Steve Courson, the former offensive lineman for the Pittsburgh Steelers who developed a heart problem after becoming one of the first NFL players to acknowledge using steroids, was killed yesterday when a tree he was cutting fell on him at his home in Henry Clay Township, Pennsylvania.

Courson, 50, was using a chain saw to cut down a dead 44-foot-tall tree when it fell on him, police said. Courson was apparently trying get his dog out of the tree’s way. The dog was injured.

Courson made the Steelers in 1978 as a free agent guard from South Carolina. He started more than half of the Steelers’ games before he was traded to Tampa Bay in 1984, where he played another two seasons before being waived. He ended his career after the 1985 season, having played on the Steelers’ Super Bowl championship teams in 1978 and 1979.

Courson was an early outspoken opponent of steroid use in the NFL, though he had used them himself and blamed them on a heart condition he said placed him on a transplant list for four years. He credited diet and exercise with reversing the condition.

He went public with his steroid use in 1985 and was cut by Tampa Bay the next season. He also criticized the NFL’s steroid testing program, which began a year after he retired.

Courson testified about steroid use before Congress last spring.

Earlier this year, Saints coach Jim Haslett claimed the Steelers’ use of the drugs during Super Bowl championship seasons in the 1970s brought steroids into vogue around the NFL.