C HAPTER 3

1. CHAPTER 3 CHAPTER 3 NEUROMUSCULAR ADAPTATIONS TO RESISTANCE TRAINING NEUROMUSCULAR ADAPTATIONS TO RESISTANCE TRAINING

2. w Note changes in the muscles and in the neural mechanisms controlling them that occur during resistance training. (continued) Learning Objectives w Learn the differences among 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. Measuring Muscular Performance Strength—the maximal force a muscle or muscle group can generate. Power—the product of strength and the speed of movement. Muscular endurance—the capacity to sustain repeated muscle actions.

5. One-Repetition Maximum (1-RM) The maximal weight an individual can lift just once.

6. Power w The functional application of strength and speed w The key component of many athletic performances w Power = (force 5 distance)/time

7. Muscular Endurance w Can be evaluated by noting the number of repetitions you can perform at a given percentage of your 1-RM w Is increased through gains in muscular strength w Is increased through changes in local metabolic and circulatory function

8. Key Points Terminology w Muscular strength is the maximal amount of force a muscle or group of muscles can generate. w Muscular power is the product of strength and speed of the movement. w Though two individuals can lift the same amount of weight, if one can lift it faster, she is generating more power than the other. w Muscular endurance is the ability of a muscle to sustain repeated muscle actions or a single static action.

9. Did You Know…? Resistance training programs can produce a 25% to 100% improvement in strength within 3 to 6 months.

10. Muscle Size wHypertrophy refers to increases in muscle size. wAtrophy refers to decreases in muscle size. w Muscle strength involves more than just muscle size.

11. Results of Resistance Training w Increased muscle size (hypertrophy). w Alterations of neural control of trained muscle. w Studies show strength gains can be achieved without changes in muscle size, but not without neural adaptations.

12. Possible Neural Factors of Strength Gains w Recruitment of additional motor units for greater force production w Counteraction of autogenic inhibition allowing greater force production w Reduction of coactivation of agonist and antagonist muscles w Changes in the discharge rates of motor units w Changes in the neuromuscular junction

13. Muscle Hypertrophy Transient—pumping up of muscle during a single exercise bout due to fluid accumulation from the blood plasma into the interstitial spaces of the muscle. Chronic—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. Fiber Hypertrophy w The numbers of myofibrils and actin and myosin filaments increase, resulting in more cross-bridges. w Muscle protein synthesis increases during the postexercise period. w Testosterone plays a role in promoting muscle growth. w Training at higher intensities appears to cause greater fiber hypertrophy than training at lower intensities.

15. Fiber Hyperplasia w Muscle fibers split in half with intense weight training. w Each half then increases to the size of the parent fiber. w Satellite cells may also be involved in skeletal muscle fiber generation. w It has been clearly shown to occur in animal models; only a few studies show this occurs in humans too.

16. RESISTANCE TRAINING IN CATS

17. SPLITTING MUSCLE FIBER

18. Neural Activation and Fiber Hypertrophy w Early gains in strength appear to be more influenced by neural factors. w Long-term strength increases are largely the result of muscle fiber hypertrophy.

19. MODEL OF NEURAL AND HYPERTROPHIC FACTORS

20. Effects of Muscular Inactivity w Muscular atrophy (decrease in muscle size) w Decrease in muscle protein synthesis w Rapid strength loss

21. STRENGTH CHANGES IN WOMEN

22. Did You Know…? Once your goals for strength development have been achieved, you can reduce training frequency, intensity, or duration and still prevent losses in strength gained for at least 12 weeks. However, you must continue training with a resistance maintenance program that still provides sufficient stress to the muscles.

23. CHANGES IN MAJOR FIBER TYPES

24. w Chronic muscle hypertrophy results from long-term training and is caused by structural changes in the muscle. (continued) Key Points Resistance Training w Neural adaptations always accompany strength gains from resistance training; hypertrophy may or may not be present. w Transient hypertrophy results from short-term increases in muscle size due to fluid in the muscle.

25. Key Points Resistance Training w Muscle hypertrophy is most clearly due to increases in fiber size, but also may be due to increases in the number of fibers. w Muscle atrophy occurs when muscles are inactive; however, a planned reduction in training can maintain muscle size and strength for a period of time. w A muscle fiber type can take on characteristics of the opposite type in response to training. Cross-innervation or chronic stimulation of fibers may convert one fiber type into another fiber type.

26. Acute Muscle Soreness w Results froman accumulation of the end products of exercise in the muscles w Usually disappears within minutes or hours after exercise

27. Delayed-Onset Muscle Soreness (DOMS) w Results primarily from eccentric action w Is associated with damage or injury within muscle w May be caused by inflammatory reaction inside damaged muscles w May be due to edema (accumulation of fluid) inside muscle compartment w Is felt 12 to 48 hours after a strenuous bout of exercise

28. Armstrong’s Sequence of Events in DOMS 1. Structural damage 2. Impaired calcium availability 3. Accumulation of irritants 4. Increased microphage activity

29. DOMS and Performance w DOMS causes a reduction in the force-generating capacity of muscles. w Maximal force-generating capacity returns after days or weeks w Muscle glycogen synthesis is impaired with DOMs

30. Reducing Muscle Soreness w Reduce eccentric component of muscle action during early training w Start training at a low intensity, increasing gradually w Begin with a high-intensity, exhaustive bout of eccentric-action exercise to cause much soreness initially, but decrease future pain

31. Key Points Muscle Soreness w Acute muscle soreness occurs late during or immediately after an exercise bout. w Delayed-muscle soreness (DOMS) occurs 12 to 48 hours after exercise (especially eccentric exercise). w DOMS may include structural damage to muscle cells or inflammatory reactions within the muscles. w Muscle soreness may be an important part of maximizing the resistance training response.

32. Designing Resistance Training Programs 1. Consider different dynamic training programs. 2. Perform a training needs analysis. 3. Select appropriate resistance levels. 4. Decide on single sets versus multiple sets. 5. Design a training program using periodization. 6. Assign specific forms of resistance training depending on the sport or desired results.

33. 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

34. Needs Analysis w What muscles need to be trained? w What method of training should be used? w What energy system should be stressed? w What are the primary sites of concern for injury prevention?

35. Selecting the Appropriate Resistance Strength—few reps and high resistance (6-RM) Muscular endurance—many reps and low resistance (20-RM) Power—several sets of few reps and moderate resistance; emphasize speed of movement Muscle size—more than 3 sets of 6-RM to 12-RM loads; short rest periods

36. Periodization w Changes in exercise stimulus over a specific period to keep an individual from overtraining w Cycle of five phases: four active phases followed by one active recovery phase w Each phase gradually decreases volume and gradually increases intensity

37. w Low-repetition, high-intensity training improves muscle strength while high-repetition, low-intensity training improves endurance training. (continued) Key Points Resistance Training Programs w Resistance training can use static or dynamic actions. w A needs analysis is necessary to design a program for a specific athlete's needs.

38. Key Points Resistance Training Programs w Periodization prevents overtraining by varying the volume and intensity of training. w Typically volume is gradually decreased while intensity is gradually increased. w Strength gains are specific to the speed of training and the movement patterns used in training.

39. Did You Know…? Resistance training can benefit almost everyone, regardless of his or her sex, age, level of athletic involvement, or sport.