Final answer:
Intense workouts lead to controlled muscle damage that causes hypertrophy as muscles repair and grow stronger. Continually increasing exercise intensity is crucial for strength gains. However, overexertion without proper rest can lead to serious injuries or adverse conditions.
Step-by-step explanation:
People who work out extensively are engaging in activities that affect their muscle hypertrophy and atrophy. When they lift weights or engage in resistance training, they're causing controlled damage to their muscle fibers including the sarcolemma and myofibrils. This damage actually leads to muscle soreness but is necessary for muscles to repair, rebuild, and eventually gain mass through the addition of structural proteins, a phenomenon known as hypertrophy. Overdoing these activities without sufficient recovery can, however, result in overuse injuries or more severe issues like muscle, tendon, or bone damage. Moreover, an emphasis on continually increasing the intensity of training is essential for effective strength gains, as muscles adapt and require heavier loads to grow.
Conversely, a lack of physical activity can lead to the loss of muscle mass or atrophy. Athletes may also ingest high amounts of protein to support this muscular enlargement. It is important to note that extreme exercise without adequate rest can be detrimental, leading to conditions such as heart scarring or rhythm abnormalities, especially if the body is not conditioned for such exercise.