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C HAPTER 3

C HAPTER 3. C HAPTER 3. NEUROMUSCULAR ADAPTATIONS TO RESISTANCE TRAINING. NEUROMUSCULAR ADAPTATIONS TO RESISTANCE TRAINING. Measuring Muscular Performance. Strength —the maximal force a muscle or muscle group can generate. Power —the product of strength and the speed of movement.

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C HAPTER 3

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

  2. 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.

  3. One-Repetition Maximum (1-RM) The maximal weight an individual can lift just once. Can be estimated submaximally Eppley Equation: 1RM = (0.033 Reps) Rep Wt. + Rep Wt. Choose a weight that is about a 10RM load. There are many other equations and tables.

  4. Are Men Stronger than Women? • Females 50-80% as strong (forearm 50%; hip 80%) • Why are men stronger? • Is it structural or simply because they are bigger?

  5. Gender differences • Strength/Unit of Body Weight (relative term which removes the influence of BW) • Men still stronger • Women have a higher proportion of their body weight which is fat and fat does not contribute to strength

  6. Gender Differences • Strength/Unit of Fat-Free Weight (determined body composition by under water weighing) • Men are still stronger per unit of FFW • A higher proportion of male FFW is muscle (FFW isn’t just muscle it is tendons, organs, bones etc…)

  7. Gender Differences • Strength/Unit of Muscle Mass • Use MRI to determine muscle mass using the cross-sectional area of the muscle • Men are no longer stronger than women • There is no structural difference in male and female muscle that allows men to produce more strength than women.

  8. STRENGTH CHANGES IN WOMEN

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

  10. 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

  11. Muscular Endurance • Sit-ups • Supine position • Fingers touching masking tape • Another piece of tape placed 12cm beyond the first piece • Metronome set at 40 beats/min • Perform as many curl-ups as possible to a max of 75

  12. Muscular Endurance • Push-ups • Males in up position • Females in modified knee position • Lower body until chin touches mat • Max numer of push-ups consecutively

  13. Muscular Endurance wwTest Battery %Body Weight to be lifted Rep-15 Men Women Arm Curl .33 .25 Bench Press .66 .50 Lat Pull-Down .66 .50 TricepsExtension .33 .33 Leg Extension .50 .50 Leg Curl .33 .33 Bent Knee Sit-ups Max Max Total_________

  14. Muscular Endurance Total Reps Fitness Category 91-105 Excellent 77-90 Very Good 63-76 Good 49-62 Fair 35-48 Poor <35 Very Poor

  15. 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.

  16. 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.

  17. 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

  18. 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).

  19. 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.

  20. 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.

  21. RESISTANCE TRAINING IN CATS

  22. SPLITTING MUSCLE FIBER

  23. 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.

  24. MODEL OF NEURAL AND HYPERTROPHIC FACTORS

  25. Did you Know? • If you train one limb but not the other, the untrained limb will get stronger. • 30-40% increase in the trained limb • 5-15% increase in the untrained limb

  26. Cross-training • Implications for rehab?

  27. Cross-training • Neural or Hypertrophy?

  28. Cross-Training • Why do we get stronger? • 1. Posturing Theory – as contract leg, are also contracting muscles in opposite leg to maintain balance. • 2. Neuroanatomy - ~80% of neurons cross-over, 10-20% do not. • 3. Increased enzymes increase your ability to store glycogen in other limb.

  29. Cross-training • This was discovered originally in children tracing shapes with one hand. • They got better at it with the other hand even though they never used that hand.

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

  31. 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

  32. 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

  33. 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

  34. 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

  35. 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.

  36. 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

  37. 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?

  38. 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

  39. Periodization • Periodization prevents over-training by varying the volume and intensity • Used for strength and power sports • Cycle of five phases: four active phases followed by one active recovery phase • Each phase gradually decreases volume and gradually increases intensity • Two cycles per year

  40. Periodization • Phase I – hypertrophy • Sets 3-5 • Reps 8-20 • Intensity Low • Duration 6 weeks

  41. Periodization • Phase II – strength • Sets 3-5 • Reps 2-6 • Intensity high • Duration 6 weeks

  42. Periodization • Phase III – power • Sets 3-5 • Reps 2-3 • Intensity high • Duration 6 weeks

  43. Periodization • Phase IV – peaking • Sets 1-3 • Reps 1-3 • Intensity Very High • Duration 6 weeks

  44. Periodization • Phase V – recovery • General activity or light resistance training • 2 weeks

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