Things are getting painful for ultramarathoner Lisa Tamati during the first week of her epic run up the length of New Zealand.

The New Plymouth woman is running approximately 2,200km in 33 days or the equivalent of 52 marathons, from Bluff to Cape Reinga.

She's now running north of Dunedin, heading up State Highway One from Waikouaiti to Oamaru.

Her latest blog posting, covering day four of her journey describes some of the punishing long hours running up and over the seemingly endless Otago hills.

"Once we left the school and headed North out of Dunedin, the hills started. For the next 38km all I did was battle through hills... I was on the road for a lot longer than I ever anticipated, 73km and 12 hours on the road was just so draining and demoralizing," she says.

Tamati reserved a special thanks to the Waikouaiti Pub for donations and even a cold beer at the finish line of Day 4.

"Wish me luck for tomorrow as we have a 78km day planned... at the moment, I can't even move from my chair, so its going to be brutal."

Tamati signs off her Day Four posting: 'Incredibly Sore' - Lisa.