Dina Asher-Smith:
Hi, I'm Dina Asher-Smith. I'm Britain's fastest female sprinter, and here's someone like me that's lucky enough to be doing a sport that she loves. Freya Nicole Christie is a British tennis player, and we're looking at her story because rigorous training has seen her body develop with thicker and stronger bones and muscles on one side of her body. Now this is quite
normal. We all favour one hand or foot. But with professional tennis players like Freya, it's much more pronounced and significant.
Freya Nicole Christie:
Definitely wouldn't class myself as a normal teenager. I don't think many teenagers do what I do. I'm very fortunate and lucky to do what I love.
NARRATOR:
Each one of us lives an entirely unique life that our bodies learn to deal with precisely. For most of her 19 years, the thing that has defined Freya Christie's life more than anything else is tennis.
Freya Nicole Christie:
My aspirations, I want to be a top 50 tennis player, especially Wimbledon, being from Britain. You know, it's my favourite Grand Slam, so hopefully one day, that's the dream.
NARRATOR:
And in the pursuit of this ambition, she plays tennis over 11 and a half months a year. When she's not competing, she's practising.
Freya Nicole Christie:
I probably hit about over a thousand forehands a day. I'm a perfectionist so I like to get everything pretty spot on.
NARRATOR:
This level of dedication has enabled Freya to develop her sport to the very highest level.
NARRATOR:
But such sustained activity has also left its mark on her body. And what's interesting about tennis is that we can see exactly how her body has adapted and learned. Because tennis divides the body in two. Whether it's serving at a hundred kilometres an hour... or smashing forehands down the line, powerful impact forces are experience far more frequently by Freya's racquet arm. And
that level of force causes some surprising one-sided changes to the skeleton that we are only just beginning to uncover.
NARRATOR:
While her body looks symmetrical from the outside, the bones in her racquet arm are 20 per cent thicker and contain more bone mineral than her other arm. Her joints act like shock absorbers, taking up the extreme forces her arm experiences repeatedly as she hits her shots.
NARRATOR:
These forces are transferred from muscle along her tendons to her arm bones. Freya's skeleton has learned to cope with her intense daily workouts by growing dramatically in order to reduce the risk of breaking.
Freya Nicole Christie:
Tennis players, we have to really focus on keeping the balance right. If you get too much on one side, then it can really throw things off.
NARRATOR:
In fact, we all have small differences in the size of the bones in our arms. Because everyone tends to favour one arm over the other. But recent studies have shown that the differences in tennis players are about ten times greater than in non-players.
NARRATOR:
And it's not just our bones that adapt and learn to deal with the stresses and strains of life. It's our muscles as well. Muscles that will need to be on top form to beat Andrea Petkovic, a former world top ten player.
NARRATOR:
Muscles also learn from the activities we do every day. In fact, skeletal muscle is the most adaptable tissue in the human body. Muscle fibre cells contain more than one nucleus. When muscles are worked hard, special satellite cells are activated. They divide. One of these cells then fuses with the muscle fibre itself. Now, with added nuclei, the muscle fibre cell builds more myofibrils,
increasing the size of both itself and our muscles, giving Freya more power for her shots. But in the end...
Umpire:
Out.
NARRATOR:
... experiences wins over power.
Freya Nicole Christie:
After the match, win or loss, I'm quite emotional. I would usually get back onto the practice court and try and, you know, work on the things that probably didn't go so well in the match.
NARRATOR:
Using the way her body can learn, she's building it into the perfect vehicle to pursue her dream.