Adidas’ sponsorship of the International Association of Athletics Federations has been on volatile terms “for some time now” and the sports brand feels it now has “valid grounds” to pull out. And one source says there has been growing tension between Adidas and the IAAF. “Obviously the overall drug issues are a big factor but the IAAF’s decision to host the 2021 World Championships in Eugene, Oregon, which is obviously Nike’s HQ, did not go down well at all,” he told Marketing Week.