Final answer:
The statement is false as muscle strength can indeed be altered by changing the muscle's starting length due to the length-tension relationship.
Step-by-step explanation:
The statement that the strength of a muscle contraction cannot be altered by changing the starting length of the muscle is false. The length-tension relationship is a key concept in understanding how muscles generate force. When a muscle fiber contracts, the sarcomeres, the basic structural units of a muscle, shorten as myosin heads form cross-bridges with actin, pulling the thin filaments towards the center of the sarcomere. The force generated depends on the initial length of the sarcomeres; there is an optimal zone of overlap between the thin and thick filaments that allows for the maximum number of cross-bridges to form and, consequently, maximal force production.
Muscles that are overstretched or too compressed before contraction do not create maximal tension. Additionally, the recruitment of motor units also influences muscle contraction force. This recruits the maximum number of motor units for the greatest contraction strength, but to avoid fatigue, not all motor units are active at once. Instead, they cycle between active and resting states, allowing for prolonged muscle contraction.