Pole Vaulting & Physics

In pole vaulting, the athlete, gripping a flexing fiberglass pole with both hands, must propel herself into the air feet-first, twist over a crossbar set at the height of a small two-story building, then fall safely into the cushioned landing pit. Doing this in one smooth-flowing motion takes a rare combination of speed, strength and coordination. Vaulters who understand and take advantage of the physical forces at work during the vault will gain an edge in attempting this spectacular, technically demanding feat.

  1. Pole Vault Basics

    • Legendary Oregon track and field coach William Bowerman and co-author William Freeman in "High Performance Training for Track and Field" divide the vault into six separate events: 1) a sprint run-up of as much as 130 feet; 2) planting the pole in the vaulting box; 3) takeoff; 4) the hang, also called the "lay back and wait," when the vaulter begins to rise off the ground; 5) the turn-rise, when the vaulter's center of mass (hips and waist) is level with the bar, and she rotates around it and attempts to cross the bar; and 6) "off the pole," when she releases the pole while clearing the crossbar to plummet into the landing pit.

    The Physics

    • Physics says that the athlete will control the vault's height by how fast she sprints during the run-up. The faster she runs, the more kinetic energy of motion builds up and the more gravitational potential energy she will have at the pole plant for vertical lift to shoot her up to the crossbar. All other things being equal, the faster a vaulter sprints down the runway, the higher the potential vault will be, assuming good technique throughout.

    The Formula

    • The formula for converting kinetic energy to potential gravitational energy, 1/2mv squared=mgh is rewritten for this purpose as h=1/2 (v squared/g), where h is the theoretical height of the vault, v is the sprint speed and g, the acceleration due to gravity on Earth, 9.8 m/sec squared. The complete formula h = .55 x vaulter's height x 1/2 (v squared/g) also takes into account the height of the vaulter's "center of mass" above the ground, assumed to average 0.55 of their height for women (it's higher in men).

    Applying the Formula

    • The American Physical Society's website gives this example, using Stacy Dragila, the 2000 Olympics women's pole vault gold medalist: She sprints 8.33 m/sec and is 1.73 meters tall, giving her a center of mass of 0.95 meters. Gravity "g" is 9.8 m/sec2.

      h= 0.95 meters + ½[(8.33 m/sec) x 2/9.8m/sec2]= 0.95 meters + 3.54 meters = 4.49 meters (or about 14 feet 9 inches).

      In actuality, Dragila cleared 15 feet 1 inch in her gold medal performance and vaulted higher afterward. So, while the formula is a theoretical tool, it predicts actual performance fairly well.

    Reality Check

    • No vaulter will convert 100 percent of the energy created at the plant into vertical lift. Much of it is lost in pole vibration and dissipation in the fiberglass. How well the vaulter executes each of the vault's six phases, the angle she plants the pole at, how much extra "oomph" she has at the turn-rise at the top of the vault, the amount of spring in the pole--all will further affect the actual height attained. But, in the final analysis, of two vaulters identical in every respect, the one able to sprint faster will reach the greater height.