Distance runner Paula Radcliffe has won dozens of long-distance r...

Question

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?

Accepted Answer

Hi everyone. Let's look at our next problem. It says which of the following is the most expensive mode of animal locomotion. That requires more energy per unit body mass per unit distance. And our choices are swimming, walking, running and flying Well, we can go ahead and eliminate walking because two of our choices are walking and running and obviously the greater speed of running will require a greater energy cost than the slower speed of walking. So they're identical other than speed. So walking we can go ahead and eliminate. So now we just have to compare swimming, running and flying as requiring the greatest amount of energy per unit of body mass, per unit of distance. Well, let's think about what's required in each case and swimming, there's almost no energy required to um remain buoyant. Um The water is supporting the weight so no need to support body weight and all you have to worry about is water resistance as the animal moves through the water and running, body weight needs to be supported and you're moving against a solid surface. So that can be a little hard to realize. You imagine yourself moving through the air but as your feet contact the ground and push against the ground, is that resistance against the solid surface that propels you forward? An animal that's flying, Its body weight needs to be supported but only moving against air resistance. So swimming, we can eliminate. That's going to be the lowest energy cost here because the water does support so much the animal's body weight. But then looking at running versus flying. In both cases, the body weight needs to be supported. But in running you're moving against that resistance of the solid surface versus just resistance of the air and flying. So running is therefore going to have the highest energy costs higher than flying. So we'll select Choice C as the answer for which is the most expensive mode of animal locomotion, requiring more energy per unit body mass, per unit distance. Hope to see in the next video.

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