onsdag 18 januari 2023

Veckans Podcast-avsnitt! v. 3


Jag har länge funderat på att dela mina tankar och tips kring saker och ting som händer i mitt liv och som jag tycker är intressanta. Därför har jag som mål att varje vecka framöver lägga upp "Veckans Podcast-avsnitt!"

Målet är att lägga upp ett tips varje vecka, men det är rätt tidskrävande att sitta och lyssna, pausa, skriva ned, spola tillbaka etc. för att summera och sammanfatta de, enligt min mening, mest intressanta delarna av avsnitten. Jag har för vana att lyssna på otroligt långa avsnitt vilket bidrar till tidsåtgången.

Vi får se hur många veckor jag klarar av men jag ska försöka åtminstone. Sedan kanske inte alla sammanfattningar blir lika långa och ingående.

Jag gillar att lyssna på experter, utövare, forskare eller tränare inom andra idrotter än cykling också, för jag är övertygad om att man kan överföra saker mellan idrotter. Denna veckas avsnitt är med Andy Jones, som specialiserar sig på marathon och har skrivit många otroligt bra studier. Han tränade även Paula Radcliffe under 15 år och hjälpte henne att ta världsrekord på marathon.

Ett riktigt intressant avsnitt!

The Marathon Running Podcast

Avsnitt: Episode #19 - Andy Jones, PhD

Längd: 74:26

Släpptes: 2022-08

Spotify-länk: https://open.spotify.com/episode/2ga4fAWZ1cvZ1DlTtKekS0?si=b5a61c40e9454f5d

If you are a 5000 meter runner, you need a really high VO2max because you are running at VO2max for the entire duration of distance. If you are running a marathon, not to say that VO2max isn’t important because it will set the ceiling, but submaximal factors are much more important in relative terms. But it takes a long time for those changes (GE, DE) to become manifested. 

The factors that are really important for marathon runners can continue to improve with time, even as you get a little bit older. While you start to lose a little bit of cardiovascular function, you can improve some metabolic functions in your muscles to compensate for that. And also you get biomechanical changes as well, as more miles you do, more time at your feet as a runner, over many weeks, many months, many years, as long as 15 years in the Paula study, the more economical you get, your running technique changes, your muscle fiber recruitment potentially changes, mitochondria in your muscles will continue to develop, the oxidative capacity in your muscles improves, and your biomechanical ability to use that energy. 

- Q: What are the metabolic improvements in the muscles, and on the other side, what are the cardiovascular deterioration that happens?

How much oxygen can you deliver to your muscles, and how much oxygen can your muscles use? We think that the issue is not with the utilization it has to do with the supply. If you are able to supply your muscles with more oxygen, they will be able to use it. The limitation appears to be in the cardiovascular system, how much oxygen can you extract from the air you breath in and then pump around your body via your heart, now when you do endurance training, the volume of the left ventricle goes you, so your stroke volume goes up every time you breathe you compact more blood full of oxygen. But the total amount of oxygen you can deliver to your muscles per minute is a function of your stroke volume and the number of heart beats per minute. The problem is, when we get older, our maximal heart rate goes down a little bit. You are losing a little bit of your cardiac output every year but you probably won’t notice it until about 35 och 40. The way to compensate for that can be the muscles way to use what oxygen that is being delivered gets even better. More capillaries around the muscle. It goes into the artery, the arterials eventually into the capillaries that surround the muscle fibers, so the more training you can do under a longer period of time the greater androgenesis, the growth of new blood vessels. The oxygen goes into that mitochondria and use it as fuel along with carbohydrate and fat to produce ATP. With endurance training you get more mitochondria, those mitochondria contain more oxidative enzymes so they can process the oxygen better. Possibly the mitochondria may get a bit more efficient, certainly in slow twitch compared to fast twitch fibers.

If you do endurance training, you get more mitochondria, and those mitochondria can process oxygen more efficiently.

RER (Respiratory Exchange Ratio): We don’t only measure VO2, we also measure VCO2. VO2 is how much oxygen is being consumed, and VCO2 is how much carbon dioxide is being produced. When you use more carbohydrate (as an energy source) you produce more CO2 relatively. That ratio between VO2 and VCO2 changes. The closer it is to 1, and if you go above 1, you start to get anaerobic. But if you are at 0.9, the majority of the substrate you are using is carbohydrate. If it is in the 0.7-0.8 then there is quite a lot of fat being used. 

Developing speed over 1500m, 3000m, 5000m, up to 10 000m is a really good schooling really for future marathon success because it gives you that buffer.

- Q: How much does your previous speed at shorter distances affect your speed at marathon racing? Kipshoges 1 mile PB is 3:50 when he was at his peak at the track. He would probably do a 4 min mile now as a marathoner. 

VO2max and running economy seems to be kind of disparate from one another. You can’t have the highest VO2max and the highest running economy. You probably have either or. To have a really high VO2max you got to have really sufficient muscles, because the more muscles you have to consume the oxygen, the higher the VO2max wound be. But if you have lots of muscles at your legs, that’s gonna cost you oxygen to carry yourself around. 

It’s not only about what's your VO2max, running economy and lactate threshold on the startline. If you do that you assume those are static variables that just don’t change. But they do change. If I measure your VO2max or running economy at mile 25 they would have been something else entirely. It’s also about resilience or durability. 

How to measure running economy, is to measure the oxygen required to cover a kilometer:  Everybody knows that 70 or 80 VO2max is really really good, the average running economy is about 200 ml (o2) per kg body weight per kilometer. The lower the better. If you are using 190, 180 or 170 ml/kg/km shows that the running economy is really really good. If you are using 210-220 ml/kg/km then that´s suboptimal, that's higher than average oxygen cost, or a relatively low running economy. What we showed in the Paula paper is that to begin with when she was 18, her running economy was pretty average, about 205. But over the years it gradually got better and better, so by 2003 when she ran her 2:15h marathon I think it was about 170 ml/kg/km, and there was an occasion afterwards when it was as low as 165 which is about the best running economy ever recorded. That's what that’s all about. 

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