David Knowles was the Mankato doctor generations of families called on to deliver their babies and Minnesota Vikings players sought to treat their training camp injuries.

He was on the team’s sideline applying ice packs, splints and bandages during preseason workouts for more than 35 years, all while running his own family practice in a two-story limestone building on Front Street and later at the Mankato Clinic.

“Players had a great deal of respect for him,” said Fred Zamberletti, the team’s primary athletic trainer from 1961 to 1998. “He was a very well-qualified sports physician. He knew the players well and administered excellent medical care to our team. We were fortunate to have him down there.”

Knowles died May 17 of pancreatic cancer at his home near St. Peter. He was 77.

Born in Tracy, Minn., Knowles served in three branches of the military after his high school graduation, including service with the Army National Guard and as a medic with the 3rd Marine Division in Okinawa in the late 1950s. He earned a bachelor’s degree with a double major in chemistry and biology from Mankato State College in 1964. Four years later he graduated from the University of Minnesota Medical School.

After completing an internship at St. Paul Ramsey Hospital (now called Regions Hospital), Knowles took over his grandfather’s private practice in downtown Mankato.

“He always kind of knew that was what he wanted to do,” said his son, Chris, of Lakeville. “If that didn’t work out, he didn’t know what he’d do.”

It worked out well. He was a solo doctor for 21 years, treating a wide spectrum of maladies. He made house calls and visited nursing homes. And he delivered countless babies. One family who had Knowles deliver seven of their eight children included him in their family portrait. Another mother sent him a letter thanking him for rushing down to Mankato after he worked a home Vikings game to deliver her child, said another son, Patrick, of Phoenix.

“He was always proud of delivering babies,” Patrick said. “That always brought joy and satisfaction.”

While Knowles was the training-camp physician for the Vikings, he occasionally worked regular-season games, too. Once, when the Green Bay Packers’ doctors could not make it to a game in Minnesota, Knowles treated players for both teams, Patrick said. During his tenure, the team presented him with seven game balls.

As pressure increased to keep up with billing and insurance demands, Knowles closed his clinic in 1990 and joined the Mankato Clinic. Many of his patients went with him. He retired in 2007.

“They loved him,” said Dr. Mike Fraley, a family practice doctor at the Mankato Clinic. “He was a common man and treated everybody incredibly well.”

Knowles was president of the Washington Elementary School PTA and during the holidays was a bell ringer for the Salvation Army. He was also president of the Blue Earth County Medical Society and chairman of the Family Practice Department at Immanuel St. Joseph’s Hospital in Mankato.

In his spare time, Knowles was a carpenter who built wine racks and tables and loved to tinker with his British sports cars. “He loved his cars,” Chris said. “He was kind of an old Austin Healy,” a reference to the British sports carmaker.

Besides his two sons, Knowles is survived by a daughter, Annie-Laurie Bissen, of Preston, Minn.; three sisters, Joyce Visker, of Tracy, Minn., Betty Ross, of Belle Plaine, Minn., and Judy Soyez, of Grapevine, Texas; his former wife, Ann Jones, of Mankato, and seven grandchildren. Services have been held.