Dassler assisted in the development of spiked running shoes (spikes) for multiple athletic events. To enhance the quality of spiked athletic footwear, he transitioned from a previous model of heavy metal spikes to utilising canvas and rubber. In 1936, Dassler persuaded U.S. sprinter Jesse Owens to use his hand made spikes at the 1936 Summer Olympics.
On 1 August 1936, a pro-Republican rally of 20,000 people confronted Blum, demanding that he send aircraft to the Republicans, at the same time as right-wing politicians attacked Blum for supporting the Republic and being responsible for provoking Italian intervention on the side of Franco.