Fairfax Board Chairman John F. Herrity cinched up the laces of his Etonic "Street Fighter" track shoes yesterday morning and then jogged 8 1/2 miles through rain and heavy traffic to work.

Herrity, 48, who suffered two heart attacks in 1975, said the 75-minute run was not a political ploy, but a sincere effort to convince county workers that jogging or cycling to work could save NERGY, increase fitness and ease perennial parking problems at the county's government complex in Fairfax City.

Vivian Watts, Herrity's Democratic opponent in the November elections, yesterday called the run "political," accusing the Republican board chairman of consistently voting against jogging, hiking, and bicycling trails in the county. Herrity "can't run on the issues, so he may as well run to work," Watts said through an aide.

Herrity, insisted to news reporters that he was a dedicated runner and cited his daily four-mile jog as proof.

Herrity said he envisioned the possibility of installing shower stalls and enclosures for bicycles at the Massey Building, if county workers would pay for them.

"I'm planning to make a motion at the next board meeting to appoint a committee to gauge interest in this," Herrity said. "The county couldn't pay to install these things. But the employees might. We could have a 'jogathon' or something to raise money for it."

Reaction from county employes ranged from ecstatic support to comic disbelief.

"Let me put it this way," said Mike Hawthorne, a maintenance worker at the county's Massey building: "I was in favor of the Vietnam War, but I didn't volunteer for that, either."

Assistant county attorneys Bob Cherin and Jack Gould praised Herrity's concept as "fantastic."

"I live off Hunters Mill Road in Great Falls and it would be dangerous as hell," said Gould, who jogs about 20 miles per week. "But it would be an impressive feat to have facilities like that."

Margaret Wilson, who lives in Reston and works for the Department of Environmental Management, said she was unmoved. She said she "wouldn't jog to work even if I lived only half a mile away."

"It's a great idea," said Jim Dellinger, a jogger and a cashier for the Massey Building cafeteria. "But, "he added," It would be pretty disgusting without showers."

Some employes said the idea of running to work was inconceivable. "That would be an awfully long jog for some of us," said Acting County Executive J. Hamilton Lambert, a resident of Loudoun County.