Principles of Aerobic Exercise

Principles of AerobicExerciseParta KinandanaKEY TERMS AND CONCEPTSFitnessFitness is a general term used to describe the ability to perform physical work.KEY TERMS AND CONCEPTSMaximum Oxygen Consumption (VO2 max) Maximum oxygen consumption (VO2 max) is a measure of the bodys capacity to use oxygen.It is the maximum amount of oxygen consumed per minute.Milliliters of oxygen per kilogram of body weight per minute (mL/kg per minute)Dependent on the transport of oxygen, the oxygen-binding capacity of the blood, cardiac function, oxygen extraction capabilities, and muscular oxidative potential.KEY TERMS AND CONCEPTSEnduranceEndurance is the ability to work for prolonged periods of time and the ability to resist fatigue.Muscular endurance and cardiovascular endurance.Muscular endurance : ability of an isolated muscle group to perform repeated contractions over a period of time.Cardiovascular endurance : ability to perform large muscle dynamic exercise, such as walking, swimming, and/or biking for long periods of time.KEY TERMS AND CONCEPTSAdaptationThe cardiovascular system and the muscles used adapt to the training stimulus over time. Significant changes can be measured in as little as 10 to 12 weeks.Adaptation is dependent on the ability of the organism to change and the training stimulus threshold (the stimulus that elicits a training response).Training stimulus thresholds are variable.KEY TERMS AND CONCEPTSDeconditioningDeconditioning occurs with prolonged bed rest, and its effects are frequently seen in the patient who has had an extended, acute illness or long-term chronic condition.These effects are also seen in the individual who is sedentary because of lifestyle and increasing age.Decreases in maximum oxygen consumption, cardiac output (stroke volume), and muscular strength occur rapidly.

Aerobic Exercise Training (Conditioning)Aerobic exercise training, or conditioning, is augmentation of the energy utilization of the muscle by means of an exercise program.improvement is a direct result of increased levels of : oxidative enzymes in the muscles, increased mitochondrial density and size, and an increased muscle fiber capillary supply.Energy Systems, Energy Expenditure, and EfficiencyEnergy SystemsEnergy systems are metabolic systems involving a series of biochemical reactions resulting in the formation of adenosine triphosphate (ATP), carbon dioxide, and water.ATP to adenosine diphosphate (ADP) and phosphate (P).The intensity and duration of activity determine when and to what extent each metabolic system contributes.1. Phosphagen, or ATP-PC, SystemPhosphocreatine and ATP are stored in the muscle cell.No oxygen is required (anaerobic).When muscle is rested, the supply of ATP-PC is replenished.The maximum capacity of the system is small (0.7 mol ATP).The maximum power of the system is great (3.7 mol ATP/min).The system provides energy for short, quick bursts of activity.It is the major source of energy during the first 30 seconds of intense exercise.2. Anaerobic Glycolytic SystemGlycogen (glucose) is the fuel source (glycolysis).No oxygen is required (anaerobic).ATP is resynthesized in the muscle cell.Lactic acid is produced (by-product of anaerobic glycolysis).The maximum capacity of the system is intermediate (1.2 mol ATP).The maximum power of the system is intermediate (1.6 mol ATP/min).The systems provide energy for activity of moderate intensity and short duration.It is the major source of energy from the 30th to 90th second of exercise.3. Aerobic SystemGlycogen, fats, and proteins are fuel sources and are utilized relative to their availability and the intensity of the exercise.Oxygen is required (aerobic).ATP is resynthesized in the mitochondria of the muscle cell. The ability to metabolize oxygen and other substrates is related to the number and concentration of the mitochondria and cells.The maximum capacity of the system is great (90.0 mol ATP).The maximum power of the system is small (1.0 mol ATP/min).The system predominates over the other energy systems after the second minute of exercise.Recruitment of Motor UnitsSlow-twitch fibers (type I) : slow contractile response, rich in myoglobin and mitochondria, high oxidative capacity and a low anaerobic capacity, and are recruited for activities demanding endurance. These fibers are supplied by small neurons with a low threshold of activation and are used preferentially in low-intensity exercise.Fast-twitch fibers (type IIB) : a fast contractile response, have a low myoglobin content and few mitochondria, have a high glycolytic capacity, and are recruited for activities requiring power.Fast-twitch fibers (type IIA) have characteristics of both type I and type IIB fibers and are recruited for both anaerobic and aerobic activitiesFunctional ImplicationsBursts of intense activity (seconds) develop muscle strength and stronger tendons and ligaments. ATP is supplied by the phosphagen system.Intense activity (1 to 2 minutes) repeated after 4 minutes of rest or mild exercise enhances anaerobic power. ATP is supplied by the phosphagen and anaerobic glycolytic system.Activity with large muscles, which is less than maximum intensity for 3 to 5 minutes repeated after rest or mild exercise of similar duration, may develop aerobic power and endurance capabilities. ATP is supplied by the phosphagen, anaerobic glycolytic, and aerobic systems.Activity of submaximum intensity lasting 20 to 30 minutes or more taxes a high percentage of the aerobic system and develops endurance.Energy ExpenditureUnits used to quantify energy expenditure are kilocalories and METs.A kilocalorie is a measure expressing the energy value of food. Five kilocalories equal approximately 1 liter of oxygen consumed (5 kcal = 1 liter O2).A MET is defined as the oxygen consumed (milliliters) per kilogram of body weight per minute (mL/kg). It is equal to approximately 3.5 mL/kg per minute.The average individual engaged in normal daily tasksexpends 1800 to 3000 kcal per day. Athletes engaged inintense training can use more than 10,000 kcal per day.Energy ExpenditureClassification of ActivitiesLight work for the average male (65 kg) requires 2.0 to 4.9 kcal/min, or 6.1 to 15.2 mL O2/kg per minute, or 1.6 to 3.9 METs. Strolling 1.6 km/hr, or 1.0 mph, is considered light work.Heavy work for the average male (65 kg) requires 7.5 to 9.9 kcal/min, or 23.0 to 30.6 mL O2/kg per minute, or 6.0 to 7.9 METs. Jogging 8.0 km/hr, or 5.0 mph, is considered heavy work.Jogging 8.0 km/hr, or 5.0 mph, requires 25 to 28 mL O2/kg per minute and is considered heavy work. The energy expended is equivalent to 8 to 10 kcal/min, or 7 to 8 METs.The energy expenditure necessary for most industrial jobs requires more than three times the energy expenditure at rest.Energy expenditure of certain physical activities can vary, depending on factors such as skill, pace, and fitness level.PHYSIOLOGICAL RESPONSETO AEROBIC EXERCISECardiovascular Response to ExerciseIncreased Cardiac OutputThe cardiac output increases because of the:Increase in myocardial contractility, with a resultant increase in stroke volumeIncrease in heart rateIncrease in the blood flow through the working muscleIncrease in Systolic Blood PressureRespiratory Response to ExerciseIncrease Gas Exchangeincreases as respiratory frequency.tidal volume increaseIncrease Alveolar ventilation 10 20x.PHYSIOLOGICAL RESPONSETO AEROBIC EXERCISEResponses Providing Additional Oxygen to MuscleIncreased Blood FlowIncreased Oxygen ExtractionIncreased Oxygen ConsumptionDETERMINANTS OFAN EXERCISE PROGRAMFrequencyIntensityDurationModeReversibility PrincipleFITTIntensityOverload Principle above the training stimulus threshold.elicits a training or conditioning responseconditioning response occurs generally at 60% to 90% maximum heart rate (50% to 85% VO2 max).Methods to Determine Maximum Heart Rate and Exercise Heart RateDetermine Maximum Heart Rate (HR)Determine Exercise Heart RateFrom multistage test (for young and healthy)HR achieved in predetermined submaximum test220 minus age (less accurate)Percentage of maximum heart rate (dependent on level of fitness)Karvonens formula (heart rate reserve)Exercise heart rate = Hrrest + 6070% (HRmax - HRrest)DurationGreater the intensity of the exercise, the shorter the duration; and the lower the intensity of exercise, the longer the duration needed.A 20- to 30-minute session is generally optimal at 60% to 70% maximum heart rate.With high-intensity exercise, 10- to 15-minute exercise periods are adequate.FrequencyFrequency of two times a week does not generally evoke cardiovascular changes.American College of Sports Medicine (ACSM), recommends aerobic exercise 3 to 5 days/week at 65% to 90% maximum heart rate for 20 to 60 continuous or intermittent minutes.ModeMode or type of exercise vary depend on what kind of effect we desired.Reversibility PrincipleThe beneficial effects of exercise training are transient and reversible.The frequency or duration of physical activity required to maintain a certain level of aerobic fitness is less than that required to improve it.EXERCISE PROGRAM(1) a warmup period, (2) the aerobic exercise period, (3) a cooldown period.Warm-Up PeriodPhysiological ResponsesAn increase in muscle temperatureAn increased need for oxygen to meet the energy demands for the muscleDilatation of the previously constricted capillariesAn increase in venous return.Adaptation in sensitivity of the neural respiratory center to various exercise stimulants

PurposesThe susceptibility of the musculoskeletal system to injury.The occurrence of ischemic electrocardiographic (ECG) changes and arrhythmias.

Guidelines10-minute period of total body movement exercises, such as calisthenics, and walking slowly.

Aerobic Exercise PeriodThe exercise period must be :within the persons toleranceabove the threshold level for adaptation to occurand below the level of exercise that evokes clinical symptoms.

Four methods of training that challenge the aerobic system :Continuousinterval (work relief)circuitcircuit interval

Cool-Down PeriodPurposePrevent pooling of the blood in the extremities.Prevent fainting by increasing the return of blood to the heart and brain as cardiac output and venous return decreases.Enhance the recovery period with the oxidation of metabolic waste and replacement of the energy stores.Prevent myocardial ischemia, arrhythmias, or other cardiovascular complications.

GuidelinesTotal-body exercises such as calisthenics and static stretching are appropriate.The period should last 5 to 10 minutes.

TerimakasihTugas Baca : Therapeutic Exercise Foundations and Techniques. Hal 231 249.