Weight Training Questions

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Weight Training Questions
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Is it possible to increase the number of muscle
fibers by resistance training?
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More Muscle Fibers?

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

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More Muscle Fibers?

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

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More Muscle Fibers?

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

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More Muscle Fibers?

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

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Alter Fiber Type?

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

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Alter Fiber Type?

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

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Alter Fiber Type?

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

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Gender Difference?

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

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Gender Difference?

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

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Gender Difference?

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

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Increased Size in Older Lifters?

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

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Increased Size in Older Lifters?

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

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Biochemical Effects

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

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Biochemical Effects

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

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Biochemical Effects

• The magnitude of testosterone and growth hormone
  release, however, is related to
• the size of the muscle groups used,
• exercise intensity ( 1-RM),
• and the length of rest between sets,
• with larger increases observed for high intensity
  (5 to 10-RM) and short (1 minute) rest periods
  involving large muscle groups.

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Biochemical Effects

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

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Biochemical Effects

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

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Biochemical Effects

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

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Biochemical Effects

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

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Cross-Training

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

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Neurological Effects

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

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Neurological Effects

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

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Neurological Effects

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

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Neurological Effects

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

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Neurological Effects

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

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Alter Metabolism?

• Many people believe that since muscle burns more
  calories than fat, building muscle by weight
  lifting will noticeably increase the bodys
  metabolism.
• This response is greatly exaggerated.

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Metabolism

• Weight lifting has virtually no effect on resting
  metabolism.
• Any added muscle is minuscule compared with the
  total amount of skeletal muscle in the body.

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Metabolism

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

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Metabolism

• Skeletal muscle burns about 13 kcals per kg of
  body weight over 24 hours when a person is at
  rest.
• A typical man who weighs 70 kg (154 lbs), has
  about 28 kgs of skeletal muscle.

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Metabolism

• His muscles, when at rest, burn about 22 of the
  calories his body uses.
• The brain and the liver use about the same number
  of calories.

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Metabolism

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

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Metabolism

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

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Body Weight

• A corollary to this hypothesis is that by adding
  muscle you can noticeably change you body weight.
• The idea is that when you do resistance training
  you may actually be thinner yet weigh the same or
  a little more, because muscle is heavier than fat.

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Body Weight

• That holds a grain of truth, because muscle is
  more dense than fat.
• The problem is that few people put on enough
  muscle in proportion to their total body mass to
  make a noticeable difference in their weight.

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Body Weight

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

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Are protein and amino acid supplements necessary
to maximize my muscle growth and strength during
resistance training?
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Protein Supplements

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