McLanachan (34), an apprentice horticulturalist at the botanic gardens, clocked a personal best time on the course of 1hr 39min 6sec, bettering the 1hr 42min 49sec
he ran three years ago in finishing fifth.
''I tried to just ease into it. But it didn't matter how hard I tried - I soon realised it was just going to hurt the whole way,'' he said.
Even on the downhill, he tried to wind it back when he realised he had a big section of flat awaiting him.
''You forget how hard this race can be. But it's totally worth doing.''
He was using the run to prepare for the half-marathon section of the Christchurch marathon at Queen's Birthday Weekend.
McLanachan has been in top form in recent weeks, winning the 12km section of the Three Peaks event last month. Despite recent Achilles problems, he raced in last week's Lovelock Relays.
''That really opened up the lungs. It felt like I had a smoker's cough the next day.''
Louisa Andrew successfully defended the open women's long-course title in 1hr 50min 53sec.
Andrew (39), an equine dentist, led all the way, mindful of the threat behind her of Mel Aitken.
Andrew, who also won the Three Peaks race, enjoyed the less demanding weather conditions yesterday, winning her fourth title on the course in five years.
She paced herself off Poolburn's Graeme Sinnamon.
''He paced a really good pace, so that pushed me to keep going,'' she said.
''The last couple of hills always kill you, so you just have to go into survival mode.''
Second in the open women's section was Otago marathon champion Mel Aitken in 1hr 54min 31sec, with Maggie Carr third in 2hr 32sec.
Otago Polytechnic student Jack Synnott won the associated 12km run in 42min 41sec.
Synnott, a second-year outdoor leadership student, decided to enter after a recent training run up the Cargill walkway. Synott (20), an old boy of St Kentigern College, prepared for the race by surfing at Aramoana on Saturday.
''It was barrelling. It was awesome. It was my warm-up, as I've just spent three days in the bush.''
National junior elite triathlon representative Karli Haugh made short work of the women's 12km run, crossing the finish in 48min 23sec.
Haugh (21), a physical of education student, held out a late challenge from Laura Holyoake, who finished second in 48min 35sec. Rosalind Poulgrain was third in 50min 46sec.
