exercise offers an athlete two distinct benefits. By selecting pre-set periods or work and various work-to-rest ratios, the athlete can adjust the specificity of the resulting training adaptations.

All Interval sessions are a form of Intermittent Exercise, all Intermittent Exercise sessions are NOT Intervals. It's all in the timing........

well, i can only tell you what i would do. your base training status, talents, weaknesses, etc. all determine what is the right training for you.

for me: i like the pyramid intervals. i've always had positive benefits from it - it's a cornerstone in my training. typically it goes like this:

1 minute on 1 minute off
2 min on, 2 min off
3 min on, 3 min off
4 min on, 4 min off
4 min on, 4 min off
3 min on, 3 min off
2 min on, 2 min off
1 min on, 1 min off

i do these as max effort intervals, so i'm basically going as hard as i can and then soft pedal in between. but, as i mentioned above, you may need to do some longer intervals as well: 3x10, 2x20, etc.

just remember to start off slowly. do intervals once a week for a while, then twice a week. i never go beyond two interval sessions a week. especially if i have a race that week.

For me, the pyramid sets have been the most time-efficient training-technique to get faster...

To answer the OP's question, the 6x6 is completely different than the 2x20. You'd do the 6x6 at 2-5% above LT (fastest pace you can hold for 6-minutes). This won't actually raise your LT-HR, but will increase muscular-efficiency so that you can generate more power at LT; you're using your oxygen more efficiently. Since it's above LT, you'll also generate more lactic acid and this will work on buffering.

While the 2x20 is a tempo workout right at or just below LT. This will improve LT and aerobic capacity, but not work the muscles like in the 6x6. You want to incorporate both workouts in your training regimen.

Am I correct in assuming that, done properly, you need a recovery day after doing these intervals? And if so, do you do these each once/week? That's 4 days out of your week right off the bat. Or do you do them less frequently?

in a way, it's probably better to think of a recovery day as something you take before a hard training day.

the idea is that you should be able to get the maximum benefit out of each workout. for example, if i did hill repeats on thursday and wore myself out, and then tried to do max effort intervals on friday, i would not be fully recovered and my friday workout would benefit me less.

however, if i moved my hill repeat day to wednesday, did a recovery spin on thursday, and then my intervals on friday - i would be much stronger on friday and benefit more.

i tend to have a recovery ride or an easier endurance ride before the most important workout of the week.

Dang! Freakin' lightbulb just went off in my head!

Thank you. :)

Yes. Ideally you need a minimum of 2 days between interval workouts to let your body adapt to the stress it's under. So on Mon and Thurs for example. Lighter workouts between or an off day after and a lower hr zone ride the day before. Doing them too close to each other doesn't allow your body time to "rebuild" and eventually you will get fried. Like someone else said, doing more than 2 of these types of workouts a week isn't advisable for that very reason.

so timhaan, youre advocating a kind of tempo training?