When skeletal muscles are trained by adding physical stress to them, this is called

Progressive resistance training

Explanation:

Progressive Resistance Training is a type of exercise where the participants exercise their muscles with some type of resistance which is increased as the strength increases.

These exercise are conducted two or three times in a week. The intensity of the exercise is increased by increasing the weight and adding machines and more exercise.

This helps in improving the strength of the muscles and improving the resistance of the body.

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