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When getting dressed in the morning, I want to warm up as quickly as possible. Should I put on my trousers or top first? (continued)
Peter Bursztyn
Barrie, Ontario, Canada
Our body has two broad temperature regulation regions: the core and the periphery. The core is the trunk and its organs, plus the brain. The periphery is everything else: limbs and their muscles, plus the skin.
Our core temperature is actively regulated, maintained close to 37°C (98.6°F). It rises perhaps 2°C (3.6°F) during strenuous exercise, and falls slightly at night.
One method our body uses to regulate its core temperature is to alter the flow of blood to the periphery. More blood is sent to the skin when we are trying to get rid of heat, less if we are conserving heat. In the limbs, we have the option of sending blood back to the heart either by surface veins, or by veins lying close to arteries feeding that area. In the latter case, returning venous blood is warmed by arterial blood flowing towards the periphery.
It is probably advantageous for you to don your top first, because the skin covering this area tends to be warmer than that covering your legs. Also, the hair on your legs (typically more hirsute than your arms) helps to insulate them.
However, the advantage is very small, particularly as there will be just a minute or two before your trousers are on, too!
Pauline Keyne
Beaconsfield, Buckinghamshire, UK
The assumption behind this question is that the requirement relates to a cold morning. This answer is: top first, with socks next. This is not empirically based, but is peer reviewed. I’ll leave it to other respondents to tackle the biophysics.
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The advantage of putting your top on first is small, as there will be just a minute or two before your trousers are on, too
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Whenever I am already dressed and cold I put on an extra layer. Hikers carry an extra jacket or fleece in case of needing to warm up, but generally only waterproof over-trousers in the event of rain. It is very common, when feeling cold, to pull sleeves down to cover wrists. Adding a scarf or other form of neck warmer is often sufficient to feel cozy. Some (many) years ago, when the bedroom windows were frosted over (yes, that long ago), I can remember my granny telling me about getting dressed in bed. That was definitely best done “top first” as the arms and shoulders were likely to become exposed when struggling to put the rest on. This method avoided getting cold before warming up, so I would recommend it to the questioner.
Finally, I would surmise from the question that the option of heating the room to the extent that there is no need to know how best to warm up has been rejected. The questioner is therefore doing their bit to reduce carbon emissions, which surely carries with it a warm glow.
Krishnan Sriram
Chicago, Illinois, US
The answer is easy based on anatomy and physiology. The rule of 9 is used often in assessing areas affected by burns, which splits the body into 11 areas of 9 per cent each. The perception of cold depends on the skin surface exposed. If we wear long-sleeved tops, the area we will cover to prevent heat loss would be 9 per cent for each arm, and 18 per cent each for the anterior (front) and posterior (back) torso, which totals 54 per cent of the body’s surface area. Compare this with the area covered by wearing trousers, which is 18 per cent for each leg, totalling 36 per cent. Most of us would subjectively experience better warming by wearing tops first.
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