Ch. 10 Adaptations to Resistance Training

- Akt is an insulin secondary messenger which is part of the insulin-dependent pathway (not the contraction-mediated pathway). - Phosphatidic acid (PA) is a lipid secondary messenger that stimulates mTor. - Leucine is a very important amino acid in role of stimulating protein synthesis by stimulating mTor. - mTor binds to the surface of a lysosome when amino acid levels are high.

- Akt is an insulin secondary messenger which is part of the insulin-dependent pathway (not the contraction-mediated pathway.) - Phosphatidic acid (PA) is a lipid secondary messenger that stimulates mTor. - Leucine also helps stimulate protein sysnthesis by stimulating mTor. - mTor binds to the surface of a lysosome when amino acid levels are high.

1. Consumption of ____________ g protein _______ minutes after resistance exercise can lead to muscle growth. 2. ACSM guidelines recommend consuming ____________ g protein per kg body weight per day to increase muscle mass.

- Resistance training increases protein synthesis. 1. Consumption of 20 to 25 g protein 30 minutes after resistance exercise can lead to muscle growth. 2. ACSM guidelines recommend consuming 1.6 to 1.7 g protein per kg body weight per day to increase muscle mass. --> Small doses (20 g) every 2 to 3 hours are recommended for protein synthesis. --> Larger doses (20-25 g) recommended immediately after resistance training.

Studies ___________________________ of fiber hyperplasia in humans.

--> Fiber hyperplasia is the increase in total number of fibers within muscle Studies still have not been able to prove the existence of fiber hyperplasia in humans: - However, in cats, intense strength training produces fiber splitting. --> Each half grows to size of parent fiber. - However, in chickens, mice, rats, intense strength training did not produce fiber hyperplasia, only fiber hypertrophy. But difference may be due to training regimen, as cats were not training in 1RM as opposed to the chickens, mice, and rats who were.

1. After ____________ months of resistance training, studies have reported a range of 25% to 100% strength gain. 2. Gains are regarded to be from increased __________________ characterized by __________________. 3. The ability to learn how to produce a true maximal movement is due to __________________. 4. The __________________ accounts for up to 50% of early strength gains.

1. After 3 to 6 months of resistance training, studies have reported a range of 25% to 100% strength gain. 2. Gains are regarded to be from increased force production characterized by the learning effect i.e. beginner gains. --> The learning effect is when individuals improve their performance on a test simply by practicing the motor skills associated with the movement. 3. The ability to learn how to produce a true maximal movement is due to muscle plasticity. --> Muscle plasticity is defined as the ability of a given muscle to alter its structural and functional properties in accordance with the environmental conditions imposed on it. - However, these gains can be somewhat misleading --> Most subjects in strength training have never lifted before 4. Learning effect accounts for up to 50% of early strength gains

1. Autogenic inhibition are the ______________ ______________ ______________ mechanisms, example being the __________________. 2. Through training, inhibitory impulses can __________________. 3. ____________ inhibitory impulses allow muscles to generate more force.

1. Autogenic inhibition are the normal intrinsic inhibitory mechanisms (i.e. protective mechanisms) --> Example: Golgi tendon organs --> Inhibit muscle contraction if tendon tension too high. --> Prevents damage to bones and tendons. 2. Through training, Inhibitory impulses can be DEcreased. --> Ex. If you were to jump from a high height and initially couldn't handle it (Golgi tendons signaling the muscles around the joint to relax --> crumbling after a jump), you could train up to the height and land with less Golgi tendon inhibition. 3. Decreased inhibitory impulses allow muscles to generate more force. --> May also explain superhuman feats of strength.

1. Chronic muscle hypertrophy is maximized by high-velocity ___________________ which disrupts ___________________. 2. ____________ training allows you to use more force than typically used in ____________ training. 3. ____________ training shows greater growth distally whereas ____________ training shows greater proximal and mid hypertrophy. 4. Chronic muscle hypertrophy can be stimulated by intensities ___________________________. 5. Chronic hypertrophy can be caused by repetitions of ____________________.

1. Chronic muscle hypertrophy is maximized by high-velocity eccentric training which disrupts sarcomere Z-disk (protein remodeling). ---> Protein remodeling is the protein-assisted change is the structure of a complex which allows for a change in the biological activity. 2. Eccentric training allows you to use more force than typically used in concentric training. Concentric training may limit muscle hypertrophy, strength gains. 3. Eccentric training shows greater growth distally whereas concentric training shows greater proximal and mid hypertrophy (so for biceps, eccentric more growth in elbow and concentric more grow in the bicep head and towards the shoulder) 4. Chronic muscle hypertrophy can be stimulated by intensities as low as 30% 1RM and as high as 90%. 5. Chronic hypertrophy can be caused by both high-rep (low-load) and low-rep (high-load) training.

1. Fiber hypertrophy is facilitated by ______________. 2. Testosterone is a natural ______________ ______________ hormone. 3. ______________ stimulates the release of IGF-1. 4. Insulin-like growth factor 1 (IGF-1) is classified as a ____________ which is a hormone that acts a mediator between ____________ and ____________. 5. Elevated post exercise __________________ are not required for anabolism and strength.

1. Fiber hypertrophy is facilitated by testosterone. --> Promotes muscle growth 2. Testerone is a natural anabolic steroid hormone. --> Synthetic anabolic steroids lead to large increases in muscle mass 3. Growth hormone (GH) stimulates the release of IGF-1. 4. Insulin-like growth factor 1 (IGF-1) is classified as a somatomedin ('so-meh-tow-me-din') which is a hormone that acts as a mediator between GH and its effects; IGF acts as the mediator between the anabolic and mitogenic effects of growth hormone. --> Mitogenic means mitosis which is seen in hyperplasia. 5. Elevated post-exercise levels of hormones are not required for anabolism and strength.

1. Hydrostatic pressure is the ____________ factor in fluid movements 2. Osmotic pressure is the ____________ factor in fluid movements.

1. Hydrostatic pressure is the push factor in fluid movements 2. Osmotic pressure is the pull factor in fluid movements.

1. Increased neural activation leads to ______________ increases in muscle strength 2. Increased neural activation can lead to substantial increases in ____________. 3. Neural factors are critical in ______________ weeks. 4. Hypertrophy leads to ______________ increases in muscle strength. 5. Hypertrophy is a major factor ______________ weeks.

1. Increased neural activation leads to short-term increases in muscle strength 2. Increased neural activation can lead to substantial increases in 1RM due to increase in voluntary neural activation. --> Voluntary neural activation is the level of neural drive from the central nervous system to produce a given force output from a muscle. 3. Neural factors critical in first 8 to 10 weeks. 4. Hypertrophy leads to long-term increase in muscle strength and take longer due to net increase protein synthesis requiring time to occur 5. Hypertrophy major factor after first 10 weeks

1. Increases in strength for older adults depend primarily on __________________. 2. In older adults, there is a ____________ mTOR signaling response and ___________________ in myofibrillar protein and muscle size.

1. Increases in strength for older adults depend primarily on neural adaptations. --> No difference across sex or race in older adult --> Same response as in younger populations but blunted (weaker). 2. In older adults, there is a decreased mTOR signaling response and smaller increases in myofibrillar protein and muscle size - 25-50 g protein necessary to stimulate muscle protein synthesis

1. Isokinetic dynamometer measures ___________________________. 2. Fiber hypertrophy leads to: - More ____________ - More ____________ - More ____________ - More _______________ which allows for greater passive energy storage. 3. __________________ leads to increased protein synthesis. 4. Muscle protein content is __________________.

1. Isokinetic dynamometer measures force through constant speed. 2. Fiber hypertrophy leads to: - More myofibrils - More actin, myosin filaments - More sarcoplasm - More connective tissue which allows for greater passive energy storage. 3. Resistance training leads to increased protein synthesis: --> Resistance training can also increase post-translations modifications (e.g., phosphorylation or the cleaving of amino acid bonds for digestion). 4. Muscle protein content is always changing. --> During exercise, protein synthesis is increased and protein degradation is decreased. --> After exercise, protein synthesis is increased 3-5x, and degradation continues.

1. Major changes can be seen after ____________ of immobilization. 2. In the first week, 3% to 4% of strength loss can be seen ____________. 3. Effects of inactivity are ____________ in type I and II fibers. 4. The effects of inactivity are more severe for Type _______ fibers than type _______ fibers.

1. Major changes can be seen after 6 hrs of immobilization. --> Lack of muscle use leads to reduced protein synthesis. --> Initiates process of muscle atrophy. 2. In the first week, 3% to 4% of strength loss can be seen per day. --> Decrease size (atrophy) --> Decrease neuromuscular activity 3. Effects of inactivity are reversible in type I and II fibers --> Inactivity can lead to decrease in cross-sectional area and degeneration of cell contents. 4. The effects of inactivity are more severe for Type I than type II.

1. Most hypertrophy in humans is caused by fiber ____________ as opposed to fiber ____________. 2. Fiber hyperplasia can occur through ___________________. 3. Satellite cells are __________________ involved in skeletal muscle regeneration. 4. Satelittle cells are activated by __________________.

1. Most hypertrophy in humans is caused by fiber hypertrophy as opposed to fiber hyperplasia. --> Fiber hyperplasia may occur only in certain individuals under certain conditions. 2. Fiber hyperplasia can occur through fiber splitting aka mitosis and satellite cells. 3. Satellite cells are myogenic stem cells involved in skeletal muscle regeneration. --> Stem cells are unspecialized cells that have the ability of self-renewal (process by which stem cells divide to make more stem cells). --> Myogenic stem cells are cells that have the ability to differentiate into muscle fibers. 4. Satellite cells are activated by stretch and injury. --> After activation: proliferate, migrate, fuse

1. Motor units are normally recruited ______________. 2. However, the number and strength of motor unit recruitment are based on ______________ motor unit firing instances. 3. Resistance training can lead to ______________ recruitment. 4. Synchronization does improve the ________________________ and the capability to exert ______________.

1. Motor units are normally recruited asynchronously. --> Asynchronous recruitment of motor units is used to prevent fatigue. While some motor units are active others are inactive. This pattern of firing of motor neurons prevents fatigue while maintaining contraction by allowing a brief rest for the inactive unit. 2. However, the number and strength of the motor unit recruitment are based on synchronous motor unit firing instances caused by a common synaptic input. --> the common synaptic input has to be interpreted as the portion of the sum of inhibitory and excitatory inputs to each motor neuron that results in the same net input to all motor neurons, besides a potential scale factor. 3. Resistance training can lead to synchronous recruitment. 4. Synchronization does improve the rate of force development and the capability to exert steady forces. Review: --> A single stimulus (action potential) results in a single contractile response - a muscle twitch (contracts and relaxes) --> More frequent stimuli increase contractile force - wave summation - muscle is already partially contracted when the next stimulus arrives and contractions are summed. --> A sustained contraction that lacks even partial relaxation is known as tetanus.

1. Muscle fatigue-associated cramps are related to ________________________ activity, with increased ___________________ activity and decreased ___________________ activity. 2. Heat-associated cramps, which typically occur in athletes who have been sweating excessively, involve a shift in fluid from ___________________ to the ___________________, resulting in a hyperexcitable _______________________.

1. Muscle fatigue-associated cramps are related to sustained a-motor neuron activity, with increased muscle spindle activity and decreased Golgi tendon organ activity. 2. Heat-associated cramps, which typically occur in athletes who have been sweating excessively, involve a shift in fluid from the interstitial space to the intravascular space, resulting in a hyperexcitable neuromuscular junction. --> The second type of exercise-associated muscle cramp involves electrolyte deficits. This type of muscle cramp typically occurs in athletes who have been sweating extensively and have significant electrolyte disturbances, mainly sodium and chloride. These types of electrolyte disturbances can occur during or after a long race, game, or match, or as a consequence of multiple exercise bouts in which sweat sodium and chloride losses exceed intake. In the muscle, to compensate for the large electrolyte sweat and plasma volume losses, fluids shift from the interstitial compartment to the intravascular compartment. It is thought that this shift in fluid can cause the neuromuscular junctions to become hyperexcitable, leading to spontaneous discharge and initiation of action potentials in the muscles.

1. Other neural factors include coactivation of ________________________ and ___________________________. 2. Training can lead to ____________ coactivation which may lead to strength gain. 3. Through strength training, there are changes to the __________________ that facilitate a greater passage of action potential.

1. Other neural factors include coactivation of agonists and antagonists and morphology of neuromuscular junction. --> Normally antagonists oppose agonist force 2. Training can lead to reduced coactivation, i.e. less activation of the antagonist muscle (and thus less opposing force), which may lead to strength gain. 3. Through strength training, there are changes to the neuromuscular junction that facilitate a greater passage of action potential.

1. Reduction or cessation of activity leads to ____________ in muscle. 2. Neural adaptations ________________________ the strength gains

1. Reduction or cessation of activity leads to atrophy in muscle structure. 2. Neural adaptations always accompany the strength gains

1. Resistance training for women is __________________. 2. Women have __________________ to develop strength compared to men. 3. Resistance training techniques for men can be applied to women ____________.

1. Resistance training for women is relatively recent. 2. Women have the same ability to develop strength as men. >>Women may not be able to reach the peaks values men produce --> Difference due primarily to size --> Related to sex differences in anabolic hormones 3. Resistance training techniques for men can be applied to women equally.

1. __________________ is controlled by mTOR (mechanistic target of rapamycin). 2. mTor integrates input from ______________, ______________, ______________. 3. mTor dictates __________________. 4. mTor synthesizes ______________.

1. Skeletal muscle protein synthesis is controlled by mTOR (mechanistic target of rapamycin). --> Rapamycin is an inhibitor of mTor which also serves as a macrolide (drug against bacterial infections), immunosppressant, and potential anti-aging drug. --> mTOR is a serine/threonine kinase (i.e. a second messenger protein such as cAMP) which senses various environmental and intracellular changes including nutrient availability and energy status, and coordinates diverse cellular processes including cell growth, differentiation, autophagy, survival, and metabolism. 2. mTor integrates input from insulin, growth factors, amino acids. 3. mTor dictates transcription of mRNA. 4. mTor synthesizes ribosomes (site of translation). --> Amino acids converted into protein via mRNA

1. Strength gain cannot occur without __________________ via ____________. 2. Strength is a property of __________________, not just of muscle. 3. The essential elements of neural control include: - __________________ - __________________ - __________________.

1. Strength gain cannot occur without neural adaptations via plasticity. - Strength gain can occur without hypertrophy (the muscle doesn't need to grow in size to get stronger) 2. Strength is a property of the motor system, not just of muscle. 3. Essential elements of neural control include: - Motor unit recruitment (increasing the number of active motor units in a muscle) - Stimulation frequency - Autogenic inhibition (Golgi tendon reflex), and other neural factors.

1. There is limited evidence that suggests rate-coding increases with _______________. 2. __________________ training appears to be effective in enhancing rate coding.

1. There is limited evidence suggests that rate coding increases with resistance training. 2. Rapid-movement, ballistic-type training appears to be effective in enhancing rate coding. --> Ballistic type training: jumps, throws, strikes.

1. Training is __________________ ____________ the basic strength, power, and endurance needs of the chosen sport. 2. Training ____________ valuable time. 3. Training results should be tested with _________________________________.

1. Training is not worth it beyond the basic strength, power, and endurance needs of the chosen sport. 2. Training costs valuable time. 3. Training results should be tested with sport-specific performance metrics.

1. Training regimen __________________ change fiber type.

1. Training regimen may not outright change fiber type, but . . . --> Type II fibers more oxidative with aerobic training. --> Type I fibers more anaerobic with anaerobic training. Fiber type conversion is possible under certain conditions. Cross-innervation: innervating a type-1 fibers with a type-II motor neuron (very rare) Chronic low-frequency stimulation High-intensity treadmill or resistance training

1. Transient hypertrophy which occurs after an exercise bout is due to ___________________________. 2. Transient hypertrophy is also referred to as __________________ in layman's terms. 3. Transient hypertrophy is gone ______________. 4. Chronic hypertrophy is the result of greater __________________ over __________________. 5a. Hypetrophy: increase in fiber ____________. 5b. Hyperplasia: increase in fiber ____________.

1. Transient hypertrophy which occurs after an exercise bout is due to edema (fluid overload) formation from plasma (blood) fluid in the interstitial and intracellular spaces. 2. Transient hypertrophy is also referred to as a muscle "pump" in layman's terms. 3. Transient hypetropy is gone within hours. - Chronic hypertrophy is long term structural change in the muscle fiber. 4. Chronic hypertrophy is the result of greater protein synthesis (MPS aka skeletal muscle protein synthesis) over protein degradation. -. Chronic hypertrophy is explained by fiber hypertrophy, fiber hyperplasia, or both. 5a. Hypetrophy: increase in fiber size. 5b. Hyperplasia: increase in fiber number.

With resistance training there is a transition of type _______ to type _______ fibers.

1. With resistance training there is a transition of type IIx to type IIa fibers. >>Type IIx to type IIa transition is common through a 20-week heavy resistance training program: --> Static strength, cross-sectional area increase --> A decrease in percent type IIx and an increase in percent type IIa - Other studies: type I to type IIa with high-intensity resistance work + short-interval speed work

1. In children and adolescents, resistance training is ___________________________. 2. ____________ can gain both strength and muscle mass. 3. In elderly people, resistance training can help restore age-related loss of muscle mass known as ____________. 4. Resistance training can help the elderly _______________.

Children and adolescents Myth: Resistance training is unsafe due to growth plate, hormonal changes. 1. In children and adolescents, resistance training is safe with proper safeguards. 2. Children can gain both strength and muscle mass. Elderly persons 3. In elderly people, resistance training can help restore age-related loss of muscle mass known as sarcopenia. Improves quality of life and health. 4. Resistance training can help the elderly prevent falls.

1. Lost strength can be regained within ______________ of detraining. 2. There is evidence that shows improved squat 1RM following ___________________________.

Detraining leads to decrease in 1RM. 1. Lost strength can be regained within ~6 weeks of detraining. 2. There is evidence that shows an improved 1RM following a period of retraining after a period of detraining (image). --> New 1RM can match or exceed old 1RM during retraining within 6 week of detraining. - Once training goal met, maintenance resistance program prevents detraining. --> Maintain strength and 1RM. --> Reduce training frequency.

1. Increase in ______________ leads to increased muscle strength. 2. The two sources of strength gains are ___________________________.

Hypertrophy versus atrophy: 1. Increase in muscle size leads to increased muscle strength --> Decrease in muscle size leads to decreased muscle strength --> But the association is more complex than that 2. The two sources of strength gains are - increased muscle size and - altered neural control.

Increased Motor Unit Recruitment can lead to: 1. Increase in neural drive which is ___________________________ and ___________________________. 2. Neural drive starts ____________ and is spread to __________________. 3. Increase in __________________ and __________________. 4. Decrease in __________________. 5. Trained muscles generate ____________ EMG activity.

Increased Motor Unit Recruitment can lead to: - Increase in neural drive during maximal contraction 1. Neural drive is the number of motor units that are activated (recruitment) and the rates at which those motor units discharge action potentials (rate coding). 2. Neural drive starts in the CNS and is spread to muscle fibers in the PNS. ---> Neural drive is the sum of the spikes (firing of action potentials) of the motor neurons in a motor unit. 3. Increase in the frequency of neural discharge (rate coding) and motor units recruited. 4. Decrease in inhibitory impulses. 5. Trained muscles generate less EMG activity. --> More efficient motor unit recruitment - Combination of frequency of discharge or reduced inhibitory influence -> strength

If hyperplasia were to occur, it is most likely through _________________________________.

Satellite cells process 1. Satellite cell activation and proliferation (self-renewal of myofiber) 2. Chemotaxis to injured fiber 3. Fusion to damaged myofiber 4. If hyperplasia were to occur, it is most likely through satellite cells combining and fusing to produce new muscle fibers. 5. Regenerated myofiber with central nuclei. 6. Resting myofiber, quiescent satellite cell, myonuclei.