1. Chapter 11 Muscle Strength and Resistance Training for Health and Athletics

2. Factors associated with muscle strength Contractility Irritability Conductivity

3. Muscle twitch Latent period—delay before contraction after stimulus applied Shortening period—the contraction Relaxation period—the lengthening of the muscle

4. The muscle twitch consists of a latent period, a shortening period, and a relaxation period.

5. The lab versus the human body In the lab: all the nerve fibers of the whole muscle are stimulated simultaneously muscle twitch is in response to a single shock. In the body: the stimulation of normal muscle is asynchronous. muscle is stimulated by volleys of nerve impulses.

6. Summation of twitches and tetanus The summation of twitches increases force production. Tetanus occurs when the excised muscle is stimulated too frequently, and muscle tension becomes prolonged.

7. The summation of twitches can increase force production.

8. Muscle twitch responses showing incomplete (A, B, C, and D) and complete tetanus. (E).

9. Temperature and muscle contraction Heating causes a muscle to contract and relax more rapidly. Cooling causes it to contract and relax more slowly. When a muscle is cooled, the relaxation phase slows two to three times as much as the contraction phase, which can contribute to muscle injury.

10. All-or-none-law of muscle contraction Stimulation of a muscle fiber by impulses much larger than threshold value will change neither the amount of shortening or the force of the contraction.

11. How the nervous system achieves gradations in the force of contractions of whole muscles Recruitment—varying the number of motor units activated Rate coding—increasing or decreasing the rate of firing for the motor units involved

12. Mechanical factors in force production Angle of pull Length of muscle

13. Force production depends on the angle of pull of the muscle and the joint angle at which the muscle action occurs

14. The relationship between tension and muscle length

15. Bilateral deficit A decrease in strength of a muscle group when the contralateral limb is concurrently performing a maximal contraction. Training should use exercises that emphasize concurrent contractions of the same muscle groups on both sides of the body.

16. Gender differences in strength Women are about 40 to 80 percent as strong as men depending on the muscle groups involved. Women are typically 40 to 50 percent as strong as men for upper body movements but 50 to 80 percent as strong for lower body movements. No qualitative difference in strength per unit of muscle.

17. Types of muscle actions Isometric Dynamic constant external resistance (DCER) Isokinetic Concentric Eccentric

18. Isometric muscle actions Isometric exercises are static. Isometric strength is joint angle specific.

19. DCER muscle actions Free weights and resistance training machines involve DCER actions. Amount of weight lifted remains constant, but the internal tension produced by the muscle changes with the joint angle. Strength expressed in RM load.

20. There is an inverse relationship between the weight lifted and the number of repetitions that can be performed.

21. Isokinetic muscle actions Have a constant velocity of movement Physical therapists and trainers use isokinetic testing and training in rehabilitation Allow measurement of maximum torque production at all points in the range of motion

22. The relationship between torque production and the range of motion

23. Concentric muscle actions Involve the production of force while muscle is shortening –An example is the biceps curl Strength decreases as the velocity of the movement increases –At slow velocities both slow and fast twitch muscle fibers at work –At fast velocities slow twitch fibers cannot contract rapidly enough to contribute to force

24. The relationship between concentric strength and velocity of muscle action

25. Eccentric muscle actions Involve force production while muscle is lengthening –Examples are walking, running, and squatting Little change in strength across velocity

26. The relationship between eccentric strength and the velocity of muscle action

27. Muscle strength gains Increase in muscle size is a result of hypertrophy Increase in strength may result from –Hypertrophy –Neural adaptations Visit Strength Training at www.healthy.net/fitness/training/strength.htm www.healthy.net/fitness/training/strength.htm

28. Hypertrophy Increase in contractile protein content of skeletal muscle Resistance training results in hypertrophy of both fast and slow twitch fibers Fast twitch fibers increase in size to greater degree Also results in conversion of fast twitch glycolytic fibers to fast twitch oxidative glycolytic fibers

29. Neural adaptations Accounts for initial increase in strength when untrained person begins resistance training Individual learns to recruit fast twitch muscle fibers Trained athletes may continue to improve using neural adaptations after they have reached genetic limit to muscle size

30. Cross-education Makes it possible to maintain muscle integrity through resistance training of the contralateral limb. Reduces the amount of time necessary for rehabilitation. Results in increase in strength to about 60 percent of the trained limb

31. Disuse and atrophy Immobilization of a limb results in decreased muscle fiber size Placing a muscle on stretch may retard atrophy

32. Health benefits of resistance training Increased bone mineral density Favorable changes in body composition Increased functional strength for daily living Improved insulin sensitivity Increased basal metabolic rate Decreased diastolic blood pressure Reduced risk of low back pain Decreased risk of injury during physical activity Improved blood lipid profiles

33. Resistance training for health Adult 1 set of 7 to 10 exercises, one exercise for each major muscle group 8 to 12 repetitions 2 to 3 days a week Cardiac patient Same program but reduce the resistance and increase the repetitions to a 10 to 15 RM load

34. Four basic principles of resistance training for athletes 1.Specificity 2.Overload 3.Progression 4.Periodization

35. Types of specificity Metabolic Movement patterns Velocity

36. Muscle overload To demand more of the muscle than it normally performs Unless a muscle is taxed it will not adapt with increases in strength or size Program that causes overload during the off season may not be sufficient to overload muscles during heavy training

37. Progression The volume of training must be increased periodically to maintain an overload and continue to see adaptations. Resistance is usually increased first.

38. Periodization Systematic changes in resistance, number of reps, and number of sets Minimizes boredom and encourages the athlete to stick with the program Results in greater and more consistent strength gains than non-periodized programs

39. Classic periodization model

40. NSCA guidelines for the resistance training of athletes 1.Schedule training at least three days a week, with a minimum of 24 hours of rest between sessions. 2.Design programs so that all the major muscle groups are targeted. 3.Take into account appropriate muscle balance across joints, as well as both the upper- and lower-body muscle groups. 4.Periodize training to vary volume and intensity. 5.Plan recovery periods to help avoid overtraining. 6.Require no more than two exercises per body part; however, different exercises per body part may be used throughout the week.

41. NCSA guidelines (cont.) 7.Specific large-muscle group exercises should be limited to two times per week. 8.Use warm-up sets that involve very light resistance. 9.Allow adequate recovery for muscle groups during a training week. 10.Perform large-muscle group exercises first in a workout. 11.Allow rest between sets depending on the goals of the program. 12.Using a four-day-per-week training protocol, divide the selected lifts into two groups (a) chest and shoulders and (b) back and legs. 13.Make use of multi-joint and Olympic-style lifts with free weights as well as isolated movements on resistance machines to promote targeted muscle hypertrophy.

42. Plyometric training Beneficial for athletes who compete in sports requiring a high level of explosive power, such as track and field, football, volleyball, basketball, and Olympic-style weight lifting. Examples: depth jumps, leaping over objects, hopping

43. Effects of concurrent strength and endurance training Results in improvements in muscular strength and aerobic capabilities Results in increases in muscle strength less than those that result form strength training alone No difference in the increase in aerobic power versus endurance training alone Visit Concurrent Resistance and Endurance Training at www.fitnessworld.com/info/info_pages/library/strength/resist0699.html www.fitnessworld.com/info/info_pages/library/strength/resist0699.html

44. Factors that contribute to overtraining Overly frequent competitions Pre-existing illnesses Dietary inadequacies Psychological stress Heavy time demands Inadequate sleep

45. Symptoms of overtraining A plateau followed by a decrease in strength gains Increased resting diastolic blood pressure Increased resting heart rate Sleep disturbances Decreased lean body weight Decreased appetite Persistent cold or flu-like symptoms Loss of interest in training Feelings of fatigue when rising Excessive muscle soreness