The Importance of ExerciseThe Importance of Exercise

Dr Reed A BergerDr Reed A Berger

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

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.

Benefits of ExerciseBenefits of Exercise Increased strength and muscular Increased strength and muscular

enduranceendurance Increased BMD—osteoporosisIncreased BMD—osteoporosisAging—decreased falls, increased Aging—decreased falls, increased

independence, increased ADLindependence, increased ADL Increased BMR—LBMIncreased BMR—LBMAppearance, self esteemAppearance, self esteem

Technology—fewer demands placed on Technology—fewer demands placed on musculoskeletal and CV systemsmusculoskeletal and CV systems

2-3 generations ago—manual labor2-3 generations ago—manual laborStairs, elevators, carsStairs, elevators, carsRecreation—playing ball, jumping, hide-n-Recreation—playing ball, jumping, hide-n-

seek vs. video games, internetseek vs. video games, internetConvenience and fast foodsConvenience and fast foods

Automation—decreased muscular Automation—decreased muscular demandsdemands

Body adapts—increased fast, weakerBody adapts—increased fast, weakerScheduled exercise used to not be needed Scheduled exercise used to not be needed

with manual laborwith manual laborToday, have to “give back” the leisure time Today, have to “give back” the leisure time

gained thru technology and purposely gained thru technology and purposely stress the muscular systemstress the muscular system

I. Basics of Exercise PhysiologyExercise is a complex molecular, cellular and systemic

physiological 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.

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 TrainingFrequency - 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

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

Exercise prescriptionExercise prescriptionTo treat various diseasesTo treat various diseasesPrimary prevention—PE classPrimary prevention—PE classClinically—discuss exerciseClinically—discuss exerciseWork—corporate wellnessWork—corporate wellnessEnd of college, athletic endeavors—need End of college, athletic endeavors—need

to have scheduled exerciseto have scheduled exercise60 min daily60 min daily

Aerobic and resistanceAerobic and resistanceConvenientConvenientTravelingTravelingPedometerPedometerMinutes per dayMinutes per day Intensity, duration, frequency (need to Intensity, duration, frequency (need to

vary)vary)

Routine exerciseRoutine exercise Improves tissue oxygen uptakeImproves tissue oxygen uptakeHDLHDLLDLLDLTG TG BPBPGlycemic controlGlycemic control

Decreased risk of CADecreased risk of CAEndometrialEndometrialBreastBreastColonColonprostateprostate

Cognitive benefitsCognitive benefits Better adjustedBetter adjusted Cognitive testsCognitive tests Decreased CV response to stressDecreased CV response to stress Anxiety Anxiety DepressionDepression People who were active and became inactive People who were active and became inactive

were 1.5x more likely to become depressedwere 1.5x more likely to become depressed CAD and depressionCAD and depression

Cognitive cont’dCognitive cont’d Improves self confidenceImproves self confidenceSelf esteemSelf esteemDecrease CV and neurohormonal Decrease CV and neurohormonal

response to stressresponse to stressShort bouts of exercise—cognitive Short bouts of exercise—cognitive

improvementimprovement

compliancecomplianceLong term adherence to exerciseLong term adherence to exerciseDecrease with age, minorities, females, Decrease with age, minorities, females,

disabled, chronic dzdisabled, chronic dzExercise program—50% cont for >6 moExercise program—50% cont for >6 mo

Types of exerciseTypes of exerciseOccupational, recreational, sportsOccupational, recreational, sportsAerobicAerobicAnaerobic—sprintAnaerobic—sprint Isometric—wtsIsometric—wts

Resistance trainingResistance trainingResistance to contracting muscles to Resistance to contracting muscles to

stimulate them for increased strengthstimulate them for increased strength Injury risk—decreasedInjury risk—decreasedLean tissue and agingLean tissue and agingHeart conditions—don’t strain or hold Heart conditions—don’t strain or hold

breathbreath

How to make exercise a lifetime How to make exercise a lifetime activityactivity

Pick activity that is enjoyable and uses Pick activity that is enjoyable and uses most musclesmost muscles

Vary duration, intensityVary duration, intensityGroup classesGroup classesMusicMusicWalk the dog!Walk the dog!Set goals—health, appearance, Set goals—health, appearance,

cholesterolcholesterol

ElderlyElderlyJoint flexibilityJoint flexibilityMuscle strengthMuscle strengthLBMLBMBalanceBalancePrevention of injuryPrevention of injury

Pulmonary dzPulmonary dzLow workloads, short durationLow workloads, short durationFrequent intervalsFrequent intervalsSupplemental O2Supplemental O2

MaternityMaternityMaternalMaternal

Increased CV fxnIncreased CV fxnDecreased wt gain and fluidDecreased wt gain and fluidMental stateMental stateLaborLaborRecovery Recovery fitnessfitness

maternitymaternityFetusFetus

Decreased fatDecreased fat Improved stressImproved stressNeurobehavioral maturationNeurobehavioral maturation

osteoporosisosteoporosisBMDBMDMuscle—balance, falls, fractureMuscle—balance, falls, fractureWorks with estrogen, dietWorks with estrogen, dietWt bearing Wt bearing

CADCADPrimary and secondary preventionPrimary and secondary prevention Increased CV functional capacity and Increased CV functional capacity and

decreased myocardial O2 demanddecreased myocardial O2 demandLipids, DM, obesityLipids, DM, obesityBP—8-10 mmHgBP—8-10 mmHg Inactivity is independent risk factor for Inactivity is independent risk factor for

CADCADSedentary have greatest CVD mortalitySedentary have greatest CVD mortality

- 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.

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 submaximal 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

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