Week 9 - Physiology of Resistance Training Flashcards
Define maximal strength
Maximal force that a muscle group can generate. E.g 1 rep max
Define muscular endurance
Ability to make repeated contractions against submaximal load
What is high resistance strength training
Results in strength increase approx 6 to 10 reps till fatigue
What is low-resistance training
Results in increases in endurance approx 35 to 40 reps to fatigue
Whats the effects of ageing on both muscle mass and strength
loss of muscle mass (termed sarcopenia)
Atrophy of type two fibers
Reduced number of both type one and two fibers loss
Resistance training promotes hypertrophy/strength gains in older individuals but lower than young individuals
What are the neural adaptations responsible for early gain in strength
Muscular strength increases in first two weeks of training without increase in muscle fiber size
Phenomenon of cross education training of one limb results in increases of strength in untrained limb
What are the adaptations of muscle fibers in increasing muscle strength
Increased muscle fibre specific tension
Increased muscle mass
What are the adaptations to neural steps resulting in muscular contraction
Increased neural drive
Increased number motor units received
Increased firing rate of motor units
Increased motor unit synchronization
Improved neural transmission across neuromuscular junction
What are the adaptations within muscle fibres to resistance training
Increased muscle fibre specific tension in type 1 fibres
Training induced increases in muscle mass - hyperplasia is increased number of fibres, hypertrophy is increased cross-sectional area of muscle fibres
How does resistance training effect muscle protein synthesis
A single bout of resistance exercise promotes increase in both muscle protein synthesis and breakdown
Muscle growth occurs because protein synthesis exceeds rate of breakdown
How is the time course of increased muscle synthesis impacted by resistance training
Increases 50 to 150% with 1-4 hours post exercise
Elevated 30 to 48hours depending on training status
What are the key factors leading to resistance training induced increass in muscle protein synthesis
mRNA increases resulting in protein synthesis at the ribosome
Ribosomes increase in number and elebvate muscle’s protein synthesis activity
Activation of protein kinase accelearates protein synthesis following a bout of resistance training
Whats the effect of Phosphaditic acid (PA) and Ras homolog enriched in brain (rheb)on mTOR activation
Muscle contractions activate sarcolemmal mechanoreceptor stimulating synthesis of PA
Contraction-induced activation of sarcolemmal mechanoreceptors also acitvate extra cellular signal-regulated kinase (Erk), active erk inhibits TSC2 which inhibits rheb resulting in mTOR activation by synthesis of PA and removing the TSC2 inhibition of Rheb
What are Other factors linked to resistance training-induced hypertrophy
Both insulin-like growth factor-1 (IGF-1) and growth hormone are linked to mTOR
activation and have potential to increase muscle protein synthesis.
Many individuals use over-the-counter nonsteroidal anti-inflammatory drugs (for
example, ibuprofen and acetaminophen) to combat sore muscles and arthritis.
What are satelite cells
Stem cells that are located between the sarcolemma and basal lamina
How do satelite cells impact resistance training
Resistance training activates satellite cells to divide and fuse with adjacent muscle fibers to increase myonuclei
Whats the effect of myonuceli and resistance training
Resistance training-induced increases in
myonuclei results in a constant ratio between
number of myonuclei and size of muscle fiber
addition of new myonuclei to fibers is likely required to support increased protein synthesis in
larger muscle fibers
How does age effect satelite cells and resistance training
Resistance training-induced satellite cell
activation is blunted in older individuals
What effect do genetics have on muscle mass
Approximately 80% of the differences in muscle mass
between individuals is due to genetic variation
These are due to variations between people in their ability to activate protein synthesis genes in
skeletal muscle in response to resistance training
What happens as a result of detraining in relation to strength training
Cessation of resistance training results in muscle atrophy
and a loss of strength.
However the rate of detraining is slower compared to resistance training
How quickly can strength loss gains be regained after detraining
Recovery of dynamic strength loss can occur rapidly
(within 6 weeks) with retraining.
Argued that this is due to muscle memory as resistance training-induced increases in myonuclei in the
trained fibers that are not lost during detraining
What is the result of prolonged muscle inactivity
0 to 30 days of muscle inactivity can result in 20 to 30% reduction in muscle fiber size (muscle atrophy)
How can muscle mass be conserved
dependent upon balance between protein synthesis and rates of
protein degradation.
What is the key mechanism responsible for inactivity induced muscle atrophy
Increased radical production promotes muscle atrophy during prolonged inactivity by
depressing protein synthesis and increasing degradation
What can result in interference of muscle adaptations
Strength training increases muscle fiber size whereas
endurance training does not
Depends on intensity, volume, and frequency of endurance
training.
What are potential mechanisms for concurrent exercise
Neural factors - impaired motor unit recruitment but there is limited evidence supporting this
Overtraining but no concrete evidence either
Depressed protein synthesis - endurance training cell signaling can interfere with protein synthesis via inhibition of mTOR by activating AMPK
