Nike’s Vaporfly Elite trainers are ultra-light and high-tech. They have carbon fiber plates in their soles. Wearing the shoes helps runners run faster. But they are often sold out. And they cost a lot of money. Some athletes can’t afford them. Some people are asking – do the shoes go too far? Should they be banned? The International Association of Athletics Federations say the shoes meet all of its requirements. So runners can wear them. But is that fair?