Distance runner Paula Radcliffe has won dozens of long-distance races and held the women's world record for the marathon since 2003. Scientists, trainers, and athletes alike have wondered about the extent to which muscle structure and function contribute to success in athletes such as Radcliffe.
What makes elite distance runners so good?
Are their muscles somehow different from those of less successful athletes and non-athletes?
Imagine that Paula Radcliffe is racing against a bird and a fish, each with the same mass as Paula. Which organism would have the highest cost of locomotion during the race?

Verified step by step guidance

1. Understand the concept of cost of locomotion, which refers to the energy expenditure required for an organism to move a certain distance. It varies among different species and modes of locomotion.
2. Consider the different modes of locomotion: running for Paula Radcliffe, flying for the bird, and swimming for the fish. Each mode has different energy efficiencies.
3. Recognize that generally, flying is more energy-efficient than running, and swimming is often more energy-efficient than both running and flying, especially over long distances.
4. Analyze the energy expenditure per unit mass for each organism. Birds typically have a lower cost of locomotion due to the efficiency of flight, while fish can be even more efficient due to buoyancy reducing the energy needed to overcome gravity.
5. Conclude that, given the same mass, the organism with the highest cost of locomotion is likely to be the human runner, Paula Radcliffe, due to the relatively higher energy demands of running compared to flying and swimming.

Key Concepts

Muscle Structure and Function

Muscle structure and function are critical in determining athletic performance. Muscles are composed of fibers that contract to produce movement, and their efficiency can vary based on fiber type composition. Fast-twitch fibers are suited for quick, powerful bursts, while slow-twitch fibers are more efficient for endurance activities. Elite distance runners often have a higher proportion of slow-twitch fibers, which enhances their endurance capabilities.

Cost of Locomotion

The cost of locomotion refers to the energy expenditure required for an organism to move a certain distance. It varies among species due to differences in body structure, metabolism, and mode of movement. Generally, running is more energetically expensive than flying or swimming, as it involves overcoming gravity with each step. Therefore, understanding the cost of locomotion helps in comparing the energy efficiency of different organisms during movement.

Comparative Physiology

Comparative physiology examines how different organisms perform similar functions, such as movement, and how these functions are adapted to their environments. By comparing a human, bird, and fish, we can explore how each has evolved to optimize energy use in their respective modes of locomotion: running, flying, and swimming. This field helps explain why certain species are more efficient in specific environments, providing insights into the evolutionary adaptations that enhance performance.