Kines 350: Exam 4

What are the principles of exercise training design?

1. training variables

2. specificity

3. overload

4. individuality

5. reversibility

6. variation

7. overtraining

what is specificity in training principles?

The training effect is specific to

• muscle fibers recruited during exercise

• energy system involved

• force and velocity of contraction

• type of contraction

(type of training dictates the adaptation)

what is overload in training principles?

system must be stressed beyond normal adaptation to occur

• overload should be progressive (training loads should be continually adjusted)

• overload achieved with FITT

what is FITT?

F - frequency of training

I - intensity of training

T - time (duration) of training

T - type of activity

what is the individuality principle of training?

• adaptations and their rate vary between individuals

• differences often have large genetic component

• program must be specific to needs of individual

• with right time/program, everyone responds

what is the reversibility principle of training?

• training adaptations measurably reverse over time (endurance: 2 weeks, strength: 3 weeks)

• few days without training could improve performance

• at certain fitness level, a minimum amount of regular exercised required to maintain adaptations

what are the common goals of cardiorespiratory training?

• start faster: decrease O2 deficit

• higher race pace: increase steady state VO2

• increase max rate of work: increase VO2 max

• increase endurance time: increase lipolysis, spare glycogen

• reduce comorbidities and risk of chronic disease

what are some of the most common adaptations after endurance training?

• more rapid transitions

• larger VO2 max and capacity to do work

• changes in the determinants of VO2max

• other adaptations: blood composition + pressure

• lower submaximal heart rate and ventilation

how does endurance training adapt the O2 deficit?

O2 deficit is smaller after endurance training

• less PCr depletion

• less lactate accumulation

• can “take out” races faster and maintain higher race pace

• faster recovery from sprints

• stronger finish

• no change in steady state VO2 for unskilled activities

how does endurance training adapt VO2max

VO2max increases by 10-40%

• greater endurance performance and capacity

• submaximal VO2 at same work rate does not change significantly (same work requires same oxygen)

• working at lower %VO2max

how can VO2max increase but submaximal VO2 not change significantly?

Training can significantly increase the amount of oxygen the heart can deliver (raising ) without necessarily making the muscles more economical in their use of oxygen at lower speeds.

what training can create adaptations in VO2max magnitude?

large muscle groups, dynamic activity

• 20-60 min

• ≥3 times/week

• ≥50% VO2max

• 6 weeks or more

what are the adaptations in the magnitude of VO2max?

average about 15-20%

• wide variation between individuals

• 2-3% in those with high VO2max

  • requires >70% VO2max

• up to 50% in those with low initial VO2max

  • requires 40-50% VO2max

how do genetics impact VO2max adaptations to training?

• predisposition for exceptional VO2max

• heritability plays an important role in determining exercise response

• polymorphisms in 21 genes account for 47% of change in VO2max in white men

why does VO2max improve with training?

central adaptations:

• enhanced delivery of blood/oxygen to muscles

• larger blood volume + stroke volume + cardiac output

peripheral adaptations

• increased oxygen extraction, widening a-vO2 difference

• increased oxidative capacity + blood supply in muscle

what is the short-duration training effects in O2 extraction?

• 26% ↑ in VO2max

• 10% ↑ in SV

• 2% ↑ in O2(a-v)

• ↑ SV > ↑ O2(a-v)

what is the long-duration training effects in O2 extraction?

• 42% ↑ in VO2max

• 15% ↑ in SV

• 25% ↑ in O2(a-v)

• ↑ O2(a-v) > ↑ SV

what are the adaptations to cardiac output from endurance training?

• no change in resting and submaximal CO

• 10-20% ↑ in CO during max exercise

• greater advective movement of O2 to muscle

• more blood flow to redistribute

how does endurance training adapt HR?

• ↓ HR at rest and fixed rates of submaximal work (↑ parasympathetic activity, ↓ intrinsic HR)

• no change/slight ↓ in max HR

• faster rate recovery post exercise

• same HR at same %VO2max

how does endurance training adapt stroke volume?

greater SV at rest, submax, and max exercise

• reflects cardiac hypertrophy

• maintains CO with lower HR

what causes maximal SV to increase with training?

↑ Preload

• ↑ plasma volume, ↑ venous return, ↑ ventricular volume

↓ Afterload

• ↑ capillaries, ↑ maximal blood flow/no change in MAP, ↓ arterial constriction

↑ Contractility

changes occur rapidly

how are the ventricles adapted from endurance training?

↑ heart size

• ↑ chamber size, ↑ wall thickness, ↑ pericardial size

↑ wall thickness (strength training)

endurance training adaptations on O2 extraction

• unchanged at rest and submax

• ↑ extraction during maximal exercise (takes very long time to occur)

• better diffusion of O2 from muscle capillaries to mitochondria

• increases O2 (a-v) difference

why does CvO2 decrease in trained athletes?

• ↑ muscle blood flow (less SNS vasoconstriction)

• ↑ capillary density (↑ recruitment + improved distribution)

• ↑ mitochondria number

how quickly are adaptations lost with detraining?

2-3 weeks

• ↓ SV

• ↓ Q

• ↓ VO2max

long term: ↓ O2(a-v)

what is the goal of cardiac rehab?

to minimize the impacts of detraining

adaptations to blood with endurance training?

• ↑ blood volume: ↑ plasma volume, ↑ RBC mass

• ↓ hematocrit

• ↓ blood pressure: ↓ SVR

endurance training on submaximal ventilatory response

• no impact on long structure

• oxygen maintained or improved

• ventilation: lower at same submax work rate, higher at max exercise

how does endurance training adapt ventilation response?

changes in aerobic capacity of ventilatory muscles

• less H+ production

• less fatigable

changes in aerobic capacity of locomotor muscles

• less H+ production

• less afferent feedback from muscle to stimulate breathing

what are the general cardiorespiratory responses to training at absolute and relative intesnity?

absolute:

• VO2 and Q are the same

• HR and ventilation are less

• (lower strain, same workload)

relative: VO2 and work is more

• HR and ventilation are the same

• workload is greater at same relative stress level

what are the implications/adaptations seen with an increased VO2max?

• greater max CO: more O2 delivery to muscle

• decreased resting HR: biomarker

• greater SV: more O2 delivery

• greater O2 extraction: better diffusion of O2 in muscles

what are the implications/adaptations seen with a smaller lower BP

less afterload

what are the implications/adaptations seen with an increased blood volume and hematocrit?

increased preload and oxygen carrying capacity

what are the implications/adaptations seen with lower ventilation?

more blood flow and oxygen available for movement

what are the five adaptations that improve oxygen extraction?

1. mitochondrial responses

2. capillary supply

3. myoglobin content

4. muscle fiber type

5. enzymatic activity

how does mitochondrial responses improve oxygen extraction?

sarcolemmal: larger, faster turnover (20%)

intermyofibrillar: more abundant, greater ATP synthesis (80%)

• endurance training increases mitochondrial volume + turnover

• decreased glucose utilization

• increased fat metabolism

• faster ADP uptake (spares PCr/tempers glycolysis)

mitochondrial response to training and detraining

• quickly adapt (half response about 1 week)

• detraining → 50% loss in 1 week, majority lost in 2 weeks

• on week of detraining requires about 3-4 weeks retraining to regain

how does angiogenesis (capillaries) improve oxygen extraction?

• 10-30% increase in capillarization after 6-8 weeks of training

• greater diffusion of oxygen

  • slower RBC transit time

  • increased O2(a-v)

how does endurance training adapt myoglobin?

• ↑ total amount of hemoglobin mass and myoglobin

• Partial pressure and concentration change little

• more O2 delivered to mitochondria

how does endurance training adapt muscle fiber type distribution?

exercise = fast to slow:

• FG fiber prevalence decreases

• FOG/IIa fiber prevalence and cross-sectional area increases (endurance)

• SO/I fibers may increase

disuse = slow to fast

• both fibers peak force + power reduced

• large and variable decreases in type I cross sectional area, peak force, and velocity

• smaller decrease in type II, area, and velocity

how do adaptations to enzymes increase oxygen extraction?

• citrate synthesis (CS) catalyzes first reaction of krebs cycle (biomarker)

• increased CS activity with all training intensities

• independent of intensity and duration of IIa fibers

• increase in CS in IIx fibers with higher intensity, longer duration trainin g

what are type IIx fibers

• fast-twitch, anaerobic muscle fibers

• maximal speed and force, but they fatigue rapidly

• recruited last

• specifically during high-intensity, explosive, or maximal-effort movements when type I and IIa fibers cannot meet the demand.

what are the overall muscle changes due to endurance training?

• reduction in O2 deficit

• increased O2 extraction

• change in fiber type

• increased capillary density

• increased myoglobin content

• increased mitochondrial content

• increased oxidative enzyme activity

what are the four bioenergetic adaptations to endurance exercise?

1. better matching of glycolytic and oxidative systems

2. greater glycogen storage in muscle and liver

3. greater lipolysis reliance

4. improved acid base status

what are the endurance exercise adaptations to bioenergetic system matching?

lactate threshold occurs at a higher work rate

• untrained: at 50% to 65% of VO2max

• trained: at 70% yo 85% of VO2max

can maintain higher exercise intensity before fatiguing, faster race pace

endurance training adaptations to glycogen availability

increased muscle and liver glycogen stores

• greater CHO availability

• delays onset of fatigue

endurance training adaptations to lipid use

adipose tissue:

• increased sensitivity of HSL to catecholamines (elevates lipolysis)

• higher pH → less suppression of FA mobilization

muscle:

• intramuscular lipid droplets smaller

• increased amount of adipose triglyceride lipase (ATGL)

endurance training adaptations to muscle fuel utilization

increased utilization of fat, sparing plasma glucose + muscle glycogen

• increased capillary density

  • slower BF in muscle, increased FFA transporters

  • increased uptake of FFA

  • increased FFA utilization

• increased mitochondria number

  • increased beta oxidation enzymes: more acetyl-CoA formation

  • increased carnitine

endurance training adaptations to acid-base balance

• increased mitochondrial content: less carb utilization → less pyruvate

• increased NADH shuttles: better NAD+ recycling

• change in LDH isoforms (H4 has less affinity for pyruvate → less lactate)

what is the exercise pressor reflex?

• feedback from working muscles

• group III and IV nerve fibers

• responsive to tension, temperature, and chemical changes

• feed to CV control center

what is central command of cardiorespiratory responses

• feed forward from CNS

• motor cortex, cerebellum, and basal ganglia

• recruitment of muscle fibers

• stimulates cardiorespiratory control centers

endurance adaptations to neural responses to exercise

mechanisms:

• reduction in stimuli to muscle chemo receptors

• fewer motor units recruited to accomplish the same absolute work

less sympathetic nervous system activation

• less E/NE

cardiorespiratory: lower HR/Ventilation

metabolism: shift in fuel toward fat

endurance training on glucose homeostasis

• insulin doesnt decrease as much (lower catecholamines)

• less rise in glucagon (lower catecholamines)

• less rise in glucagon/insulin ratio:

  • glycogen sparing

  • greater reliance on FFA

what is muscular strength?

maximal force a muscle/muscle group can generate

• often measured with 1-repetition maximum (1-RM)

what is power?

rate of work → Force x distance/time

• requires measurements of force and velocity

what is muscular endurance?

capacity to sustain repeated muscle contractions, or maintain a single contraction

• e.g., number of repetitions at 80% 1-RM

what are the goals of resistance training?

strength/size:

• increase strength/size/alter proportions

• reduce risk of muscle tension/injury

power

• increase speed, power, and agility

endurance

• maintain high force for more repetitions

what are the general responses to resistance training?

• improved motor unit recruitment

• hypertrophy of muscles

• fiber type shift from FG to FOG

• metabolic adaptations

how quickly does strength increase in response to resistance training? why does it increase?

quickly, days to weeks of training

• improved motor unit recruitment → ↑ force generation

• little changes in muscle size

how does muscle hypertrophy occur in response to resistance training

months to years of training

• increased cross sectional area

• increase in size of muscle fibers

• more cross bridges = more force

what role do neural responses have in early strength gaining?

• responsible for early gains

• 8-20 weeks

• increased ability to recruit motor units

• altered motor neuron firing rates

• enhanced motor unit synchronization

• removal of neural inhibition

what is a “pump”

it is an edema

• high muscle forces occlude blood flow

• metabolites accumulate, drawing water into muscles via osmosis

• not associated with strength, but water

• Preworkout could promote pumps:

  • Stimulants increase focus/motivation

  • Amino acids increase resting muscle blood flow

is muscle enlargement attributed to increase in size or number?

size (hypertrophy)

• englargement of type I and (mostly) II

• increase in myofibrillar proteins

hyperplasia usually occurs in response to injury

• increase in number of muscle fibers

what is myonuclear domain theory?

each nucleus affects protein synthesis in a limited volume of muscle fiber

• when the volume is exceeded more nuclei are added

• satellite cells donate nuclei → more nuceli = more domains = more protein synthesis

how are muscle fiber types adapted in response to resistance training?

all fiber types hypertrophy

• type IIx and IIa fibers more than type I

• modest fast → slow shift (IIx to IIa)

how is muscle fiber strength and size impacted by detraining?

slower change in size from detraining

• small changes in fiber size

• CNS changes help maintain strength despite reduced muscle/fiber mass

retraining

• rapid regain of strength and muscle size “muscle memory”

why is there “muscle memory”

when a trained muscle is detrained:

• additional nuclei remain

• rehab proceeds more quickly

• retraining occurs more quickly because nuclei domains are small, fewer satellite cells are needed

does exercise training increase oxidative capacity/capillary density

conflicting results

• different frequencies and duration of resistance training

• long term high-volume to improve oxidative capacity (HIIT)

what are the benefits of resistance training in older individuals

• causes muscle hypertrophy and strength gains

• delays sarcopenia

• improves activities of daily living and balance

• reduces risk of falls

what about exercise triggers training adaptation?

stress activates gene transcription, increases specific muscle proteins

• form adaptation is specific to the type of training

what is the process of training induced muscle adaptation

muscle contraction activates primary and secondary messengers

• results in expression if genes and synthesis of new proteins (peak mRNA lvls 4-8 hrs)

5 steps of protein synthesis

1. gene activation

2. transcription

3. mRNA processing

4. translation

5. post-transactional modification

what are the steps leading to exercise adaptations?

1. primary signals: stretch, Ca2+, low O2, etc

2. activation of cell signalling pathways

3. transcriptional activator enters the nuclei and binds to gene promoter

4. DNA transcribed to mRNA

5. mRNA leaves nucleus and binds with ribosomes

6. mRNA translated to amino acids

what are