Day two in Vienna and all’s going well, the conference started off with a fantastic keynote lecture by Benno Nigg discussing impact forces and muscle activation in running. It was interesting to note he stressed the importance of muscle activation in the running strike and not just peak force, which has been used recently to promote barefoot running. Muscle activation is a good indicator of fatigue levels and should reveal if wearing trainers can reduce the effort required to run as there’s been no evidence that running barefoot reduces injury.
He also mentioned that the promotion of barefoot running roughly has a 25 year cycle (big news in 1960, 1985 and 2010), if this blog is still going in 2035 and barefoot running becomes big news again I’ll try to remember to mention it. (See here for some videos of Benno and more detail on his work)
A lot of football aerodynamic papers today all with some really interesting results.
See this paper for some very interesting flow visualisation using clouds of (toxic?) titanium tetrachloride. It shows the wake of the ball oscillating with time, suggesting an oscillating force creating a ‘knuckleball’ effect.
To follow up, this paper visualised the flow after an Adidas Teamgeist ball from a wind tunnel and found that even when completely stationary, the direction of the force oscillates with time at high velocities.
A great paper from Norway looked at a number of balls including an Adidas Europass (a pimpled Teamgeist) and found that at low velocities the Adidas ball is at risk of ‘reverse swing’ an effect in which the ball curves in the opposite direction to which you might expect.
Every presenter seemed to agree that a football that is too smooth and too round is likely to behave oddly when compared to a more traditional design. However they did concede that players may get used to this effect with time.
A number of Sheffield presenters today all doing fantastically, Heather Driscoll got lots of praise regarding her work in the photoelastic effect and football stud traction and it was a great conference debut.
John Kelley presented a program he’s developed that measures the spin and speed of a tennis ball using only a single high speed camera. With some developments it would be great to see this technology used during live match play in order to see just how fast and spinny (must cut down on the techno-jargon) shots are from the top players. It would also be interesting to see just how wrong the commentators are.
Half way through, I’m presenting tomorrow, off for a practice.