J. V. Cain, a tight end for the St. Louis Cardinals, died tonight after he collapsed during a practice at training camp.

He reportedly had suffered a cardiac arrest.

Mr. Cain had just gone out for a pass during a night workout at Lindenwood College and returned to the huddle when he collapsed.

Mr. Cain, whose heart and breathing had temporarily stopped, was revived for a few minutes. Players began cheering and encouraging him to pull through but Mr. Cain passed out again and never regained consciousness.

He was rushed to St. Joseph Hospital, where he died about two hours later.

Today was Mr. Cain's 28th birthday.

The team was practicing in muggy, 90-degree temperatures. Witnesses said several other players were so shaken by the incident when Mr. Cain first collapsed that they were crying.

Mr. Cain missed last season due to an injury, and the Cardinals were awaiting his comeback to help the team rebound from last year's 6-10 record.

Mr. Cain, a star at the University of Colorado, was the Cardinals' top draft choice in 1974. He played backup to Jackie Smith for three seasons before taking over at the position in 1977. CAPTION: Picture, J. V. Cain