When you push hard, your muscles contract inward. At this time, if you exceed the strength limit, you will strain your muscles.

Centripetal contraction refers to the shortening of muscle fiber length when muscle resists resistance.

Centrifugal contraction refers to the elongation of muscle fibers when muscles resist resistance.

These are two types of muscle contraction, both red and white muscles have such contraction function, and these two contraction forms usually appear alternately for the same muscle during fitness.

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Centripetal contraction is a very common way of muscle contraction, and there are many examples of centripetal work in daily life and exercise, such as: during bench press, the contraction of prime movers such as pectoralis major makes dumbbells or barbells move in the direction of muscle force, that is, the bench press stage; When jumping, the prime movers such as quadriceps femoris contract and jump upward; When the dumbbell flexes and stretches, the brachialis muscle and biceps brachii contract, making the forearm close to the trunk. Another example: when sitting on the bench and standing up, the quadriceps and other muscles do centripetal work.

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