The NFL commissioned a study of obesity and other factors on the cardiac health of its players, whose weights have soared the past two decades.

Dr. Andrew Lincoln, director of orthopedics and sports health research at MedStar Research Institute in Hyattsville, Md., said NFL medical officials, after initial research, asked him to conduct the study after several active and retired players died of heart disease.

Lincoln said the size of NFL players has increased dramatically the past 15 to 20 years.

While players have grown stronger and increased muscle, many also have increased body fat, which can increase cardiovascular risks such as high blood pressure, high cholesterol or diabetes, MedStar said.

Lincoln said he will study 700 NFL players from 12 teams, subjecting them to physical exams, echocardiograms, ultrasounds and sleep studies to check for apnea.

The data will be compared with that collected by the National Institutes of Health from a group of men the same age in the general population.

"There's no question that, in the general population, increasing body size is associated with increasing cardiovascular risks," said Dr. Arthur Roberts, chairman of the Living Heart Foundation, which studies health risks among former football players.

"The argument that is undecided is, with superior, well-trained athletes such as football players, does that training and background offer them protection or insulation from developing problems after football?"

Roberts is a former NFL quarterback and a cardiac surgeon and his organization isn't involved in the NFL study.

Numbers on the NFL's Web site show the average weight of players was 245.2 pounds in 2003. A January study by Scripps Howard News Service found the 2006 average at 246.4, down from 247.5 in 2005.

In August 2005, 49ers offensive lineman Thomas Herrion, who weighed 320 pounds, collapsed and died after a preseason game against the Broncos at Invesco Field at Mile High. He was 23.

Reggie White, a Hall of Fame defensive tackle, died of a heart attack at 43. His playing weight was about 300 pounds.

Greg Aiello, an NFL spokesman, said the league's cardiovascular subcommittee began studying heart-disease risk factors in 2005. The committee then selected MedStar to coordinate the study.

"Preliminary findings from a sample group that the committee studied suggest that NFL players do not have a higher risk factor for cardiovascular disease than men of the same age," he said.

ETC.: The Colts signed quarterback John Navarre and linebacker Mike Labinjo, both little-used backups the past three years. Navarre appeared in two games with the Cardinals; Labinjo played in three games with the Eagles in 2004 and seven with the Dolphins in 2005. . . . The Redskins re-signed tight end Todd Yoder to a three-year contract.