Final answer:
An increase in resting cardiac muscle length will increase contraction strength.
Step-by-step explanation:
An increase in resting cardiac muscle length will increase contraction strength. As the sarcomeres within the cardiac muscle are stretched to greater lengths, more myosin heads can bind to actin on the thin filaments, forming cross bridges and increasing the strength of contraction. This process is known as the Frank-Starling mechanism, which states that within physiological limits, the force of heart contraction is directly proportional to the initial length of the muscle fiber.