Wire services are reporting the former Canadian marathoner and PowerBar founder, Brian Maxwell, died Friday of a heart attack. He was 51 years-old.

According to the Canadian Press Association, Maxwell collapsed at a post office in San Anselmo, Calif., and emergency rescue personnel were unable to revive him. He died at a local hospital.

Maxwell developed the PowerBar with his wife, Jenny, and the couple built it into a major global brand, eventually selling the company to Nestlé in 2000 for USD 375 million.

Maxwell was named to the 1980 Canadian Olympic marathon team, but never competed in the Games because of the U.S.-led boycott. Canadian Press reported that Maxwell was the #3-ranked marathoner in the world in the 1977 Track & Field News rankings.

According to Athletics Canada, Maxwell had a marathon personal best of 2:14:43 set in Seaside, Ore., USA in 1977. That made him #19 on the Canadian all-time list.