According to the all or none law, what is true about skeletal muscles?

The all or none law states that a muscle fiber will either contract fully or not at all when it receives a sufficient stimulus. This principle applies to the functioning of individual muscle fibers rather than the entire muscle as a whole. When a muscle fiber is activated by a motor neuron and reaches the necessary threshold of stimulation, it will respond with a complete contraction; if the threshold is not met, there will be no contraction.

This concept is critical in understanding how muscle contractions operate on a cellular level. Each muscle fiber behaves independently regarding contraction, so the overall strength of a muscle's contraction depends on how many muscle fibers are recruited and firing at a given time, rather than the degree of contraction of each individual fiber. Therefore, while a muscle as a whole may appear to "partially contract" due to some fibers being engaged and others not, the all or none law applies strictly to each muscle fiber's activation response.