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Lecture 10

BPK 143 Lecture Notes - Lecture 10: Figured Bass, Bulgarian Lev, Yokohama Rubber Company


Department
Biomedical Physio & Kines
Course Code
BPK 143
Professor
Tony Leyland
Lecture
10

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Body composition is a result of fitness and diet rather than a component of fitness (argued by teacher,
currently is a component of health). The number one reason why people start to exercise is to "get in
shape" or "lose weight", most of us just want to feel good about our physical appearance (this can be in
looking thin, lean, or toned). Ideal appearance is different for everyone
Having a goal of "losing weight" is not correct, for one due to it does not adhere to SMART goal setting
and is not very specific, since losing weight could be due to losing muscle mass and decrease bone
density. Therefore these common goals are better termed by wanting to "lose body fat" or "increase
muscle mass" etc. These adhere more to SMART goal setting
Accurately measuring if you achieved these goals is very difficult and expensive (through DEXA,
assesses body composition), just stepping on a scale is not as accurate because you may have lost body
fat and gained muscle and this would not show if you step on the scale.
If we were better reward these goals to make them easier to assess when they are completed. For
example, you could plan to maintain body mass while increasing strength (your predicted 1-rep bench
press, and/or squat, and/or deadlift). Achieving this goal would require loss of fat and a gain in
muscle. A goal like this focuses on body composition changes people want, but they are more easily
measurable and cheaper (than DEXA)
Even though these goals appear valid, they are worried about weight training and "bulking up"
WEIGHT LOSS AS THE HOLY GRAIL OF THE FITNESS INDUSTRY
Strength is developed by improving neuromuscular efficiency and increasing muscle size, and younger
males who have higher levels of testosterone tend to increase strength by increasing muscle mass
whereas females and older males tend to rely on more improvements in neuromuscular efficiency
A study conducted an 8 week program with 40 obese women, these subjects were assigned to one of
four groups (control, diet only, weight training only, and diet and weight training). The group that
weight trained and dieted lost more fat than the other groups. (results shown in table 10.1)
Strength, Muscle, Fat, and Body Composition
An important highlight from this study is the loss of muscle mass that occurred with the diet only
approach, if you are working out to improve your health diet alone is not sufficient
Health includes being able to function independently later in life, so dieting and losing muscle mass is
not a good strategy to keep you independent as you age.
The conclusion of the study, the endurance-only group had lost a total of 3.5lbs, 3lbs of which was fat
and a 0.5 was muscle. On the other hand, the endurance and weight-resistive group lost 8lbs, with an
actual fat loss of 10lbs, and an increase of 2lbs of lean body weight.
Incorporating weight training may help you improve body composition more effectively than aerobic
endurance work alone.
Resistance training maintains or improves muscle mass due to overload. But, it also helps you burn
more calories because you are doing more. For many people, changing exercise mode makes the
workout more interesting. After 30 minutes of aerobic exercise, adding 30 minutes of resistance work
can be a more attractive proposition than continuing for an additional 30 minutes of aerobic work.
Regardless of total body weight loss, if you lose body fat and gain muscle, you will “trim down even
if your weight remains constant. Muscle is about 18% denser than fat (muscle density = 1.06 g/mL and
fat density = 0.9 g/mL). Therefore, if you stay the same weight but lose five pounds of fat and gain five
pounds of muscle, you get trimmer.
Individuals who eat correctly, exercise correctly, and manage their stress level appropriately will
maintain a healthy body composition (unless there is an underlying disease e.g. metabolic)
Performance measures are better indicators of health and fitness, performance could be measured in
terms of workout or competition results (e.g. fitness test results), blood lipid profiles, ECG, liver
function, and glucose tolerance tests
WEIGHT MANAGEMENT
One main message is that nutrition research has been conducted very poorly because of bias, most
studies have been structured to prove that low-fat diets are good for you rather than being objective
and looking at the effects of diets without and pre-conceived beliefs
Insulin:a hormone that regulates carbohydrate and fat metabolism. When you secrete insulin it
signals cells in the liver, muscle, and adipose (fat) tissue to take up sugar from the blood. In the liver
and muscle glucose is stored as glycogen and in adipose tissue it is converted to fat.
Glycemic index (GI) is a measure of the effects of foods on blood sugar levels. Carbohydrates with a
high GI rating can be digested quickly causing a rapid rise in blood sugar levels. Carbohydrates that
break down more slowly, releasing glucose more gradually into the bloodstream, have a low GI. Often
this rapid rise in blood sugar results in a rise in insulin levels.
Dietary Fat and Body fat
THE ENERGY BALANCE EQUATION
When it comes to weight control, many have used the first law of thermodynamics (conservation of energy)
and the energy balance equation (EBE) to promote low-fat diets. The EBE states:
However, most weight loss programs have simply (and wrongly) treated energy intake and energy
expenditure as two independent variables. Therefore, the message conveyed is that individuals who
want to lose weight need to focus on decreasing caloric intake, increasing energy expenditure, or a
combination of the two. This might appear reasonable, since a gram of fat is nine calories, and
protein and carbohydrate are approximately four calories per gram, this approach would seem to
support low-fat diet is best for weight loss.
Change in energy stores = Energy intake Energy expenditure
Some individuals tend to gain more weight due to the food we eat elicits hormonal responses, which
determines how energy is stored in the body (aka fat). Therefore energy intake is not independent of
energy expenditure, and the type of calories you eat does affect your energy output. Energy intake
and energy expenditure are dependent variables. High sugary foods and easily digestible
carbohydrates trigger an immune response, and insulin drives fat storage
The fat storage and release of fat from adipose tissue (fat cells) is hormonally driven, e.g. the
hormonal response to pregnancy stimulates fat accumulation in order to build energy stores (fat
usually stored in the butt, thighs and breasts) for the mother and fetus. This energy will move out of
cells when the energy is needed during pregnancy/lactation. After birth, if exercise is assumed with
good nutrition she will return to a normal amount of adipose tissue for her body regardless of
calories consumed
So what are cause and effect in the EBE? Do you necessarily store energy just because you eat more?
poor eating habits (not simply eating too many calories, it is food high in carbs/refined sugars) that
cause a hormonal response, which then forces the body to store excess calories as fat.
It has been shown that restricting total carbohydrates, along with eating only carbohydrates that are
low on the glycemic index is the most effective for weight control and good health
Another way to demonstrate that the EBE is controlled by hormonal response is to look at growing
children, children grow due to the influence of hormones. Hormones stimulate their appetite and
dictate how this excess” of nutrients is stored. When children eat and exercise properly, the growth
will be primarily vertical and include muscle, bone, and organ growth as well as some adipose tissue.
For an adult eating a diet high in easily digestible carbohydrates, the hormonal response will cause
growth in the form of fat accumulation.
Studies have shown that individuals on low-calorie weight-loss diets tolerate high-fat, high-protein,
low-carbohydrate diets better than low-fat diets. Despite low overall calorie intake, they do not
report feeling hungry all the time, and their metabolism does not slow down in an attempt to
maintain fat stores.
Your body secretes the hormone, insulin, in response to a rise in blood sugar.
Insulin drives the body to store the excess blood sugar as fat. We do not store a lot of energy in
the form of glycogen.
Insulin inhibits your body’s ability to mobilize fat out of adipose tissue and burn it as a fuel.
Therefore, high insulin levels work against fat loss.
Simple carbohydrates (e.g., high-fructose corn syrup, sugar, and white flour) increase blood
sugar levels the most, and increase insulin levels.
Very high total-carbohydrate quantities in diets also increase insulin levels.
Chronically elevated levels of insulin are responsible for metabolic syndrome, which includes
obesity, Type 2 diabetes, high blood pressure, and more.
So when you are looking at the energy intake variable in the EBE, a calorie is not just a calorie. All
calories are not equal; the quality of those calories (the type of nutrient and overall nutrient balance)
is very important. Restricting caloric intake but continuing to eat much of it in the form of high-
glycemic foods will make your body fight to maintain its fat stores and will lower your metabolism.
Energy Intake
Understanding the relationship between exercise and weight control lies in understanding the body's
hormonal response to exercise. Most epidemiological evidence looks at subjects doing low power
activities such as walking, jogging and cycling for 20-60 minutes. These modes are less than ideal for
improving aerobic conditioning and ineffective at stimulating significant production of testosterone,
human growth hormone etc. that are involved in optimal health and body composition. Chronic low
power output endurance exercise has been shown to lower testosterone levels in male subjects
The "calorie is a calorie" logic is flawed with regard to energy intake, similar to the type of calories
consumed makes a difference.
Interval work (series of sprints) burns more body fat than steady-state cycling, the sprint-interval
group did the same amount of external work and yet lost more body fat, which correlates with the
notion that high power outputs elicit hormonal responses that low power outputs
If sprinting is to intense, there is some evidence that simply breaking up your workout can be
beneficial allowing time for a rest period burned more fat than exercising for one continuous session
A greater amount of fat breakdown (lipolysis) was seen from performing two 30 minute sessions than
one 60 minute session. The repeated trial also caused a greater increase in free fatty acids and glycerol,
which is released when stored fat is burned. As well increased levels of epinephrine increased while
levels of insulin and blood glucose decreased significantly more than during the single session, which
may have further contributed to fat breakdown and enhanced fat metabolism.
Clearly, if you are doing the same amount of work in two different exercises and yet find one type of
exercise more fatiguing, and if you do the same amount of work and yet lose more subcutaneous body
fat with one type of exercise, then something else is going on other than calories expended. One factor
is that we are measuring external work (how far you move your body and in what time frame).
However, the actual total energy (internal and external) cost of acceleration (overcoming inertia) is
very high.
In athletic performance, acceleration requires a huge effort and use of resources (energy). And
overcoming inertia (accelerating, lifting, resisting, and changing direction) is a key factor in athletic
performance. Olympic lifts and maximal sprints use an incredibly high number of muscle fibres in the
explosive effort to produce high accelerations. Although squats and deadlifts are slow lifts, the sheer
weight being lifted also means they are very taxing lifts that will stimulate positive hormonal
responses.
The endocrine (hormonal) response to exercise is vitally important. For example, hormonal response
to high-power activities includes increased levels of testosterone, insulin-like growth factor, human
growth hormone, and many others. Intense work also causes more cellular damage. On the cellular
level, exercise is a stressor that forces the body to rebuild tissue and strengthen (hormones involved in
this rebuilding process). Your metabolism stays elevated for much longer after a high power activity,
due to the action of adrenal gland hormones (epinephrine and norepinephrine), as compared with a
low power workout. This factor is often overlooked in terms of the energy expended in an exercise
session.
The adaptation and hormonal response to performing only long, slow, low-powered aerobic work is
less effective in driving a healthy hormonal response and a healthy body composition, that includes
adequate musculature in all regions of the body, good bone and connective tissue density, and healthy
body fat levels.
In summary, a crucial flaw in the way health researchers have been viewing the energy balance
equation and its application to weight loss. By regarding energy in and energy out as independent
variables, they have ignored the large quantity of research on both humans and animal models that
shows the importance of quality as well as quantity (the vital importance of the type of calories
consumed).
Similarly, many who prescribe exercise for weight loss and health improvement fail to understand the
importance of how the energy is expended. The focus is almost always just on quantity. But, the calories
consumed, the quality of the exercise performed is as important as the quantity of calories expended.
ENERGY OUT
Fat cell hypertrophy: enlarging/filling existing fat cells with more fat
Fat cell hyperplasia: increasing the total number of fat cells
The body can increase the quantity of stored fat in two ways:
Average, non-obese person: 25-30 billion
Moderately obese person: 60-100 billion
Massively obese person: up to 200 billion
The major structural difference in adipose tissue mass between obese and non-obese people is in cell
number. Typical fat cell numbers are:
During the last trimester of pregnancy
During the first year of infancy
During the adolescent growth spurt
A decrease in the size of fat cells, with no change in the number of cells is how you lose weight, once a
cell is made you cant get rid of it, it can only get smaller. Liposuction is the only way to decrease the
number of fat cells. There are 3 critical periods when the number of fat cells increases significantly:
Undesirable life-style habits developed during childhood, coupled with little exercise will not be
beneficial when going into adulthood
The number of fat cells becomes stable before adulthood. Any weight gain or loss thereafter is usually
related to a change in the size of the individual cells. However, massively obese adults appear to be an
exception to the general rule. There is an upper limit to fat cell size, beyond which hypertrophy fails to
occur followed by further increases in adiposity then occurs by increases in the number of fat cells.
FAT CELL SIZE AND NUMBER
Set point theory is the body's internal control mechanism (a set point) controlled via the hypothalamus
which drives the body to maintain a particular level of body fat. This is why some have difficulty in
maintaining weight loss.
When a reduction of body fat is managed and drops below your natural set point, your body attempts
to resist this change and you conserve body fat by lowering your basal metabolic rate (BMR: the
amount of energy expended while at rest), which is the base level of your daily energy expenditure
When very low-calorie diets (fewer than 800 kilocalories/day) are used, BMR may be decreased by as
much as 45%. This greatly conserves energy and causes the diet to become much less effective.
Different people have different set points which can be affected by hereditary, dietary and
environmental factors. Drugs such as nicotine and amphetamines as well as exercise are some factors
that may lower your set point, whereas dieting appears to have much less of an effect.
SET-POINT THEORY
Caloric balance= kilocalorie from food -(kilocalories of resting metabolism + kilocalories of
physical activity + kilocalories used to digest food + kilocalories lost excreta)
more detailed version of the energy balance equation
Kilocalories lost in excreta: unless the food is digested, it should not be counted as "calories in"
The net energy exchange that expresses the process of metabolism can be written as:
The law of conservation of energy states that energy can be neither gained nor lost but only changed in
form. Therefore, for a person in positive energy balance, the extra energy is stored in the form of fat,
assuming that muscle and liver glycogen stores are filled. One pound of human adipose tissue is stored
in the body when an excess of approximately 3,500 kcal of energy is consumed.
If you develop a negative energy balance of 500 kilocalories per day, in one week you will have a
deficit of 7x500kilocalories= 3500kilocalories which is equivalent of 1lbs of human adipose tissue (daily
caloric intake should not be less than 1,200 kilocalories on a regular basis), it is recommended not to
lose more than 2lbs of body fat per week. *the quality and quantity of food as well quality and quantity
of exercise that will decide whether you achieve a negative energy balance. A combination of
decreased caloric intake and increased energy expenditure has the distinct advantage of accelerating
weight loss.
The maintenance of improved body composition that is difficult, because it involves a change in
lifestyle from the one that promoted fat accumulation to one that discourages it. Therefore, the ideal
weight loss diet is one that can be incorporated into an individuals lifestyle, and is fundamentally a
change in their eating and/or exercise habits for life.
The fact that the body doesn’t fluctuate in weight shows that the body works to stay at the set point.
Some research suggests that humans change their BMR in an attempt to stay at their set point. For
example, some studies show that many individuals simply waste excess energy by subconsciously
fidgeting more and being slightly more active to achieve correct energy balance.
The recommended type of exercise program for weight control is one of continuous aerobic activity,
supplemented by resistance training.
When fat accumulation begins as a result of inactivity or overeating, it is important to start corrective
efforts as soon as possible, waiting until they are 20, 30, or more pounds overweight before starting to do
something about their poor body composition. The longer you wait, the harder it will be to achieve
success. Set up an exercise and diet program with habit formation in mind. Reduce caloric intake by
300 to 500 kilocalories per day and progressively build up your exercise levels. It is usually easier to
sustain dietary changes with simple strategies.
SENSIBLE FAT LOSS (SLOW AND STEADY)
Many people develop exercise programs to help reduce body fat and increase or maintain muscle
mass. As energy is expended in physical activity is difficult to accurately estimate via EBE. While
caloric cost of steady-state running and other cyclic activities are easier to estimate, these can be
influenced by hormonal balance and mechanical efficiency. How do we calculate/estimate how much
energy is expended?
Two methods can be used to determine the amount of energy used/heat production during activity
CALORIC COST TABLES
Direct measurement of heat production. This is direct measurement of heat production.
Calorimeters come in several types and sizes. Direct calorimetry is very accurate; however, these
techniques are impractical for studies of human energy expenditure during various sport, recreational,
and occupational activities. In these situations, indirect calorimetry is used.
Direct Calorimetry
These methods obtain an indirect estimate of energy production by measuring oxygen consumption.
Oxygen consumption can be converted to energy production. It can be measured by using a portable
spirometer, Douglas bags, or computerized instrumentation.
Basal metabolic rate is a larger portion of expenditure and that is highly variable.
Indirect Calorimetry
Some tables of energy expenditure save you from needing to know exactly how far you have run by
focusing on the time. You still need an idea of the pace at which you run, but you could measure this
on a 400-metre running track. Table 10.3 shows this information.
1.0 kcal per kg of body weight per kilometre (1.0 km = 0.62 miles)
Skill level and style of player.
Skill level and style of opponent(s).
Intensity of competition.
Motivation (psychology) of all players
Total duration of each rally (e.g. tennis, squash, badminton, and volleyball).
Time interval between rallies in such sports.
Total duration of entire game.
The energy expenditure in game situations will depend on factors such as:
Tables of energy expenditure may be useful to show you which are the potentially more demanding
sports, but how intensely you play and how many calories you burn is determined by many factors.
SLOW AND STEADYDOES IT REALLY BURN MORE FAT?
Why do so many people think slow and steady burns more fat? What actually happens in lower-
intensity exercise is that a greater percentage of fat is burned (shown in Figure 10.4). When looking at
Figure 10.4 it is just showing a higher percentage of calories burned are coming from fat rather than
carbohydrate.
Let’s look at an example shown in Table 10.4 for a subject who has a VO2 maxof 2.0 litres/min. This
subject does two 30-minute workouts, one at 50% of her VO2 max (60% max heart rate) and one at 70%
of her VO2max (80% max heart rate). This table shows the fat burned during these two exercise
sessions
The greater your energy requirements become, the more your body will switch to glucose and
glycogen use (because of its efficiency). This is why, working at the lower intensity, burns a greater
percentage of fat than at the higher intensity. Row #2 reflects this higher fat utilization per litre of
oxygen.
Row #5 shows that you burn more fat at a higher intensity of exercise over the same duration.
Therefore, if you have limited time, it is best to exercise as hard and as safely possible. An added
benefit to higher intensity work is that body temperature may be raised higher, and thus, metabolism
will stay higher for longer. In addition, high-intensity exercise may increase muscle mass and have a
slight effect of increasing your endurance to do more activity throughout the day.
Figure 10.4 Carbohydrate (CHO) and fat metabolism during prolonged exercise.
During high-intensity exercise, you burn a lot of muscle and liver glycogen. When you eat
carbohydrates, your glycogen stores are replaced. If you haven’t depleted your glycogen stores, any
digested carbohydrates that exceed your immediate energy needs will be stored as fat. This leads us to
another misconception, that the only way to reduce the amount of fat stored in the body is to burnit.
However, when glucose intake exceeds your body's energy needs, which often happens after a high-
carbohydrate meal followed by rest, your body has no need to create more ATP. Acetyl-CoA starts the
process of fatty acid synthesis becoming triglycerides that are stored in the fat tissues. These are a great
source of energy that can be broken down later to provide energy.
When you workout intensely you will have depleted your glycogen stores and these will be
replenished by eating carbohydrate. If you have not depleted much glycogen, excess carbohydrate in
the diet will be stored as fat. The higher intensity work will burn more energy and therefore help you
lose fat.
Fat in your diet cannot be used to replenish glycogen stores. If you eat a high-fat low-carbohydrate
diet, you may not fully replace muscle and liver glycogen, and your ability to exercise will be
diminished.
Burning Glycogen Will Help You Lose Fat
The added benefit of higher-intensity work is that your metabolic rate and metabolism stays higher for
longer after your workout. Intense exercise (weight training, plyometrics, or sprints) can increase your
metabolic rate for 3-14hrs after a vigorous workout. Slow aerobic exercise does not raise your
metabolism as much and has little effect after your workout
Weight training and other high intensity exercise will increase muscle mass, and metabolically active
than adipose tissue. Muscle burns 10 kilocalories per kilogram of muscle (or slightly less than 5
kilocalories per pound), fat burns approximately 2calories per pound per day.
Why does everyone think muscle is so much more metabolically active? We see that those who are
exercising and gaining muscle mass increase their daily energy output (daily metabolic rate)
The metabolic activity of muscle at rest, is having more muscle mass increases feelings of "having
energy" and your ability to perform and required exercise, meaning you will probably due more
activity throughout the day
ENERGY EXPENDITURE THROUGHOUT THE DAY
TARGET HEART RATE REVISITED
We have seen that high-intensity 30-90-second intervals are the best way to improve aerobic capacity and
that such high-power interval training can greatly improve fat loss compared to steady state aerobic
exercise. Athletes, all over the world, routinely go into the red-line zone” (140-200 bpm) and are generally
the better for it.
OTHER MISCONCEPTIONS REGARDING THE ROLE OF EXERCISE IN
WEIGHT CONTROL
Spot reduction is an attempt to focus exercise on one body part and to lose fat in a particular area, this
usually involves localized exercises in belief that the muscle utilizes fat stores in the active areas.
However, there is no significant difference in the effect of spot reduction and the generalized effects of
exercise on fat distribution
Muscles cannot obtain energy from adipose tissue that just happens to be close to them, blood supplies
the nutrients and oxygen that your muscles need. When in negative caloric balance, fat is mobilized
from areas in the reverse pattern of where fat was last deposited regardless of how exercise is
performed
Spot Reduction
Studies have shown that vigorous exercise of moderate duration does not markedly increase appetite
and food intake. Physical activity is necessary for the normal functioning of the brain's feeding control
mechanisms. A fine balance between energy expenditure and food intake is frequently not maintained
in sedentary people. Daily caloric intake generally exceeds energy requirement.
Exercise Effects on Appetite
“It takes a ridiculous amount of physical activity to lose a pound of fat.” People who make this
statement do not understand that the calorie-expending effects of exercise are cumulative. Running
10 kilometres per day, you will lose one pound of fat in five days, because the calorie-expending effects
of exercise are cumulative. If he runs only five kilometres per day, he will lose one pound of fat in 10
days.
If a 70-kilogram man runs 10 kilometres per day, he will expend an extra 70 ´ x 10 = 700 kcal of energy
per day. Therefore, in five days, he will expend 5 ´ x 700 kcal = 3500 kcal = 1.0 lb. of fat. In 30 days, he
will expend an extra 21,000 kcal = 6 lbs. of fat. It isn’t that simple, due to other factors affecting
hormones and metabolic rate, but it does show the potential for the cumulative effect of exercise.
Exercise Effects on Energy Expenditure
Intense exercise in a training program is optimal in terms of aerobic fitness and strength gains, as well
as improving body composition (you don’t have to perform intense exercise to experience health
benefits from exercise). If intensity level is low, your work out will have to be a longer durations if
your plan is to reduce body fat percentage
The energy cost of walking increases directly with body weight, for horizontal walking on grass/paved
surface, the net energy cost is approx. 0.75 kilocalories/kg for every km (0.55 kilocalories per pound
every mile). This applies as well to walking speeds 2-4 mph
Surface type effects energy cost, walking on sand is 1.8x than walking on a firm surface, and the
energy cost is significantly higher when walking in snow/uphill. The efficiency of walking changes
with speed such that, at 5mph, the energy cost of walking and jogging the energy cost of walking and
jogging is similar; at 6-7mph, the energy cost of walking is higher
The caloric cost of running a given distance is approximately the same whether the speed is fast or
slow. For horizontal running, the net energy cost is estimated as one kilocalorie/kg for every km (0.73
kilocalories/pound per mile)
Is it better to work on increasing speed of running or distance? The answer, from perspective of a
simple energy-expenditure calculation, is clearly to increase distance, not speed. But interval sprint
work or high-paced running will elicit hormonal responses and increased core temperatures, which
will result in your burning additional energy for a much longer time after exercise, compared to low-
intensity work. Also, a faster pace will allow more distance to be covered in a given time, so more
calories will be expended in a given period of time.
The landing impact in running results in a force equal to 3x your body weight. Because walking has no
airborne phase that must be controlled, the forces are much lower (1.2x body weight). For these
reasons, heavier individuals often develop lower limb injuries if they try to incorporate too much
running in their training program. As with most things a combination of low-intensity and high-
intensity work is best.
Walking versus Running
THE BOTTOM LINE (NO PUN INTENDED)
Modify your diet (usually a reduction of refined, processed carbohydrate and a reduction of total
calories are key factors).
Move whenever possible (take the stairs rather than the elevator, walk rather than drive).
Exercise for quite long periods of time when doing low-intensity endurance activities (45 minutes or
more); rest periods may help, but total work time needs to be high when doing low-power exercises.
If short on time, exercise as intensely as is safe for you (start carefully but work up to where you can
tolerate intense exercise). High-intensity interval training is an excellent way to lose body fat.
Include resistance training in your exercise regime.
Be realistic about what you can achieve and focus more on fitness performance measures than on
body composition.
The list below should remind you of the above discussion on how to improve your body composition.
Basically you need to do the following:
Do not stress about it. The evidence suggests being a little overweight is probably quite healthy; being
chronically stressed out about your weight is definitely, unhealthy.
Chapter 10: Exercise to Improve Body Composition
Most people start exercising to "lose weight" or to "get in shape", in terms of physique this
would cause people to get "leaner" or more "toned", the problem with having a goal with
"losing weight" is not specific enough (does not adhere to SMART goal setting) and losing
muscle mass and decreasing bone density is not something most individuals want to do or
accomplish. Better termed goals are "losing body fat" or "increasing muscle mass", these goals
are more specific and one will know when they accomplish them.
What is the main reason most people start exercising? What is the problem with this outcome
measure?
1.
A study conducted an 8 week program with 40 obese women, these subjects were assigned to one
of four groups (control, diet only, weight training only, and diet and weight training). The group
that weight trained and dieted lost more fat than the other groups.
An important highlight from this study is the loss of muscle mass that occurred with the diet only
approach, if you are working out to improve your health diet alone is not sufficient
The conclusion of the study, the endurance-only group had lost a total of 3.5lbs, 3lbs of which was
fat and a 0.5 was muscle. On the other hand, the endurance and weight-resistive group lost 8lbs,
with an actual fat loss of 10lbs, and an increase of 2lbs of lean body weight.
Incorporating weight training may help you improve body composition more effectively than
aerobic endurance work alone.
Resistance training maintains or improves muscle mass due to overload. But, it also helps you
burn more calories because you are doing more. For many people, changing exercise mode makes
the workout more interesting. After 30 minutes of aerobic exercise, adding 30 minutes of
resistance work can be a more attractive proposition than continuing for an additional 30 minutes
of aerobic work.
Regardless of total body weight loss, if you lose body fat and gain muscle, you will “trim down
even if your weight remains constant. Muscle is about 18% denser than fat (muscle density = 1.06
g/mL and fat density = 0.9 g/mL). Therefore, if you stay the same weight but lose five pounds of
fat and gain five pounds of muscle, you get trimmer.
Discuss the evidence that combining resistance training, aerobic conditioning and diet is the best
policy to produce positive body composition changes.
2.
Regardless of total body weight loss, if you lose body fat and gain muscle, you will “trim down
even if your weight remains constant. Muscle is about 18% denser than fat (muscle density = 1.06
g/mL and fat density = 0.9 g/mL). Therefore, if you stay the same weight but lose five pounds of
fat and gain five pounds of muscle, you get trimmer.
How can you trim down and yet not loose weight?3.
Change in energy stores = Energy intake Energy expenditure
Basically, energy intake is not independent of energy expenditure, and the type of calories you
eat does affect your energy output. Energy intake and energy expenditure are dependent
variables. Sugar, high-fructose corn syrup, and easily digestible carbohydrates drive an insulin
response, and insulin drives fat storage. Restricting caloric intake but continuing to eat much of it
in the form of high-glycemic foods will make your body fight to maintain its fat stores and will
lower your metabolism, thus lowering your energy expenditure.
Explain the energy balance equation.4.
The problem with the traditional views of the energy balance equation is that health researchers
view the equations and its application to weight loss. By regarding energy in and energy out as
independent variables, they have ignored the large quantity of research that shows the importance
of quality as well as quantity (the vital importance of the type of calories consumed). Many who
prescribe exercise for weight loss and health improvement fail to understand the importance
of how the energy is expended. The focus is almost always just on quantity. But, the calories
consumed, the quality of the exercise performed is as important as the quantity of calories
expended.
What is the problem with traditional view of the energy balance equation namely that it is simply
an issue of quantities?
5.
What is meant that you cannot state that a "calorie is a calorie" is that the type of calories that
are consumed are very important and they are not all the same. The quality of those calories
(the type of nutrient and overall nutrient balance) is very important. Restricting caloric intake but
continuing to eat much of it in the form of high-glycemic foods will make your body fight to
maintain its fat stores and will lower your metabolism.
What do I mean by this statement in Chapter 10: So there is strong evidence that you cannot
simply state that a calorie is a calorie.?
6.
If you regularly eat too many high-glycemic foods, your body will secrete the hormone
insulin, in response to the rise in blood sugar that is brought on by eating high glycemic foods
Insulin drives the body to store the excess blood sugar as fat. We do not store a lot of energy in the
form of glycogen.
Insulin inhibits your body’s ability to mobilize fat out of adipose tissue and burn it as a fuel.
Therefore, high insulin levels work against fat loss.
Simple carbohydrates (e.g., high-fructose corn syrup, sugar, and white flour) increase blood sugar
levels the most, and increase insulin levels.
Very high total-carbohydrate quantities in diets also increase insulin levels.
Chronically elevated levels of insulin are responsible for metabolic syndrome, which includes
obesity, Type 2 diabetes, high blood pressure, and more.
What happens if you regularly eat too many high-glycemic foods? Be sure to discuss the hormonal
response to such foods.
7.
The endocrine (hormonal) response to exercise is vitally important. For example, hormonal
response to high-power activities includes increased levels of testosterone, insulin-like growth
factor, human growth hormone, and many others. Intense work also causes more cellular damage.
On the cellular level, exercise is a stressor that forces the body to rebuild tissue and strengthen
(hormones involved in this rebuilding process). Your metabolism stays elevated for much longer
after a high power activity, due to the action of adrenal gland hormones (epinephrine and
norepinephrine), as compared with a low power workout. This factor is often overlooked in terms
of the energy expended in an exercise session.
The adaptation and hormonal response to performing only long, slow, low-powered aerobic work
is less effective in driving a healthy hormonal response and a healthy body composition, that
includes adequate musculature in all regions of the body, good bone and connective tissue
density, and healthy body fat levels.
Why do I argue that the quality of exercise is very important and not simply how many calories
you burn during a workout?
8.
Set point theory is the body's internal control mechanism (a set point) controlled via the
hypothalamus which drives the body to maintain a particular level of body fat. This is why some
have difficulty in maintaining weight loss.
When a reduction of body fat is managed and drops below your natural set point, your body
attempts to resist this change and you conserve body fat by lowering your basal metabolic rate
(BMR: the amount of energy expended while at rest), which is the base level of your daily energy
expenditure
Different people have different set points which can be affected by hereditary, dietary and
environmental factors. Drugs such as nicotine and amphetamines as well as exercise are some
factors that may lower your set point, whereas dieting appears to have much less of an effect.
Explain the set-point theory.9.
3500 kilocalories
How many kilocalories are stored in 1.0 lb. of human adipose tissue?10.
No, he shouldnt have a difficult time maintaining his new body weight of 185lbs because he
has been progressively exercising for over a year, and if he continues to exercise and eat
healthy he shouldn’t face any problems in trying to maintain his new weight
An obese, 300 lb. man goes on a diet and progressive exercise program and over a period of one
year he reduces his body weight to 185 lbs. which represents a "normal" body weight for him. Is he
likely to have a difficult time maintaining this body weight of 185 lbs.? Explain.
11.
His body fat percentage would be lower even if he did gain 3kg of weight. This weight is due to
the fact that muscles are 18%more dense than fat and his training method encourages muscle mass
and growth.
Describe the probably effects of a high force, low repetition weight-training program on the body
composition of a 20-year-old male. What would likely happen to his body fat percentage if he
gains 3 kg
12.
She would have lost fat and muscle by only participating in a running program
There is not much of a significant change in her body fat percentage since she lost fat, but also her
muscle
The proportion of fat vs. fat free weight remain relatively the same
Describe the effects of a running program on the body composition of a 30-year-old female. What
would likely have happened to her body fat percentage if she loses 3 kg?
13.
Endurance training and resistance training helps with weight loss because training both
aspects together will overall burn more calories will building and maintaining muscle
mass. Overall this will affect body composition because you will lost more fat (gain more
muscle) causing your body composition to "slim down" due to the loss of body fat.
How do endurance training and resistance training help with weight loss? How do they affect
body composition?
14.
Start to eat high nutrient dense food (avoid high glycaemic foods)
Exercise in both aerobic and resistance training to see the best results
Describe the advice that you would give to a 26-year-old female who wants to lose 10 lbs. of excess
fat.
15.
One shouldn’t reduce their caloric intake to less than 1200kcal a day because below this your body
stores more fat because less than 1200kcal your body thinks it is starving itself.
In order to lose 15 pounds of excess fat, a 30 year old, sedentary female decides to decrease her
caloric intake to 600 kcal per day. Using only this method, she plans to lose 15.5 lbs. in 5.5
weeks. Is this a weight loss method that you would recommend? Give reasons to justify your
answer.
16.
The reason why you cannot eat as much as you want anymore because your basal metabolic rate
decreases as you get older so your metabolism is not working at as high as a level so you do not
burn as many calories.
A 49-year-old accountant says to you: "When I was young, it seemed that I could eat as much as I
wanted without gaining weight. Why does everything that I eat now seem to turn to fat?" Describe
the answer that you would give to this person.
17.
Direct calorimetry is a direct measure of heat production
Indirect calorimetry is an indirect estimate of energy production by measuring oxygen
consumption. Oxygen consumption can be converted to energy production
Define indirect and direct calorimetry.18.
While caloric cost of steady-state running and other cyclic activities are easier to estimate, these
can be influenced by hormonal balance and mechanical efficiency
What is the problem with calorie cost tables?19.
Working at a lower intensity during exercise will burn a greater percentage of calories
from fat, but if you work at a higher intensity you will overall burn more calories which
will cause you to lose a greater percentage of body fat because you will have a greater
calorie deficit.
Working at a higher intensity overall during exercise is that there may be a increase in
body temperature which will cause your metabolism to increase and will work at a higher
level for a longer period of time. In addition, high-intensity exercise may increase muscle mass
and have a slight effect of increasing your endurance to do more activity throughout the day.
Working at lower intensities during exercise does not raise your metabolism at all and has no
effect on it as well after exercising has ceased (causing you to burn fewer calories and to lose less
weight).
Weight training and other high intensity exercise will increase muscle mass, and metabolically
active than adipose tissue. Muscle burns 10 kilocalories per kilogram of muscle (or slightly less
than 5 kilocalories per pound), fat burns approximately 2kilocalories per pound per day
A friend wants you to go to a "fat-burner" exercise class with her. This class has a fairly low
intensity level and you find that you could work at a higher intensity. When you tell your friend
this she says that you will not loose as much fat if you work at the higher intensity and that this
class is a better option for weight management. Explain what your response to her would be.
20.
Spot reduction is an attempt to focus exercise on one body part and to lose fat in a particular area,
this usually involves localized exercises in belief that the muscle utilizes fat stores in the active
areas. However, there is no significant difference in the effect of spot reduction and the
generalized effects of exercise on fat distribution
Muscles cannot obtain energy from adipose tissue that just happens to be close to them, blood
supplies the nutrients and oxygen that your muscles need. When in negative caloric balance, fat is
mobilized from areas in the reverse pattern of where fat was last deposited regardless of how
exercise is performed
Does spot reduction work? Explain.21.
You would need to burn 3500kcal to loose 1lbs of fat, so if you burned 500kcal a day when
exercising and had a deficit each day of 500kcal, in one week you would lose 1lbs of fat from
exercising.
A friend tells you "It takes a ridiculous amount of physical activity to lose a pound of fat so only
diet is important in weight loss”. How would you respond to this statement?
22.
As we move further into the course some questions may require you to use earlier material -to combine
many aspects of the course into the design of exercise programs.
Chapter(10
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Having a goal of "losing weight" is not correct, for one due to it does not adhere to SMART goal setting
and is not very specific, since losing weight could be due to losing muscle mass and decrease bone
density. Therefore these common goals are better termed by wanting to "lose body fat" or "increase
muscle mass" etc. These adhere more to SMART goal setting
Accurately measuring if you achieved these goals is very difficult and expensive (through DEXA,
assesses body composition), just stepping on a scale is not as accurate because you may have lost body
fat and gained muscle and this would not show if you step on the scale.
Even though these goals appear valid, they are worried about weight training and "bulking up"
WEIGHT LOSS AS THE HOLY GRAIL OF THE FITNESS INDUSTRY
Strength is developed by improving neuromuscular efficiency and increasing muscle size, and younger
males who have higher levels of testosterone tend to increase strength by increasing muscle mass
whereas females and older males tend to rely on more improvements in neuromuscular efficiency
A study conducted an 8 week program with 40 obese women, these subjects were assigned to one of
four groups (control, diet only, weight training only, and diet and weight training). The group that
weight trained and dieted lost more fat than the other groups. (results shown in table 10.1)
Strength, Muscle, Fat, and Body Composition
An important highlight from this study is the loss of muscle mass that occurred with the diet only
approach, if you are working out to improve your health diet alone is not sufficient
Health includes being able to function independently later in life, so dieting and losing muscle mass is
not a good strategy to keep you independent as you age.
The conclusion of the study, the endurance-only group had lost a total of 3.5lbs, 3lbs of which was fat
and a 0.5 was muscle. On the other hand, the endurance and weight-resistive group lost 8lbs, with an
actual fat loss of 10lbs, and an increase of 2lbs of lean body weight.
Incorporating weight training may help you improve body composition more effectively than aerobic
endurance work alone.
Resistance training maintains or improves muscle mass due to overload. But, it also helps you burn
more calories because you are doing more. For many people, changing exercise mode makes the
workout more interesting. After 30 minutes of aerobic exercise, adding 30 minutes of resistance work
can be a more attractive proposition than continuing for an additional 30 minutes of aerobic work.
Regardless of total body weight loss, if you lose body fat and gain muscle, you will “trim down even
if your weight remains constant. Muscle is about 18% denser than fat (muscle density = 1.06 g/mL and
fat density = 0.9 g/mL). Therefore, if you stay the same weight but lose five pounds of fat and gain five
pounds of muscle, you get trimmer.
Individuals who eat correctly, exercise correctly, and manage their stress level appropriately will
maintain a healthy body composition (unless there is an underlying disease e.g. metabolic)
Performance measures are better indicators of health and fitness, performance could be measured in
terms of workout or competition results (e.g. fitness test results), blood lipid profiles, ECG, liver
function, and glucose tolerance tests
WEIGHT MANAGEMENT
One main message is that nutrition research has been conducted very poorly because of bias, most
studies have been structured to prove that low-fat diets are good for you rather than being objective
and looking at the effects of diets without and pre-conceived beliefs
Insulin:a hormone that regulates carbohydrate and fat metabolism. When you secrete insulin it
signals cells in the liver, muscle, and adipose (fat) tissue to take up sugar from the blood. In the liver
and muscle glucose is stored as glycogen and in adipose tissue it is converted to fat.
Glycemic index (GI) is a measure of the effects of foods on blood sugar levels. Carbohydrates with a
high GI rating can be digested quickly causing a rapid rise in blood sugar levels. Carbohydrates that
break down more slowly, releasing glucose more gradually into the bloodstream, have a low GI. Often
this rapid rise in blood sugar results in a rise in insulin levels.
Dietary Fat and Body fat
THE ENERGY BALANCE EQUATION
When it comes to weight control, many have used the first law of thermodynamics (conservation of energy)
and the energy balance equation (EBE) to promote low-fat diets. The EBE states:
However, most weight loss programs have simply (and wrongly) treated energy intake and energy
expenditure as two independent variables. Therefore, the message conveyed is that individuals who
want to lose weight need to focus on decreasing caloric intake, increasing energy expenditure, or a
combination of the two. This might appear reasonable, since a gram of fat is nine calories, and
protein and carbohydrate are approximately four calories per gram, this approach would seem to
support low-fat diet is best for weight loss.
Change in energy stores = Energy intake Energy expenditure
Some individuals tend to gain more weight due to the food we eat elicits hormonal responses, which
determines how energy is stored in the body (aka fat). Therefore energy intake is not independent of
energy expenditure, and the type of calories you eat does affect your energy output. Energy intake
and energy expenditure are dependent variables. High sugary foods and easily digestible
carbohydrates trigger an immune response, and insulin drives fat storage
The fat storage and release of fat from adipose tissue (fat cells) is hormonally driven, e.g. the
hormonal response to pregnancy stimulates fat accumulation in order to build energy stores (fat
usually stored in the butt, thighs and breasts) for the mother and fetus. This energy will move out of
cells when the energy is needed during pregnancy/lactation. After birth, if exercise is assumed with
good nutrition she will return to a normal amount of adipose tissue for her body regardless of
calories consumed
So what are cause and effect in the EBE? Do you necessarily store energy just because you eat more?
poor eating habits (not simply eating too many calories, it is food high in carbs/refined sugars) that
cause a hormonal response, which then forces the body to store excess calories as fat.
It has been shown that restricting total carbohydrates, along with eating only carbohydrates that are
low on the glycemic index is the most effective for weight control and good health
Another way to demonstrate that the EBE is controlled by hormonal response is to look at growing
children, children grow due to the influence of hormones. Hormones stimulate their appetite and
dictate how this excess” of nutrients is stored. When children eat and exercise properly, the growth
will be primarily vertical and include muscle, bone, and organ growth as well as some adipose tissue.
For an adult eating a diet high in easily digestible carbohydrates, the hormonal response will cause
growth in the form of fat accumulation.
Studies have shown that individuals on low-calorie weight-loss diets tolerate high-fat, high-protein,
low-carbohydrate diets better than low-fat diets. Despite low overall calorie intake, they do not
report feeling hungry all the time, and their metabolism does not slow down in an attempt to
maintain fat stores.
Your body secretes the hormone, insulin, in response to a rise in blood sugar.
Insulin drives the body to store the excess blood sugar as fat. We do not store a lot of energy in
the form of glycogen.
Insulin inhibits your body’s ability to mobilize fat out of adipose tissue and burn it as a fuel.
Therefore, high insulin levels work against fat loss.
Simple carbohydrates (e.g., high-fructose corn syrup, sugar, and white flour) increase blood
sugar levels the most, and increase insulin levels.
Very high total-carbohydrate quantities in diets also increase insulin levels.
Chronically elevated levels of insulin are responsible for metabolic syndrome, which includes
obesity, Type 2 diabetes, high blood pressure, and more.
So when you are looking at the energy intake variable in the EBE, a calorie is not just a calorie. All
calories are not equal; the quality of those calories (the type of nutrient and overall nutrient balance)
is very important. Restricting caloric intake but continuing to eat much of it in the form of high-
glycemic foods will make your body fight to maintain its fat stores and will lower your metabolism.
Energy Intake
Understanding the relationship between exercise and weight control lies in understanding the body's
hormonal response to exercise. Most epidemiological evidence looks at subjects doing low power
activities such as walking, jogging and cycling for 20-60 minutes. These modes are less than ideal for
improving aerobic conditioning and ineffective at stimulating significant production of testosterone,
human growth hormone etc. that are involved in optimal health and body composition. Chronic low
power output endurance exercise has been shown to lower testosterone levels in male subjects
The "calorie is a calorie" logic is flawed with regard to energy intake, similar to the type of calories
consumed makes a difference.
Interval work (series of sprints) burns more body fat than steady-state cycling, the sprint-interval
group did the same amount of external work and yet lost more body fat, which correlates with the
notion that high power outputs elicit hormonal responses that low power outputs
If sprinting is to intense, there is some evidence that simply breaking up your workout can be
beneficial allowing time for a rest period burned more fat than exercising for one continuous session
A greater amount of fat breakdown (lipolysis) was seen from performing two 30 minute sessions than
one 60 minute session. The repeated trial also caused a greater increase in free fatty acids and glycerol,
which is released when stored fat is burned. As well increased levels of epinephrine increased while
levels of insulin and blood glucose decreased significantly more than during the single session, which
may have further contributed to fat breakdown and enhanced fat metabolism.
Clearly, if you are doing the same amount of work in two different exercises and yet find one type of
exercise more fatiguing, and if you do the same amount of work and yet lose more subcutaneous body
fat with one type of exercise, then something else is going on other than calories expended. One factor
is that we are measuring external work (how far you move your body and in what time frame).
However, the actual total energy (internal and external) cost of acceleration (overcoming inertia) is
very high.
In athletic performance, acceleration requires a huge effort and use of resources (energy). And
overcoming inertia (accelerating, lifting, resisting, and changing direction) is a key factor in athletic
performance. Olympic lifts and maximal sprints use an incredibly high number of muscle fibres in the
explosive effort to produce high accelerations. Although squats and deadlifts are slow lifts, the sheer
weight being lifted also means they are very taxing lifts that will stimulate positive hormonal
responses.
The endocrine (hormonal) response to