Walking faster than preferred speed increases metabolic cost because muscles must rapidly accelerate and forcefully do what to the legs?

Walking faster than preferred speed increases metabolic cost because muscles must rapidly accelerate and forcefully do what to the legs?

• A. Adduct only
• B. Decelerate
• C. Invert
• D. Relax

Answer: (B)

When you walk faster than your comfortable pace, the body has to produce more momentum for the leg to swing forward and, just as importantly, quickly check that motion so the foot can land under the body. That braking, or decelerating, of the leg during late swing and at foot strike requires large, rapid muscle forces, often in an eccentric (lengthening) manner, which costs more metabolic energy. So the best choice is decelerate—the muscles are actively slowing the leg to control the motion. Adducting, inverting, or relaxing the leg aren’t the primary actions that drive the extra energy cost in faster walking.

When you walk faster than your comfortable pace, the body has to produce more momentum for the leg to swing forward and, just as importantly, quickly check that motion so the foot can land under the body. That braking, or decelerating, of the leg during late swing and at foot strike requires large, rapid muscle forces, often in an eccentric (lengthening) manner, which costs more metabolic energy. So the best choice is decelerate—the muscles are actively slowing the leg to control the motion. Adducting, inverting, or relaxing the leg aren’t the primary actions that drive the extra energy cost in faster walking.