Final answer:
Body weight and composition are important components of related fitness, particularly for athletes who can manipulate these factors to enhance performance for specific sports. Relative fitness is an evolutionary concept that helps explain an organism's ability to survive and reproduce in comparison to others.
Step-by-step explanation:
One component of related fitness is body weight and composition, which is especially significant in the context of athletics. Body weight and composition are key aspects of physique for athletes because they can be extensively manipulated for performance enhancement. In sports where having increased muscle mass is beneficial, such as football and weightlifting, athletes can achieve desirable physique changes through a diet plan with increased energy and protein intake. However, it is critical to remember that there is no single, rigid 'optimal' body composition for all athletes, as different sports may require different physiques.
Fitness is not only about absolute measurements but also about the size relationship of body parts to one another and to the whole, and the relative fitness of an individual when compared to others in a population. This concept is important in evolutionary biology, as relative fitness determines which individuals are more likely to pass on genes to the next generation.
In conclusion, body weight and composition are important elements of fitness that can be tailored to an athlete's specific sport requirements, and fitness must be understood in relative terms to appreciate the full picture of an individual's physical capabilities.