Expert advice needed:

I've been doing a 20 minute session: 2 sets of 5 x 30second sprints with 30 second recovery...and seen great gains. But I'm wondering about which approach to intensity is better, in 2 areas:

1. For each effort, should I try to start less intense so I can maintain consistent effort over 30 seconds, or start all-out and let myself fade?

2. For the whole session, should I start the first efforts all-out, knowing that the power output will fade as I go, or start at a lower intensity so I can maintain consistent power for each effort? I suppose that would mean that only the last effort would be all-out.

Thanks!

What I've been doing is to maintain constant power on each interval and the same power for all of them. That takes a bit of practice to dial in and it's complicated by the fact that we hope that power changes over time! I'd like to hear what others think about this.

I do my 30" on/offs all out to better mimic a race scenario. I know that power will fade as the set progresses, but I am training the ability to dig deep while insufficiently recovered. On these, I don't even look at power on my Garmin, just lap time.

30secs and shorter, I think going all out makes sense even if you fade a bit by the end and don't hit the same power for every interval. Those intervals are about building explosive power, not aerobic conditioning.

For longer intervals (even "short" VO2Max intervals in the 3:00 range) pacing is more important as it's about time in spent in the training zone that produces the adaptations you're after (eg VO2, threshold/FTP, tempo, etc).

30 secs on with 30 secs off is more vo2/ aerobic (though there may be more beneficial workouts for that, or at least a different stimulus). Explosive power is built by being explosive, ie, doing maximal sprints.

I don't think 30s/30s are all that great to begin with. What are you trying to improve, exactly?

Initially, it was to improve overall cycling fitness. I have aspirations to try cyclocross racing in the fall.

They have worked well for me. Perhaps I will reach a point at which they lose their benefit, but I feel like I'm not close to that level yet.

At this point any and all riding will improve cycling fitness.

If it's a workout you enjoy, then why not.

I'd work towards trying longer stuff in the near future.

I like it because I can fit it into my schedule. I try to do it once or twice a week, and get in one 20 mile group ride that keeps a brisk pace and includes one significant climb. Doing that last rising season allowed me to keep pace with some riders who rode 4-5K miles last year but didn't do intervals....I rode about 1,000, and on group rides, we were about even.

I'm a big believer in the short intervals, and it seems that the science backs it up. Even doing just the 20 minute interval session most of this winter (with NO long rides) put me near the front when we did our first 2 hour spring group ride a few weeks ago. So the aerobic efforts were conditioning my aerobic system as well.

That's called a bit of talent.

I experienced the same when I first started riding. A month or two after riding as fast as I could on every ride, I could drop every guy on the race group ride. It was awesome. I just started doing 1-2 min hill repeats as often as I could because I kept getting faster. But 6 months later though and I was sooo fried. I had to make a lot of adjustments. At some point the gains will slow down or cease entirely. That's when you've got to start trying something else. And again, that's when the longer intervals might start helping quite a bit more.

Granted, I suspect anything longer than 2 hours would have seen me fizzle...some of those guys just rode 3-4 hours regularly, but at a pretty steady effort level.

I do mine on the trainer paced based on cadence and perceived effort. My trainer resistance is pretty consistent after the first 10 minutes and I mount the bike with the same number of turns and have the tire at the same pressure each time. Having done this enough times, I know that in a specific gear at a certain cadence, I can barely maintain the effort to the end. And then I add one more rpm for the next set.

For me this is mentally taxing enough. The thought of doing 5 consecutive 30 sec all-out efforts would make me reconsider why I ride bikes.