She boasted endurance and natural pace, a ferocious competitive instinct, and an enviable ability to race well at the highest level when form, fate, and even motivation, seemed against her.
When she won her first Scottish age-group cross-country title, in 2001, the Auchterarder girl seemed piqued because she'd had to miss a Scottish girls' football trial, but there was little subsequent reason to question her choice. Since then there have been 30 Scottish gold medals on the track, indoors and out, and over the country.
The cv is impressive: AAA under-17 champion at 800 metres, AAA under-20 champion at 1500m, a World Youth finalist at 17, chosen for the Commonwealth Games at 20, and fourth in the European cross-country championships at 22, helping Britain to team gold.
Famously, she logged the European Under-20 Championships 800m qualifying standard, but said she'd rather run the 1500m. Even though she had not achieved the required performance, UK selectors sent her to Kaunas, where she knocked five seconds from her best time to win the gold, topping the UK rankings for the year. Then she defied the mythology that Scots could not perform Down Under in winter by going to Australia and winning the Commonwealth Youth Games 1500m title in December.
When she moved to Dundee to study medicine she left Derek Easton, her long-time club coach at Central, and joined Liz McColgan's group. "I had not been at my best, but Liz quickly got me running well," she said. After early success, however, injury and illness dogged MacLarty as she pursued medical studies. She won the trial for the 2010 Commonwealth Games but suffered from an iron deficiency, and as she chased the qualifying standard needed to go to Delhi, she sustained a stress fracture.
As she attempted to come back from that, she suffered Achilles tendon problems on both ankles, and then a hamstring injury. In the whole of 2011, she raced just twice, and only six times in 2012. Last year, uniquely, there was not a single race victory. With the European Championships beckoning, MacLarty had hoped to qualify for the 1500m, but the time eluded her. Meanwhile, academically, she was working hard. Even half-way through the course she knew medicine was not for her. "I completed the course because I was told that if I did not, it would look like I couldn't do it," she said. So having done so, she then embarked on a five-year dentistry degree. She graduated in July and is working in Blairgowrie.
But with coach McColgan moving south, MacLarty began to reflect on the training she had been doing, and even questioned whether she should stay in the sport. "Things weren't going well," she said. "Last summer was pretty awful for me. I found it a bit embarrassing, putting in so much work and not getting the qualifying time. So I sought advice, and spoke to several people."
Having been training up to 90 miles a week, some of it "junk mileage", she concluded that former world 10k champion McColgan was "just not the right coaching option for me, personally. Everything worked well initially, and Liz always encouraged me. Last year, I ran 4:13 with her on just six weeks' training, but some of the sessions I don't think were right for me. I should probably have switched coaches earlier."
After much heart and soul-searching, and confidence at a low ebb, she joined Andy Young in August. The former World Schools Gymnasiade 800m champion from Bearsden also coaches Glasgow vet student Laura Muir, who at 19 this year took European under-23 bronze at 1500m, and then reached the 800m semis at the World Championships in Moscow.
Young slashed MacLarty's mileage, but increased the quality. Change has been dramatic: the fastest stage in Scottish national and district relay championships, second in the Scottish 4k championships, and then, victory in the East District cross-country championships in Dundee this month.
The identity and status of the runner-up in Dundee (Olympic marathon runner Freya Ross) should help convince MacLarty she is on the way back. Ross (formerly Murray) has been multiple national champion and a revelation since stepping up and qualifying for the marathon in Glasgow 2014. But MacLarty declines to read too much into having beaten her.
"It was just three weeks after Freya had run a marathon - two weeks off, then a week's steady running. Freya did not use that as an excuse. We chatted, and she has been really decent to me with advice over the last few months. Andy has been a good choice, and it is working well. I feel I am doing stuff that is right for me. That was the first race I have won in absolutely ages. It was nice to win again."
So what are her plans? "Well, I don't like making ridiculous claims about what I can or can't do," she says cautiously, "but I am definitely hoping for Commonwealth selection at 1500 metres. I just do what Andy tells me to do. If I didn't get the time in the 1500, I'd be looking to see what I can do at 5000.
"I train with Laura Muir and she is an absolute machine - fast and strong. She is hoping for a Commonwealth medal. I have started to close the gap now, but the Games are coming round so quickly. Obviously, I hope to make the final.
"The trouble with me is I am a good racer, but I do struggle to get qualifying times. I'm not kidding myself. It is going to be difficult."
She reels off the names of seven other Scots, including defending bronze medallist Steph Twell, who either have achieved or are capable of the required time. "It's only seven months and it's not that far away.
"The last few years have been a bit of a struggle and I think I may have been getting injured because of the high mileage. I'm 27 now, and Laura is only 20. I do feel I may have lost a few years, but you can only go from where you are at the moment. Running is only for a limited amount of time, so I am back home, working two days a week pretty intensely, with a study day once a fortnight. I stay with my parents and I am looking around for sponsorship."
MacLarty went to the 2006 Commonwealths, selected on appeal despite having failed to achieve the Scottish standard.
"I have a history of not getting the time, but I am a good racer. Put me in a race and I will be competitive. Laura has kindly offered to help me get the 2014 qualifying standard. I'm not a very good time trialist. I am more of a racer. That's really, really nice of her. I come down to Glasgow to train with her twice a week."
Attempting to rebuild confidence while working regularly with someone so talented is a brave gamble. MacLarty's 800m PB of 2:05 dates back to when she was 19, which she concedes is "ridiculous".
"I am not the same runner as before. When you're young, you are shiny when you go out and run. Now my confidence is hit a bit, so I am not sure what to expect. I will just try to keep doing the right thing." With a serious off-track career beckoning, has she set any time limits?
"No. I don't feel I want to give up any time soon. I'm not sure how long I have left. My parents are so supportive and dad's great - tells me to look at Kelly Holmes [2004 Olympic 800 and 1500m champion after years plagued by injury] and reminding me she was 33.
"It might seem more mental time than body time. It depends how much enthusiasm and motivation you have to keep going, but I am enjoying my running again, and feel so much better than I did even just a few months ago. It's fun, and I know things can turn around quickly.
"I do feel I'm trying to make up for lost time, the lean years in the middle, a wee bit. I don't feel the same person I used to. With Derek, he would make me feel I was talented, and I feel like I have lost that. I feel like I am trying to get back to how I used to feel, but that's difficult. I don't want to come across as a bit pathetic, and negative.
"Sometimes you are going along and feel really good. I really enjoy those moments. Looking back over the past few years you would not appreciate the work I put in. So to get those results at the end of it is a bit disappointing."