Bodies in space: The physics of pole vaulting
There’s a particular moment in a pole vault jump that seems to defy both the laws of physics and human strength.
Just as the athlete takes off from the ground, she appears to be using her full weight to bend the pole back into a 90-degree angle, while simultaneously hauling her entire body off the ground and upside-down.
Watch the footage, slowed-down, multiple times, and it still doesn’t make sense.
What does it take to even think about doing that?
“Insane upper-body strength,” performance and technique analyst Deborah Sides says.
Working at High Performance Sports New Zealand, Sides has been helping New Zealand’s growing pole vaulting team to fine-tune every single moment of their jumps.
Rio Olympics bronze medallist Eliza McCartney trains here, as do fellow Commonwealth Games team members Olivia McTaggart and Nick Southgate. Imogen Ayris, 17, missed out on selection for the Games but is in training for the Junior World Athletics Champs in July.
The sport combines that upper-body strength with gymnastic ability and speed: a female pole vaulter can reach speeds of up to 8.5 metres a second (30km/h) with a run-up of just 10 to 16 steps.
“The purpose of the pole vault is to convert that kinetic energy from the approach into the vertical energy to get over the bar,” Deborah said.
Other athletic jumps, such as high jump, use the same approach, but pole vault is unique in that athletes actually gain energy during a jump due to the elastic energy stored in the pole as it’s bent back at take-off.
“[That’s] how they’re able to jump these five-metre heights.”
The take-off foot is on the ground for about 0.4 seconds, and the jump itself is all over in about a second.
In that time, a pole vaulter has to exert as much weight on the pole as they can to bend it back into that 90-degree angle – known as the C-position – while using their upper body to swing their legs off the ground, head toes-first towards the bar, and as they reach it, twist their body 180 degrees so they cross over facing the ground, body curving over the bar.
Can you impale yourself on the pole?
Difficult, Dr Sides says.
However, getting the take-off position wrong can mean an athlete misses the landing pad – and that’s why you’ll sometimes see a pole vaulter run through without attempting a jump.