23 Things I Learned From The Science of Running By Steve Magness

Good review of some key points. I liked the book. Certainly more useful and interesting than the usual training book, which lays out plans with little in the way of explanation. Very poorly written though, which detracted a bit for me.

The first one is seriously in doubt. If the brain did all it could to protect the heart, then how is that people who have had heart attacks can exercise and some do so at a reasonably high intensity. Some run marathons. I think even the Central Governor folks have changed their tune on this one.

People marshal their energy for a kick at the end.

Of course your brain tells you to slow down when it is hot.

I hope that is a poor interpretation of what happens with heat. It is not like altitude. Heat training leads to expansion of plasma volume. I would like to see the evidence that heat training increases RBC count. Exercise training in general will increase RBC.

For a miler, the higher LT might compromise anaerobic capacities, but for longer distance, LT is the prime predictor of endurance performance.

lfk wrote:

Good review of some key points. I liked the book. Certainly more useful and interesting than the usual training book, which lays out plans with little in the way of explanation. Very poorly written though, which detracted a bit for me.

Haha yeah, there were a ton of typos if that's what you're referring to.

You're right that, in reality, people often save for the kick. But even without saving for the kick, it is possible. Almost all world records have a slightly faster last 400. There's no way they were all consciously saving something for the kick - if they were, that was probably unwise. If you save something for the kick in a time trial, you'll have a faster kick, but a slower overall time.

Why do you reject the Central Governor Model then say 'Of course your brain tells you to slow down when it's hot.'? The old conventional wisdom would say that the heat was directly preventing the muscles from going as hard. That turned out to be wrong.

I said "increase the volume of blood flow."

We agree on the last point. "A higher lactate threshold is not always better.

luv2run wrote:

The first one is seriously in doubt. If the brain did all it could to protect the heart, then how is that people who have had heart attacks can exercise and some do so at a reasonably high intensity. Some run marathons. I think even the Central Governor folks have changed their tune on this one.

I agree. Cardiac muscle has built-in protection mechanisms to keep it from exceeding its theoretical maximum of some 230bpm - a *healthy* heart quite simply *cannot* pump fast enough to exceed the limits of its own blood supply. Pacemaker cells have a self-exitatory level of some 80-100bpm due to unique properties of cardiac muscle cells, and these properties also limit the speed by which action potentials may be propagated across the T tubules and into the myofibrils.

Cardiac muscle cells reach threshhold quickly but repolarise slowly, because the sodium channels close late and potassium channels open late as well. There is also a significant amount of calcium ions passing through the cell membrane, which slows repolarisation to below threshold as well. This lengthens the absolute and relative refractory periods of cardiac muscle, creating a plateau which limits the heart's ability to go into fibrillation.

However, this also means cardiac muscle drifts toward threshold by itself without receiving an action potential.

The brain has less direct effect on the heart than people think. It is carefully evolved to have a layered mechanism of self-stimulation and built-in 'speed limiters' - both are based on hard chemistry and aren't prone to failure.

That's all well and good from an entry-level physiology standpoint, but there is a lot more at play than just neurochemical regulation of heart rate/SV/CO. Your discussion entirely omits consideration of fluid dynamics and structural mechanics (Frank-Starling curve, preload/afterload, TPR, blah blah blah) which, particularly in exercise, will directly impact and to some degree control heart rate and its associated variables.

You're correct this is entry-level physiology, however that also incorporates Frank-Starling curve, preload and afterload, fluid dynamics and quite a bit of 'blah'. You're being hubristic. The comment was not intended to serve as a roundup of every aspect of exercise-specific cardiology. To expect such is ludicrous, and to dismiss the comment on that basis is silly.

It was intended to demonstrate the heart has several specific mechanisms limiting its ejection potential over and above that of the pymapthetic and parasympathetic nervous system. I believe it achieved that while not going into *too much* detail.

If, as an MD, you'd like to add to my comment with your vastly superior learning (I genuinely intend no snark with that statement) then please do so. But attacking me serves only yourself.

14. How aerobic and anaerobic capacities can oppose each other - Aerobic capacity can be thought of as the ability to minimize lactate levels. Anaerobic capacity is analogous to pyruvate produced. Through anaerobic respiration, pyruvate is converted to lactate. This means that a larger aerobic capacity sometimes can actually shrink the anaerobic capacity. FT runners should be careful not to overload on threshold work because of this.

15. A higher lactate threshold isn't always better - This follows from #14. A higher lactate threshold is usually the result of a greater aerobic capacity, but it can also be the result of a decreased anaerobic capacity.

Both aerobic capacity and anaerobic capacity are genetics plus basic fitness. They don't go up and down in the way Jan Olbrecht and thus Steve Magness say they do.

And Lactate is the end product of glycolysis and glycogenolysis. Magness should know this by now. Pyruvate is always converted to lactate and then reconverted to pyruvate before carbohydrate metabolism goes through the mitochondrial stages leading to ATP production.

I've heard this last point before, but I haven't been able to find a source. Could you direct me to one?Thanks

biochemistry wrote:

And Lactate is the end product of glycolysis and glycogenolysis. Magness should know this by now. Pyruvate is always converted to lactate and then reconverted to pyruvate before carbohydrate metabolism goes through the mitochondrial stages leading to ATP production.

CoachJP wrote:

I've heard this last point before, but I haven't been able to find a source. Could you direct me to one?

Thanks

biochemistry wrote:

And Lactate is the end product of glycolysis and glycogenolysis. Magness should know this by now. Pyruvate is always converted to lactate and then reconverted to pyruvate before carbohydrate metabolism goes through the mitochondrial stages leading to ATP production.

Look up the Cori Cycle, which is the mechanism by which lactate is converted to pyruvate, and the onto gloucose once more.

Here's a video explaining it simply.

(dot) youtube.com/watch?v=yejE9Q06XwQ

The importance of a half-decent editor! Or hell, any editor at all. I know, ironic that I'm posting this on LRC. But if you want your writing to be taken seriously, you go to the effort of presenting it seriously, right?

Anyhow, I found it totally unreadable. I found it really insulting to be charged $20 for something that came across as a half-assed first draft. I mean, who mistakes the Nobel Peace Prize for the Nobel Prize in Physiology/Medicine?

One and only thing I learned wrote:

The importance of a half-decent editor! Or hell, any editor at all. I know, ironic that I'm posting this on LRC. But if you want your writing to be taken seriously, you go to the effort of presenting it seriously, right?

Anyhow, I found it totally unreadable. I found it really insulting to be charged $20 for something that came across as a half-assed first draft. I mean, who mistakes the Nobel Peace Prize for the Nobel Prize in Physiology/Medicine?

I was a sub-editor (copy editor in the US) for nearly ten years before returning to uni to study physiotherapy. Why? Nobody cares about proofreading or editing. And, if they do, they get some community-college undergrad to edit it for free, for something to stick on the CV. The audience has no respect for good editors, hence canot tell the difference btween good editing and bad editing, hence refuse to pay for good editing.

I hold a journalism degree and worked full-time for the second-highest selling magazine in my country as a senior editor... tried doing some freelance to augment my uni income and somebody wanted to pay me 10c per word to edit what was basically illiterate twaddle. When I refused it become clear they thought my role was Microsoft Spellcheck with a heartbeat.

Be assured many in the audience cannot tell the difference either. OMG lol, rite?

*between.

It was bound to happen.

*cannot.

any college soph's biochem book.

CoachJP wrote:

I've heard this last point before, but I haven't been able to find a source. Could you direct me to one?

Thanks

biochemistry wrote:

And Lactate is the end product of glycolysis and glycogenolysis. Magness should know this by now. Pyruvate is always converted to lactate and then reconverted to pyruvate before carbohydrate metabolism goes through the mitochondrial stages leading to ATP production.

SKIPPY HONEY NUT wrote:

any college soph's biochem book.

CoachJP wrote:

I've heard this last point before, but I haven't been able to find a source. Could you direct me to one?

Thanks

I have a good understanding of the biochemistry. My question was directed toward why "pyruvate is ALWAYS converted to lactate". Any exercise physiology textbook I've read gives two paths for pyruvate: the mitochondrion and conversion to lactate. However, I've seen on this message board only that pyruvate is always converted to lactate and then reconverted to pyruvate before entering the mitochondria. It seems inefficient to me.

CoachJP wrote:

I've heard this last point before, but I haven't been able to find a source. Could you direct me to one?

Thanks

biochemistry wrote:

And Lactate is the end product of glycolysis and glycogenolysis. Magness should know this by now. Pyruvate is always converted to lactate and then reconverted to pyruvate before carbohydrate metabolism goes through the mitochondrial stages leading to ATP production.

CoachJP wrote:

SKIPPY HONEY NUT wrote:

any college soph's biochem book.

I have a good understanding of the biochemistry. My question was directed toward why "pyruvate is ALWAYS converted to lactate". Any exercise physiology textbook I've read gives two paths for pyruvate: the mitochondrion and conversion to lactate. However, I've seen on this message board only that pyruvate is always converted to lactate and then reconverted to pyruvate before entering the mitochondria. It seems inefficient to me.

No. After production pyruvate goes into the mitochondria, OR it gets turned into lactate. Lactate can be burned in the mitochondria, indirectly, but that's a matter of MCT proteins and the lactate shuttle, which is another matter.

This is what Magness cited when he said pyruvate either enters the mitochondria, or gets converted to lactate. You can't see the whole thing online but it seems to say pyruvate is mostly used for CHO oxidation, but also some gets converted to lactate.

asdfdsfsdfds wrote:

CoachJP wrote:

I have a good understanding of the biochemistry. My question was directed toward why "pyruvate is ALWAYS converted to lactate". Any exercise physiology textbook I've read gives two paths for pyruvate: the mitochondrion and conversion to lactate. However, I've seen on this message board only that pyruvate is always converted to lactate and then reconverted to pyruvate before entering the mitochondria. It seems inefficient to me.

No. After production pyruvate goes into the mitochondria, OR it gets turned into lactate. Lactate can be burned in the mitochondria, indirectly, but that's a matter of MCT proteins and the lactate shuttle, which is another matter.