Sports Theory - Training & Muscle

Strength endurance explained simply

Strength endurance is the ability to produce force over and over again without giving out. What counts is not how much you can lift once, but how long you can keep going. The key lies in the power plants of your cells.

Strength endurance = force × repetitions What matters is how fast energy is resupplied
10 s60 sO₂ = 0O₂ +++

The body has three energy sources that take over one after another: an instant store lasting a few seconds, a fast store without oxygen for about a minute, and burning with oxygen for everything after that.

💬 Mia & Grandpa Theo

Mia

I can do 30 push-ups but only 5 pull-ups. Why is the difference so big?

Grandpa Theo

In a pull-up you lift almost your whole body weight, in a push-up only part of it. The closer an exercise sits to your maximal strength, the fewer repetitions you have left.

Mia

And why do my arms burn?

Grandpa Theo

Because your muscles need energy faster than the oxygen arrives. Then the fast route kicks in, and that produces lactate. The burn is not damage - it is a sign that the emergency supply has taken over.

With training, mitochondria grow in number and size. More power plants mean the oxygen route lasts longer and you tire later.

Fun Fact

Lactate was long blamed as waste and as the cause of sore muscles. Neither is true: the body burns lactate again as fuel, in the heart muscle among other places. And soreness comes from tiny tears in the fibres, not from lactate.

This text explains the basics of training and is not a substitute for individual training or medical advice.

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