The competitions ranged from lifting a 30-foot-high tree trunk to tossing a 56-pound weight up into the air over a cross bar.
He was unsuccessful at tossing the caber, as the tree trunk pole is called in Gaelic. He said the trick is being able to balance the weight of the trunk and then tossing it up high enough to get it into a throwing position.
He said only one of a dozen competitors was able to succeed at getting the trunk up and tossing it.
Some of the traditional Scottish events, such as the rock toss, in which competitors hurl a 22-pound stone, evolved into the shotput.
Other events, such as tossing the caber and throwing a weighted pitch fork, seem to be uniquely Scottish events, he said.
Johnston, who works out at the Engle Switch Gym with other police officers, said he did better than he expected.
"I intend to start going to other competitions," he said.
The rest of his family had followed their Scottish roots more closely than he had before the competition.
His father has played the bagpipes for years and his mother made his kilt out of material of the proper plaid for the family's ancestral clan. She also made a kilt for his 3-year-old son.
Some of the other officers have joked about whether Johnston, an eight-year police veteran, will be wearing dresses for undercover work now that he has become comfortable with wearing a kilt.
Johnston said that since the competition, he's been on the Internet to find other Scottish events to attend, such as the Highlands weekend at the Maryland Renaissance Festival in Crownsville, Md.
And he intends to proudly wear his kilt. Just not around the office.