Chapter 21
A training induced reduction in submaximal cardiac output reflects which two factors?
1. more effective redistribution of blood flow 2. trained muscles' enhanced capacity to generate ATP aerobically at a lower tissue PO2 (Partial Pressure of O2)
SAID Principle
Specific Adaptations to Imposed Demands Promotes specific training effects that produce specific performance improvements. Only limited interchange of benefits between different types of training
Specific Overload of short duration =
Specific strength power adaptations
Exercise training principles
Stimulating structural and functional adaptations to improve performance in specific physical tasks remains a major objective of exercise training
How long before improvement occur?
for aerobic fitness, improvement occur within several weeks and adaptive responses eventually 'level off' as subjects approach 'genetically predisposed' maximums
To improve energy transfer capacity by short-term lactic acid energy system, training must....
overload this anaerobic energy system blood lactate rises to near peak levels with 1 min maximal exercise; repeat same exercise bout after 3-5 min recovery --> lactate stacking
Oxygen Extraction (A-vO2 difference)
results from more effective cardiac output distribution to active muscles combined with enhanced capacity of trained muscle to extract and process available O2
Specific endurance training elicits...
specific aerobic system adaptations
Aerobic training enhances fat catabolism in ___________________ exercise
submaximal
Greatest improvements in VO2max occur when...
test exercise duplicates training exercise
Distinction between %HRmax and lactate threshold
%HRmax method establishes level of exercise stress to overload central circulation Exercise intensity from lactate threshold reflects capacity of peripheral vasculature and active muscles to sustain steady-rate aerobic metabolism
Cardiovascular adaptations from aerobic training include:
+Plasma volume +red blood cell mass +total blood volume
What factors formulate aerobic training?
1. Cardiovascular overload must be intense enough to sufficiently overload stroke volume and cardiac output 2. cardiovascular overload must occur from activation of sport specific muscle groups to enhance local circulation and muscles "metabolic machinery" ** brief bouts of repeated exercise and continuous long duration efforts enhance aerobic capacity, provided they reach sufficient intensity to overload aerobic system --> interval, continuous and fartlek represent three common training methods
When training for specific aerobic activities, overload must...
1. ENGAGE appropriate muscles required by activity 2. PROVIDE exercise at a level sufficient to stress cardiovascular system
Four additional aerobic training adaptions are:
1. Favorable body composition changes 2. more efficient body heat transfer 3. enhanced endurance performance 4. positive psychological benefits that include: - reduced anxiety - reduced neuroticism - improvement in mood, self esteem and self concept - reduction in various indices of psychological stress
How does the aerobic system increase intramuscular fatty acid oxidation?
1. Greater blood flow within trained muscle 2. More fat-mobilizing and fat-metabolizing 3. Enhanced muscles mitochondrial respiratory capacity 4. Decreased catecholamine release for the same absolute power output
What are some important changes that occur with anaerobic power training?
1. Increased levels of anaerobic substrates 2. Increased quantity and activity of key enzymes that control the anaerobic phase of glucose catabolism 3. Two factors increase capacity to generate high levels of blood lactate during all out exercise - Increased levels of glycogen and glycolytic enzymes (aka more lactate production in untrained people) - Improved motivation and tolerance to "pain"
Two clinical forms of over training
1. Sympathetic 2. Parasympathetic
Reduced carbohydrates as fuel source and increased fatty acid combustion in submaximal exercise results from which 3 combined effects?
1. decreased muscle glycogen use 2. reduced glucose production 3. reduced use of plasma-borne glucose
Endurance training lowers blood lactate levels and extends exercise before onset of blood lactate accumulating during exercise of increasing intensity by...
1. decreasing rate of lactate formation during exercise 2. increasing rate of lactate clearance during exercise 3. combined effects of decreased lactate formation and increasing lactate removal
What are two major goals or aerobic training?
1. develop the capacity of the central circulation to deliver oxygen 2. enhance the capacity of the active musculature to supply and process oxygen
Factors that increase stroke volume are:
1. increased internal life-ventricular volume and mass 2. reduced cardiac and arterial stiffness (stretchy) 3. increased diastolic filling time during submax exercise 4. improved intrinsic cardiac contractile function
What factors affect aerobic training responses?
1. initial level of aerobic fitness 2. training intensity 3. training frequency 4. training duration
What are the 4 factors that impact interval training prescription?
1. intensity 2. duration 3. length of recovery 4. number of reps of exercise-relief interval
Maximal exercise causes what changes to blood flow and distribution?
1. larger maximal cardiac output 2. greater blood distribution to muscle from nonactive areas 3. enlargement of cross-sectional areas of arteries and veins; 20% increase in capillarization/g muscle
Why does HRmax during swimming or during other upper body exercise average 13 beats/min lower than running?
1. less feed forward stimulation from motor cortex to medulla during swimming 2. less feedback stimulation from smaller active upper-body muscle mass in swimming 3. horizontal body position and cooling effect of water during swimming
What are the four categories of diverse physiologic and metabolic factors related to O2 transport and use?
1. ventilation-aeration 2. central blood flow 3. active muscle metabolism 4. peripheral blood flow With training, positive adaptations in the above categories remain independent of race, gender, age and health status
What happens to plasma volume after aerobic training?
12-20% increase in plasma volume after 3-6 wks of aerobic training plasma volume increase enhances circulatory reserve and increase end-diastolic volume, stroke volume, O2 transport, VO2max and temperature regulation during exercise Expanded plasma volume returns to pretraining levels within 1wk following training
Endurance athletes average _____% larger heart volume than sedentary counterparts
25%
Typical aerobic training programs take place ______days/week usually with a rest day separating workout days
3
What energy pathway is used at 4s, 10s, 1.5min and 3+ min of exercise?
4s - ATP (strength power) 10s - ATP + PCr (Sustained Power) 1.5min - ATP + PCr + Lactic Acid (Anaerobic power-endurance) 3min - Electron Transport Oxidative Phosphorylation (Aerobic Endurance)
To produce weight loss with exercise each session should last a minimum _______min at sufficient intensity to expend 300kcal or more
60
Overload
A planned, systematic and progressive increase in training to improve to performance
Overload Principle
Achieving appropriate overload requires either manipulation training frequency, intensity and duration or combining these factors Concept of individualized and progressive overload applies to athletes, sedentary persons, disables persons and even cardiac patients
Train at a percentage of HRmax
Aerobic capacity improves if exercise intensity maintains heart rate between 55-70% of maximum - during lower body exercise heart rate increase equals about 40--55% of VO2max
Metabolic Adaptations of the aerobic system
Aerobic training improves capacity for respiratory control in skeletal muscle Endurance-trained skeletal muscle fibers contain larger and more numerous mitochondria than less active fibers Mitochondrial enzyme activity increases by 50%
Individual Difference Principle
All individuals DO NOT respond similarly to a given training stimulus When a relatively homogenous group beings exercise training, one cannot expect each person to achieve same fitness improvements. OPTIMAL TRAINING benefits occur when exercise programs focus on individual needs and participants capacities
Physiologic Factors that limit VO2max and aerobic performance for PERIPHERAL BLOOD FLOW
Flow to nonactive regions Arterial vascular reactivity Muscle blood flow Muscle capillary density O2 diffusion Muscle vascular conductance O2 extraction Hb-O2 affinity Venous compliance and reactivity
Tapering for peak performance
Before competition, athletes taper training intensity and/or volume to reduce physiologic and psychological stress and optimize performance Taper period and alterations will vary by sport - taper of 1-3 weeks reduces training volume by 40-60% while maintaining training intensity; most efficient way to maximize performance goals From a physiological perspective, 4-7 days provides time for maximal muscle and liver glycogen replenishment, optimal nutritional support and restoration, alleviation or residual muscle soreness, and healing of minor injuries
How does overloading specific muscles with endurance training enhance performance and aerobic power?
By facilitating O2 transport and use by trained muscles
Maintaining gains in aerobic fitness
Can involve reduced frequency and duration of training - intensity is a key factor in maintaining fitness - aerobic capacity improvement involves different training requirements than maintenance - with intensity constant, frequency and duration required to maintain aerobic fitness remain lower than requires for improvement
Physiologic Factors that limit VO2max and aerobic performance for CENTRAL BLOOD FLOW
Cardiac output (heart rate and volume) Arterial blood pressure Oxygen Transport Capacity (Hb)
Significant effects of over training
Functional impairments in hypothalamopituitary-gonadal and adrenal axes and sympathetic neuroendocrine system reflected by depressed urinary excretion or norepinephrine and desensitization of the B2 adrenergic system exercise induced increases in adrenocortocotropic hormone and growth hormone and decreases in cortisol and insulin levels reflects body's attempt to provide athlete with appropriate recuperative period from intense training and competition
Sympathetic Over training
Characterized by increased sympathetic activity during rest; typified by hyper-excitability, restlessness, impaired performance may reflect excessive psychological/emotional stress
Parasympathetic Over training
Characterized by predominance of vagal activity activity during rest and physical activity; more properly termed overreaching in early stages (within 10d); qualitatively similar in symptoms to full-blown parasympathetic over training syndrome but of shorter duration
Reversibility Principle
Detraining rapidly occurs when terminating a training program Only 1 or 2 weeks of detraining reduces both metabolic and exercise capacity - many training improvements are lost fully within several months
Functional versus pathologic cardiac hypertrophy
Disease induces considerable cardiac enlargement exercise training in the healthy imposes a temporary myocardial stress so rest periods provide for "recuperation"
Exercise stroke volume: trained vs untrained
Endurance athletes heart exhibit larger stroke volume during rest and exercise Greatest stroke volume increase during upright exercise for trained and untrained occurs in transition from rest to moderate exercise Maximum stroke volume occurs between 40-50% of VO2max in untrained people for untrained, a small increase in stroke volume occurs during transition from rest to exercise For endurance athletes, heart rate and stroke volume increase to increase cardiac output
What happens to stroke volume after aerobic training?
Endurance training causes stroke volume to increase during rest and exercise regardless of age or gender
How does aerobic training effect muscle fiber type and size?
Enhanced metabolic adaptations in each muscle type all fibers maximize existing aerobic potential Endurance athletes have larger Slow Twitch fibers than Fast twitch fibers in the same muscle ** ST-Fibers with high capacity to generate ATP aerobically contain large quantities of myoglobin
Physiologic Factors that limit VO2max and aerobic performance for ACTIVE MUSCLE METABOLISM
Enzymes and oxidative potential Energy stores and substrate availability Myoglobin concentration Mitochondria size and number Active muscle mass Muscle fiber type
Specificity Principle
Exercise training specificity refers to adaptations in metabolic and physiologic functions that depend upon the type and mode of overload imposed The most effective evaluation of sport-specific performance occurs when measurement most closely simulates the actual activity and/or uses the muscle mass and movement patterns sport requires
Training at the lactate threshold
Exercising at or slightly above lactate threshold is effective --> higher exercise levels produce greatest benefits --> need to evaluate blood lactate/exercise intensity relationship (intensity adjusted as fitness improves)
what is the Karvonen method?
HR threshold = HRrest + 0.60 (HRmax - HRrest) --> as aerobic fitness improves, exercise level must increase periodically to achieve desired exercise heart rate
What happens to cardiac output after aerobic training?
Increase in maximum cardiac output is the most significant cardiovascular adaptation with aerobic training --> Results directly from improved stroke volume In trained athletes, cardiac output increases linearly with VO2 throughout the major portion of exercise intensity
Greater blood flow in active tissues results from...
Increased Microcirculation More effective redistribution of cardiac output Combined effect of both factors (capacity for blood exceeds what the heart can pump) ** Adaptations occur only in specifically trained muscles and become apparent in exercise that activates this musculature **
Adaptations in metabolic and physiologic functions depend on...
Intensity Duration Frequency Mode of imposed overload
Continuous training
Involves steady-paced, prolonged exercise at moderate or high aerobic intensity, usually 60-80% VO2max continuous training ideally suits novices who wish to accumulate a large caloric expenditure for weightloss Continuous training also allows endurance athletes to exercise at nearly same intensity as in competition
Athletes heart
Long-term aerobic training increases heart's mass and volume with greater life-ventricular end-diastolic volumes during rest and exercise Cardiac enlargement is caused by BOTH eccentric hypertrophy and concentric hypertrophy
Blood Flow and Distribution
Lower cardiac output (and slightly lower muscle blood flow) in submaximal exercise with training due to: 1. Rapid training-induced changes in vasoactive properties of large arteries and local resistance vessels within skeletal cardiac muscle 2. muscle cell changes that enhance oxidative capacity
Initial Level of aerobic fitness
Magnitude of training response depends on initial fitness level - someone who rates low at start has considerable room for improvement - aerobic fitness improvements with endurance training rage between 5-25%
What are the pulmonary adaptations of aerobic training?
Maximal exercise VE (tidal volume and breathing frequency) increases from increased tidal volume and breathing rate as VO2max increases Submaximal exercise reduces VE/VO2 and lowers % total exercise )2 cost attributable to breathing ** MAIN POINT: Training increases tidal volume and decreases breathing frequency, increasing O2 extraction from inspired air
Physiologic Factors that limit VO2max and aerobic performance for VENTILATION
Minute ventilation Ventilation:perfusion ratio Oxygen diffusion capacity HB-O2 affinity Arterial oxygen saturation
Training increases inspiratory muscle capacity to generate force and sustain inspiratory pressure, benefiting exercise performance by:
Reducing overall exercise energy demands because of less respiratory work reducing lactate production by ventilatory muscles during intense, prolonged exercise Enhancing how ventilatory muscles metabolize circulating lactate as metabolic fuel
what effect does aerobic training have on blood pressure?
Regular aerobic training reduced systolic and diastolic blood pressure during rest and submaximal exercise --> largest reduction occurs in systolic pressure, particularly in hypertensive subjects
Interval Training
Repeated activity bouts with brief rest periods permit completion of intense exercise without appreciable fatigue ** as little as 6 sessions of near all out effort over a 2 week time increase skeletal muscle oxidative capacity and enhances performance
Trainability and Genes
Strenuous exercise enhances level of fitness regardless of genetic background - Limits for developing fitness capacity link to natural endowment - Genotype dependency exists for much of one's sensitivity in responding to maximal aerobic and anaerobic power training, including adaptations of most muscle enzymes
Heart Rate and VO2 during graded exercise for athletes and sedentary students
There is some suggestion that the elite athlete will have a lower heart rate max
How does aerobic training impact carbohydrate metabolism?
Trained muscles exhibit enhanced capacity to oxidize carbohydrates during maximal exercise
How do you determin the "training sensitive zone" ?
Training at percentage of HRmax Age predicted max HR: HRmax= 220 - age Modified equation: HRmax = 206.9 - 0.67 x age
What happens to heart rate after aerobic training?
Training decreases intrinsic firing rate of SA nodal pacemaker tissue --> contributes to resting and submaximal exercise bradycardia in trained endurance athletes or the previously sedentary who train aerobically Submaximal heart rate for standard exercise decreased by 12-15 beats/min with endurance training --> smaller heart rate decreases for resting heart rate --> reduction coincides with increased maximum stroke volume and cardiac output
Training intensity
Training induced adaptations rely on OVERLOAD intensity
Over reaching
Unplanned, excessive overload with inadequate rest; poor performance observed in training and competition successful recovery results from a few days to 1 or 2 weeks interventions
Over training syndrome
Untreated overreaching that produces long term decreased performance and impaired ability to train
Training at a perception of effort
Utilizing rating of perceived exertion (RPE) allows exerciser to rate perceived feelings relative to exertion level exercise at higher levels of energy expenditure and physiologic strain produces higher RPE ratings
Anaerobic Training - the Intramuscular High-energy phosphates
engaging specific muscles in repeat 5-10s maximal bursts of effort overloads energy transfer from intramuscular high energy phosphates ATP and PCr --> HIIT training Physical activities to enhance ATP-PCr energy transfer capacity in a specific sport must engage muscles at movement speed and power output similar to performance of that sport
Pathologic "hypertrophied" heart:
enlarged, distended, functionally inadequate organ unable to deliver blood sufficient for resting requirements
Is there a duration threshold per workout for optimal aerobic improvement?
no. if one exists, it likely depends on interaction of four variables... 1. total work accomplished 2. exercise intensity 3. training frequency 4. initial fitness
Exercise mode
maintaining constancy for exercise intensity, duration and frequency produced similar training response independent of training mode, provided exercise involves large muscle groups
Fartlek training
meaning "speed play", this training uses alternate running at fast and slow speeds over level and hilly terrain
Training Frequency
more frequent training produced beneficial effects when training at lower intensity
Over training
when person fails to adapt to training so performance deteriorates, it becomes difficult to fully recover from workouts also relates to increased incidence of infections and injuries, persistent muscle soreness and general malaise and loss of interest in sustaining high level training
