Final answer:
Too much overlap of filaments in a sarcomere impairs muscle contraction, leading to less tension as improper cross-bridge formation occurs between actin and myosin. The sarcomere has an ideal length for maximal tension, but deviation from this length reduces efficiency. Accessory proteins and tissues help maintain this optimal length.
Step-by-step explanation:
When there is too much overlap of filaments in a muscle's sarcomere, the efficiency of muscle contraction is reduced, leading to lesser tension produced. This occurs because excessive overlap prevents proper cross-bridge formation between actin and myosin, which is essential for muscle contraction. Generally, a sarcomere produces maximal tension when it is at an ideal length, where actin and myosin overlap to the greatest extent without interference.
In the context of muscle physiology, sarcomeres are the basic units of a muscle's fibres, and their optimal function depends on the optimal overlap of thick (myosin) and thin (actin) filaments. When a muscle contracts, the filaments slide past each other to produce tension. If a sarcomere is over-shortened, the thin filaments may overlap with each other, or if it is excessively stretched, there might be little to no overlap, leading to a decrease in or absence of tension. Accessory proteins and connective tissues help prevent extreme stretching that would result in no overlap and no tension.