At very fast walking speeds, cost may become so high that the body transitions into what to restore efficiency?

At very fast walking speeds, cost may become so high that the body transitions into what to restore efficiency?

• A. Standing
• B. Crawling
• C. Running
• D. Sitting

Answer: (C)

As speeds rise, the energy cost of walking per kilometer increases, so the body switches to a gait that preserves efficiency. Transitioning to running lets the leg function more like a spring, with an aerial flight phase and elastic energy storage that reduce collision losses and vertical work, making movement more economical at higher speeds. That shift—walking becoming running—keeps energy expenditure lower per distance covered, which is why the body adopts running to maintain efficiency.

As speeds rise, the energy cost of walking per kilometer increases, so the body switches to a gait that preserves efficiency. Transitioning to running lets the leg function more like a spring, with an aerial flight phase and elastic energy storage that reduce collision losses and vertical work, making movement more economical at higher speeds. That shift—walking becoming running—keeps energy expenditure lower per distance covered, which is why the body adopts running to maintain efficiency.