W3 - Resistance Training Flashcards
why does resistance training result in strength increase?
- Muscle hypertrophy
- Muscle hyperplasia
- Neural adaptations
How does training impact muscles?
muscle hypertrophy (fibre size ↑)
How does the increase in muscle size effect performance?
Increases performance
How does sex difference effect muscles?
Different muscle size, hormones (testosterone, males more muscle mass, less fat mass)
How does resistance training impact gains in muscular fitness?
- Resistance training yields strength gains via neuro-muscular changes
- After 3 to 6 months of resistance training:
~25 to 100% strength gain
○ More effective force production (physiological adaptations) - bigger fibres & neural system is better at accessing the working muscles
○ Optimisation of movements (technique) - coordination & technique between muscles (only accessing muscles that facilitate the movement)
- After 3 to 6 months of resistance training:
Describe the mechanisms of muscle strength gain
- Strength gain can occur without hypertrophy
○ Normally motor units are recruited asynchronously - Strength training makes the muscle recruitment from asynchronous to synchronous - increase in force over time is steeper
- Nerves send signals in a more synchronous fashion
○ Resistance training → more synchronous recruitment → strength ↑ - Improved rate of force development
Describe how motor unit recruitment can generate strength gains
- Strength gains may also result from greater motor unit recruitment
- Neural drive during maximal contraction ↑
- Frequency of neural discharge ↑ (higher neural output makes us contract more forcefully)
- Inhibitory impulses ↓ (e.g.: these become lost as we fall asleep, sudden kicking) Improved capability to exert steady forces
Explain autogenic inhibition
- Normal intrinsic inhibitory mechanisms
– Golgi tendon organs (inhibit muscle contraction if tendon tension too high, monitor stretch of the tendon)
→ Prevent damage to bones and tendons via inhibitory neuron - Decreasing inhibitory impulses
– Training → Force ↑
– Superhuman feats of strength(e.g.: under extreme stress, mother child reaction can prevent these inhibitory impulses)
Describe the muscle strength gain in antagonists vs agonists
- Co-activation of agonists and antagonists
- Normally antagonists oppose agonist force (training reduces the antagonist force to as little as possible)
- Reduced co-activation may result in (slight) strength gain
What are the short/long term muscle strength gains?
- Short-term increase in muscle strength
– Substantial increase in maximum force
– Increase in voluntary neural activation
– Neural factors critical in first ~8 to 10 weeks - Long-term increase in muscle strength
– Associated with fibre hypertrophy
– Net increase in protein synthesis takes time to occur
– Hypertrophy major factor after first ~10 weeks that drives strength gain
Explain the chronic and transient hypertrophy that takes place to increase muscle size
- Hypertrophy: increase in muscle size
- Transient muscle hypertrophy (after exercise bout)
○ Due to edema formation from plasma fluid
○ Disappears within hours - Chronic muscle hypertrophy (long term)
○ Reflects actual structural change in muscle
○ Fibre hypertrophy (bigger fibres), fibre hyperplasia (more fibres), or both: animal experiments show before training there is 1 big fibre, after training there are 2 smaller fibres
- Transient muscle hypertrophy (after exercise bout)
What are some benefits of fibre hypertrophy?
- more myofibrils,
- more actin and myosin filaments,
- more sarcoplasm,
- more connective tissue, or
- any combination of these.
What are the 3 main mechanisms of muscle strength gain through fibre hypertrophy?
- Resistance training → protein synthesis ↑
– During exercise: synthesis ↓, degradation ↑
– After exercise: synthesis ↑, degradation ↓ - Hormones
– Testosterone facilitates fibre hypertrophy (natural anabolic steroid hormone)
– Synthetic anabolic steroids → large increases in muscle mass - Genetics: e.g., mutation in myostatin gene (Belgian Blue cows)
How does eccentric training impact muscle strength gain ?
- Maximized by eccentric training → Force increase
- Maximized by eccentric training
– Disruption of sarcomere Z-lines- After a training session → protein remodelling → overreaching of capabilities
- Long term trajectory increases
How does concentric training impact muscle strength gain?
- Concentric training may limit muscle hypertrophy and strength gains
- Left side of diagram is where muscle lengthens because the weight is too heavy for muscle shortening
- Why not only eccentric training is done:
○ More risk of injury
○ Training the specific movements for competition
Explain fibre hyperplasia
- Most hypertrophy due to fibre hypertrophy
- Fibre hyperplasia: fibre splitting, each half grows to size of parent fibre
– may also contribute (some evidence in animal studies, very little evidence in humans)
How does fibre type determine the type of exercises for strength gain?
- Fibre type conversion is possible under certain conditions
– High-intensity treadmill or resistance training:
Type I → Type IIa
– Heavy resistance training programme:
Percent Type IIx ↓, percent Type IIa ↑
What is the role of the sarcomere Z-disks?
- Sarcomere Z-disks: anchoring points of contact for contractile proteins
– Transmit force when muscle fibres contract
– Z-disk, actin/myosin damage after eccentric work
e.g.: After a marathon there is a lot of damage to muscle cells
What does DOMS stand for?
Explain what DOMS is & what it tells us
- 1-2 days after exercise
- Muscle strain (range: stiffness → severe, restrictive pain)
- Major cause: eccentric contractions
– Level run pain < downhill run pain
– Cycling: mostly concentric → mostly no DOMS
– Not caused by increases in blood lactate concentrations - Indicated by muscle enzymes in blood (e.g., creatine kinase)
– Suggests structural damage to muscle membrane (leak)
– Index of degree of muscle breakdown
What effect does DOMS have on a persons strength?
How does this effect performance?
- DOMS → muscle force generation ↓
- Loss of strength:
– Physical disruption of muscle / Loss of contractile protein
– Failure in excitation-contraction coupling (appears to be most important) - neuron signal doesn’t travel as efficiently as it did before
- Loss of strength:
What are some strategies that athletes can use to reduce DOMS?
- Athletes must reduce excessive DOMS for effective training!
- Strategies to reduce DOMS:
– Minimize eccentric work early in training
– Start with low intensity training and gradually increase throughout session
How does DOMS effect white blood cells?
Explain inflammation of the muscle:
Muscle damage → inflammation → pain
- White blood cells (neutrophils, macrophages) defend body against foreign materials and pathogens, clean up altered/destroyed cells– Damaged muscle cells attract neutrophils
– Neutrophils release attractant chemicals, radicals - stimulates pain receptors
– Released substances and swelling stimulate pain nerves
– Macrophages remove cell debris
