Final answer:
The statement is true; training with both heavy and light loads is beneficial for developing speed strength due to the different responses of muscle fibers.
Step-by-step explanation:
The statement by Young that one needs to train with both heavy and light loads to develop speed strength is true. This is because different types of muscle fibers respond to different types of training. Using heavy loads tends to activate and develop fast-twitch muscle fibers, which are essential for generating power and speed. Additionally, incorporating lighter loads with higher repetitions helps to improve muscle endurance and can still contribute to speed strength by enhancing the ability of muscles to sustain repeated contractions against resistance. It's important to balance training to target both fast-twitch and slow-twitch muscle fibers to achieve optimal speed strength.
There is false information suggesting that all people have the same proportion of slow-twitch to fast-twitch muscle fibers. In fact, individual genetic makeup greatly influences muscle fiber composition, and thus the ability to develop muscle mass and strength. Research indicates that athletes who engage in power activities often have a higher ratio of fast-twitch fibers, which contribute more to muscle size and strength, compared to endurance athletes who may have more slow-twitch fibers.
Moreover, effective strength training requires the progressive increase of exercise intensity. Continuously lifting heavier weights challenges the muscles to adapt and grow stronger. This principle of progressive overload is fundamental for increasing muscle mass and developing strength over time.