Transcript OBESITY - Jan Roscoe Publications

Jan Roscoe Publications
OCR A Level Examinations
Physical Education
Advanced GCE A2 7875
A2 Unit G453
Principles and Concepts across different areas of Physical
Education
Option B - Scientific Options
Option B3 - Exercise and sport physiology
H - Health components of fitness
Body composition - Obesity
Body composition - obesity
INDEX
A2 Physical Education unit G453
3 - WHY IS BODY COMPOSITION SO IMPORTANT?
5 - OPTIMAL BODY MASS
6 - OBESITY
8 - ENERGY BALANCE
11 - HEALTH IMPLICATIONS OF OBESITY CHD
13 - HEALTH IMPLICATIONS OF OBESITY TYPE 2 DIABETES
16 - HEALTH IMPLICATIONS OF OBESITY TYPE 2 DIABETES MANAGEMENT
18 - HEALTH IMPLICATIONS OF OBESITY METABOLIC SYNDROME
20 - HEALTH IMPLICATIONS OF OBESITY TEMPERATURE CONTROL
22 - EXERCISE AND OBESITY
23 - WEIGHT LOSS PLAN
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Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
WHY IS BODY COMPOSITION SO IMPORTANT?
the table below shows how the body fat content for people of various age
groups depends on whether they are fit or not
age group
15-19
20-29
30-39
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relative body fat (%)
untrained
trained
females
males
females
males
20-24
22-25
24-30
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13-16
15-20
18-26
12-20
10-18
12-20
7-13
6-12
8-14
Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
WHY IS BODY COMPOSITION SO IMPORTANT?
from the table on the previous slide:
– the average body fat for untrained females is about 8% higher
than untrained males
– trained females are exceptionally lean and their relative body fat
values are well below those values for untrained males
– therefore females can reduce fat stores well below what is
considered normal for their age
– untrained males and females have increased body fat when they
get older, whereas trained people (both sexes) remain lean
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Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
OPTIMAL BODY MASS
achievement of optimal body mass
requires manipulation of the energy
balance
when energy input and output are
balanced:
energy input = energy output
a person’s body mass will be stable,
and adipose tissue (fat) will neither
increase nor reduce
hence a diet which matches energy
output is necessary to maximise
performance
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Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
OBESITY
OVERWEIGHT
“a body weight that exceeds the norm or
standard weight for a particular
height
frame size
gender”
OBESITY
“a surplus of adipose tissue resulting from
excessive energy intake relative to energy
expenditure”
males - body fat greater than 25%
females - body fat greater than 35%
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Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
OBESITY
inactivity
too much
dietary fat
positive
energy
balance
more
exercise
fat stores in
adipose tissue
OBESITY
less food
weight loss
plan
BMI
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measure
body fat
Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
ENERGY BALANCE
CAUSE OF OBESITY
the main cause of obesity is a positive energy balance
ENERGY INTAKE > ENERGY OUTPUT
or more food than exercise
excess carbohydrate (CHO) is stored as glycogen
when glycogen stores are filled, CHO together with excess fat intake, is
converted to fatty acids and glycerol, and then is stored as
triglycerides or fat in adipose tissue
situated around major organs such as the heart and stomach, underneath
the skin, and in skeletal muscle
upper body obesity poses a significantly greater risk to disease
health conditions such as coronary heart disease, diabetes and
hypertension with an increased risk of mortality and morbidity
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Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
ENERGY BALANCE
CONTROLLING OBESITY
the only method of controlling obesity
is to shift the energy relationship so
that energy output exceeds energy
intake
known as a negative energy
balance and expressed as:
– ENERGY OUTPUT > ENERGY
INTAKE
a negative energy balance can be
achieved with the help of a Weight
Loss Plan
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Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
ENERGY BALANCE
WHAT IS A GOOD LEVEL OF FAT?
a minimum requirement which would allow full body functions
body fat percentage for men is between 2% and 3% and for
women between 8% and 12%
normally only healthy elite athletes attain these percentages
relative body fat is a major concern of sportspeople
achieving a desired weight goal can lead to clinical eating
disorders such as anorexia nervosa
caused by a person restricting food intake to levels well below
energy expenditure
it is important to have a diet that maintains appropriate weight
and body composition to maximise physical performance
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Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
HEALTH IMPLICATIONS OF OBESITY
CORONARY HEART DISEASE - CHD
obese people have a high risk factor of developing coronary heart
disease (CHD)
CHD is one of Britain’s greatest killers and encompasses conditions
such as angina / heart attacks / coronary thrombosis
angina begins as a chest pain, which is due to ischemia
ischemia is a condition in which there is a reduction in flow of blood
and hence oxygen to the heart muscle itself
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Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
HEALTH IMPLICATIONS OF OBESITY
CORONARY HEART DISEASE - CHD
the first symptoms of CHD are usually noticed during physical
exertion or excitement and the subsequent increase in heart rate
angina is normally treated and controlled with drugs and relaxation,
but a person suffering from this condition has a higher risk of
suffering from a coronary thrombosis
health risks from CHD can be reduced by regular aerobic exercise
this helps to maintain good coronary circulation (blood flow in the
heart muscle itself), and strengthens and improves cardiac function
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Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
HEALTH IMPLICATIONS OF OBESITY
TYPE 2 DIABETES
diabetes is a condition which occurs when a person’s body
cannot regulate glucose levels
glucose is regulated by the release of the hormone
insulin from the Isles of Langerhans situated in the pancreas
too much glucose present in the bloodstream causes more
insulin to be released to help remove it
obesity is a major risk factor for type 2 diabetes
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Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
HEALTH IMPLICATIONS OF OBESITY
TYPE 2 DIABETES
if not enough glucose is present, the insulin available is
reduced, and glucose levels are allowed to build up
the insulin enables the transfer of glucose from the blood
into cells where it is needed for metabolism
type 2 diabetes usually occurs in older people and is
caused by age-related changes in the way the body reacts to
insulin production
obesity is a major risk factor for type 2 diabetes
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Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
HEALTH IMPLICATIONS OF OBESITY
TYPE 2 DIABETES
obesity is a major risk factor for type 2 diabetes
symptoms of type 2 diabetes are:
 lack of circulation to the hands and feet
 extremes of thirst or hunger
 unexplained weight loss
 partial or total sight loss
regular aerobic exercise improves the regulation of blood
glucose levels in the blood of type 2 diabetes sufferers
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Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
HEALTH IMPLICATIONS OF OBESITY
TYPE 2 DIABETES MANAGEMENT
if exercise is continued through middle-age and oldage (from 40 onwards), blood glucose is broken
down and hence the proportion of glucose carried by
blood is reduced and the chances of type 2 diabetes
reduced
muscle cell walls in people with type 2 diabetes
become less permeable to glucose needed for
exercise
therefore normal levels of insulin can’t transfer blood
glucose into the cells for metabolism
this is insulin resistance
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Body composition - obesity
A2 Physical Education unit G453
HEALTH IMPLICATIONS OF OBESITY
TYPE 2 DIABETES MANAGEMENT
but during exercise, muscle contraction increases cell
membrane permeability to glucose which means
glucose can pass naturally into the cells
this in turn means that cell requirement for insulin is
reduced (called insulin sensitivity)
this means that acute bouts of exercise reduce the
effects of type 2 diabetes
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Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
HEALTH IMPLICATIONS OF OBESITY
METABOLIC SYNDROME
metabolic syndrome is a term used to link coronary artery
disease, hypertension, abnormal blood lipids (fats), type 2
diabetes and abdominal obesity to insulin resistance
the syndrome refers to the fact that some people develop a
resistance of their muscle cells to the action of insulin
and therefore not enough glucose finds its way into the cells
to enable them to work properly
thus making type 2 diabetes worse
hence cells (particularly muscle cells) will not have enough
glucose to function properly - and the person feels exhausted
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Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
HEALTH IMPLICATIONS OF OBESITY
METABOLIC SYNDROME
the



risk factors for metabolic syndrome are:
arterial plaque build-up
excessive fat deposits in the abdominal region / obesity
high blood triglycerides, low HDL cholesterol and high LDL
cholesterol
 raised blood pressure (hypertension)
this syndrome brings a higher risk of circulation and eyesight
problems in older people
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Body composition - obesity
A2 Physical Education unit G453
HEALTH IMPLICATIONS OF OBESITY
TEMPERATURE CONTROL
obese people have difficulty in regulating heat
loss and hence body temperature
this is because of the excess adipose tissue layer
under the skin
this layer in effect acts as an insulating barrier to
heat conduction from the body core to the skin
where it would be radiated off to the surroundings,
or lost by convection and evaporation
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Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
HEALTH IMPLICATIONS OF OBESITY
TEMPERATURE CONTROL
therefore, when exercising, an obese person would
become unduly hot and uncomfortable
and require extra cooling methods such as ice
packs or cold drinks
conversely, the same layer helps keep obese people
warm in winter!
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Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
EXERCISE AND OBESITY
EXERCISE
exercise reduces obesity by burning off excess fat during and
after activity when the body’s metabolic rate remains
elevated
cardiac workload (hence risk of CHD) is less with a lower body
mass
the capability to move around (walk, run and climb) is therefore
better with a lower body mass
this is because a person’s strength to weight ratio will become
less as he / she becomes lighter
exercise relieves symptoms of osteoarthritis
as flexibility of joints improves
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Section B Option B3 H: Exercise and Sport Physiology
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Body composition - obesity
A2 Physical Education unit G453
WEIGHT LOSS PLAN
specific
personal
realistic
WEIGHT LOSS
PLAN
measurable
activity log
food diary
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Section B Option B3 H: Exercise and Sport Physiology
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