skeletal muscle adaptation to endurance training

major limiting factor of VO2max

delivery of O2/rate of diffusion from capillary to mitochondria

to improve muscles capacity to produce ATP anaerobically, must

optimize ability to deliver O2 to working tissues

exercise can increase what intramuscularly

more myoglobin, causing more stored intramuscular oxygen

exercise induced stimuli on skeletal muscle leads to

vascular endothelial growth factor which stimulates angiogenesis

angiogenesis

increased amount of blood vessels available, increased capillary density = increased ability to get O2 into the muscle (sprouting collaterals)

rarefaction

reversal of angiogenesis if we stop training

strong correlation of increased capillary density

and increased VO2max

result of angiogensis

decreased distance for O2 to travel to get to mito., easier to remove metabolic byproducts from cell, increased availability of O2

changes to mitochondria with exercise

increased size and number, better capacity for aerobic metabolism, decreased diffusion distance of O2, and better uptake of H carriers (less pH changes)

mitochondria can change

within 5 days of training, and up to 50-100% increased within 6 weeks

twitch

force produced by activation of a single muscle fiber

muscle fiber type shift

fast twitch to slow twitch via metabolic properties changing, protein synthesis can change myosin heavychain isoforms, more fatigue resistant (increased number and hypertrophy of T1 fibers)

exercise induced oxidative stress

physiological stimulants produce oxidants which can cause cell damage, but it also increases antioxidants that can decrease amount of cell damage and death

endurance training and muscle energy usage

increased fat mobilization and utilization (faster usage and sooner), increased glycogen and triglyceride stores intramuscularly - CHO sparing

aerobic activities stress

oxidative pathways

anaerobic activities stress

glycolytic pathways

long slow distance workouts

aerobic stress

fartlek workout

aerobic and anaerobic stress

interval straining

aerobic and anaerobic stress

hormone changes with metabolic adaptations to exercise

pattern of blunted response - decreased rise in glucagon, Epi/NE, GH, cortisol, suppression in insulin (maintain equilibrium for longer) (less changes in hormonal response will result in less changes in energy needs)

CHO changes with metabolic adaptations to exercise

increased muscle and liver glycogen, slower rate of liver glycogen depletion, less CHO in fuel mixture/CHO sparing, increased rate of glycogenolysis to use as glucose

fat changes with metabolic adaptations to exercise

increased mobilization of FFA from adipose, plama FFA during submax exercise, fat storage adjacent to mito/ within muscles, ability to utilize fat at any given plasma concentration

protein changes with metabolic adaptations to exercise

increased ability to utilize leucine and form alanine - use for gluconeogenesis in liver = increased glucose production in liver

enzyme activity with metabolic adaptations to exercise

increased glycogen phosphorylase activity (breakdown glycogen), increased PFK (rate limiting enzyme for glycolysis), decreased LDH activity in skeletal muscle with aerobic (converts pyruvate into lactate so decreased lactate production) - opposite strength and sprint training

shuttles of enzyme activity

increased activity of bringing H carriers into mitochondria for ETC

mitchocondrial enzymes with metabolic adaptations to aerobic exercise

increased size and number of mitochondria in all muscle fibers, increased activity enzymes in krebs, ETC and oxidative phosphorylation in working/active muscles (not with resistance training)

oxygen utilization changes with metabolic adaptations

maximal O2 consumption increased, increased myoglobin causes unchanged submax O2 cost, decreased oxygen drift and deficit, less EPOC (blunted neurohormonal effects and CHO sparing)

lactate accumulation changes with metabolic adaptations

decreased lactic acid/lactate production due to fuel shifts, enzyme activity changes and blunted neurohormonal responses)

ATP production/storage/turnover changes with metabolic adaptations

equal ATP/substrate but produced much faster, greater PCr/ATP storage, decreased depletion at absolute workload - equal at relative, increased ATP-PC turnover, improved work output

training significantly impacts anaerobic pathways to

produce energy faster

training changes based on age and sex are

similar across age and gender

endurance training results in a more

efficient utilization of oxygen by muscle

cardiorespiratory fitness reflects

functional capacity of heart, BV, lungs, and skeletal muscles to transport and utilize ocxygen

HIIT training

demostrates similar improvements in CRF as traditional endurance training

freqeuncy of aerobic exercise recs

>/= 3 days/week

intensity of aerobic exercise recs

moderate (40-59% HRR) and/or vigorous (60-89% HRR)

time of aerobic exercise recs

150min/week moderate or 75min/week vigorous

type of aerobic exercise

continuous or intermittent - evidence supports ten minute bouts, or exercise snacks at max intensity for 1sec or less

any amount of aerobic exercise

is better than nothing (benefits can occur with just 1-2 days, especially for deconditioned individuals)

dose response of exercise intensity

more exercise/higher intensity will yield more/greater health benefits (positive dose response)

vigorous is more effective at

increasing VO2 than moderate

minimizing risk does not

prevent adverse events from happening (some things are out of our control)

aerobic intensity is measured in

watts - 6.1kgxm/min (power component with time)

very light

9-11 RPE

very light to fairly light

12-13 RPE

fairly light to somewhat hard

14-17 RPE

somewhat hard to very hard

>18 RPE

very hard

HRR method

takes into account resting HR (added back into equation)

%HR max

is just about max, doesnt account for resting HR

quick/dirty age predicted max HR

220-age (not the most accurate)

for deconditioned individuals, measuring intensity is prefered via

relative measures like HRR and %HRmax

measured/estimated absolute intensity via

caloric expenditure, VO2, METs

methods of estimating relative intensity

%HRR, %HRmax, %VO2R, %VO2, %METs

methods of estimating intensity

RPE, affecting valence, talk test

for RPE to be accurate

patient needs to be familiar with the sensation of exercise

for deconditioned individuals or prescription beta blocker patients

HR may not align with RPE - expect a lower RPE

HR and RPE typically

increase linearly together - can be used to estimate lactate threshold (also increasing just not linearly)

recommended aerobic exercise volume

7,000-8,000 steps/day with atleast 3,000 steps at a brisk pace