Рет қаралды 785,307
DENJIRO: This man here is lifting a weight. It weighs 14 kg. Let’s look at this movement using a model. You can actually explain the mechanism with a lever model. This spring scale is the bicep.
NARRATOR: The elbow is the fulcrum, the muscle is the effort, and the hand holding the weight is the load.
DENJIRO: If we say that the distance between the muscle and the fulcrum, or elbow, as 1, then the distance between the elbow and load, or weight, is 6 times. This ratio determines the amount of force applied on the muscle.
This bottle with water weighs about 300 grams. Let me put it on where the load is. We see that the scale shows roughly 1.8 kg. The amount of force on the muscle is 6 times 300 grams, so 1.8 kg.
NARRATOR: Therefore, if we increase the distance from the elbow and attach a 2-kg weight at the tip…
BOY: It looks really heavy.
NARRATOR: There’s great force applied to his arm.
DENJIRO: Now, let’s perform an experiment related to acute low back pain. This here is the spine. These rubber bands attached to the spine are back muscles. Let’s use a polarizing sheet and see what happens when we push the model from above. You can see that the color of the spine is changing, and that there is force being applied. When you hold something while standing straight… only the force of the weight is applied to the spine, and it changes color just a bit. Let’s see what happens when you lift something while leaning forward. You can see that the spine changes color, and that there is a greater force applied to the spine.
When you pick up something heavy while leaning forward, your back muscles end up supporting a large amount of weight. This results in pressure on the spine. This is how you hurt your spine or back muscles and experience acute low back pain.
NARRATOR: You can prevent acute low back pain by bending your knees when picking up something heavy.
DENJIRO: I hope energy will bring you all happiness. Our magic word is "Happy Energy!”