Final answer:
To improve muscular strength, an individual's muscles must be exercised with more intensity than normal. This means increasing the weight or resistance used in exercises over time. The muscle adapts to the increased load, resulting in greater strength.
Step-by-step explanation:
For effective strength training, the intensity of the exercise must continually be increased. This means that an individual's muscles must be exercised with more intensity than normal in order to improve muscular strength. For example, in weightlifting, if the weights lifted are not increased over time, the muscles will not increase in size. The muscle needs to adapt to a heavier load in order to become stronger.