Final answer:
Higher protein intake during vigorous exercise is essential for muscle maintenance, growth, and repair, rather than fueling the exercise itself.
Step-by-step explanation:
The higher intake of protein during brief durations of vigorous exercise is required not as a primary fuel but for the maintenance, growth, and repair of muscles. During vigorous physical activities, muscle fibers can undergo stress and damage, necessitating repair and growth, processes that require an increased amount of protein. Moreover, protein plays a vital role in enzymatic reactions and other bodily functions that support overall exercise performance and recovery.