It has been a team effort for Summers and Bigg. She started in 1992 when he was her coach.
Bigg only got into it four years ago.
"I must have had a rush of blood to the head to do it before I got too old," says the 67-year-old who feels age relaxes him more and helping his wife train gave him a better understanding of what bodybuilding entails.
She said the sport is booming overseas among the over-60s and it's just a matter of time before New Zealand cottons on.
"We're more health conscious and fitter than we were a decade ago.
"The 60s is the new 50s so things have sort of changed."
Summers says she fixed niggles and groans since taking up bodybuilding.
She now runs and cycles because of the discipline as well as meets people with amazing physiques from around the world.
As amateurs their paths cross professional bodybuilders who apply to graduate after meeting criteria such as securing national titles.
"They get money and we get a little trophy," she says with a laugh, after returning with a silver medal in the 50-plus age division in San Diego two years ago.
She won't know how many people will be in her division in Las Vegas until competition day but she hopes to secure a top-three place.
Bigg was sixth in San Diego and is happy to give it his best shot in Las Vegas.
He believes a lot of people don't appreciate or understand bodybuilding and that sees them turn into shrinking violets at the very thought of slipping on budgie smugglers, let alone bronzing their torsos to take centre stage.
"I'll just get on stage without looking completely stupid and do what I can and not worry about what others think."
He'll shed 12-15kg to be around the 61kg mark when he "gets on stage with not much on" to have a lot of fun.
The sense of self-satisfaction acquired from such an exercise and helping individuals break out of their cocoons are pronounced despite it coming across as somewhat vain.
"In fact I recommend it to everyone to try it once because the satisfaction from it is immense."
Bigg acknowledges "it's a personal sport, not for other people".
Regrettably in some quarters the code is depicted in poor light.
"In some cases, people [portrayed] on TV and magazines are chemically enhanced.
"You don't have to be 150kg and really huge to be a bodybuilder."
It's about finding proportion in one's height to muscle ratio.
Representing New Zealand is the pinnacle for him and Summers "because not many people can say they have represented their country in any sport and hold their own".
"You go out there to enjoy yourself, not to win but if you do [win] then it's a bonus.
"It'll be a very big surprise if I do," he says with a laugh.
Limiting alcohol intake and eliminating sugar has worked wonders for a man who still harbours a burning desire to fulfil fitness ambitions.
"I have this silly goal to compete as a 70-year-old so we'll wait and see what happens."
