Slide 1 - PBRC HOME by jizhen1947


									 Exercise and Your Health

Pennington Biomedical Research Center
          Division of Education
First, we’ll need to define some terms…
1.   Homeostasis: This refers to the ability or
     tendency of an organism or cell to maintain
     internal equilibrium by adjusting its
     physiological processes. Once a weight loss
     or desired weight is achieved, this is what
     you want. This is what your body strives for
     at all times.

2.   Energy Expenditure: The act or process of
     using up energy. This is one component that
     must be considered when striving to achieve

3.   Thermogenesis: Generation or production of
     heat, especially by physiological processes.
     This is one of three components to energy

                                       2009         2
First, we’ll need to define some terms…
4.   Basal Metabolism: The minimal amount of
     energy required to maintain vital functions
     in an organism at complete rest. This is
     measured by the basal metabolic rate
     (BMR) in a fasting individual who is resting
     in a warm and comfortable environment.

5.   Satiety: The condition of being full or
     gratified beyond the point of satisfaction.
     Often times, we ignore this feeling or fail
     to notice it when eating.

6.   Hunger: Refers to a strong desire or “need”
     for food. It is the discomfort, weakness, or
     pain caused by a prolonged lack of food. It
     is not the same as appetite, or craving
                                         2009       3
                     Energy Expenditure
 Made up of three dominant components:

        Basal metabolism
        Thermogenesis
        Physical activity

 Thermogenesis includes the dietary-induced and
    thermoregulatory components

 Only physical activity has a substantial element of
    voluntary control.

                                           2009         4
                Energy Intake

 Energy intake, on the other hand, is
   entirely voluntary, except in clinical

 Therefore, the modifiable aspects of
   the energy balance equation amount
   to just two variables:
      Physical activity
      Food intake

                                  2009      5
                          The Two Sides to Over Eating

                  Under Activity                             Over Eating
                    Driven by the                             Driven by the
                    technological                              agricultural
                      revolution                               revolution

     Inactivity, combined with overeating appear to be the largest contributors to the
 obesity epidemic. When energy intake (energy in) and physical activity (energy burned)
  are at balance with one another, the body is at homeostasis. There is no weight loss,
            and there is no weight gain. Weight is simply maintained where it is.         6
2009     This is the ideal situation, provided the individual is at a healthy weight.
                         Set Point Theory
                              Body homeostasis
 Previous animal experiments indicate that there is
   a “set point” of body weight that is correctly
   defended under most conditions.

 Studies have demonstrated that there are natural
   feedback systems capable of regulating energy
   homeostasis with great precision in animals.

 The same is true for humans. The body wants
   there to be a balance between energy intake and

                                              2009     7
            Overview of Energy Balance
 When energy intake is greater than energy
   expenditure, there is a net weight gain                       The Energy Balance
        Energy intake > Energy expenditure = weight gain

 When energy intake is less than energy
   expenditure, there is a net weight loss
        Energy intake < Energy Expenditure = weight loss                         Output

 When energy intake and energy expenditure are at
   equilibrium with one another, weight is maintained
        Energy intake = Energy Expenditure = weight        Calories             Calories Used
         maintenance                                        From Foods           During Physical

         To lose weight, an energy imbalance
       eliciting an energy deficit is required.
    This can be done through dieting, exercising,
               or a combination of both.
                                           2009                                          8
                        Set Point Theory
                              Body homeostasis
 However, these feedback loops have been shown to only
    function appropriately within the settings in which they
    were originally developed. They have been shown to be
    easily disrupted by changes in the external environment,
    such as inactivity and the over consumption of energy-
    dense foods.

 In experimental animals, research shows that their ability
    to regulate energy balance was impaired once their
    movement was restricted and they were forced to
    become physically inactive.

 In addition, when their low-fat laboratory chow was
    replaced by a “cafeteria diet” with energy-dense and
    highly palatable foods, extreme obesity with massive fat
    deposition was the outcome.

                                            2009               9
                        Set Point Theory
                             Body homeostasis
 Similar outcomes have been noted in experiments involving humans where normal
   lean volunteers were asked to eat a diet prepared for them at the amount that they
   would normally consume per meal.

 These individuals were unaware that the fat content (and hence energy density) of the
   diets differed between each of the three dietary treatments.

 Energy balances were shown to be strongly influenced by the energy densities of the
   diets. This was believed to be due to a physiologic failure to recognize that the energy
   content of the diets differed and so, appetite or energy expenditure was not modified

                                            2009                                          10
               Physical Activity and Food Intake
 A survival imperative common to all mammals is:
        The ability to maintain the body’s energy reserves in the form of hepatic (liver) and
         muscle glycogen, together with at least a limited supply of fat

 These energy reserves are necessary to support basic physiologic and immune
   functions, and to mount fight or flight responses.

 Because of these essential needs, hunger is believed to have evolved to be a strong
   physiologic drive made up by robust neuro-endocrine mechanisms, which are
   protected by multiple levels of redundancy.

 The same is true for humans.

                                             2009                                           11
               Physical Activity and Food Intake
 Due to recurrent periods of food shortage and famine
   throughout time, it is believed that evolutionary pressures led
   to the ability for fat storage to well exceed that which is
   needed for day-to-day survival in humans.

 As a result, there has never been the imperative to develop
   strong satiety mechanisms.

 This imbalance between effectiveness of hunger and satiety
   signals is believed to lead to an asymmetry in appetite control.
   This could possibly explain why current lifestyles create such
   a high level of susceptibility to obesity in most individuals.

                                            2009                      12
               Physical Activity and Food Intake

 Because of this imbalance, many individuals have to
   learn to adopt cognitive dietary restraints in place of
   their natural physiologic regulatory system in order to
   maintain leanness.

 With the previous evidence in mind, this provides
   further support on the importance of exercise in aiding
   in body weight regulation.

                                            2009             13
              Physical Activity and Food Intake
 Consequences of this asymmetry in appetite control
   are believed to be further confounded by marketing
   trends towards larger portion sizes and increased
   energy density of foods, each of which opposes the
   need of adapting a lower calorie intake in a
   progressively more sedentary world.

                                          2009          14
           The Importance of Exercise

 There are a number of published studies indicating that
    physical activity benefits stable weight maintenance,
    especially after a weight loss.

 The real benefit is not particularly during the weight loss
    itself, although it does contribute to the weight loss when
    combined with a dietary restriction, but more so in
    maintaining the weight loss once it is achieved.

                                              2009                15
           The Importance of Exercise
 The importance of exercise in aiding in weight
   maintenance is due to reasons discussed previously
   with respect to the asymmetry in appetite control, but
   is also due to the physiological effects of exercise in
   enhancing well-being and status of control, and hence
   compliance with a restrictive dietary regime.

 It is important to remember that there are many
   additional benefits of exercise. The benefits of exercise
   are not limited to just those previously discussed.

                                            2009               16
              The Importance of Exercise
                      It is beneficial in that it:
 Reduces your risk of heart disease, high blood
    pressure, osteoporosis, diabetes, and obesity
   Reduces both total blood cholesterol and
    triglycerides and increases high-density
    lipoproteins, known as the “good” cholesterol.
   Reduces your risk for having a second heart attack
   Reduces your risk of developing colon cancer.
   Contributes to mental well-being and helps to
    treat depression
   Helps relieve stress and anxiety
   Increases your energy and endurance

                                           2009          17
              The Importance of Exercise
                       It is beneficial in that it:
 Helps you maintain a normal weight by
    increasing your metabolism.
    (the rate in which your burn calories)
   Helps you sleep better.
   Keeps joints, tendons, and ligaments flexible so
    it’s easier to move around.
   Reduces some of the effects of aging.
   Helps older adults become stronger and better
    able to move about without falling or becoming
    excessively fatigued.

                                            2009       18
 Physical Activity &Coronary Heart Disease
 A major, underlying risk factor for coronary heart
    disease is inactivity.

 In a study published in JAMA, men, who were initially
    unfit and became fit, were found to have a 52%
    lower age-adjusted risk of cardiovascular disease
    mortality than their peers who remained unfit.

 Regular physical activity has been shown to impact
    blood pressure beneficially.

 One study found that for every 26.3 men who walked
    more than 20 minutes to work, one case of
    hypertension would be prevented.

                                            2009          19
Physical Activity &Coronary Heart Disease
 It is important to note that these acute effects of exercise
  on blood pressure lowering do not require vigorous
  efforts. They can be achieved at 40% of maximal capacity
  during exercise.
 Blood lipids play a major role in the development of
  atherosclerosis, which is the underlying cause of
  coronary heart disease.
 Moderate to vigorous-intensity aerobic exercise training
  has been shown to improve the blood lipid profiles of
 The most commonly observed changes have been:
  increases in High density lipoprotein cholesterol (HDL),
  with reductions in total blood cholesterol, low-density
  lipoprotein cholesterol (LDL), and triglycerides.

                                             2009                20
 Physical Activity and Type 2 Diabetes
 Physical activity is associated with:
        A reduced risk of type 2 diabetes
        Improved insulin sensitivity
        Glucose homeostasis

 From participating in physical activity 30
    minutes/day, overweight subjects were able to
    reduce their risk of getting type 2 diabetes by
    58% in a recent study.

 Physical inactivity has been shown to elevate the
    risk of developing type 2 diabetes in normal-
    weight individuals as well.

                                               2009   21
Physical Activity & Overweight/Obesity
 Physical activity appears to be an important
  component in weight stability for healthy individuals.
 In a recent study looking at the effects of physical
  activity on body composition in 3,853 healthy
  subjects between the ages of 15 and 64, it was
  concluded that physical activity is able to limit both
  fat mass and weight gain in men and women.
 Many studies are in agreement with one another
  when stating that exercise + diet lead to greater
  weight losses than just diet-alone.
 In a review of 11 studies looking at the influence of
  both exercise and diet on weight loss, the average
  weight loss of the diet-only group was shown to be
  6.7 kg; whereas, the average weight loss of the diet
  + exercise group was 8.5 kg.

                                            2009           22
Physical Activity & Overweight/Obesity
 Weight loss is not only achieved, but is
    also maintained through physical activity.

 In 2001, a study was conducted on 3000
    previously obese subjects, who reported a
    weight loss of 30 kg, on average, which
    was additionally maintained for an
    average of 5.5 years.

 When looking at those who did not
    continue to participate in physical activity,
    it was found that only 9% of these
    participants were able to maintain their
    weight loss in the absence of physical              This further supports the
    activity.                                         importance of exercise in the
                                                       prevention of weight regain.
                                               2009                               23
  Physical Activity & Overweight/Obesity

 The optimal amount of weekly exercise necessary to
    prevent weight gain is still a topic under much debate.

 The current recommendations include, at a minimum,
    150 minutes/wk of moderate-intensity exercise, or 30
    minutes a day on most days of the week (5 or more).

 This should be the initial targeted amount of exercise
    each week

                                             2009             24
  Physical Activity and Appetite Control

 Physical activity has the potential to adjust appetite control by:
        Improving the sensitivity of the physiological satiety signaling system
        Adjusting macronutrient preferences or food choices
        Altering the hedonic (pleasurable) response to food

 There exists a belief that physical activity drives up hunger and
    increases food intake, thereby rendering it useless as a means of
    weight control.

 In a recent study, researchers set out to examine this very idea.

                                          2009                                     25
Physical Activity and Appetite Control
                              Recent Findings
 Short term (1-2 day) and medium term (7-16 day) studies demonstrated that men and
    women can tolerate substantial negative energy balances when performing physical
    activity programs.
   The immediate effect of taking up exercise is weight loss.
   This isn't always easy to assess; however, due to changes in body composition or fluid
    compartmentalization that arise.
   Once around 30% of energy is expended in activity, food intake then begins to
    increase in order to provide compensation for this loss.
   This compensation (up to 16 days) is partial and incomplete.

                                            2009                                         26
 Physical Activity and Appetite Control
                             Recent Findings
 Subjects have been separated into compensator and non-compensator groups.
 The exact nature of the differences noted in these 2 groups has yet to be determined.
 Some subjects performing a set routine of activities for a 14 day period showed no
  differences in energy intake.
 More studies are needed to further classify individuals who are compensators versus
  non-compensators and to identify the mechanisms responsible for the rates of
  compensation and its limits.

                                           2009                                           27
       Physical Activity and Osteopenia
 Everyday physical activity has a positive
    effect on skeletal mass.

 It has been suggested that electrical
    currents are developed when bone is
    mechanically stressed, leading to the
    formation of new bone.

 When comparing whole body, leg, and
    trunk body mineral densities in women
    who walk 7.5 miles/week versus those
    who walk 1 mile per week or less,                Normal bone   Osteoporotic bone
    women in the group with the most
    distance were shown to have significant
    increases in bone density.

                                              2009                               28
       Physical Activity and Sarcopenia
 Sarcopenia can be defined as the age-
  related loss of muscle mass, strength, and
 Physically active subjects aged over 65
  years have a significantly higher level of
  lean tissue mass than sedentary
 It has also been shown that healthy older
  people can safely tolerate higher intensity
  strength training with improvements
  comparable with those seen in younger

                                           2009   29
Physical Activity & Psychological Disorders
 Physical activity is associated with elevations in mood states
    and heightened psychological well-being.

 On the other hand, inactive persons have been shown to be 1.5
    times more likely to become depressed than those who
    maintain an active lifestyle.

 Physical activity is believed to be protective against the
    development of Alzheimer’s disease.

 This is believed to be due to increased blood flow, which may in
    turn promote nerve cell growth.

 It has been suggested that people who are intellectually and
    physically inactive have a 250% better risk of developing the
                                             2009                    30
                  The Truth on Exercise
 The bad news is that people still
   are not getting enough exercise.

 This map specifically looks at
   physical activity trends in women
   and finds that only 4 in 10 women
   are engaging in the recommended
   levels of activity.

 Activity has been shown to
   generally decrease with age, and is
   less common among women than
   in men and among those with lower
   income and less education.

                                       Source: CDC. Behavioral Risk Factor Surveillance System, 2001.
                                                   Photo from:               31
 Inactivity leads to a loss of muscle, to obesity, and to
    reduced functional ability.
   Low physical fitness increases the risk for
    cardiovascular disease, diabetes, and some cancers.
   Individuals who are physically fit can do more things,
    have better endurance for activities and tasks, and
    are healthier than individuals with low fitness.
   Even small increases in physical activity can make a
    big difference to an individual’s health.
   Try to incorporate small changes into your daily
    activities. This, in time, will gradually improve your
    fitness, leading to a better you.

                                             2009            32
    Physical Activity and Physical Fitness
                     What’s the difference?

 Physical activity is defined as any bodily
    movement produced by skeletal muscles
    that results in an expenditure of energy.

 Exercise is defined as a subset of
    physical activity that is planned,
    structured, repetitive, and purposeful.

 Physical fitness is a measure of one’s
    ability to perform physical activities that
    require endurance, strength, or
    flexibility, and is determined by a
    combination of regular activity and
    genetically inherited ability.

   Simply put, fitness is good, but physical
    activity is a must!

                                        2009      33
                         Types of Exercise
              Aerobic, anaerobic, and resistance

             Aerobic exercise is exercise that involves
               large muscle groups (arms and legs) in
               dynamic activities that result in substantial
               increases in heart rate and energy
Anaerobic                                                            Aerobic

             Anaerobic exercise is exercise done at very
               high intensities such that a large portion of
               the energy is provided by glycolysis and
               stored phosphocreatine. These activities
               build and tone muscles, but are not as
               beneficial to the heart and lungs as aerobic
               activities are.

             Resistance exercise is exercise designed
               specifically to increase muscular strength,
               power, and endurance by varying the
               resistance, the number of time the
               resistance is moved in a single group (set) of
               exercise, the number of sets done, and the
               rest interval provided between sets.             Resistance   34

  Aerobic                  Anaerobic

 Brisk walking            Baseball
    Dancing               Sprinting
    Jogging                Tennis
   Bicycling            Weightlifting
    Skating               Leg lifts
   Swimming              Arm circles
Snow shoveling            Curl-ups
 Lawn mowing               Dusting
  Leaf raking           Doing laundry
  Vacuuming            Washing windows

                    2009                 35
        Physical Activity for Everyone
 Everyone can benefit in some way by regular physical activity. Whether you are trying
    to maintain a weight loss or just feel more energetic when you incorporate exercise into
    your daily activities. There are also the benefits later in life from exercising. These
    include reductions in the risk of developing chronic diseases and overall improvements
    in your quality of life.

                                            2009                                          36
           Who Benefits and How?
   Older adults:  No one is too old to enjoy the
    benefits from regular physical activity.
    Evidence indicates that muscle-strengthening
    exercises can work to reduce the risk of
    falling and fracturing bones, and can improve
    the ability to live independently.

   Parents and children: Parents can help their
    children maintain a physically active lifestyle
    by providing them with encouragement and
    opportunities for exercise. Outings and
    family events are encouraged, particularly
    when everyone in the family is involved.

                                                      Centers for Disease Control
                                                        and Prevention (CDC)
                                      2009                                    37
           Who Benefits and How?
 Teenagers: Regular physical activity improves
   strength, builds lean muscle, and decreases
   body fat. Activity can build stronger bones to
   last a lifetime.

 People trying to manage their weight:
   Regular physical activity helps to burn
   calories while preserving lean muscle mass.
   Regular physical activity is an important
   component to any weight-loss or weight-
   maintenance activity.

 People with high blood pressure:
   Regular physical activity helps to lower blood

                                                    Centers for Disease Control
                                                      and Prevention (CDC)
                                   2009                                     38
         Who Benefits and How?

 People with physical disabilities, including arthritis:
   Regular physical activity for individuals with
   chronic, disabling conditions is important because
   it can help improve their stamina and muscle
   strength. It can also improve the quality of life
   by improving the individual’s ability to perform
   daily activities.

 Everyone under stress, including persons
   experiencing anxiety or depression:
   Regular physical activity has been shown to
   improve one’s mood, help relieve depression, and
   increase feelings of well-being.

                                                            Centers for Disease Control
                                                              and Prevention (CDC)
                                     2009                                           39
                          Getting Started
 You will first want to begin by speaking with your doctor.

 This is particularly important if you:
        Are elderly
        Currently smoke
        Have any health problems
        Are overweight or obese
        Have not been active in a while
        Are currently pregnant
        Are unsure of your health status
        Feel pain in your chest, joints or muscles during activity

 When it is okay to begin, you want to start out slowly. A good suggestion could be to
    begin with a 10-minute period of light exercise or a brisk walk every day. You can then
    gradually increase how hard you exercise for and how long.

                                              2009                                        40
    Ways to Improve Your Health
 Walking or jogging
 Swimming
 Bicycle riding
 Group exercises
 Weight-bearing exercise, such as weight lifting,
  resistance bands, or activities involving the
  whole body
 Stretching, such as yoga or tai chi exercises
 Participation in active sports, such as tennis,
  basketball, and soccer

                                          2009       41
 Ways to Add Activity to Your Day
 Park the car in the furthest spot from the entrance and walk the extra distance
 Get off of the bus one stop before your destination and walk
 Take the stairs instead of the elevator
 Take walking breaks during the work day
 Take a 10-minute walk during your lunch break
 Walk a dog or play outside with the kids
 Dance to your favorite music
 Use housecleaning as an exercise opportunity
 Ask a friend, family member, or coworker to walk with you

                                             2009                                   42
   Physical Activity Calorie Use Chart
         Activity      100 lb      150 lb     200 lb
Bicycling, 6 mph        160            240     312
Bicycling, 12 mph       270            410     534
Jogging, 7 mph          610            920    1230
Jumping rope            500            750    1000
Running, 5.5 mph        440            660     962
Running, 10 mph         850            1280   1664
Swimming, 25 yds/min    185            275     358
Swimming, 50 yds/min    325            500     650
                                                         The chart shows the
Tennis singles          265            400     535      approximate calories
Walking, 2 mph                                           spent per hour by a
                        160            240     312
                                                       100, 150 and 200 pound
Walking, 3 mph          210            320     416          person doing a
Walking, 4.5 mph                                          particular activity
                        295            440     572
Adults should strive to meet either of the following
       physical activity recommendations…

 Adults should engage in moderate-intensity physical
   activities for at least 30 minutes on 5 or more days of
   the week (CDC/American College of Sports Medicine).        While activity at a higher
   This 30 minutes per day can be accumulated in bouts          intensity or performed
   of 10 minutes throughout the day.                           longer does offer more
                                                             health benefits, this level of
                                                                 activity may not be a
                                                             realistic goal for everyone,
                                                              at least not to start with.
                                                              Again, work your way to
 Adults should engage in vigorous-intensity physical                 this, slowly,
   activity 3 or more days per week for 20 or more           by setting realistic goals for
   minutes per occasion (Healthy People 2010)                         each week.

                                           2009                                         44
           Moderate Intensity Activity
                                 What’s is it?
 This is an activity which generally causes a slight, but
    noticeable increase in breathing and heart rate. It may also
    cause light sweating.

 Some examples of moderate intensity activity include:
        Brisk walking
        Swimming
        Cycling
        Dancing
        Doubles Tennis

                                             2009                  45
   Exercise: A Healthy Habit to Start and Keep. Available at:
   Exercise: When to check with your doctor first. Available at:
   Physical Activity. Available at:
   Physical Activity Calorie Use Chart. Available at:
   The Journal of the American Medical Association (JAMA). Available at:
   Physical Activity for Everyone: The Importance of Physical activity. Available at:
   General Physical Activities Defined By Level of Intensity. Available at:
   Sarcopenia: The Mystery of Muscle Loss. Available at:
   Physical Activity and Weight Control. Available at:
   Aerobic or Anaerobic? Quick Activity. Available at:

                                             2009                                        46
   Melzer K, Kayser B, Pichard C. Physical activity: the health benefits outweigh the risks.
    Current Opinion in Clinical Nutrition and Metabolic Care. 2004; 7: 641-47.
   Prentice A, Jebb S. Energy intake/physical activity interactions in the homeostasis of
    body weight regulation. Nutrition Reviews. 2004; 62(7): S98-S104.
   Blundell JE, Stubbs RJ, Hughes DA, Whybrow S, King NA. Cross talk between physical
    activity and appetite control: does physical activity stimulate appetite? Proceedings of
    the Nutrition Society. 2003; 62: 651-661.
   Moore M. Interactions between physical activity and diet in the regulation of body
    weight. Proceedings of the Nutrition Society. 2000; 59: 193-198.
   Jakicic J, Otto A. Physical activity considerations for the treatment and prevention of
    obesity. Am J Clin Nutr. 2005; 32(suppl): 226S-9S.

                                             2009                                          47
About Our Company…
   The Pennington Biomedical Research Center is a world-renowned nutrition research center.
   Mission:
   To promote healthier lives through research and education in nutrition and preventive medicine.
   The Pennington Center has several research areas, including:
   Clinical Obesity Research
   Experimental Obesity
   Functional Foods
   Health and Performance Enhancement
   Nutrition and Chronic Diseases
   Nutrition and the Brain
   Dementia, Alzheimer’s and healthy aging
   Diet, exercise, weight loss and weight loss maintenance
   The research fostered in these areas can have a profound impact on healthy living and on the prevention of common
    chronic diseases, such as heart disease, cancer, diabetes, hypertension and osteoporosis.
   The Division of Education provides education and information to the scientific community and the public about research
    findings, training programs and research areas, and coordinates educational events for the public on various health
   We invite people of all ages and backgrounds to participate in the exciting research studies being conducted at the
    Pennington Center in Baton Rouge, Louisiana. If you would like to take part, visit the clinical trials web page at or call (225) 763-3000.                                                                                     48

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