Final answer:
The main goal of performing flexibility training during a cool-down is to restore the optimal length-tension relationship of muscles, aiding in recovery and injury prevention.
Step-by-step explanation:
The primary goal of repeating flexibility training during a cool-down is to restore optimal length-tension relationships. This practice helps to lengthen the muscle as tension diminishes, which contributes to muscle tissue's elasticity, the ability to stretch and rebound. Flexibility exercises like stretching increase the range of motion of muscles and joints and help keep the endomysium, the connective tissue covering each muscle fiber, loose and well-hydrated. This is crucial after a workout because it aids in reducing muscle stiffness and soreness, supporting muscle recovery, and preventing injuries.