“Those who think they have not time for bodily

exercise will sooner or later have to find time for illness”

Edward Stanley, Earl of Derby

December 20, 1873

Exercise Biology and Implications for Health Care

BMS 650Spring 2004

Karyn Esser, Ph.D.School of Kinesiology

Today, why do people exercise?

Athletic/Artistic Performance Physical appearance

HealthHow can we increase exercise for health reasons?education - require PE for schools?support - physicians, familyresearch - understand and define “dosing”, motivation,

molecular targets

Human beings have evolved with movement as a necessity for survivale.g. to obtain food, to escape predators

thus, numerous systems in the body are sensitive to movement.

What is Exercise? --- Physical ActivityMajor problem is that most information in the publicdomain comes from personal experiences and not based on sound research.

Points of lecture:

• Basic exercise information• Common exercise misunderstandings• Application of exercise for Health Care

 I've devoted my life to health and fitness and I recommend the Ab Mouse for people of all ages who want firm and tight abs.

Exercise Expert - Fitness Champion

Most Common Form of Exercise Education/Information

“Fitness experts” commonly are people who have performed well in competition and do not have any academic training in exercise

I. Basics of Exercise Physiology

Exercise is a complex molecular, cellular and systemicphysiological stimulus

With every single bout of exercise, skeletal muscles, heart, brain, vasculartissue, bone, liver, etc. experience some form of environmental “stress”. The type and magnitude of an adaptation or response to exercise thus

results from a sum total of all these contributing factors. Some examples include:

- mechanical, stress/strain- temperature- pH- redox state- free radical production- hormones/growth factors- calcium

Specificity of Exercise: Adaptations that occur in response to training are specific to the nature of the training stimulus

Cardiovascular fitness: requires that the persontrain in a manner that challenges heart rate, cardiacoutput, capillarity … with the underlying change beingimproved oxygen delivery to working tissues

Muscular strength: requires that the person train in a mannerthat challenges the recruitment and force output of specificmuscle groups … with the underlying change being increasedmuscle mass.

The corollary to this is that training for endurance will not augment strength or vice versa.

Also from research perspective, one must test the systemsone trains/challenges to determine efficacy. e.g. DMD Gene therapy trial

Cardiovascular fitness - endurance type activities: fuel challenginglarge muscle massrepetitivelower intensitywalking, running, swimming, cycling

Muscular strength: high resistance, high force outputfocus on muscle groups not on systemic “exercise”

e.g. knee extensors vs. flexors

Can a type of exercise be both strength and endurance?yes BUT the effectiveness of any one form of activity to elicita specific adaptation is dependent on the endurance/strength starting state of the individual.

Basic Principles of Exercise Training

Frequency - how often is the exercise performedeach week? For cardiovascular training effects3-4x per week is suggested

Intensity - the exercise must be performed at a level that challenges the cell/tissue/system for adaptations to occur.Totally dependent on starting state. Lower the starting fitnesslevel the lower the starting intensity. Must build to continue adaptations. Most important variable in training regimen for most.

Duration - length of each training session. For cardiovascularAdaptations it is suggested to start at 30 minutes/session

MORE IS NOT NECESSARILY BETTER!overtraining/system failure

Known adaptations to endurance exercise

Skeletal Muscle mitochondria capillary density oxidative enzymes

Heart heart volume max stroke volume max cardiac output resting heart rate blood pressure

Brain (very new studies) neurogenesis protection from seizures, injury

Bone density? Type of exercise

What is Maximum Oxygen Uptake?VO2 Max

Maximal amount of oxygen consumption per minute

The more muscle used the higher the oxygen use

Predictor of performance?

Correlates with changes in cardiac output

Training will result in an increasecardiac indices (CO, SV)skeletal muscle contribution (mito)ventilatory contribution?

Known adaptations to resistance exercise

Brain/Neural improved recruitment

Skeletal Muscle Fiber size Mitochondria?

Bone density

Aerobic exercise = rely only on oxidative metabolismAnaerobic exercise = do not rely on oxidative metabolismAnaerobic threshold = switch from aerobic to anaerobic metabolismFat-burning exercise = low intensity exercise to lose body fatBurning sensation = caused by lactic acidHigh protein diets = good for muscle buildingNo pain, no gain = only way exercise can be beneficialSit ups/leg lifts = make the waist/thighs smallerCaloric cost of running vs. walking = running mile > walking mile

Each of the statements above are wrong

Why do many hockey players wear nose strips? Why do many football players grab oxygen on sideline?

II. Significant Misunderstandings in Exercise

Role of exercise in weight and/or body fat control

Exercise can increase caloric expenditure

Exercise can spare loss of lean body mass during times of caloric deficit

Increases in lean body mass will increase basal metabolic rateBUT …. 10lbs of lean body mass will lead to about 70-80kcal/day

ALL forms of exercise will burn fat, even at Max VO2

Amount of fat burned during exercise is NOT important.

Total calories used during exercise IS important

For patients/clients, pick an exercise/activity modality thatthey will do and do regularly. Type of exercise less important

Calories in vs. Calories out

Surgeon General David Satcher:

- Obesity is reaching "epidemic proportions” in the United States- could soon cause as much preventable disease and death as cigarette smoking.

III. Application for Health CareObesityType II Diabetes

For the vast majority of individuals, overweight and obesity result from excess calorie consumption and/or inadequate physical activity.

Unhealthy dietary habits and sedentary behavior together account for approximately 300,000 deaths every year.

Many adult Americans have not been meeting physical activity recommendations to accumulate at least 30 minutes of moderate physical activity most days of the week.

In 1997, less than one-third of adults engaged in the recommended amount of physical activity, and 40 percent of adults engaged in no leisure-time physical activity.

Although nearly 65 percent of adolescents reported participating in vigorous activity for 20 minutes or more on 3 or more out of 7 days, national data are not available to assess whether children and adolescents meet the Federal recommendations to accumulate at least 60 minutes of moderate physical activity most days of the week.

Many experts believe that physical inactivity is an important part of the energy imbalance responsible for the increasing prevalence of overweightand obesity.

Our society has become very sedentary; for example, in 1999, 43 percent of students in grades 9 through 12 viewed television more than 2 hours per day.

Obesity and Exercise

Exercise and Type II DiabetesPosition statement ACSM

About 10.3 million diagnosed cases and about 5.4 million undiagnosed

Accounts for 90-95% of all cases of diabetes

Characterized by insulin resistance and moderate insulin deficiency

Skeletal muscle: site of about 80-90% of glucose uptakeinsulin and contraction act INDEPENDENTLY to increaseGLUT4 translocation and glucose uptake. Ideal target for exercise and/or pharmacological therapies

Acute Effects of Physical Activity

Glucose Levels

Most obese Type II diabetics experience decreases in bloodglucose following mild-moderate exercise

magnitude of effect is dependent on duration and intensity

blood glucose increases with short term high intensity exercise

Insulin resistance

Insulin resistant individuals have 35-40% reduction in insulin mediated glucose uptake

Low to moderate intensity exercise improves insulin sensitivity

High intensity exercise variable response

Transient effect (about 72 hrs) so requires regular activitynot really the “trained state”

Physiological Benefits of Exercise for those with Type II Diabetes

Lower resting heart rateLower sub-maximal exercise heart rateIncreased stroke volumeIncreased cardiac outputEnhanced oxygen extractionLower resting BPLower exercise BPInfluence lipid profile

Psychological Benefits of Exercise

Reduced stress response to psychosocial stimuliLessened sympathetic nervous system activation to cognitive stressReductions in depressionImproved self-esteemReduction in emotional perturbations to stress

Contribute to sustained behavioral changes and adherence

Exercise and Chronic DiseasesBooth et al., 2000

Cardiovascular DiseaseType II DiabetesObesityObesity related diseasesAging

While all these diseases have some contribution from genetic the rapid increases in the last 20+ years aredue to environmental factors.

Sedentary living is responsible for about 34% of deaths due to coronary heart disease, colon cancer and Type II diabetes

CDC has concluded that “physical inactivity is one of the major underlying causes of premature mortality in the US”

Take home message

1. Consider exercise/physical activity for both disease prevention as well as treatment

2. When considering exercise think movement or activity not athletic performance

3. Consider the importance of exercisefor children. Growing evidence for mental as well asphysical development. Educate for healthy lifestyle

4. Good resource for exercise and health informationAmerican College of Sports Medicine www.acsm.org

Commonly used terms in exercise

Improved Fitness - increase functional performanceIncreased Strength - increase ability to generate forceEndurance - increase ability to sustain activityMuscle tone - increased tonus, unknown causeLactacte threshold - exercise intensity at which blood

lactate levels rise significantly above baselineVO2 max - maximal oxygen uptake. Concentric contractionsEccentric contractionsIsometric contractionsOxygen consumption can be used to predict caloric cost