Muskett (54), of Waikouaiti, won the New Zealand 100km championship around Lake Taupo in February in 9hr 38min 55sec.
She was 11th in the International Association of Ultra Runners 24-hour championship in Seoul in October, covering a personal best distance of 205.140km.
Muskett has also represented New Zealand in the world 100km championships for nearly a decade.
Her performances are all the more remarkable given she was diagnosed in 1988 with a rare lung disorder, spontaneous pneumothorax, that required a series of operations to correct.
Muskett will be joined by Lisa Tamati (New Plymouth) and Vivian Cheng (Wellington) in the women's team, while Alex McKenzie (Auckland) will compete in the men's 24 hour event.
Tamati won the 24-hour track running championships last November with a total distance covered of 192.5km.
She spent 13 years in Austria before returning to New Zealand in 2006.
She was second in the 2007 and 2008 national 100km championship and has competed in the Badwater Ultra marathon of 217km through Death Valley in the United States.
The championships will be held in Lake District of Keswick, Cumbria, on September 17-20.
Muskett's husband, John Muskett, will manage the team.
