JC's Musings

Titin the Big Player

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Titin, muscle function, endosarcomeric, passive tension, muscle tension, rehabilitation

How much do you know about titin? Here is a couple of quick facts. First it is the largest protein known in the human body – aptly named from the Latin word meaning strong or giant. Second it provides ~90- 95% of endosarcomeric (within sarcomere) passive force and is a big player in terms of muscle function, mechanics, functional and sporting performance.

As you can see in the diagram, a number of tissues have passive elastic qualities, modelled as springs. Sarcomeres has resting tension as shown in A, and when the actin and myosin filaments slide past each other to longer lengths, the resting tension increases due to titin elongation as can be seen in diagram B i.e., the titin is stretched.

Can you “feel” titin? Richard Lieber in his book Skeletal muscle structure, function and plasticity: the physiological basis of rehabilitation, stated that “because titin is the primary source of passive tension in muscle… during normal range of motion manipulations…the “feel” of a patient may be dominated by this intramuscular protein.”

Given the size and quantity of this protein, intuitively you would surmise that it is an important player in human movement. If you want to find out more about titin and how to train it, click the link (https://lnkd.in/gAHcPw2h). I have just updated my Optimising Strength and Power course, with a module on titin.