Complex sentence: At the international level, the two most prestigious international track and field competitions are athletics competition at the Olympic Games and the IAAF World Championships in Athletics, while the International Association of Athletics Federations is the international governing body.
Split into simpler sentences: At the international level, the two most prestigious international track and field competitions are athletics competition at the Olympic Games and the IAAF World Championships in Athletics. The International Association of Athletics Federations is the international governing body.