In a plot of work capacity, what do the vertical and horizontal axes represent?

• A. Vertical: power; Horizontal: time
• B. Vertical: time; Horizontal: power
• C. Vertical: distance; Horizontal: time
• D. Vertical: energy; Horizontal: velocity

Answer: (D)

Work capacity refers to the total amount of work you can perform, which is a measure of energy expended. Therefore, the vertical axis uses energy to show how much work (energy) you can put out. The horizontal axis uses velocity because pace or movement speed defines the rate at which you perform that work. As you change velocity, the amount of energy you can expend before fatigue changes, so plotting energy against velocity makes sense. This contrasts with plotting power (work per time) or distance/time on the axes, which would describe different relationships.