Brian Maxwell, the founder of PowerBar, died of an apparent heart attack on Friday. He was 51 years young. Maxwell, who was ranked as the number three marathoner in the world in 1977, is credited with starting the energy bar industry that today is a necessary staple of most every performance athlete’s requirements.

Maxwell reportedly collapsed at a post office and was unable to be revived by EMTs. He was pronounced dead at a hospital.

Brian and wife Jennifer, a nutritionist, founded PowerBar in the kitchen of their home in 1986. The company, based in Berkeley, CA, grew to achieve $150 million in annual sales and employed more than 300 people. The Maxwells sold the business to Nestle SA for a reported $375 million in March 2000.

Maxwell was born in the U.K., but grew up in Canada where he excelled as a world-class long-distance runner. He was part of Canada's 1980 Olympic team that boycotted the games in Moscow.

He is survived by his wife and five children.