Jogging, sit-ups and weightlifting soon will be as much a part of every Alexandria firefighter's day as climbing ladders and dousing blazes.

The city began its physical fitness program yesterday morning for the 183 men and women who are responsible for emergency fire service in Alexandria. Half a dozen firefighters - along with Alexandria Fire Chief Charles H. Rule and City Manager Douglas Harman - greeted the program's inception with a few grimaces and some nervous but good-natured joking at the Old Town fire station, where blood samples were taken.

Over the next few weeks, the firefighters and harman will be given several medical tests designed to measure such things as pulse rates and percentage of body fat. An individual daily exercise program will then be drafted for each participant.

Such programs are necessary to ensure that firefighters, who undergo uncommon mental and physical stress, are fit to do their jobs, Alexandria officials said.

A recent University of Maryland study of firefighters in the Washington area showed that the average firefighter is overweight, has a low endurance level and has poor muscle flexibility. Almost half of the 100 firefighters who died last year throughout the nation at the scene of fires died of heart attacks, according to a survey by the International Association of Firefighters.

Alexandria's fire department is the second in the Washington area to have a system-wide physical fitness program. Fairfax County has had one since June, 1972, although it is not as extensice as the one in Alexandria. A spokeman for Montgomery County's fire department said some of its divisions and rescue squads have their own fitness programs, and added that Montgomery is studying a uniform countywide program.

Arlington County had a fitness program "10 years ago or more" but suspended it because of injuries and doubts about its effectiveness, according to a fire department spokeman.

The Arlington official said the county currently is working on a new program to be started sometime this year. Fire department officials in the District of Columbia and Prince George's County said they also are studying fitness programs.

Alexandria Fire Chief Rule noted that the only time a firefighter undergoes a grueling fitness test is just before he or she is hired.

"He's tested when he's hired at 21, and then for the next 20 years there's no physical testing, though he's aged," Rule said. "We check the fire trucks out every day and maintain them. But we don't check out the people who run them."

The cost of the program is $20,135 for the program's first year and then about $400 annually. The eight fire stations in the city will have their own exercise equipment, mats, weights, stationary bicycles, jump ropes, and scientific monitoring equipment.

A survey of 1,000 fire departments in the nation showed that 17 per cent have some type of physical fitness program, 13 per cent had one but discontinued it and 70 per cents do not, according to David Gratz, vice president of the International Association of Fire Chiefs Foundation. Of the 70 per cent without a program, 80 per cent said they are planning to start a fitness plan, he added.

In addition to developing a special exercise program, Alexandria also plans to have an antismoking campaign for the firefighters and a nutritionist to advise on proper diets, according to Capt. Jack Beam.

Beam said that Alexandria has had a voluntary fitness program for firefighters for about two years. A study of the voluntary system showed it helped reduce sick leave by about 20 per cent, Beam said.