Carter is coached by her father, who also played American Football with the San Francisco 49ers and is the only man in history to win an Olympic medal and a Super Bowl ring within 12 months. She is also assisted by Jon Drummond, the 2000 Olympic 4x100m gold medallist and 9.92 100m sprinter, who works on her speed and conditioning work.
Standing at 1.75m tall and weighing 107kg she is considerably shorter in stature than her good rival and friend. In fact, she adds of the height differential: "I remember looking at Valerie when we first competed and thought she was so tall and I needed to grow a few more inches."
The Texan, who is one year and six days younger than Adams, landed the 2004 world junior title but struggled to make the transition to the senior ranks. She made her first major senior final at the 2009 world championships, finishing sixth. But last year she banked her first major senior championship medal with bronze at the world indoor championships before finishing fifth at the London Olympics.
Yet after working hard in the gym during the off season and cracking the 20m barrier for the first time the US thrower believes she is capable of blossoming on the global stage.
"I've always been weak for a shot putter," she admits, "but this fall we really focused on the weights room. Last year, I could bench press 175 pounds but it was hard and I could do only maybe one or two reps. This year, I can do maybe five sets of five at 175 pounds. The quality of the work is much better."
Carter says the pair started to form a close bond three years ago after both spent part of the European athletics season based in Paris. Adams and Carter hung out together and it is clear the US athlete revels in the Aucklander's company.
"She has a great heart and she likes to have fun and enjoyment, so she is always someone you want to be around," says Carter.
The question is in the heat of battle, and with Carter posing a new threat to Adams, will their friendship stand the strain of more intense competition?
"It can be difficult because [you are competing against] someone you know and you want them to do well. We support each other but we know at the same time it is what we do for a living.
"I know that nine times out of 10, Valerie is going to have a big throw, but at the same time anybody in the top five or six is liable to have a big throw, so you never know. It is anybody's game. May the best athlete win."
