Weight Training Questions

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

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

More Muscle Fibers? n However, this has not been clearly demonstrated in human skeletal muscle tissue.

More Muscle Fibers? n 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.

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

Alter Fiber Type? n 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.

Alter Fiber Type? n Resistance training does not alter the percentage of Type I and II muscle fibers.

Alter Fiber Type? n 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.

Gender Difference? n Muscle strength is directly related to the cross-sectional area of the muscle tissue.

Gender Difference? n Strength per unit of cross-sectional area is similar for men and women.

Gender Difference? n Absolute hypertrophy varies between men and women, whereas relative hypertrophy is similar.

Increased Size in Older Lifters? n Exercise-induced hypertrophy appears to be an important mechanism underlying strength gains in older men and women.

Increased Size in Older Lifters? n This implies that age-related loss in muscle mass can be countered effectively by participating in a vigorous resistance training program.

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

Biochemical Effects n 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.

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

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

Biochemical Effects n 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.

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

Biochemical Effects n 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.

Cross-Training n Participation in heavy resistance training does not negatively affect aerobic power.

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

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

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

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

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

Alter Metabolism? n Many people believe that since muscle burns more calories than fat, building muscle by weight lifting will noticeably increase the body’s metabolism. n This response is greatly exaggerated.

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

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

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

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

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

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

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

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

Body Weight n 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.

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

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