On the Endurance Nation forum recently someone noted that she’d heard a coach say it’s good to run about 90 seconds/mile slower, presumably to encourage the development of all the elements needed to build a foundation for faster running. In our little world, we look for the most efficient way to get faster. Some do it because they work, are mothers, travel a lot, basically just don’t have the time for a lot of exercise. I do it because I’m lazy. So I first responded by saying:
“Running slower than my natural Easy Pace (EP, Zone 1), what I call my “all day pace”, I think just messes up my running form. Going slower than EP, for me, just makes me go at too slow a cadence, or too short a stride, neither of which I want to program into my neruromuscular memory. As long as my heart rate is in Z1, I’m getting all those benefits noted. Specifically, fat-burning is basically an “on-off” switch. You are ALWAYS fat burning at the same level, even when running very fast. So there’s nothing special about going slower as far as fat-burning. The two advantages I see of Z1/EP over going faster all the time are: you don’t deplete your glycogen stores, and so do not interfere with you upcoming/downstream harder interval workouts, and you don’t risk slamming your knees, feet, hips, and lower back so much. While still getting some benefit within the muscles of mitochondria efficiency, benefits in a bigger, stronger heart, and benefits of improved neuro-muscular communication, all good for running faster.
But will running that much slower than EP magically help you run intervals faster? Only if you’ve never run intervals before, I guess.
And besides, it’s just too boring.”
This relatively general reply triggered others to start getting more technical, so I joined in with more detailed specifics:
“A key concept is the word “efficiency”. Without going into the molecular details of muscle contractions, what’s going on when we train at different speeds is really all the same thing. We are increasing all the elements necessary to make muscle contract. More small blood vessels to carry oxygen. More mitochondria to create the adenosine tri-phosphate (ATP), needed for muscle contraction, from either glucose/glycogen (CHO) sources or fatty acid sources. More muscle fibers themselves, with more nerve connections so they brain can oversee things.
So what does efficiency mean? It does not mean that one molecule of fat (or CHO) will start producing more ATP – that amount is limited by the chemical pathways involved. What it does mean is that more fat molecules can be used as fuel source per unit time, because there are more vessels delivering O2, and more mitochondria to convert the fat to ATP.
Fat and sugar are not two different systems for generating muscle contraction. They operate in the same pathways, using the mitochondria to produce the “energy pellets” – ATP – which make muscle contract. The big difference: fat >> ATP requires oxygen, and generates ATP at a constant rate. The amount produced is limited by the oxygen available. CHO can generate ATP much faster, without needing O2.
Bottom line: if you become more ‘efficient’ at using fat for fuel, that efficiency will bleed over into more efficiency at using CHO, and vice versa. But a key concept is, training in the zones which require more CHO turbo charges the development process. There is much more stress on this system when going anaerobic, so growth of blood vessels, mitochondria, and muscle fibers happens both faster and to a greater extent. This is why training at faster speeds will make you better at running for longer times at slower speeds.
But the reverse is not true, as least to as great an extent. Fat burning rate is limited by the availability of oxygen, and so it can’t stimulate as great a growth in the elements of muscle contraction as anaerobic metabolism. A (flawed) analogy is weight lifting. A body builder wanting to get bigger muscles would be much more likely to succeed by using very high weights, stressing to failure, than by lifting endless repetitions of light weights.
Running longer at slow speeds will eventually get you more efficient, but it takes a lot more time, and has a lower upper limit, than running at fast speeds. The reason we don’t run lots of time, all the time @ fast speeds is due to the high recovery cost.”
Next, someone asked, So is there a value to running at EP/Z1? What are “Endurance Adaptations”? And What does it mean to “build far under fast”? I couldn’t help expanding on my earlier response with:
“So, question 1: Short answer – YES. Value to Z1/2 running: In addition to the (hopefully) obvious value of the warm-up and cool-down, there are indeed some benefits. To restate what I wrote above: ALL RUNNING we do triggers our body to build (or at least maintain) the plumbing, muscle mass, nerve-muscle connections, and micro power stations needed for muscle contraction. Also, we can add the value of stress on ligaments, tendons, and bones that trigger strengthening of those important parts of the architecture. FASTER running will increase the stimulus so the system is triggered to build more of the above (up to our genetic maximum) with the added benefit of getting better at burning CHO for fuel.
If we tried to rely solely on faster running to get better, though, we could probably not get enough running in to do the trick. Since hard workouts drain our glycogen stores and create more micro injuries that must be healed, we simply can’t get enough stress in without breaking down or becoming chronically fatigued. (I’m leaving out a whole other area of longer-term stress and growth in areas such as hormones, kidneys, sweat glands, etc, where the same principles apply). So the idea is to do the maximum amount of harder running which we can reproduce day after day, week after week, and add to that slower running to “top up” the training effect.
E.g., this week I ran 23+ miles. 7 of it was @ TP pace (1 and 2 mile intervals), 1/4 @ IP (strides), and about 3 or 4 at half marathon pace (HMP). About 50/50 “easy” running vs “harder” running, which is a usual ratio for me, and probably for many half and full Ironman training athletes, as well as HM and marathon runners.
Question 2: Short Answer: YES. What are “Endurance adaptations”? Humans are probably hard-wired to be able to perform for long periods at about 60-75% maximum capability. Everything in the body has to “adapt” to do that, starting with the heart’s ability to get bigger and keep beating, the gut’s ability to absorb fluid and fuel, to all of the other things I mentioned above. The fact that modern humans can get off the couch and in many, if not most cases, train themselves to run a marathon or finish an Ironman shows our bodies are designed (pick your method, by intelligence or evolution) to work this way. To me, that phrase Endurance Adaptations merely means we are returning our bodies to their natural capabilities that are stunted by our modern lifestyle.
Question 3: Short Answer: We build far on top of fast. EN Kool-Aid is First Build Fast, Then Far. The logic behind it has to do with timing of training for an IM or HIM. If you first focused on far, then tried to add fast, you would lose some of that far stuff in the 2-3 months before your race, if you only did OS type stuff. If you try to do both… well six weeks into the Out Season of repeated hard workouts, isn’t it evident you would not be able to do both long runs and rides several days a week along with the level of “fast training” we are doing now?