The New Zealand mountain running championships alternate between an uphill event and an undulating race.
Crumpton always competes when it is an uphill event but stays home when downhill running is involved.
"I don't like running downhill," Crumpton told the Otago Daily Times.
"That is why I am not defending my title this year."
Otago's best prospect to win the women's race is Erin Whitla (University), who finished runner-up in the 5000m at the national track and field championships in Wellington last month.
It was a meritorious performance because she pushed Crumpton back into third place.
The other Otago runner in the 8km senior women's race is Romana Salis (Hill City), who won a bronze medal in the junior women's 2km steeplechase at the national track and field championships.
This will be the first time Salis (19), a zoology student at the University of Otago, has contested a senior women's event at national level.
She is a dedicated trainer and is particularly strong on the hills and is expected to demonstrate this ability today.
The favourite in the race is two-time world mountain running champion Melissa Moon, who last won the national title in 2005 when the championships were on Mt Victoria, just before the world championships in Wellington.
Today's race will be held on the hills around Wainuiomata.
Moon won the first of her five New Zealand mountain titles in Blenheim in 1998.
Competition for Moon is expected to come from Lara Phillips (Auckland), Demelza Murrihy-Topp (Taumarunui) and the two Otago runners.
Moon said her decision to contest the championships had been a late one.
"I only decided to run when I learnt the championships were in Wellington," she said.
"I've only done three weeks training, but I have 15 years of training in me."
Glenn Hughes, of Wellington, who finished 74th in last year's world mountain running championships in Switzerland, will be aiming for his first senior men's 12km title after winning the junior title in 2000 and 2001.
Chasing Hughes will be Daniel Jones (Whakatane), who won the junior title last year and finished 22nd at the world junior championships last year.
The only Otago runner in the field is Michael Wakelin (Hill City).
The other Otago runner competing at the championships is Claire Giles (Caversham) in the women's aged 50 to 54 event.
