Final answer:
The strength of muscle contraction is measured by the number of myofibers activated and the frequency of motor neuron stimulation. A myogram can track the tension throughout a muscle twitch's phases. For strength training, increasing resistance is essential for muscle adaptation and growth.
Step-by-step explanation:
To measure the intensity or strength of muscle contraction, several factors can be assessed, the most significant of which is the number of myofibers contracting within the muscle. Each myofiber contracts fully when stimulated by an action potential from a controlling neuron. The force of muscle contraction increases as more fibers are activated. Additionally, the frequency of motor neuron stimulation affects the muscle's force production, with higher frequency leading to increased tension.
Another tool used to measure muscle contraction is the myogram, which records the tension produced over time during a muscle twitch, which involves a latent period, a contraction phase, and a relaxation phase. An increase in muscle contraction intensity is also crucial for strength training, wherein increasing resistance compels the muscle to adapt and grow stronger.