Final answer:
In early adulthood, individuals reach their peak of physical performance, including muscle strength, reaction time, sensory abilities, and cardiac functioning.
Step-by-step explanation:
In early adulthood, physical development reaches its peak. This is when individuals experience their highest level of physical performance, including muscle strength, reaction time, sensory abilities, and cardiac functioning. Outstanding athletes, as well as the average young adult, experience this peak of physical performance.