Cold causes an increase in metabolic rate to produce heat to try
and counteract the effects of cold resulting in increased calorie/fat burning. However,
exposure to cold has a far deeper biological and hormonal impact on the body.
Cold Therapy (CT) is proven to increase adiponectin levels.
Adiponectin is a hormone that stimulates fatty acid oxidation in muscle cells
by activating AMP-activated protein kinase. Or in simple terms – cold increases
adiponectin, adiponectin burns fat.
CT also lowers blood sugar levels by burning glucose as heat, and increases
glucose uptake into muscle helping speed up recovery times. Clearance of excess
blood glucose into muscle helps prevent blood sugar being converted into fat by
the liver. Meaning a cold shower after a high carb meal might prevent a lot of
the negatives from high sugar intake!
CT also activates conversion of regular body fat (known as white
adipose tissue or WAT) into brown adipose tissue (BAT – aka Brown Fat). BAT is
very different than typical fat in that it is dense in energy producing
mitochondria (hence its brownish color) and utilizes body fat (typically from
the belly and back) as its fuel source.
Cold and Norepinepherine
Norepinepherine (NE for short) is an excitatory neurotransmitter
that is one of the primary initiators of fat burning. NE is the key initiator of the Sympathetic
Nervous System’s (SNS) Flight or Fight Response.
The Flight or Fight Response is something we have all experienced
anytime we are really scared such as almost getting into a serious car
accident. If you recall an experience like that you will remember that you are
often shaking after the danger has passed.
Shaking occurs because when you perceive a threat the brain pushes
out high levels of NE. High levels of
NE stimulate a cascade of effects including:
Increased heart rate
Increased oxygen consumption
Increased circulation
Shut-down of digestive tract while pushing more blood to muscles
for action
Increased pupil dilation
Increased mental focus
Reduced perceived exertion, pain, and inflammation.
Release of fatty acids and glucose from storage to fuel high
levels of muscular activity.
High levels of NE also stimulate the adrenal glands to secrete
epinephrine (EP). EP is also known as
adrenalin. NE and EP are chemically
almost identical with NE being a neurotransmitter and EP being a hormonal
version.
This strong SNS response prepares you for action!
Even brief exposure to extreme cold (20 seconds at 40°F, 4.4°C) causes
a 200-300% boost in norepinephrine that lasts for an hour. As stated above increased
NE stimulate release of EP as well. You experience a noticeable boost in
vigilance, focus, attention, and mood, along with improved oxygen delivery,
blood circulation, antioxidant function, mitochondrial biogenesis, and reduced perceived exertion, pain, and inflammation.
Cold and Sleep
Although cold exposure initially causes a strong sympathetic
nervous response (like what occurs during any high intensity exercise) later
the body rebalances and there is an increase in your Parasympathetic Nervous
System (PNS) response as a reaction to this stimulus.
Your PNS is basically your rest/sleep/repair mode. So the increased PNS response to cold
exposure after the acute SNS response helps with sleep quality.
Takeaway – Cold Showers can be an effective
tool to boost exercise performance and fat burning. For those seeking lower
body fat levels do 5-10 minute sessions in the morning, dry off and then
warm-up and exercise – you will feel rocket charged!
To learn more about all the positive
effects of using cold exposure for positive health and fitness benefits check out this great podcast and article on the subject: https://www.foundmyfitness.com/episodes/cold-stress-hormesis
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