Most of the 1980 presidential candidates have been declared in "excellent" health by their doctors, despite a variety of aches, pains and problems that afflict many men in their mature years.

Sen. Howard H. Baker Jr. (R-Tenn.) has had "several" recent health problems, including a heart valve defect that does not keep him from playing tennis or climbing stairs. An electrocardiogram taken in 1977 by Sen. Bob Dole (R-Kan.) showed some evidence of a possible heart incident that did not keep him from jogging. His latest electrocardiogram showed no heart disease.

And Republican Ronald Reagan, at 69 the oldest candidate, was declared by his physician, Dr. James Reynolds of Los Angeles, to be in "remarkably good physical condition" with no major problems, only a arthritic right thumb. Reagan passed a stress test on a treadmill.

All these reports are part of a summary of candidates' health in Medical World News, a McGraw-Hill magazine for doctors. Writer Mark Bloom succeeded in getting a recent medical report from every candidate except California Gov. Edmund G. (Jerry) Brown Jr., a Democrat.

"By far the sketchiest" report, Bloom said, was President Carter's. His doctor only repeated a January verdict that the president remains "in excellent health," though, like many other joggers, he suffers occasional shin splints or leg pains.

Sen. Edward M. Kennedy (D.-Mass.), who made his report public in November, was declared in "superior physican condition" despite "minor residual effects" of injuries suffered in a 1964 airplane crash. Last June he had a tiny skin cancer, of a kind that usually responds fully to treatment, removed from his chest.

Baker, said Dr. Freeman Cary, congressional physician, sometimes has elevated blood pressure and has had to go on a limited-salt diet to prevent fluid retention. His heart valve abnormality is causing no symptoms. In 1978 he fell on the tennis court, hit the back of his head and suffered a concussion from which he has recovered "completely."

Republican John Connally also has mild blood pressure, "well controlled" with drugs, and is in "excellent health," said his doctor, despite the scars of the 1963 gunshot wounds suffered during President Kennedy's assassination.

Dole, too, was found "in excellent health" despite extensive wounds suffered in World War II, wounds that left him with a partly paralyzed right hand.

Republican George Bush was declared an "active healthy person," although he had an ucler in 1960 that recurred in 1966 and then healed. Rep. John B. Anders (R-Ill.) was declared healthy, too, despite a heart valve abnormality that causes him no symptoms.

But doctors recommended that both Anderson and Baker take antibiotics to prevent heart infections.

In answer to the question, "Do you believe the state of a candidate's health is pertinent as an issue in a presidential campaign?" 91 percent of 550 doctors answered "yes" in a Medical World News poll. But a majority said the release of candidate's records should be voluntary, rather than required by law.