weight training questions. is it possible to increase the number of muscle fibers by resistance...

Weight Training QuestionsWeight Training Questions

Is it possible to increase Is it possible to increase the number of muscle the number of muscle fibers by resistance fibers by resistance

training?training?

More Muscle Fibers?More Muscle Fibers?

Heavy resistance training has been Heavy resistance training has been reported to increase the number of reported to increase the number of muscle fibers in animals due to muscle fibers in animals due to longitudinal splitting and satellite longitudinal splitting and satellite cell proliferation.cell proliferation.


However, this has not been clearly However, this has not been clearly demonstrated in human skeletal demonstrated in human skeletal muscle tissue.muscle tissue.


Some data suggesting that human Some data suggesting that human skeletal muscle has the potential skeletal muscle has the potential to increase muscle fiber number, to increase muscle fiber number, however however hyperplasiahyperplasia probably probably contributes less than 5% to overall contributes less than 5% to overall muscle growth in response to muscle growth in response to heavy resistance training.heavy resistance training.


The major factor contributing to The major factor contributing to exercise-induced hypertrophy for exercise-induced hypertrophy for humans apparently is an increase humans apparently is an increase in the size of existing muscle in the size of existing muscle fibers.fibers.

Alter Fiber Type?Alter Fiber Type?

Although strength training Although strength training produces greater hypertrophy in produces greater hypertrophy in fast-twitch (Type II) muscle fibers fast-twitch (Type II) muscle fibers than in slow twitch (Type I) fibers, than in slow twitch (Type I) fibers, there is no evidence to support the there is no evidence to support the conversion of slow-twitch to fast-conversion of slow-twitch to fast-twitch fibers.twitch fibers.


Resistance training does not alter Resistance training does not alter the percentage of Type I and II the percentage of Type I and II muscle fibers.muscle fibers.


However, heavy resistance training However, heavy resistance training appears to increase the appears to increase the percentage of Type IIB (fast-twitch-percentage of Type IIB (fast-twitch-glycolytic) muscle fibers, while glycolytic) muscle fibers, while decreasing the percentage of Type decreasing the percentage of Type IIA (fast-twitch oxidative) fibers in IIA (fast-twitch oxidative) fibers in both men and women.both men and women.

Gender Difference?Gender Difference?

Muscle strength is Muscle strength is directly related to directly related to the cross-the cross-sectional area of sectional area of the muscle tissue.the muscle tissue.


Strength per unit of cross-sectional Strength per unit of cross-sectional area is similar for men and women.area is similar for men and women.


Absolute hypertrophy varies Absolute hypertrophy varies between men and women, between men and women, whereas relative hypertrophy is whereas relative hypertrophy is similar.similar.

Increased Size in Older Increased Size in Older Lifters?Lifters?

Exercise-induced hypertrophy Exercise-induced hypertrophy appears to be an important appears to be an important mechanism underlying strength mechanism underlying strength gains in older men and women.gains in older men and women.

Increased Size in Older Increased Size in Older Lifters?Lifters?

This implies that age-related loss This implies that age-related loss in muscle mass can be countered in muscle mass can be countered effectively by participating in a effectively by participating in a vigorous resistance training vigorous resistance training program.program.

Biochemical EffectsBiochemical Effects

The morphological changes in The morphological changes in skeletal muscle due to resistance skeletal muscle due to resistance training are caused by hormones.training are caused by hormones.


AnabolicAnabolic (protein building) (protein building) hormones hormones such as testosterone, such as testosterone, growth hormone (somatotropin), growth hormone (somatotropin), and insulin-like growth hormone and insulin-like growth hormone (IGH) increase in response to (IGH) increase in response to heavy resistance exercise and heavy resistance exercise and interact to promote protein interact to promote protein synthesis.synthesis.


The magnitude of testosterone and The magnitude of testosterone and growth hormone release, however, growth hormone release, however, is related to:is related to:– the size of the muscle groups used,the size of the muscle groups used,– exercise intensity (% 1-RM), exercise intensity (% 1-RM), – and the length of rest between sets, and the length of rest between sets,

with larger increases observed for high with larger increases observed for high intensity (5 to 10-RM) and short (1 minute) intensity (5 to 10-RM) and short (1 minute) rest periods involving large muscle groups.rest periods involving large muscle groups.


In men, high-intensity resistance In men, high-intensity resistance training produces significant training produces significant increases in testosterone and increases in testosterone and growth hormone.growth hormone.


Levels of catecholamines Levels of catecholamines (norepinephrine, epinephrine, and (norepinephrine, epinephrine, and dopamine), which augment the dopamine), which augment the release of testosterone and IGF, release of testosterone and IGF, also increase in men in response to also increase in men in response to heavy resistance exercise.heavy resistance exercise.


In women, the growth hormone In women, the growth hormone response to resistance exercise response to resistance exercise varies over stages of the varies over stages of the menstrual cycle.menstrual cycle.


Although high intensity resistance Although high intensity resistance training results in substantial training results in substantial increases in muscle proteins, it increases in muscle proteins, it appears to have little or no effect appears to have little or no effect on muscle substrate stores and on muscle substrate stores and enzymes involved with the enzymes involved with the generation of ATP.generation of ATP.

Cross-TrainingCross-Training

Participation in heavy resistance Participation in heavy resistance training does not negatively affect training does not negatively affect aerobic power.aerobic power.

Neurological EffectsNeurological Effects

Neurological adaptations account Neurological adaptations account for much of the improvement in for much of the improvement in muscle strength in the early stages muscle strength in the early stages of resistance training.of resistance training.


Increased muscle size alone Increased muscle size alone cannot account for the rate of cannot account for the rate of strength gain due to resistance strength gain due to resistance training.training.


In the early stages ( 2 to 8 weeks) In the early stages ( 2 to 8 weeks) of resistance training, neural of resistance training, neural factors are also involved.factors are also involved.


At about 8 to 10 weeks of At about 8 to 10 weeks of resistance training, muscle resistance training, muscle hypertrophy contributes more than hypertrophy contributes more than neural adaptations to strength neural adaptations to strength gains, but eventually levels off.gains, but eventually levels off.


At least 16 resistance training At least 16 resistance training workouts are needed in order to workouts are needed in order to produce substantial increases in produce substantial increases in muscle contractile proteins muscle contractile proteins (hypertrophy).(hypertrophy).

Alter Metabolism?Alter Metabolism?

Many people believe that since Many people believe that since muscle burns more calories than muscle burns more calories than fat, building muscle by weight fat, building muscle by weight lifting will noticeably increase the lifting will noticeably increase the body’s metabolism.body’s metabolism.

This response is greatly This response is greatly exaggerated.exaggerated.

MetabolismMetabolism

Weight lifting has virtually no Weight lifting has virtually no effect on resting metabolism.effect on resting metabolism.

Any added muscle is minuscule Any added muscle is minuscule compared with the total amount of compared with the total amount of skeletal muscle in the body.skeletal muscle in the body.


And, muscle actually has a very And, muscle actually has a very low metabolic rate when it is at low metabolic rate when it is at rest, which is most of the time.rest, which is most of the time.


Skeletal muscle burns about 13 Skeletal muscle burns about 13 kcals per kg of body weight over kcals per kg of body weight over 24 hours when a person is at rest.24 hours when a person is at rest.

A typical man who weighs 70 kg A typical man who weighs 70 kg (154 lbs), has about 28 kgs of (154 lbs), has about 28 kgs of skeletal muscle.skeletal muscle.


His muscles, when at rest, burn His muscles, when at rest, burn about 22% of the calories his body about 22% of the calories his body uses.uses.

The brain and the liver use about The brain and the liver use about the same number of calories.the same number of calories.


If the man lifts weights and gains 2 If the man lifts weights and gains 2 kg (4.4 lbs) of muscle, his kg (4.4 lbs) of muscle, his metabolic rate would increase by metabolic rate would increase by 24 kcals per day.24 kcals per day.


The average amount of muscle The average amount of muscle that men gain after lifting weights that men gain after lifting weights for 12 weeks is 2 kg.for 12 weeks is 2 kg.

Women will gain less.Women will gain less.

Body WeightBody Weight

A corollary to this hypothesis is that A corollary to this hypothesis is that by adding muscle you can by adding muscle you can noticeably change you body weight.noticeably change you body weight.

The idea is that when you do The idea is that when you do resistance training you may actually resistance training you may actually be thinner yet weigh the same or a be thinner yet weigh the same or a little more, because muscle is little more, because muscle is heavier than fat.heavier than fat.


That holds a grain of truth, because That holds a grain of truth, because muscle is more dense than fat.muscle is more dense than fat.

The problem is that few people put The problem is that few people put on enough muscle in proportion to on enough muscle in proportion to their total body mass to make a their total body mass to make a noticeable difference in their weight.noticeable difference in their weight.


The idea that you will weigh the The idea that you will weigh the same or more, but you really are same or more, but you really are thinner may be true if you work thinner may be true if you work hard at weight lifting for many hard at weight lifting for many months, otherwise, it is another months, otherwise, it is another myth.myth.

Are protein and amino Are protein and amino acid supplements acid supplements

necessary to maximize my necessary to maximize my muscle growth and muscle growth and

strength during resistance strength during resistance training?training?

Protein SupplementsProtein Supplements

There is no scientific evidence to There is no scientific evidence to justify the claim that amino acid justify the claim that amino acid supplements stimulate muscle supplements stimulate muscle growth or increase muscle growth or increase muscle strength and performance.strength and performance.

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