Creighton J. Hale testing the safety of catcher's equipment. (Little League International )

To reduce the danger of being struck in the head by a pitch, baseball players have experimented with helmets made of leather, metal and other materials since the turn of 20th century.

The National League required batters to wear some kind of protective headgear in 1956, followed by the American League two years later.

Most of those early helmets covered only the top of the head. The modern, hard-shell batting helmet, instantly familiar to anyone who has played or watched baseball, was a surprisingly late development.

It was patented in 1959 by Creighton J. Hale, a physiologist who was the first director of research for Little League Baseball. He later became the president and chief executive of Little League, making him one of the most influential people in baseball.

Dr. Hale died Oct. 8 at a hospital in Williamsport, Pa., the headquarters of what is now called Little League International. He was 93. The Little League organization announced his death, but the cause was not disclosed.

Creighton J. Hale using his baseball cannon to test a catcher's mask. (Little League International)

Little League baseball was founded in 1939. When its annual world series was first televised in 1953, doctors and psychologists became concerned about the physical and emotional toll that intense competition could have on athletes no older than 12.

Dr. Hale, then on the faculty of Springfield College in Massachusetts, wrote to Little League president Peter J. McGovern, suggesting that a commission investigating the sport’s safety would need a qualified scientist.

In 1955, McGovern offered Dr. Hale a temporary assignment as research director.

“I took a year-and-a-half leave of absence, and I’m still on it,” Dr. Hale said in 1985.

One of the first things he studied was why Little League batters were more likely to be hit by pitches than their adult counterparts. By measuring how fast hitters could react to thrown balls, he discovered that a simple adjustment would alleviate the problem: He moved the pitcher’s mound back two feet, putting the pitcher 46 feet from home plate instead of 44.

Dr. Hale addressed other safety issues, as well, most notably the batting helmet. With an air cannon built out of parts he bought in a hardware store, he fired baseballs at speeds up to 100 mph. The helmets broke apart on impact.

He devised a hard plastic helmet with interior padding, then added flaps over both ears that would protect a batter’s temples and cheekbones. The helmets, which could deflect a pitch without breaking, were required for Little League hitters and base runners in 1961.

“Everybody’s made their own little designs, but the major idea, the major design, was his,” Jim Easton, president of the Easton sporting goods manufacturer, told the Associated Press in 2001. “There was a lot of resistance, just like you saw in hockey, where some players didn’t want to wear helmets. But with Little League making it mandatory, then people grew up with it, and eventually everyone wore them.”

The helmets soon became standard at other levels of baseball, from high school through the minor leagues. In 1983, earflap helmets were required in the major leagues, although many players still wear helmets covering only the ear exposed to an oncoming pitch.

Dr. Hale used his air cannon to test other equipment and developed a one-piece helmet and mask for catchers. He sought to make bats out of shatterproof materials and designed a catcher’s chest protector with a protective throat guard.

He also conducted a battery of physiological and psychological tests on players, concluding that Little Leaguers often handled stress better than their coaches and parents.

Adults were so gripped by tension that “they had symptoms of appendicitis or heart attacks” during games and for hours afterward, Dr. Hale told the Los Angeles Times in 1985.

But the pulse rates of young players typically returned to normal within 15 minutes after a game.

“The public was concerned about the kids,” Dr. Hale said. “I was worried about the parents.”

Creighton J. Hale — the “J” was merely decorative — was born Feb. 18, 1924, in Hardy, Neb. Both of his parents were teachers.

He served in the Navy during World War II before graduating from Colgate University in Hamilton, N.Y., in 1948. He received a master’s degree in physiology from Springfield College in 1949 and a doctorate from New York University in 1951.

After a year as Little League’s research director, he joined the organization permanently. He became president in 1973 and added the title of chief executive a decade later.

Under his leadership, Little League participation expanded from 31 countries to more than 80. The number of players between the ages of 4 and 16 taking part in Little League baseball and softball programs grew from 370,000 to more than 3 million.

During his final year as chief executive in 1994, Dr. Hale helped coordinate a moment of “Little League diplomacy” when a group of Taiwanese Little Leaguers became the first sports team from their country to compete in mainland China.

Dr. Hale remained on the Little League board of directors until 2014. He twice served on the President’s Council on Physical Fitness and was a charter fellow of the American College of Sports Medicine. In addition to his work on sports safety, he helped developed an infantry pack used by the Army and led research efforts to develop Kevlar helmets and bulletproof vests for the military.

His marriage to the former Rita Hugo ended in divorce. A son preceded him in death.

Survivors include his wife of 13 years, the former Beverly J. Gray of Williamsport; two children from his first marriage; a brother; 10 grandchildren; and nine great-grandchildren.

In 1971, the National Organization for Women filed a lawsuit against Little League on behalf of a girl in New Jersey, Maria Pepe, who “just wanted to play baseball with my friends.”

Dr. Hale testified that girls were not physically able to withstand the rigors of the sport, asserting that they could be easily injured because their bones and muscles were weaker than boys’. An orthopedic surgeon refuted his claims, and a judge ruled that girls were eligible to play Little League baseball alongside boys.

Dr. Hale came to regret his early position, particularly after his granddaughter made an all-star team. In 2014, he said that having girls take part in baseball and softball was “one of the greatest things that ever happened to Little League.”