Last updated at 08:40 20 February 2008







Brrr: Feeling cold?

How cold can you get?

Normal body temperature varies between individuals but is typically just over 37C. Should this drop by even a small amount, then hypothermia sets in.

At 36C, reaction times and judgment become impaired. At 35C you will be unable to write your own name and even walking is very difficult. At 33C you may become completely irrational, throwing away survival gear and stripping off your clothing. At 32C, most people will collapse, becoming unconscious when their core temperature drops to around 30C.

At this point the body has given up trying to maintain core temperature. Breathing drops to just one or two breaths a minute.

By 28C, cardiac arrhythmia (an irregular heartbeat) sets in and by the time you have cooled to 20C, your heart will have stopped beating altogether. However, doctors have a saying: "You aren't dead until you are warm and dead."

This is because extreme cold slows the cellular breakdown that causes irreversible damage. You can improve your chances of survival by being warmed up very gently and having paramedics on hand with a defibrillator.

It helps if you're young, too, because children's organs are more resilient. The theoretical absolute lower limit, however, is zero degrees centigrade. At this temperature, ice crystals would form in your tissues, destroying all cells.

Theoretical limit: 0C



Current record: 16C

In 2001, a toddler was revived after wandering out in -20C weather. Her heart had stopped for two hours and her core temperature was 16C.

Punchbag: Sylvester Stallone as Rocky Balboa

The human punchbag

Muscle tissue generates about 0.3 micronewtons of force per muscle fibre. This translates into about 100 Newtons (roughly 10kg) for each square centimetre of cross-sectional area in your muscle.

But the bones in your forearm will shatter above 200 megapascals of compression, roughly equivalent to 50 kilonewtons (1kN = 1,000 Newtons) of force.

If we assume that the arm muscles contribute half of the force of the punch (with the rest coming from the legs, hips and shoulder acting in concert), you would need a tricep with a circumference of around 55cm to reach this limit, as well as lots of training to maximise the efficiency of your technique.

Theoretical limit: 50kN



Current record: 3kN (estimated)

In 1931 boxer Max Baer landed what's regarded as the hardest punch ever - in a fight with Ernie Schaff, who never fully recovered and died six months on.

How much blood can you lose - and live?

A healthy adult has between 3.8 and 5.6 litres of blood. You can lose up to 15 per cent of your total volume rapidly without any immediate effects. Above this, your pulse will become more rapid and you may feel dizzy, irritable or cold.

At around 40 per cent loss, your blood pressure is too low to refill the heart chambers and the heart goes into ventricular tachycardia (a fast rhythm that can be fatal).

Good cardiovascular fitness improves your chances of survival - and it also helps to be large, as you can lose a greater volume for the same percentage loss.

Lying still and keeping calm will also delay the onset of shock by reducing adrenalin levels.

Theoretical limit: 1.9-2.8 litres, 50 per cent



Current record: 75 per cent

In 1987, cancer patient Melissa Koslosky was found with just 0.9 litres (25 per cent) of blood in her system. But the blood was lost slowly over weeks.

How much water can you drink in an hour?

Ten litres: the most water you can drink in an hour without diluting your electrolyte levels, resulting in seizure or death.

What is the hottest curry you can bear to eat?

Some like it hot: Prawn curry

The active ingredient in curry or chilli is capsaicin. The more capsaicin present, the hotter the curry. Ordinary Tabasco sauce is about 260 parts per million capsaicin. A habanero chilli contains about 17,000ppm.

Theoretically, the hottest curry you could make would be a bowl of pure capsaicin crystals. This dish would be 10,000 times hotter than a vindaloo.

Although capsaicin does not actually cause a chemical burn or any direct tissue damage itself, the impact on the nervous system of such powerful stimulation is similar to an allergic reaction. As well as incredible pain, you could expect uncontrollably streaming eyes and nose, upper body spasms, and severe difficulty breathing for 30 to 45 minutes.

In fact, our ultimate curry would be five times stronger than the pepper spray used by police for riot control.

Provided you are healthy with no history of heart conditions or asthma, it might be possible to survive a teaspoon of pure capsaicin, but impossible to eat anything else for a few hours.

Theoretical limit: 5g capsaicin



Current record: 0.1g

In 2005, Blair Lazar refined 500g of capsaicin from chilli peppers to create a sauce. He tried a single crystal. "It was like having your tongue hit with a hammer," he said.

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Mr Incredible: His body has no limits

How many balls can you juggle?

Only a handful of people have ever managed to juggle 11 or 12 balls and no one has done 13.

The problem is that the more balls are in the air at once, the faster your hands need to move to keep them up.

A 1997 study using accelerometers attached to the hands of some of the best jugglers in the world showed that - with perfect technique - it might be possible to juggle 16 balls at once. But for this to happen, every ball would have to be thrown to exactly the same height and land in exactly the same location.

How fast can your legs carry you?

The question of how fast it is possible for a human to run is more complicated than it sounds. Even deciding who is today's fastest human is tricky.

The current world record for the 100m sprint is held by Asafa Powell of Jamaica, who clocked a time of 9.74 seconds in 2007. This gives an average speed of 36.96km/h, but since the runners must begin from a standstill, this includes the time taken to accelerate.

Sprinters in a 200m race will complete their second 100m in a shorter time than the first because they are already running at full speed as they cross the 100m mark.

Since the advent of electronic timing in 1968, the men's world record for the 100m has been beaten 11 times (but never by more than 0.05 seconds). Improvements in track and running shoe technology or the effects of wind and altitude are the most likely causes of this.

Most of the forward force in a running stride is supplied by the quadricep muscles. These are attached to the knee by the quadriceps tendon. Work done by Dr Gideon B. Ariel in the 1970s suggested that any time faster than 9.60 seconds would require forces high enough to rupture this tendon from its attachment point. Taking this as the fastest possible time for the 100m would give an average speed 37.5km/h.

Top sprinters peak around the 80m mark. Taking this as a guide, it's possible to estimate a runner's maximum speed as 11.96m/s or 43.06km/h.

Theoretical limit: 43.06km/h



Current record: 42.52km/h

In 2007, Asafa Powell ran with a 1.7m/sec tailwind. Despite this, he only improved on the record by 0.05 seconds.

How many bee stings can you survive?

2243: the greatest number of bee stings ever survived.

600: the theoretical dose needed to give a 50 per cent chance of death.

HIs Master's Voice: That's loud, man

How loud is too loud?

Sound volume is measured in decibels, a dimensionless, logarithmic scale where an increase of 3dB corresponds to a doubling in power. At 125dB (a jet taking off 50 metres away), sound becomes painfully loud.

The loudest sound you can safely hear is 160dB because above that there is a chance your eardrums will rupture. But sound is just a pressure wave and there is almost no theoretical upper limit to its intensity.

The existence of a "brown note", that resonates to cause victims to lose control of their bowels, has been postulated but never demonstrated in tests. But internal organ damage from very loud sounds is perfectly possible.

The loudest sound ever recorded was the eruption of Krakatoa in 1883, which measured 180dB, 160km away.

Anyone closer than 20km would have experienced sound levels of 200dB and, at this volume, the pressure wave would rupture their lungs and force air into the bloodstream, causing a fatal pulmonary embolism.

Theoretical limit: 200dB



Current record: 175dB at 2m

The T-429 stun grenade produces a 175dB bang at 2 metres. At point blank range, this would rise to 186dB, which is enough to trigger cardiac arrest.

What's the biggest electric shock you can take?

In classic electrocution, the heart is shocked out of its beating rhythm in a process called ventricular fibrillation. It's not voltage that kills but electrical current, measured in amps.

The threshold of sensation for humans is one milliamp (1mA), while a sustained current of 200mA is fatal - able to stop a typical human heart weighing around 300g.

According to Ohm's Law, current passing through a conductor is given by voltage divided by electrical resistance, measured in ohms. The resistance of human skin varies between 1,000 ohms (wet skin) to 100,000 (dry), so the lethal voltages are 200V and 20,000V respectively.

A 400g heart (the most a healthy heart can weigh) might take up to 27,000V.

At high voltages, extra physics comes into play. For example, only ten per cent of lightning strikes are fatal. Most injuries result from arc flash - the intense heat, light and pressure from the sudden heating effect of electrical currents.

Theoretical limit: 27,000V



Current record: n/a

U.S. PARK Ranger Roy Sullivan survived seven lightning strikes between 1942 and 1977.

How hard can you get struck by a car and live?

At 30mph, the chance of surviving a car crash falls to 27 per cent. At speeds above 38 mph, you have less than a 1 per cent chance of surviving.