The follow-up is often along the lines of “Well then, you must use ‘spotting’ like dancers.” Again, the answer is no. Spotting is actually considered a bad habit in throwing. But when they ask why we don’t get dizzy, I don’t really have an answer.
Just a few weeks ago I was complaining about the lack of research going on in the event and someone must have heard me because the question the puzzled me also stumped a team of European researchers, especially when they noticed that discus throwers can get dizzy. The researchers surveyed 22 discus and hammer throwers. About half of the discus throwers experienced dizzyness, while none of the hammer throwers did. Even more puzzling was that some of the throwers did both events and only experienced symptoms in the discus. This lead them to believe that it was the different movements, and not simply different physiology among athletes, that caused the different results.
After completing the research, the researchers published the paper “Dizziness in Discus Throwers is Related to Motion Sickness Generated While Spinning”. And the reason I found out about this paper is because the intuitive conclusion in the paper’s title earned it the Ig Nobel Prize in physics and was featured on the Scientific American homepage. (The Ig Nobel Prizes are a parody of the Nobel Prizes given every year to research that “first make people laugh, and then make them think.”) Indeed, the funny premise for a study turns out to be quite interesting for hammer throwers and also has implications on research the team is doing on motion sickness in general, which is a concept that is still not fully understood. They identified three distinguishing factors that likely prevent hammer throwers from getting dizzy.
- Hammer throwers use the arms and hammer to visually orient themselves. While the surroundings whirls around, the hammer and arms remain in front of the thrower through the throw. This provides them with spatial orientation. In a way, the hammer thrower is actually ‘spotting’ like a dancer. But rather than spotting on a fixed point as the dancer does, they are spotting on a point that is moving along with them. In the discus, both the surroundings and the implement are constantly changing position relative to the thrower, making it impossible for the throw to fix their eyes on anything.
- In the hammer throw, the head remains immobile in comparison to the torso. There are slight movements throughout the throw, but generally the head looks straight ahead. In the discus, on the other hand, the head is constantly in a new position compared to the torso as the torso twists and the head moves. According to the authors, this produces “Coriolis forces”, which are known to prompt motion sickness.
- Hammer throwers always keep contact with the ground, while discus throwers spend some time suspended in the air. Jumping can significantly hamper spatial orientation.
The best way to demonstrate the first two points is by showing a video of Olympic champion Primoz Kozmus throwing with a camera attached to his head. While the camera is above his head (and thus reduces the amount of arm that his eyes would actually see), you can see that the hammer provides a point of visual fixation and that the head is relatively immobile compared to the torso. I watched the video twice, first looking at the surroundings and then focusing on the ball and actually noticed a small difference from the comfort of my computer. Maybe next time this team can work on a topic that can help me throw farther.