C H A P T E R 3

1. C H A P T E R 3 NEUROMUSCULAR ADAPTATIONS TO RESISTANCE TRAINING

2. w Note changes in the muscle structure and in the neural mechanisms controlling the muscle that occur during resistance training. (continued) Learning Objectives w Learn the differences among the terms muscular strength, power, and endurance. w Examine how strength is gained through resistance training.

3. Learning Objectives w Learn what causes muscle soreness and how to prevent it. w Discover how to design and tailor a resistance training program to the specific needs of an individual. w Find out if there are strength training differences between women and men and between younger and older persons.

4. Defining Muscular Performance __________—the maximal force a muscle or muscle group can generate. ______________—the product of strength and the speed of movement. __________________—the capacity to sustain repeated muscle actions.

5. w The one-repetition maximum (1RM) is a functional test that is often used to measure strength; it is the maximum weight that can be lifted once. Evaluating Strength

6. Power w The ______________________ of strength and speed w The key component of many athletic performances. w Power = (force x distance)/time, or work/time, or force x velocity w If two individuals can lift the same amount of weight, but one can lift it faster, he/she is generating more power.

7. Muscular Endurance w Can be evaluated by noting the __________ of repetitions you can perform at a given percentage of your 1RM w Is increased through ___________________________ w Is increased through changes in local muscular ___________ and _________________ capacity

8. Dramatic effects of strength training Resistance training programs can produce a 25% to 100% improvement in strength within 3 to 6 months, irrespective of age or gender.

9. Results of Resistance Training on Muscle Strength in Males 1 - Alterations of neural control of trained muscle. 2 - Increased muscle size (hypertrophy).

10. 1 - ________________________ w Synchronization and recruitment of additional motor units • Decreased neural inhibition; e.g., decreased GTO effects w Decreased co-activation of antagonist muscles w Increased rate coding (increased firing frequency of active motor units) 2 - ___________________________ w Fiber hypertrophy w Fiber hyperplasia (??? – probably not) Mechanisms of Gains in Muscle Strength

11. Muscle Size w__________________ refers to increases in muscle size. w______________ refers to decreases in muscle size. • Although muscle strength involves more than just muscle size, in general strength is directly related to the ____________________ of the muscle or muscle group (specific force, e.g., kg force/cm2).

12. Muscle Size

13. Muscle Hypertrophy __________________—pumping up of muscle during a single exercise bout due to “squeezing” of fluid from the blood plasma into the interstitial spaces of the muscle because of high muscle pressures. _______________—increase of muscle size after long-term resistance training due to changes in muscle fiber number (fiber hyperplasia) or muscle fiber size (fiber hypertrophy).

14. Muscle Fiber Hypertrophy w The numbers of myofibrils and thick and thin filaments increase, so there are more cross-bridges in the cross-section of muscle, and hence, greater strength. wProtein ____________ is continuous in the muscle; during hypertrophy, muscle protein ___________ increases more than protein___________ during the post-exercise period. w____________ plays a role in promoting muscle growth. w Training at higher intensities, i.e., performing lower reps with higher loads, appears to cause __________ fiber hypertrophy than training at lower intensities.

15. Fiber Hypertrophy A,B – Former weight lifter C,D – Distance runner E,F – Sprinter Muscle Biopsy

16. Muscle adaptability 1966: 260 lbs. (2 years of weight training) 1958: 172 lbs. (no weight training)

17. Effects of resistance training on Aggie football players: 1954-2004 _______________________________ Offensive Guards1954 – 187 lbs. 2004 – 307 lbs. Offensive Tackles1954 – 203 lbs. 2004 – 320 lbs. Running Backs1954 – 171 lbs. 2004 – 211 lbs. Fullbacks1954 – 183 lbs. 2004 – 247 lbs.

18. FIBER HYPERTROPHY AFTER TRAINING

19. Muscle Fiber Hyperplasia w Muscle fibers may split with intense weight training. w Each half may then increase in size. • Hyperplasia has been shown to occur in some experimental animal models; it has not been clearly demonstrated in human subjects. • - Quail and chicken: hanging a weight on the wing – hypertrophy of the latissimus muscles • - Cat: pulling a lever to obtain food (not as clear) – hypertrophy of the wrist flexor muscles

20. RESISTANCE TRAINING IN CATS

21. SPLITTING MUSCLE FIBER

22. “Double-Muscled” Animals Belgian Blue bull: genetic mutation resulting in increased number and size of muscle fibers

23. “Double-Muscled” Animals Genetically engineered mouse that does not produce _________________, which turns off muscle development in the fetus and inhibits muscle growth after birth.

24. “Double-Muscled” Humans? Do heavily muscled humans have the genetic mutation that suppresses myostatin production?

25. Science and Strength Training Is genetic engineering the new frontier for development of super strength? Although anabolic steroids, human growth hormone, and other pharmacological interventions are effective, altering genes may be the most dramatic intervention in the near future.

26. STRENGTH CHANGES IN WOMEN Strength trained for 20 weeks; then no training for 30-32 weeks; then retrained for 6 weeks

27. CHANGES IN MAJOR FIBER TYPES

28. This study demonstrated: • Dramatic strength gains with resistance training • Relatively __________ losses of strength during a period of reduced training • __________ recovery of strength with retraining • ____________ of all three fiber types, but greater enlargement of fast twitch fibers

29. Effects of Muscular Inactivity w Muscular atrophy (decrease in muscle size) w Decrease in muscle protein synthesis and/or an increase in protein degradation w Rapid strength loss

30. Models of Muscular Inactivity • Human: • Casting • Bed rest • Animal • Hindlimb suspension • Casting • Denervation These models are particularly useful for studying the effects of 0 gravity (space flight) on muscles.

31. Thought Question • We generally consider the loss of muscle tissue during inactivity to be “bad.” Is there any biological advantage to the organism when muscle atrophies during inactivity? If so, what is the advantage?

32. Are Muscle Fiber Type Alterations Possible? Type FTb (IIb) fibers are converted to type FTa (IIa) with ___________________. There is recent evidence that some conversion from ST to FTa may occur with a combination of resistance training and short-interval speed work..

33. Acute Muscle Soreness w Probably results froman accumulation of ________ (edema) or ___________ in the muscles (e.g., lactic acid) w Usually disappears within __________ after exercise, with no lasting effects This may be experienced, for example, after a hard bout of uphill running, stair climbing, or other concentric exercise.

34. Delayed-Onset Muscle Soreness (DOMS) w Results primarily from ________________ contractions w Is associated with _________ or _______ to muscle fibers w Probably is caused by _______________ in the damaged muscles w May be due to __________ (associated with the inflammation) in the muscle compartment w Is felt 12 to 48 hours after a strenuous bout of exercise, and may last up to a week First paper to use the acronym, “DOMS” - Armstrong, RB. Med Sci Sports Exerc 16: 529, 1984

35. Muscle before and immediately after running a marathon Myofibrils (sarcomeres) Disrupted sarcomeres Mitochondria

36. Muscle Fibers Immediately after a Marathon

37. Exercise-induced muscle injury Inflammation 2 days after downhill running Normal Inflamed

38. Satellite Cells Satellite cells are “adult stem cells” that are available to maintain a relatively constant _________ to _____________ ratio. Bischoff, The Satellite Cell, Myology, 1994

39. SATELLITE CELL RESPONSE TO INJURY

40. Armstrong’s Sequence of Events in DOMS 1. ____________ damage to muscle fibers from high forces 2. Impaired calcium homeostasis resulting in ___________ 3. ________________: macrophage invasion of the damaged tissue 4. Accumulation of irritants that stimulate _______________ within muscle

41. Muscle Injury and Performance • Injury causes a ____________ in the force-generating capacity of muscles due to: • physical disruption of the muscle • failure in the excitation-contraction coupling process • loss of contractile protein w Maximal force-generating capacity returns after ________ w Muscle ___________ synthesis is impaired

42. Prolonged nature of the strength loss 3 sets of 15 eccentric contractions done by the elbow flexors Soreness Howell et al., J Physiol 464:183, 1993

43. Crouse and co-workers

44. DECREASE IN STRENGTH AFTER INJURY

45. Reducing Muscle Injury w Reduce eccentric component of muscle action during early training w Start training at a low intensity, increasing gradually or w Begin with a high-intensity, exhaustive bout of eccentric-action exercise to cause much soreness initially, but decrease future pain Over-the-counter anti-inflammatory drugs (e.g., aspirin) have not been shown to be effective in alleviating DOMS, although there is some disagreement on this issue.

46. Thought Question Should an athlete include eccentric movements in the weight training workouts? Why?

47. Historical Note on DOMS “Men out of training suffer pains after the slightest exercise, as no part of their body has been inured to any exercise. Trained bodies feel pains after unusual exercises, some even after usual exercises if they be excessive.” (Right so far.) “Moderate toil is not followed by pain, but when immoderate it dries the flesh overmuch, and this flesh being emptied of its moisture, grows hot, painful and shivery, and falls into a longish fever.” (Thus, he attributed DOMS to excessive sweating – not a bad deduction, really.) Hippocrates, Regimen in Health, ~420 B.C.

48. Historical Note on DOMS If all else failed, Hippocrates advised athletes with sore muscles to “get drunk once or twice.” (Segan, F., Recipes from Ancient Greece and Rome for the Modern Cook, 2004.

49. Exercise-Induced Muscle Cramps wMay be due to ________ or _____________ imbalances and/or sustained alpha-motoneuron activity from increased muscle spindle activity and/or decreased Golgi tendon organ activity. w Rest, ________________, and holding the muscle in the stretched position can be effective treatments w Proper conditioning, stretching, and nutrition are possible _____________ strategies.

50. Dynamic actions w Free weights w Eccentric training w Variable resistance w Isokinetic actions w Plyometrics Resistance Training Actions Static (isometric) actions Electrical stimulation training