July 30 (Reuters) - Indoor cycling fitness chain SoulCycle Inc filed with U.S. regulators for an initial public offering of common stock, underscoring the rising popularity of boutique chains that cater to specific workout methods such as spinning, yoga and barre.
Analyze the relationship between 'SoulCycle' and 'Indoor cycling' within the context of the input sentence.
Options: industry, parent organization, location of formation, creator