How does altitude affect the body and why does it affect people differently?

How well you’ll cope on a mountain has little to do with how fit you are.
wynand van poortvliet unsplash, CC BY-SA

Brendan Scott, Murdoch University

Every year, thousands of people travel to high-altitude environments for tourism, adventure-seeking, or to train and compete in various sports. Unfortunately, these trips can be marred by the effects of acute altitude sickness, and the symptoms vary from person to person. To understand why people are affected differently, we have to look at how the body is affected by altitude.

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Read more:
From Kilimanjaro to Everest: how fit do you have to be to climb a mountain?

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How is ‘altitude’ different to sea level?

Air is comprised of different molecules, with nitrogen (79.04%) and oxygen (20.93%) making up the majority of each breath we take. This composition of air remains consistent, whether we are at sea level or at altitude.

However, with altitude, the “partial pressure” of oxygen in this air (how many molecules of oxygen are in a given volume of air) changes. At sea-level, the partial pressure of oxygen is 159 mmHg, whereas at 8,848m above sea level (the summit of Mt Everest), the partial pressure of oxygen is only 53 mmHg.

At high altitudes, oxygen molecules are further apart because there is less pressure to “push” them together. This effectively means there are fewer oxygen molecules in the same volume of air as we inhale. In scientific studies, this is often referred to as “hypoxia”.

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Author provided/The Conversation, CC BY-ND

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What happens in the body in high altitudes?

Within seconds of exposure to altitude, ventilation is increased, meaning we start trying to breathe more, as the body responds to less oxygen in each breath, and attempts to increase oxygen uptake. Despite this response, there’s still less oxygen throughout your circulatory system, meaning less oxygen reaches your muscles. This will obviously limit exercise performance.

Within the first few hours of altitude exposure, water loss also increases, which can result in dehydration. Altitude can also increase your metabolism while suppressing your appetite, meaning you’ll have to eat more than you feel like to maintain a neutral energy balance.

When people are exposed to altitude for several days or weeks, their bodies begin to adjust (called “acclimation”) to the low-oxygen environment. The increase in breathing that was initiated in the first few seconds of altitude exposure remains, and haemoglobin levels (the protein in our blood that carries oxygen) increase, along with the ratio of blood vessels to muscle mass.

Despite these adaptations in the body to compensate for hypoxic conditions, physical performance will always be worse at altitude than for the equivalent activity at sea level. The only exception to this is in very brief and powerful activities such as throwing or hitting a ball, which could be aided by the lack of air resistance.

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Read more:
Tall tales misrepresent the real story behind Bhutan’s high altitude tigers

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Why do only some people get altitude sickness?

Many people who ascend to moderate or high altitudes experience the effects of acute altitude sickness. Symptoms of this sickness typically begin 6-48 hours after the altitude exposure begins, and include headache, nausea, lethargy, dizziness and disturbed sleep.

These symptoms are more prevalent in people who ascend quickly to altitudes of above 2,500m, which is why many hikers are advised to climb slowly, particularly if they’ve not been to altitude before.

It’s difficult to predict who will be adversely affected by altitude exposure. Even in elite athletes, high levels of fitness are not protective for altitude sickness.

There’s some evidence those who experience the worst symptoms have a low ventilatory response to hypoxia. So just as some people aren’t great singers or footballers, some people’s bodies are just less able to cope with the reduction in oxygen in their systems.

There are also disorders that impact on the blood’s oxygen carrying capacity, such as thalassemia, which can increase the risk of symptoms.

But the best predictor of who may suffer from altitude sickness is a history of symptoms when being exposed to altitude previously.

How are high-altitude natives different?

People who reside at altitude are known to have greater capacity for physical work at altitude. For example, the Sherpas who reside in the mountainous regions of Nepal are renowned for their mountaineering prowess.

High-altitude natives exhibit large lung volumes and greater efficiency of oxygen transport to tissues, both at rest and during exercise.

While there is debate over whether these characteristics are genetic, or the result of altitude exposure throughout life, they provide high-altitude natives with a distinct advantage over lowlanders during activities in hypoxia.

So unless you’re a sherpa, it’s best to ascend slowly to give your body more time to adjust to the challenges of a hypoxic environment.

Brendan Scott, Senior Lecturer (S&C), Murdoch University

This article was originally published on The Conversation. Read the original article.

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Why a walk in the woods really does help your body and your soul

Jeffrey Craig, Murdoch Childrens Research Institute and Susan L. Prescott, University of Western Australia

Have you ever wondered why you feel healthier and happier when you stroll through the trees or frolic by the sea? Is it just that you’re spending time away from work, de-stressing and taking in the view? Or is there more to it?

For more than 20 years, scientists have been trying to determine the mechanisms by which exposure to biodiversity improves health. Japanese scientists pioneered the search when they travelled to the island of Yakushima, famous for its biodiversity.

The Japanese already had a name for the experience of well-being in nature: shinrin-yoku or “forest bathing”.

Bathe yourself in the forests of Japan’s Yakushima island.
Alan Logan, Author provided

We do know that a diverse ecosystem supports a varied and beneficial microbial community living around and inside us.

We also know that exposure to green space, even within urban environments, increases our physical and mental well-being. But what are the mechanisms?

The forest air

The Japanese researchers suggested that we are taking in beneficial substances when we breathe forest air.

Research has identified three major inhaled factors that can make us feel healthier. These factors are beneficial bacteria, plant-derived essential oils and negatively-charged ions.

From birth to the grave, beneficial bacteria surround us; they live in the environment and, importantly, in the air we breathe. We also share almost our entire body with them. The more interaction we have with them, the happier and healthier we are.

This is in part due to our gut-dwelling bacteria, which break down the food we cannot digest and produce substances that benefit us both physically and mentally.

Plants and the bacteria living on them can produce essential oils to fight off harmful microorganisms. These are referred to collectively as phytoncides, literally, “plant-derived exterminators”.

Research on the health benefits of plant essential oils is in its infancy. But one recent study found that a phytoncide from Korean pine trees improved the health and bacterial make-up of pigs.

Notwithstanding some of the pseudoscience that gets wrapped around negative ion generating machines, there is evidence that negative air ions may influence mental outlook in beneficial ways. There are relatively higher levels of negative air ions in forested areas and close to bodies of water. This may factor into the benefits of walking in a forest or near the ocean.

But as the German writer Goethe once said:

Nature has neither kernel nor shell; she is everything at once.

Bacteria, essential oils and negative ions interact and influence each other. For example, negative ions and phytoncides may dictate the microbial make-up within a natural environment. There is evidence that this could also be taking place in the human gut.

More to be done

Nature-relatedness, or biophilia in which an individual feels connected to nature, has been linked with better health.

But we have a long way to go before we can more fully understand the mechanisms by which an innate love of nature can benefit our health. An important part of this discussion – an overlooked one in our opinion – is further understanding of an individual’s connection to nature.

Psychologists have convincingly demonstrated connections between nature relatedness and mental well-being. But how does a greater personal affinity to nature interact with dietary habits, personal microbiome, physical activity levels and many other lifestyle variables that might be intertwined with having such an affinity?

In the meantime, while scientists turn over stones and search for important mechanistic clues – including those related to biodiversity – there are many simple ways to capitalise on our biophilia.

Live in a city? The take time to walk in the city’s parks and gardens such as Melbourne’s Botanical Gardens.
Flickr/Stephen Barber, CC BY-NC-ND

Why not run in the park or by a river instead of on a treadmill, or take a walk through a park on the way to work or at lunchtime?

Critically, there is increasing evidence that we can help shape our children’s mental and physical health by exposing them to more green environments as they work, rest and play. The US-based Children and Nature Network is a great resource of research news and activities bringing children and nature together.

In the World Health Organization report Connecting Global Priorities – Biodiversity and Human Health, released in December last year, it was concluded that:

Considering ‘microbial diversity’ as an ecosystem service provider may contribute to bridging the chasm between ecology and medicine/immunology [… ] the relationships our individual bodies have with our microbiomes are a microcosm for the vital relationships our species shares with countless other organisms with which we share the planet.

It is easy to see that discussions of natural environments and human health are no mere matter of intellectual fancy.

In a paper published last month in Journal of Physiological Anthropology, we’ve called for more research into the links between biodiversity and human physical and mental well-being, particular in relation to childhood, that most formative of times.

Wouldn’t it be good if by nurturing our environment we were also nurturing our children’s future health?

Jeffrey Craig, Principal Research Fellow, Murdoch Childrens Research Institute and Susan L. Prescott, Professor of Paediatrics, University of Western Australia

This article was originally published on The Conversation. Read the original article.

Mount Everest to be Given a Clean Up

The world’s highest mountain, Mount Everest, is to be given a clean up. Everest, which was first climbed by Edmund Hillary in 1953, has become something of a garbage tip. Everything from climbers rubbish to dead bodies has been left on the mountain. Now a Nepalese expedition made up of twenty Sherpa mountaineers and eleven support crew is seeking to remove some of the garbage left behind since that first ascent.

The government of Nepal wants to clean up the popular tourist attraction, bringing down rubbish that includes old tents, climbing equipment and the odd body. Global warming has led to much of the rubbish (and several bodies) no longer being covered by snow and ice.

Over 300 people have been killed attempting the climb to the top of the world, the Mount Everest summit.

For more on this story, see the Reuters article at:

http://af.reuters.com/article/worldNews/idAFTRE63I0XE20100419

AUSTRALIA: TRAGEDY IN THE OUTBACK – Man Found Dead in the Kimberley

A man thought to be from Queensland has been found dead in the Australian outback. The body was found in Western Australia’s Kimberley region, in the far north of the state on the Meda cattle station, about 40km west of Derby.

Near the body was the man’s desperate plea for assistance with the word ‘help’ written in the dirt. He had constructed a shelter and his water bottle was empty. No vehicle has yet been found.

The man was some 15km from the Meda cattle station homestead on the 1.25 million acre property.

The temperatures in this region had reached 40C last week. The man is thought to have died a few days ago.

CROCODILE ATTACK: TRAPPING BEGINS NEAR COOKTOWN

The body of Vietnam veteran Arthur Booker, of Logan, Queensland, has still not been found following a suspected crocodile attack earlier this week. It is thought that Booker was taken by a large crocodile while checking crab traps along the Endeavour River near Cooktown on Tuesday. All that has been found in the search for the missing 62-year-old man has been his footwear and watch.

The search for Booker has now entered a new stage with police suspending their search of the river. Queensland Environmental Protection Officers (EPA) have now begun to lay crocodile traps in the area so that crocodiles can be examined for remains without harming or killing them.

The investigation into the disappearance of Arthur Booker has yet to determine if he was in fact taken by a crocodile, although this remains the most likely scenario.  There are a number of large crocodiles inhabiting the area, including the 6m ‘Charlie.’

Charlie is known to be responsible for the loss of pet dogs, livestock, eating a 3.5m crocodile and was once seen taking a horse.

The probable crocodile attack has once again brought the call for crocodile culling back into the public arena. At the moment any thought of culling by officials has been dismissed.

BELOW: Footage reporting the disappearance of Arthur Booker