One is a 49 kilogram pocket rocket gymnast and the other is a weightlifter three times her size, but both possess the key to Olympic Games success – genetic predisposition.
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Lauren Mitchell and Damon Kelly have almost nothing in common and their sports require completely different skills.
But Australian Institute of Sport senior physiologist Philo Saunders says their respective genes are crucial to becoming world-class athletes.
The pursuit of Olympic gold will begin in 20 days in London with thousands of different athletes competing on the world's biggest stage.
So what makes an athlete perfect for their sport?
It's a combination of oxygen capacity, muscle make-up and the hunger for success.
For world champion Mitchell it's her speed, flexibility and aerial awareness.
For weightlifter Kelly it's his "big quads and big arse".
And for superstar basketballer Lauren Jackson it was being taller than every other kid her age.
"Sometimes you get someone who breaks the mould. But if you're genetically not disposed to a certain sport, you're just not going to be good at it," Saunders said.
"Some people are just faster because they've got that fast-twitch muscle fibre make-up.
"You can change it to a certain degree, but there's a limit you reach while others just push through it naturally."
The breakdown is pretty simple and a lot of physical attributes filter into different sports.
Pole vaulters are tall, muscular, possess explosive speed and have a big vertical jump.
Gymnasts are the same, but shorter with superior flexibility.
Sprinters and long jumpers are similar with powerful legs and can vary in height.
A middle-distance runner is lean and not as muscular with predominantly slow-twitch muscle fibres while a weightlifter is the opposite – tall, heavy, high skinfolds and has a moderate vertical leap.
But it's not as simple as walking down the street and picking athletes out of the crowd.
Physical attributes are one thing, but it's when Saunders gets athletes in the AIS laboratory that he discovers their full potential.
He tests anthropometry, body composition, height, weight, muscle mass and maximal oxygen capacity.
Natural talent is the first step, but Saunders has seen athletes with the perfect physical attributes fail because of their lack of hunger to compete at the top.
Australian head coach Peggy Liddick revealed one of our best Olympic medal hopes doesn't possess the natural finesse on the floor.
"But she's got guts," Liddick said.
The average age of the Australian gymnastics squad is 21 and the average weight is 49kg.
They will be some of the smallest athletes in London. But if you think a lack of size means a lack of power, you're wrong.
"Gymnastics has really evolved over the last three Olympiads, it's no longer the little, mini, pixie 14-year-olds," Liddick said.
"We've got every body type in the spectrum ... you need the vaulters who are the short, fireplug, pocket rockets so the body type has changed.
"The shorter they are, the faster they twist and turn. The average weight is about 49kg and pound for pound they're probably as strong as a 100kg weightlifter and can perhaps even lift more.
"I want guts, I want the kid climbing the curtains and up the poles, gymnastics is about being courageous.
"Lauren Mitchell fits all the body types, but she's not that coordinated. She's like a bulldog, she just won't quit or let go."
Olympic champion pole vaulter Steve Hooker is often in the gym with Liddick's squad working out.
Hooker is perfectly suited to his sport because he's lean, tall and has fast-twitch muscle fibres.
Fast-twitch muscle fibres are crucial in the explosive sports – short-distance athletics and swimming, pole vault, long jump, high jump, shot put and weightlifting.
If you don't have fast-twitch fibres, you're more suited to endurance events.
"You can get a good gauge when you look at someone and what sport that would be suited to and specifications just occur naturally," Saunders said.
"If your vertical jump is 60 or 70cm, you're going to have more fast-twitch fibres, if you're under 50, you don't have that naturally and no matter how much training you do, you're not going to be able to get to that level.
"With sprinters and jumpers, it's innate whether they're going to be good or not."
Damon Kelly is a pure power athlete.
He's 149kg of muscle and he'll need all of it when he competes in the weightlifting competition in London.
The former rugby union front-rower started in the sport 14 years ago.
His body type suits shot put or discus, but his passion and technique has helped him excel in weightlifting.
Compared with Mitchell, he's a monster.
"I was 123kg in my first weightlifting competition as a 14-year-old," Kelly said.
"I still miss rugby, but I couldn't keep doing both, the Olympics and Commonwealth Games is what drove me to keep going in weightlifting.
"We use our legs and our backs ... but some guys in other weight classes just look like average Joes.
"We're generally a bit shorter and stockier, some big glutes. But you also need agility and flexibility to get under the bar as well as power and balance.
"It's the big quads and big arse, they're the ones that stand out."
Of course, there are always exceptions to the body rules.
Saunders has often seen athletes competing in sports not suited to their body types and biometrics.
Australian middle-distance runner Craig Mottram is the perfect example.
He doesn't fit the typical mould and at 188cm is more than 10cm taller than most of his competitors.
"If you saw him [Mottram] walking down the street with his height and broad shoulders, there's no way you'd think he's a distance runner," Saunders said.
"He's racing against the Africans who are much smaller than him, but he has a huge aerobic capacity and is a great mover.
"The general thought is that his size does hinder him, but for some people like Craig it just doesn't matter.
"That's why you can't have too many restraints when recruiting. You can look for general things, but you can never rule someone out based on their size or first looks.
"You need to cover everything."
Individual sports require the perfect genetic make-up to be a world leader.
But in team sports, you need a variety to chase the gold medal.
The shortest athlete in the Australian Opals squad is Kristi Harrower at 162cm. She's 41cm shorter than the tallest, Elizabeth Cambage.
Superstar Lauren Jackson was always destined to succeed in the sport.
It's hard to believe a lanky Jackson being left out of junior representative teams in Albury.
But it wasn't until she was 14 that her basketball career exploded.
Being 196cm helped her cause and she's been one of the best players in the world for the past decade.
"Genetics definitely helped me," Jackson said.
"I was tall when I was young and I could run, I didn't move like a 6'6" person.
"I had that agility whereas a lot of people my height didn't have that ... I did athletics and played tennis and I was a bit of natural because it just felt comfortable.
"But I enjoyed basketball more because I was around other people and I was naturally suited because I loved it ... even when I wasn't that good or didn't make teams, I still wanted to be a basketball player."
But don't be fooled, being tall, powerful, flexible, a high aerobic capacity or having the perfect muscle fibres doesn't equal success.
"That's the biggest misconception out there," Jackson said.
"There are people who are genetically superior to anybody, but they don't have the desire or the hunger.
"When I step on to the basketball court, my personality changes and if you don't have that desire, belief or will to be the best you can be, you won't be touted as one of the best or the greatest. You'll just be another player."
Saunders and the AIS are trying to tinker with which body shapes are in which sports. Recently they started experimenting with sprint athletes in the 800m athletics event instead of the traditional long distance runners.
They haven't unearthed a star yet, but Saunders believes it can happen.
The challenge is to keep the top amateur athletes away from the mainstream sports of rugby league, union and Australian football.
"There's always someone who will defy the general mould ... coaches always come to us and ask us what we've seen at the AFL or football camps here," Saunders said.
"There are some basic measures which can give you an indication of someone's future.
"But I think athletes can be groomed to a certain event as well."