Does intensity matter for capillary development?

Yes, I think it does matter. As you run harder, the muscles' O2 levels decrease. This stimulates the muscles to build more capillaries.

For my money, steady state paced training is the most bang for the buck. It is fast enough to create slightly hypoxic muscle conditions but slow enough that you can do a fairly high volume of it.

Word of caution on steady state training....It is easy for those steady runs to turn into tempo runs if you are not careful.

At some level it does, since you require a stronger stimulus to see improvements as you get fitter and significant capillarization won't continue to occur without more time spent at faster speeds, inducing more prolonged hypoxia within the Type I fibers and providing greater activation of the Type II fibers. However, during initial stages of fitness building or following a peaking stage (i.e., during base training), running at moderate intensities (somewhere between a normal recovery day pace and a decent "threshold" pace for most runners) for sufficient duration extends capillaries equally around both Type I and Type II muscle fibers even if it's predominantly the Type I units that are actually recruited. This could possibly be due to the fact that expression of vascular endothelial growth factor (VEGF) messenger RNA occurs both within and between muscle fibers following endurance exercise.

Yes and no. A possible "no" in the sense that if you need an easy day and a faster pace would just run you into the ground, grinding it out for the sake of development in some other area (capillarization, etc.) makes the negatives outweigh the positives. But if you feel fine, there are quite a few positives associated with picking up the pace to near marathon pace during the last fourth to last half of a long run.

Yes. Capillary development will be minimal to nonexistent if you never operate at any stronger an effort level than about 45% of max VO2. For most competitive runners, this means a pace of roughly 60% of 5k race pace, or in the neighborhood of 3 minutes per mile slower than 5k race pace. This isn't to say that running really slowly on occasion doesn't have some benefits; it's just that the benefits at these super-slow speeds don't extend to capillary development.

Bambi,

Thanks for your response. You state: "Capillary development will be minimal to nonexistent if you never operate at any stronger an effort level than about 45% of max VO2. For most competitive runners, this means a pace of roughly 60% of 5k race pace, or in the neighborhood of 3 minutes per mile slower than 5k race pace."

The Japanese tend to "jog" a lot, I'm talking 8:00/mile pace for a 2:06:57 marathoner (Inubushi). That's about 53% of their 5K-pace. Of course the Japanese do long tempo's and such, but those 2-3 sessions are not going to make a 2:06:57 marathoner. There are a lot of other runners that have had success with running mostly at "slow" paces, van Aaken's runners (only 5% "speedwork"), Whitlock, Maffetone-followers, etc...

Could you explain the success of runners that use a long slow distance approach, or run most of their mileage slower than 60% of 5k race pace? What other factors are involved that enables these runners to succeed with this type of training?

Yes, and Morceli used to do some easy ambling at 9-10 minutes per mile. Shorter said he couldn't find many people who could run fast enough for him to work out with on hard days and also couldn't find enough people who would run as slow as he did on easy days. Willis once remarked that he hadn't seen college teams that ran as slow as he likes to run on recovery days either. There are plenty of other examples.

However, those runners neither sprang forth from the womb able to do 30k at 4:50 pace nor decided one day that they'd jump into running and schedule a few of these long, fast runs during their first season. They had to work up to that level over many years with thousands of hours of running at all manners of speeds, and the cumulative stimulus of all this created the performances they ultimately produce.

The slow running can be helpful, just not in the area of capillarization. As mentioned, the sum total of tens of thousands of miles created all the physical and mental components of success, including the wisdom to find the proper balance between fiery determination, patience and prudence in training and in racing. Most of these runners have already reached their physical limits in many of the measurable physiological facets of running performance before they reach their peak performances, yet they continue to improve in more subtle areas, such as efficient mobilization and sequencing of motor recruitment.

Those extremely slow runs can be very useful for regeneration by keeping connective tissue healthy, providing weight maintenance and promoting running economy through a tremendous amount of repetition in an utterly relaxed state. Even thought the speed seems useless (and would be largely ineffective if this was only speed used), as supplementary running, the sheer act of step after step on autopilot while in no metabolic distress fosters extreme efficiency in the neurons and muscle fibers responsible for fine motor control. Runners who already have a substantial high mileage background have also trained well beyond the point of experiencing a glycogen sparing effect in their long runs; therefore, they may need this easy jogging to provide a fat-burning stimulus to help stabilize weight at an ideal level for running.

In addition, if you're doing a decent number of regular hard workouts during a certain stage of a season, you should run your recovery runs as easy as you need to. While easy doesn't necessarily mean really, really slow, if this is what it takes to recover sometimes, so be it. The time for significant capillary development is probably past by that stage of a season, anyway, so recovery from hard efforts (with maybe a little maintenance of the vascular component as an afterthought) is the name of the game at that time.

Bambi Berenbaum wrote:

Yes. Capillary development will be minimal to nonexistent if you never operate at any stronger an effort level than about 45% of max VO2. For most competitive runners, this means a pace of roughly 60% of 5k race pace, or in the neighborhood of 3 minutes per mile slower than 5k race pace. This isn't to say that running really slowly on occasion doesn't have some benefits; it's just that the benefits at these super-slow speeds don't extend to capillary development.

This has very interesting implications. But, let me just play devils advocate. I'm not trying to be a jerk I just want to make sure it makes sense.

Where do these numbers come from? Are there actual studies on humans that actually measured capillary growth NOT occuring below 45% of Max VO2?

So walking wouldn't develop capillaries at all? Based on the 45% logic that you write about above, a fit person who walked 2 hours a day would have the same amount of capillaries in their leg muscles as someone who was sedentary? I find this hard to believe.

I agree that there's probably an optimal range where you get more bang for your buck, but my hunch is you get some benefits at even slower/easier efforts than 45% of VO2 max or 60% of 5k pace. But, I'm no physiologist so.....please educate me.

~40% of VO2max is considered the maximal intensity that can be sustained day in and day-out, week-in and week-out, during 8 h shifts of manual labor by untrained persons.

I can't find the paper, but I know I've seen this before. So, at that low level of intensity, you're not going to induce very much adaptation at all.. There would be no reason to.

Go out and run at a pace where you can keep it up for 40 hours per week (you'd probably be walking), there's no real oxygen-robbing from muscle tissue.. no capillary growth is needed.

There was at least one in the early 1980s using human subjects. Admittedly, these were already active subjects and the sample size was small (as is the norm for many of these larks). But the conclusion was that capillary development did not take place at 45% of max VO2 and it is therefore prudent to keep exercise intensity from becoming too low to effect change in this area.

There have been other studies within the last decade using groups of rats running for various durations and intensities. But rat muscle fiber composition differs markedly in homogeneity from that of the corresponding muscle groups in humans and rat recruitment patterns are altogether different, often involving Type II fibers where Type I fibers are recruited at the same relative intensity in humans. Interested runners should therefore be skeptical of any sweeping conclusions about the effects of various intensities and durations of exercise on human fiber types if the test subjects are rats.

Perhaps it would in completely sedentary subjects who had never undertaken any exercise regime, but that doesn't really apply to any competitive runners that I'm aware of, so I've never thought it was worth looking into.

Bambi,

Your words inspire. You seem to be extremely well-educated in the physiology field.

Just wondering, do you double as a coach, because I've been looking for something to "believe in" and your posts ( and I've read many on these boards ) ring true.

This all seems in line with Lydiard's "best aerobic pace" (or effort, if you like).

It seems that the best "base phase" is not made up of "easy running", but steady paced running instead. The most miles you can run at the best average pace.

However, after a certain mileage level the "best average pace" might drop to levels at which the overal effect due to the lower pace outweighs the effect of the added miles, which leads to lower performance.

If we would plot MPW, average pace and overall benefit in a 3-dimensional chart, we would find a maximum, which is somewhat different for everybody.

Lydiard's recommendations could well be very close to the mean value of this maximum. Then it is no wonder that Lydiard's "system" would work for a tremendous amount of people.

I think this is what Lydiard was on to... the reason why he said "if you can run more than 100mpw in the conditioning phase, run faster instead".

Only my theory, of course. Correct me if I'm wrong?

Too bad I cannot edit my post.

What I said about mileage levels could better be replaced with time spent running. About 10 hours per week according to Lydiard.

Actually the animal models are quite useful, especially if you can let go of the old V02 oxygen delivery fixation. Yes, intensity matters.

Truth is if you consider isolated muscle exercise, you can see vascular development at exercise levels well below 40% V02, probably closer to 10%. Keep things in perspective, though. The average human self selects an exercise intensity well above 40% V02 and often well above lactate threshold (~50% VO2) untrained. Whether or not development occurs has much to do with where you are in your progression.

Bambi is actually Jordan Hasay. Bambi will crush the field tomorrow. Including the Godzilla that is that Barringer girl.

Impressario wrote:

Bambi is actually Jordan Hasay. Bambi will crush the field tomorrow. Including the Godzilla that is that Barringer girl.

Actually, "Bambi" sound a lot like John Kellogg. Some of the phrases in his post are almost identical to some on Kellogg´s old site.