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THE LAST WORD

Fish suppers

How do traditional Inuit

avoid scurvy?

■ Humans – along with other primates, guinea pigs and fruit bats – cannot produce their own vitamin C and so need to get at least 10 milligrams per day from their diet to stay healthy. A deficiency results in scurvy, but it can take several weeks or months before the body shows signs of the disease – starting with bleeding gums and progressing to death if left untreated.

The Inuit avoid scurvy as they, too, get all the vitamin C they need from their diet, especially from eating raw meat. Muktuk – a mixture of frozen whale skin and blubber – is the richest source: 100 grams of muktuk yields 36 milligrams of vitamin C. Weight for weight, this is as good as orange juice. Raw caribou, kelp and whale skin also provide more than enough vitamin C. The Inuit practice of freezing any food that is not eaten raw helps to conserve vitamins, in contrast to cooking food which destroys vitamins. Mike Follows

Willenhall, West Midlands, UK

Form is temporary

Twice at the weekend I went out

running. I ran at the same time

on both days and for the same

distance. I slept well the night

before both runs, ate similar meals,

drank the same amount of liquid

and felt generally fine on both days.

On the first day I bounced along,

running as well as I would expect.

On the second day it felt like I was

running through treacle; I was

lethargic and it was dreadfully hard

work. I haven’t subsequently gone

down with any illness, so why did

this happen?

■ I row at school, and know exactly how your correspondent feels on his runs.

What he is experiencing is the result of his previous exertions. When someone runs, rows, or does any other kind of endurance activity, lactic acid builds up in the muscles due to incomplete respiration resulting from the body’s inability to get enough oxygen to the muscles. If an individual does not warm down properly after exercise then the lactic acid is not removed, leading to weakness in the muscles the following day. Felix Chapman

Salisbury, Wiltshire, UK

■ Establishing proper controls for a biology experiment is not as easy as it looks. Even using the same organism is not enough, because yesterday’s guinea pig is not today’s guinea pig, and yesterday’s runner is not today’s.

For example, yesterday the runner did not have a day’s run behind him. While the body’s feedback to exercise is poorly understood, the problem does not sound like lactic acid or any obvious physiological damage. Instead, it is more probably a mental defence against

unnecessary exertion.Jon Richfield

Somerset West, South Africa

■ As an enthusiastic swimmer, I have kept records of the time it takes me to swim 2.5 kilometres on almost 500 occasions over the past three years. On almost all occasions I felt like I was pushing myself to within 5 per cent of my maximum ability, and a majority of the times would be within 20 seconds or so of each other. Every so often, however, maintaining the usual pace

would be completely out of the question and I would end up with a time substantially slower than usual, without any obvious explanation such as poor sleeping, eating or the onset of an illness.

I noticed that there appeared to be a roughly monthly cycle, and that the poorest result often occurred a few days after a very good one. When I charted all the results together, I found that more than half of my best monthly times fell within three days of a 30-day cycle, and most of my worst monthly times fell shortly afterwards. A graph of the three years shows a repeating pattern of gradual improvement followed by a “crash” of almost 30 seconds in my time over a period of about five days . Having

only noticed this pattern after most of the data had been collected, I believe I can discount any psychological effect.

Since discovering this I have searched unsuccessfully for an explanation, which I would anticipate is related to some fluctuation in hormones or other biorhythm. Indeed, I haven’t even been able to find an acknowledgement that this is a known effect in athletes, but I know that if I was competing at an elite level, it would be pointless to enter a competition that coincides with the worst days of my 30-day cycle. Is anyone aware of a study that examines this effect?Ian Bradford.

Flemington, Victoria, Australia

This week’s questionsFADE TO GREY

Why do slowly cooked red onions – despite still tasting great – turn an unappealing grey?Christopher Smithson

Leicester, UK

GOTTA NEW MOTOR?

Why do all new cars smell the same? It is very distinctive and seems unchanged over decades and brands, but does it come from paint, plastic or something else? And if so, why is it the same across all cars? Or have the manufacturers bottled a fragrance which they secretly spray to seduce new car buyers?William Coley

London, UK

Last words past and present, plus questions, at www.last-word.com

“There seems to be a monthly cycle with the poorest results occurring a few days after good ones”