Page 15 - BBC Knowledge - October 2017 IN

DOES HOLDING YOUR BREATH
MAKE YOU STRONGER?

It won’t make you stronger in the sense of building muscle in
your heart or diaphragm, but holding your breath while training
for certain sports has been shown to improve the ability of
your muscles to cope with short, intense exertions. This works by
increasing the concentration of bicarbonate in the blood, which
helps to neutralise the lactic acid produced during anaerobic
exercise. For this technique to work, you need to exhale normally
and hold your breath when your lungs are empty, rather than taking
a big breath in and holding that. There are significant risks, though.
A 2009 study found that free divers who regularly held their breath
for several minutes had elevated levels of a protein called S100B in
their blood, which is an indication of long-term brain damage. LV

WHY DOES 37°C FEEL
SO HOT WHEN OUR
BODIES ARE AT THAT
TEMPERATURE ALREADY?

That’s the temperature of HOW DO STARS DIE?
your core. Your skin is usually Stars die because they exhaust their nuclear fuel. The events
around 34°C, and your face, at the end of a star’s life depend on its mass. Really massive
fingers and toes can be stars use up their hydrogen fuel quickly, but are hot enough to
much colder. The receptors fuse heavier elements such as helium and carbon. Once there
in your skin react to is no fuel left, the star collapses and the outer layers explode
differences in temperature, as a ‘supernova’. What’s left over after a supernova explosion
so, when you put your hand is a ‘neutron star’ – the collapsed core of the star –
on your bare stomach, or, if there’s sufficient mass, a black hole.
your hand registers warmth Average-sized stars (up to about 1.4 times the mass of the Sun)
but your belly shrieks ‘cold!’, will die less dramatically. As their hydrogen is used up,
even though both are ‘skin they swell to become red giants, fusing helium in their cores,
temperature’. Similarly, before shedding their outer layers, often forming a ‘planetary
the inside of your mouth nebula’. The star’s core remains as a ‘white dwarf’,
feels warm to your finger, which cools off over billions of years.
but not to your tongue. LV The tiniest stars, known as ‘red dwarfs’, burn their nuclear fuel
so slowly that they might live to be 100 billion years old –
much older than the current age of the Universe. AGu
15
OCTOBER 2017