An increase in muscle temperature during a warm-up contributes to what change?

An increase in muscle temperature during a warm-up is significant because it enhances muscle elasticity and reduces viscosity. When muscles are warmed up, the increased temperature causes the muscle fibers and connective tissues to become more pliable and flexible. This increase in elasticity allows muscles to stretch more effectively without injury, enabling better performance during physical activity.

Additionally, as the temperature rises, the viscosity of the muscle's tissues decreases. Reduced viscosity means that there is less resistance to movement within the muscle fibers, which can lead to more efficient contractions. This combination of increased elasticity and decreased viscosity helps in preparing the muscles for the demands of exercise, potentially enhancing overall performance and reducing the risk of injury.

While reduced fatigue, increased muscle mass, and better coordination are important aspects of athletic performance, they are not directly related to the specific physiological changes that occur in muscles due to elevated temperature during a warm-up. The primary effect is on the physical properties of the muscle tissue itself, which directly supports option B as the correct answer.