Resistance exercise 1 and 2 Flashcards
What is resistance exercise?
Any exercise that causes the muscle to contract against an external resistance with the primary aim of improving muscle strength
Three types of resistance exercise?
Concentric, eccentric, isometric
How do concentric exercises work?
They shorten the muscle
How do eccentric exercises work?
They lengthen the muscle
How do isometric exercises work?
They generate force without changing the length of the muscle
Issue with definition of resistance exercise?
“external resistance” is a relative term
What is strength?
Capacity to exert force under a set of biomechanical conditions
What is the short term effect of resistance training?
negative
Actual short term effects of resistance training?
Fatiguing, damaging
What is supercompensation?
An increase in capacity after a recovery from a resistance exercise
What is involution?
The returning to original capacity after a supercomposition if nothing is done to maintain it
What makes a muscle stronger?
size
What attaches a muscle to a bone?
A tendon
Name for a bundle of muscle fibres?
Fasiculus
How many myofibrils in a single muscle fibre?
roughly 2000
What makes up muscle fasicles?
Muscle fibres
How many myonuclei per muscle fibre?
200-300
What connects myosin to Z lines?
titin
Step 1 of muscle contraction?
AP arrives at neuromuscular junction
What happens after AP arrives at neuromuscular junction?
ACh is released
What happens as a result of ACh release in muscle?
Depolarization as a result of binding to receptors in myocyte membrane
What happens as a result of depolarisation?
Ca2+ is released inside the cell from the sarcoplasmic reticulum
What does Ca2+ bind to after being released?
Troponin
What happens as a result of Ca2+ binding to tropinin?
Troponin changes shape
What happens as a result of troponin changing shape?
Tropomyosin is moved from the active site of the actin filament
What happens after tropomyosin has moved from the actin filament’s active site?
Myosin attaches to actin, forming a cross bridge at a binding site?
What happens as a result of myosin forming a cross bridge?
ATP attached to the myosin head it broken down to release energy for a power stroke of the myosin filament
What happens as a result of a power stroke?
Z lines move together
What does it mean if Z lines have moved together?
Sarcomere length is reduced–> contracting
What happens after the Z lines have moved closer together?
A new ATP molecule binds to the myosin head
What happens as a result of a new ATP binding to the myosin head?
The head is released from the actin binding site
What happens if there is still calcium left in the cell once the myosin head has released?
It will attach to the next nearest actin filament binding site
What happens if there is no Ca2+ or ATP?
The process stops
What is hypertrophy?
Net muscle gain
What is atrophy?
Net muscle loss
What happens to muscle synthesis when amino acids are ingested?
The rate of muscle synthesis increases
What happens to the rate of muscle breakdown when AAs are ingested?
decreases
What happens to the rate of muscle synthesis a while after AA ingestion?
Decreases
What happens to the rate of muscle breakdown a while after AA ingestion?
Increases/ returns to original level
What happens to muscle breakdown if you do exercise a while after eating?
It increases higher than it would do if you hadn’t done exercise
What happens to muscle synthesis if you do exercise after eating?
It increases a lot
How does muscle synthesis increase after doing exercise?
The anabolic response is primed as a result of doing resistance exercise
How long is the anabolic response primed post exercise?
24-48 hrs
What happens to hypertrophy after the onset of training?
It is delayed
Why is hypertrophy delayed after training?
A lot of the muscle protein synthesis is repairing the muscles that were damaged as a result of the training, so it isnt “new” muscle
What happens to muscle synthesis as you train more?
There is less muscle damage, so more of the muscle synthesis is going to hypertrophy instead of repair
Why do muscles look larger after training even though they have been damaged?
Oedema induced muscle swelling
What is Oedema induced muscle swelling?
A swelling in response to the muscles being damaged
What happens as a result of Oedema induced muscle swelling?
The muscle size/cross sectional area is artificially increased
Why does hypertrophy slowly plateau as you train more?
The “priming effect” loses its potency so less hypertrophy occurs
What did the Damas 2017 study show about trained muscle hypertrophy effect in response to damage compared to non-trained muscle?
The initial increase in hypertrophy immediately post training for the trained muscle was the same as the untrained muscle (“priming effect”) however it dropped off over time a lot faster than the untrained muscle did
What is muscle fibre hypertrophy?
The muscle cells getting bigger
What is muscle fibre hyperplasia?
The amount of cells increasing
What increases post resistance training?
Fibre hypertrophy
How does myofiber hypertrophy happen?
myofibril splitting
What is a myofibril?
An organelle in a muscle cell
Role of myofibril?
produce contraction
Why is it a challenge to measure hyperplasia
Would have to chop leg in half, count number of cells, do exercise, chop leg in half and count cells again
When does hyperplasia definitely occur?
In utero (when foetus is growing)
At what point in utero does myofiber hyperplasia stop?
24 weeks (60-70% of mammalian gestation)
