Interviewer:
Hi, I'm Dina Asher-Smith and as a sprinter I do my training on the running track and at the gym. But as you may well know, some long distance athletes like to train at altitude in the weeks before a big event. The idea is that their body gets used to dealing with less oxygen and then when they return to the normal ground levels they've got an advantage. So what
actually goes on in the body? Here's a clip to explain what happens in an oxygen scarce setting and it involves a trip to the Rocky Mountains in Colorado and a training exercise with the Mountain Rescue Service.
Interviewer:
Mark Benson is a member of the Summit County Rescue crew. A search and rescue team working at altitudes of up to 14,000 feet near Breckenridge, Colorado.
Mark Benson:
We've got one person injured up there in an avalanche. She's partially buried. I need you guys to go in as my AC team, Helen and Mark, give me a quick patient assessment and we need to get up there. Everybody's got their coordinates and what they need to do. Let's go.
Helen:
Let's go.
Interviewer:
Just a few months ago Mark would have found this impossible.
Interviewer:
Above 7,000 feet the air is a third less dense than at sea level. Every breath takes in 30 percent less oxygen. And our bodies strain to work normally.
Mark Benson:
When I first moved here to Summit County one of the hardest things to do was go upstairs. LAUGHS You go up two flights of stairs and you're winded.
Mark Benson:
You cannot move as quickly as I did when I was in the uh, flat lands.
Interviewer:
Today though he is leading the team on a training mission.
Mark Benson:
Time is very much of the essence especially in an avalanche situation. You just don't know how badly they're hurt.
Interviewer:
The low oxygen environment, ...
Interviewer:
... a pack weighing 25 kilograms, ...
Interviewer:
... and a kilometre uphill climb mean the demands on his body are immense.
Mark Benson:
Found UNSURE OF WORD. Ma'am can you hear me? Are you okay?
Female being rescued:
Okay.
Mark Benson:
Can you sit back? Are you comfortable? Yep.
Male Rescuer:
Let's put this coat on her. UNSURE OF WORD on your right.
Interviewer:
With Mark's body under extreme, physical stress it's now that the affects of altitude would be felt the most. But he's remarkably unaffected. Over the last few months his body has learnt to deal with this new environment and the secret as to how lies deep inside.
Interviewer:
The reduced oxygen levels in the air mean less can make it's way into the bloodstream.
Interviewer:
And these low levels are detected by cells in his kidneys.
Interviewer:
They trigger an increase in the production of erytrhpoietin, known as EPO, a hormone that controls red blood cell production. A flood of EPO is released into the blood vessels and travels to the larger bones in our bodies leading to an increase in the number of oxygen carrying red blood cells.
Interviewer:
So even though the air is thinner, inside the body oxygen levels are largest unaffected. It's this process that gives us the ability to carry out such physically demanding missions at altitude.
Interviewer:
And the way Mark's body has learnt to cope with the new environment, is driven by his genes.
Interviewer:
Inside our kidney cells EPO is normally produced at relatively low levels, as and when we need it.
Interviewer:
But after prolonged exposure to hypoxia we now know that a physical change gets made to the DNA that codes the production of EPO. A chemical tag is removed from the DNA. This changes the way the gene is read, acting like an on switch to boost it's activity.
Interviewer:
A change that our genes remember so that it's easier to adapt the next time we ascend.
Interviewer:
This is an example of epigenetics, a genetic change induced by the environment.