Lecture 33 - Muscle plasticity: exercise and adaptation Flashcards
true or false
with endurance exercise training only part of the muscle is being used
true
true or false
intensity determines which motor units are recruited
true
With electrical stimulation all of the fibres are activated regardless of fibre type
Nevertheless, adaptive changes during physical training are qualitatively similar to ….
those during electrical stimulation
The adaptations during training are ____and _____ reversible
easily and rapidly reversible
there is a fast decline of these activities within a few week of stopping training
the extent of skeletal muscle adaptations depends upon:
the mode, frequency, intensity and duration of the stimulus
What are the limitations to exercise adaption?
genetics
we are not all created equal with the same adaptive potential for exercise
explains why athletes that exercise under identical training conditions often show different levels of improvement
What are the advantages of electical stimulation?
standardised model - adaptive responses occur in a reproducible well-defined manner
elicits maximal ladaptive potential of the muscle
adaptations occur in a shorter period of time compared with voluntary activity
adaptations restricted to target muscle; therefore minimise systemic effects
does not induce muscle damage in rodents, allowing for a ‘‘clean’’ investigative model
Principles of training
What is overload?
a system of tissue must be challenged with an intenity, duration or frequency of the exercise to which it is unaccustomed
over time the tissue or system adapts to this load
What is specificity?
the training effect is limited to the muscle fibres involved un the activity
the muscle fbre adapts to the type of activity (SAID)
mitochondrial and capillary adaptations to endurance training
contractile protein adaptations to resistance exercise training
What are the adaptations of skelelal muscle to endurance training?
changes to central and peripheral circulation
CO, muscle blood flow
muscle metabolism
muscle respiratory capacity
What are the fibre composition changes in endurance training?
little or no change in fibre size
generally little or no change in fibre type proportions
subtle change among fast fibre subtypes: IIB –> IIA or intermediates
chronic training may recruit IIB (glycolytic) fibres in a manner normally expected of the IIA fibres
How is oxygen delivery enhanced in endurance training?
capillarisation
15% increase in number of capillaries after 8 weeks training
greater exchange of gases (and waste) and fuels between blood and working muscles
How is energy production enhanced in endurance training?
Increase in mitochondrial capacity to produce ATP
number, size and efficiency of mitochondria increases
oxidative enzyme activity: SDH, CS are increase
release of FFA, shift to a reliance on fat for ATP production
What adaptations in resistance fatigue?
hypertrophy - increase in size of muscle fibre
muscle size generally correlated with ___
strength
tempting to conclude that cause-effect relation ships, but is it that simple?
What is hyperplasia?
an increase in the number of muscle fibres
doesn’t contribute much to increase in size
most of the hypertrophy that we get with resistance training is due to..
an increase in the size of the indivudual fibres
but also increases in myofibrils and filaments, connective tissue
True or false
The greatest change accompanying strength training can be seen in the exercise itself rather than objective assessments of strength or size
true
improvement in exercise performance (how much weight) is the best way to tell
What neural mechanisms are important in muscle strength changes?
Think about motor units.
First changes in muscle strength during training are the result of altered neural drive
large, fast MUs are only recruited at higher forces
training can facilitate recruitment of these large and fast MUs
changes int the pattern of MU stimulation or synchronisation of MU firing
the major determinant of strength is muscle size, or more , specifically ….
muscle cross-sectional are
variation in strength between people can be explained by difference in muscle size
true or false
As an adaptation to resistance training - all muscle fibres get bigger because they are all recruited in consecutive order to produce high levels of forces
(what can happen with advanced lifters)
true
in advanced lifters the DNA might adapt to allow these athletes to recruit some MUs not in consecutive order
i.e by recruiting larger ones first to help with greater production of power or speed in a movement
Can fibre hyperplasia occur in muscle as a consequence of strngth training?
two possible ways:
splitting of hypertrophied fibres into two or more daughter fibres
satellite cell proliferation following muscle damage
cats and birds have exhibited _______.
hyperplasia
Each person resposnds ____ to each training program
differently
an individualised training program is needed to address the specific needs and responses of the athlete
the magnitude of physiological or performance gain is related to the size of an athletes adaptation window
true or false
exercise training programs need to change and provide variation to keep the exercise stimulus effective in eliciting positive changes or maintaining sport fitness
true
training for peak athlete performance is different from training for optimal health and fitness:
training intensities, frequencies and volumes
what are five acute program variables of a resistance exercise protocol:
choice of exercise
order of exercise
resistance or intensity
number of set
length of rest between sets
For sporting success, ______ is critical for peaking for specific events
periodisation
prep, transition, competition phases
