US-based gym chain Planet Fitness has strengthened its leadership team with high-level appointments in its digital and development divisions.

Craig Miller has been appointed to the post of chief digital and information officer and Rob Sopkin as chief development officer.

Miller will be responsible for leading the company's technology innovation as well as managing its digital information systems. He has more than 20 years of experience in building technology systems and innovative customer facing applications, having previously held roles at Sonic Drive-In, Bank of America and PepsiCo.

Sopkin will lead the brand's strategic and aggressive expansion efforts. He has two decades worth of regional and national real estate and development experience, having spent 18 years at Starbucks.

Founded in 1992, Planet Fitness has more than 10 million members and 1,400 gyms in 48 US states, the District of Columbia, Puerto Rico, Canada and the Dominican Republic.