Final answer:
Maximal gains in strength, power, or hypertrophy are seldom achieved with cross-training as it lacks the specific progressive overload necessary for significant muscle growth seen in resistance training.
Step-by-step explanation:
True, maximal gains in strength, power, or hypertrophy are rarely achieved with cross-training. For individuals aiming to significantly increase muscle mass, a targeted approach focused on progressively overloading the muscles is vital. While cross-training provides a variety of health benefits and can improve overall fitness, it typically does not produce the same level of muscle hypertrophy as resistance training, which requires consistently increasing exercise intensity.
Resistance training leads to hypertrophy by increasing the number of sarcomeres and myofibrils within skeletal muscles. Unlike endurance training, it does not significantly increase mitochondria or capillary density but does contribute to the development of connective tissue and tendon strength. This is essential for supporting the muscles as they manage more potent contractions from lifting heavier loads. The muscle adapts to the heavier load, thereby requiring an even heavier load for further muscle mass gains.