1 / 40

Muscle Hypertrophy and Anabolic Agents I

Muscle Hypertrophy and Anabolic Agents I. Lecture 20. Muscle Anatomy. Muscles are made up of bundles of individual fibers. Each fiber is a single elongated cell with a nucleus, mitochondria, endoplasmic reticulum, etc. Muscle cells are subdivided into myofibils composed of

Download Presentation

Muscle Hypertrophy and Anabolic Agents I

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Muscle Hypertrophy and Anabolic Agents I Lecture 20

  2. Muscle Anatomy • Muscles are made up of • bundles of individual fibers. • Each fiber is a single • elongated cell with a • nucleus, mitochondria, • endoplasmic reticulum, etc. • Muscle cells are subdivided • into myofibils composed of • actin and myosin filaments • linked in series in units • called sarcomeres. • Stimulus by motor neuron • causes actin and myosin to • interact; sarcomeres shorten • and produce force

  3. Muscle Anatomy (continued) Fat droplet • 3 main types of muscle fibers • Type I: slow contraction, small, low • glycogen and CP, many fat droplets • and mitochondria, fatigue-resistant. • Type IIa: fast, intermediate size, high • glycogen and CP, pretty rich in • mitochondria, less fatigue-resistant • Type IIb: fast, large, high in glycogen • and CP, few mitochondria, not • fatigue-resistant. Mitochondria Type I Fibers Type IIb Fibers

  4. All muscles • contain a mix of • fiber types. • Muscles that show • large gains in size • with training • usually have a • fairly high % of • Type-II fibers (e.g. • gastrocnemius vs. • soleus).

  5. Muscle Anatomy and Training • What are the stimuli for hypertrophy? • 1. nutritional (energy balance, protein) • 2. hormonal (testosterone, insulin, growth hormone) • 3. stress (active training, passive stretch) • Most “trainable” fibers are Type-IIa. • After training they take on • characteristics more like Type I or Type • IIb depending on type of training.

  6. Muscle Anatomy and Training • Fibers most sensitive to hypertrophy are Type-IIb. • This explains why muscle hypertrophy occurs in • response to stress of high force (resistance • training). These fibers are only used when rate of • force production is high. • There is huge individual variation in hypertrophy • response to training.

  7. Muscle Hypertrophy • Hypertrophy: increasing muscle size. Hypertrophy • refers to increase in both the cross-sectional area of • the muscle (more myofibrils) and increase in length • of the muscle (more sarcomeres per myofibril). • Does the number of muscle fibers increase • (hyperplasia)?

  8. Hyperplasia? HYPERTROPHY HYPERPLASIA VS.

  9. Muscle Hypertrophy • Hypertrophy: increasing muscle size. Hypertrophy • refers to increase in both the cross-sectional area of • the muscle (more myofibrils) and increase in length • of the muscle (more sarcomeres per myofibril). • Does the number of muscle fibers increase • (hyperplasia)? Yes in some animals (e.g. cats) but • this does not seem to be a mechanism of hypertrophy • (ADULT) humans.

  10. Satellite Cell Repair Hawke et al. 2001

  11. Muscle Hypertrophy • Fibers do split as they get larger to maintain a • minimal surface area to volume ratio. • This splitting is beneficial because if volume • increases more than surface area diffusion • distance will increase and access to oxygen and • other compounds might be limited. • Splitting is not considered hyperplasia • because the fiber shares nuclei.

  12. The combined • effects of nutrients, • hormonal environment • and mechanical load • (training) are • manifested by • changes in both gene • transcription and • mRNA translation to • increase myofibrillar • protein content in the • muscle cell

  13. strength cross-sectional area Muscle Hypertrophy and Strength • Force generating capacity in muscles depends on • cross-sectional area. As area increases so does • capacity to generate force (strength). • Relationship is not 1:1 however. • Strength increases at a faster • rate than area (e.g. a 10% • increase in area results in a • 30% increase in strength). • This, in reverse, is a major problem in the elderly. • They lose muscle mass and small decline in muscle • size = big decline in strength. X

  14. Metabolic “cost” of muscle • Besides obvious advantages of having more muscle • mass in terms of strength - larger muscle mass • helps with weight management. • Muscle tissue consumes a lot of energy (high • maintenance) and basal metabolic rate (energy • required for basic life function) is directly • proportional to muscle mass. • More muscle mass = higher basal metabolic rate = • more energy expended per day = require more • energy to maintain the same weight.

  15. Muscle Building Nutrition • To gain muscle tissue it is necessary to create an • “anabolic” environment. Nutritionally, creating that • anabolic environment requires positive energy • balance (more energy in than out). • How much more energy in than out? This is the $$ • question b/c energy surplus also increases body fat • Competitive (natural) body builders know this and • incorporate 2 general phases: • 1. gain muscle and some fat (minimal if possible) • 2. lose fat and some muscle (minimal if possible)

  16. The million dollar question… • How to minimize the fat gain while • maximizing muscle gain? • Maintain energy balance in state sufficient to • gain muscle while minimizing fat gain • 2. Hard resistance training • 3. Incorporation of cardiovascular training into routine • 4. Manipulation of the hormonal environment • (nutritionally and pharmacologically)

  17. ANABOLIC STEROIDS

  18. “STEROIDS FOR SALE!”

  19. Steroid Hormones • Steroids are a group of • chemical messengers • that are synthesized • from cholesterol. Since • steroids are fat soluble, • they are membrane • permeable and often act • directly on the nucleus • of the cell. As you can • see by the structures to • the right, many of the • sex hormones have • similar structures.

  20. Ganong, 1995

  21. Testosterone • Testosterone contributes to male • sex characteristics including • muscle growth. Most testosterone • is produced in the testes (~95%); • remainder is produced by the • adrenal glands. Testosterone • has both anabolic (muscle building) effects as well as • androgenic (masculinizing) effects. Anabolic steroids mimic the actions of testosterone. Anabolic steroids are used medically to treat male patients with low levels of testosterone as well as muscle-wasting diseases. First used during WWII to help malnourished POW’s regain weight and strength.

  22. Athletes and Androgens • Athletes have used anabolic agents to enhance • performance for 50 years. The goal is to maximize • anabolic actions (incr. strength and muscle mass) • while minimizing androgenic effects. • Testosterone is classified as a drug and requires a • prescription to obtain. It must be injected for • maximal effect. Banned by • most athletic bodies • (USOC, NCAA, etc)

  23. (5-alpha reductase) (aromatase) DHTEstradiol Responsible for male secondary sex characteristics 3 times as androgenic as testosterone, yet only 50% as anabolic Responsible for female secondary sex characteristics Testosterone

  24. Ganong, 1995

  25. Are steroids effective? • Bhasin et al. “Effects of a supraphysiological dose of • testosterone on muscle size and strength in healthy • men”. NEJM 1996. • • 600mg testosterone enanthate given for 10 weeks • • Weight-trained drug group; gain in LBM of 13.6 lbs • • Untrained drug group; gain in LBM of 6 lbs • • Considerable strength gains reported from both • trained and untrained drug groups • • No noticeable side effects reported by subjects. • HOWEVER, this tells us nothing about the long term • effects. Anabolic steroids reduce HDL, increase LDL

  26. Muscle Quality?

  27. AAS and HIV

  28. Orals vs Injectables • There are two types of anabolic steroids – orals and • injectables. Besides the obvious differences in • delivery method, orals have much shorter half-lives • than injectables. The half-life of most orals is 3-5 • hours. The main consequences of the short half-life • is that (a) they must be taken much more frequently • than injectables (b) they are designed to withstand • the digestive system as well as a trip through the • liver and thus must be taken in larger doses than • injectables.

  29. Often oral steroids are methylated to decrease • degradation as they pass through the liver. • As a consequence, such drugs alter liver • enzyme levels and can cause hepatoxicity. • Methylation may also increase aromatization to • estrogen. • Injectables tend to have longer half-lives • (increased serum testosterone levels may • last up to 14 days). For this reason athletes • tend not to take injectable steroids before • competition because they are easy to detect.

  30. WELL, IF WE PUT MORE BUILDING BLOCKS IN, MAYBE WE WILL MAKE MORE “NATURAL” TESTOSTERONE...

  31. Prohormones • Prohormones are marketed to provide a “raw • material” that the bodies own metabolic machinery • can convert to testosterone. • Are “prohormones” • safer? If so, are • they effective?

  32. OH Testosterone O

  33. OH Testosterone O

  34. IOC BANNED SUBSTANCES • STIMULANTS • NARCOTICS • DIURETICS etc • PEPTIDE HORMONES • HCG; LH; HGH; ACTH; IGF-1 • ANABOLIC AGENTS • DHT; ANDRO; DHEA; TESTOSTERONE ETC • TESTOSTERONE/EPITESTOSTERONE > 6:1

  35. Studies from Doug Kings lab at Iowa State show that: • DHEA does not increase testosterone or strength • compared with placebo (but no increase in estrogen) • 2. Androstenedione does increase testosterone but • also increases estradiol. No impact on strength • compared with placebo. • BUT: this study was criticized b/c subjects were not • weight trained. Other studies done after this one • suggest that androstenedione supplementation DOES • raise testosterone levels and increase gain of muscle • mass relative to placebo

  36. DO PRO-HORMONE SUPPLEMENTS WORK? •  andro/DHEA • No  serum T •  estrogens •  good cholesterol • No  from trained/no supp

  37. From bodybuildingforyou.com:

  38. REAL WORLD VS RESEARCH Serving Size: 1 packet Servings Per Box: 30Whole Pituitary: 100mg Lyophilized Pineal: 250mcgHypothalmus: 100mg Orchic Powder: 100mgL-Glutamine: 150mg L-Tyrosine: 100mgL-Lysine: 100mg L-Arginine: 100mgL-Ornithine: 100mg Glycine: 600mg4-Androstenediol: 25mg 5-Androstenediol: 25mgNor-4-AndroDione: 25mg Nor-4-AndroDiol: 25mg

  39. Cessation of Steroid Use • In order to understand the physiological • consequences of stopping steroid use here is a brief • review of the Hypothalamic-Pituitary-Testicular Axis • (HPTA) • hypothalamus  GnRH •  • anterior pituitary  LH and FSH •  • testes •  • testosterone

  40. Cessation of Steroid Use (cont’d) • When using anabolic agents, high androgen levels exert • negative feedback on the hypothalamus and decrease the rate • at which GnRH is produced. The lower GnRH levels reduce the • amount of endogenous testosterone produced and if steroid • use stops it takes a while for the body to reequilibrate its own • testosterone production. • hypothalamus  GnRH •  • anterior pituitary  LH and FSH •  • testes •  • testosterone inhibition inhibition estrogen Androgen use

More Related