Category Archives: endurance athletes

How slow muscle fibers convince their neighbors to join them

Researchers from Tokyo Metropolitan University have discovered that a protein excreted by type I (slow) muscle fibers, key to muscle endurance, can cause surrounding myoblasts, precursors to muscle cells, to differentiate into type I fibers. This upturns prevailing wisdom which says our fast/slow fiber ratio can’t be significantly changed. They also identified the chemical pathway by which the protein affects differentiation. Such findings may one day lead to therapies to control slow muscle health.

Rspo3 is excreted from “slow” type I fibers (not from “fast” fibers), which promotes the accumulation of beta-catenin inside myoblasts. This leads to the increased production of MyHC I and the eventual differentiation of the myoblast into a type I fiber.

Skeletal muscle tissue is made up of hundreds of thousands of fibers which contract on command. However, they are not all the same. There are “slow” type I muscle fibers, important for endurance exercise, and “fast” type II fibers which can respond much more quickly but for shorter periods of time. Type I fibers might be likened to marathon runners, while type II fibers might be called sprinters. For a long time, the prevailing wisdom has been that the ratio of type I to type II fibers in our muscles is largely determined at birth.

But scientists are beginning to find that this is not the case. A team of researchers from Tokyo Metropolitan University led by Professor Nobuharu Fujii have now discovered that a protein excreted by type I muscle known as R-spondin3 (Rspo3) may hold the key to the development of new type I fibers. When myoblasts, precursors to muscle cells, were treated with Rspo3, they began to produce significantly higher amounts of Myosin Heavy Chain I (MyHC I), a protein produced by type I muscle. The effect seemed to be unique to myoblasts in early stages of their development. This means that type I fibers actively induce the formation of more type I fibers in their vicinity, excreting Rspo3 and acting on the differentiation of nearby cells. The finding sheds new light on the role of muscles in our bodies and upturns conventional wisdom which says that the ratio of type I to type II fibers can’t be changed. The team were also able to show that this happened via a specific cascade of chemical reactions known as the Wnt/beta-catenin pathway, responsible for the necessary accumulation of beta-catenin inside cells. Experiments to artificially reduce the amount of beta-catenin in cells, for example, led to suppression of increased MyHC I expression.

Type 2 diabetes and lack of exercise are two of many reasons why slow muscle fibers may atrophy. The team’s findings suggest that it is actually possible to specifically encourage the development of type I fibers through therapeutic means. For example, Rspo3 may be used directly as a treatment, or used to differentiate muscle cells taken from a patient before the tissue is replanted. If cells can excrete Rspo3 and affect surrounding cells, the benefits will be more than just the mass that is reintroduced. Such insights promise exciting new possibilities for treatments to improve muscular function, a key challenge for aging populations and society.

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Filed under endurance athletes, endurance sports, muscles

Mr. Lazy Cook recommends oatmeal …

I haven’t done one of my Lazy Cook posts in quite a while. Since I am a Lazy Cook, I am not sure if my oatmeal recipe even qualifies as there are several ingredients and steps. Why oatmeal?

bunch of nuts served on bowls

Photo by Mike on

“I’ve asked a lot of elite endurance athletes about their breakfast foods, particularly before races, and oatmeal comes up again and again and again,” says Matt Fitzgerald, endurance coach, nutritionist, and author of The Endurance Diet.

The following is from GetPocket, “In a world of green juice and chia seed pudding, this age-old dish is the original, and perhaps most powerful, superfood, especially for athletes competing at the highest levels.”

Here is the recipe: (almost right off the box)

1/2 cup oats – 150 calories

One hand full of broken walnuts – 80 calories

One hand full of frozen blueberries – 30 calories

One tablespoon hemp seeds – 60 calories

One tablespoon chia seeds – 50 calories

Light brown sugar ( to taste ) 30 calories

Bring a cup of water to a boil.  (Here, I differ. I use 1-1/4 cups of water because I don’t want the oats to dry out in my bowl.) Add the oats and frozen blueberries. I turn off the heat and let it cook for five minutes. (I have an electric stove). Mix up the remaining seeds, etc well before pouring the hot oatmeal on top.

It is the best part of 400 calories, a great flavorful, chock full of energy, breakfast, second breakfast or lunch if you are home. I have one every day. Don’t forget I am retired and start most mornings with a bike ride.

I am always interested in variations on a theme. If you are also into oatmeal, but make it with different ingredients, please feel free to share.






Filed under endurance athletes, lazy cook, oatmeal, super foods, superfoods