On this day in 1974, Los Angeles Dodger Mike Marshall sets a major league record for most games pitched in consecutively when he relieves starting pitcher Tommy John to pitch in his 13th consecutive game. Marshall’s was remarkable for his ability to pitch every day without experiencing the soreness and injury that plagued other pitchers, like Tommy John.

In his 13th consecutive game, Marshall pitched the last two outs of the ninth inning in the first game of a doubleheader between his Los Angeles Dodgers and the Cincinnati Reds. Tommy John had thrown the first 8 1/3 innings. John was an old-school workhorse pitcher, for whom pitching deep into the game was not unusual. He had already pitched 11 major league seasons and thrown 200 innings five times, including 269 in 1970 with the Chicago White Sox.

Later in the 1974 season, John ruptured his ulnar collateral ligament, “blowing out” his elbow. His career was saved when Dr. Frank Jobe reconstructed the ligament. The surgery, now known as “Tommy John surgery,” involves replacing a medial ligament in the elbow with a ligament from elsewhere in the body, often the forearm. John credits the rehabilitation and strength training he undertook under his teammate Marshall’s direction with strengthening his elbow and shoulder post-surgery and allowing him to pitch until 1989, when he was 46 years old. In 1979, John pitched 276 innings for the New York Yankees. In 1980, he threw 265, again for the Yanks. “Tommy John surgery” has since become fairly common among major league pitchers, and, today, the inch-long scar under the elbow it produces can be spotted on established big league stars like John Smoltz and Mariano Rivera.

After retiring from baseball, Mike Marshall earned his Ph.D. in exercise physiology with the intent of preaching good mechanics to young pitchers to help prevent the injuries that commonly require surgery among players in all levels of baseball. Marshall used his own experience as a guide: After experiencing shoulder soreness in 1968 during his rookie season with the Detroit Tigers, Marshall studied film of himself pitching and then altered his style to take stress off of his shoulder and elbow. Today, Marshall runs a school for pitchers in Zephyrhills, Florida, north of Tampa. He believes that the pitching mechanics he teaches there can eliminate pitching injury completely while improving velocity and movement in pitches. So far, however, all the major league franchises have rejected his unorthodox style.