1. Muscular Strength n Maximal amount of force that can be generated by a specific muscle or muscle group in a single contraction (1RM) n Important component of fitness

2. Reasons to Test Strength n 1. Predict Performance –can predict what sport you are most suited for (ie., Thorstenssen Test) n 2. Implement a training program –pre-training values  training  re- evaluate  training etc...

3. Muscular Strength n 3. Measure of rehabilitation –measure strength pre-season  injury during season  use pre-season value as a guideline for rehab (“back to 100% of pre-season value”) n 4. Identify Muscle Imbalance –muscle imbalance may lead to injury –hamstring to quadricep ratio.65-.75

4. Ways to Measure Strength n 1. Isometric - muscle action when tension is produced but there is no change in the length of the muscle –ie., hand grip dynamometer –Is work being done? (FxD) –no distance but physiological work is being done since we are using ATP

5. Isometric Testing n Advantages –simple –cheap –saves time

6. Isometric Testing n Disadvantages –specific to the joint angle (doesn’t reflect the full ROM) –doesn’t correlate with sports performance –more likely to perform the Valsalva Maneuver

7. Ways to Measure Strength n 2. Isotonic –muscle action in which a muscle shortens or lengthens with varying tension and velocity while overcoming a constant resistance throughout a ROM –ie., bench press

8. Isotonic n Advantages –correlates better with sports performance –relatively inexpensive –accessible –psychologically seeing work done

9. Isotonic n Disadvantage –measuring the weakest point in the ROM –doesn’t measure strength at different speeds

10. Ways to Measure Strength n 3. Isokinetically –maximal tension is developed at all joint angles throughout the ROM with speed being constant (have accommodating resistance at a controlled speed of movement

11. Isokinetic n Advantages –measure strongest point in ROM –measure strength at different speeds

12. Isokinetic n Disadvantages –expensive (40-80K) –not readily accessible –need someone knowledgeable to run the equipment

13. What Affects Strength? n 1. Training Status/size of muscle fibers n 2. Type of muscle action n 3. Velocity n 4. Joint Angle (muscle length) n 5. Fiber type n 6. #Activated Motor Unit

14. What Affects Strength? n 7. #Fibers within an activated motor unit n 8. Frequency of Impulses n 9. Fatigue

15. Training Status

16. Types of Muscle Actions n Static - no change in length n Concentric - muscle shortening n Eccentric - muscle lengthening

17. TYPES OF MUSCLE ACTION

18. Muscle Action vs. Velocity

19. MUSCLE LENGTH vs FORCE PRODUCTION

20.  High aerobic (oxidative) capacity and fatigue resistance  Low anaerobic (glycolytic) capacity and motor unit strength  Slow contractile speed (110 ms) and myosin ATPase Slow-Twitch (ST) Muscle Fibers  10–180 fibers per motor neuron  Low sarcoplasmic reticulum development

21.  Moderate aerobic (oxidative) capacity and fatigue resistance  High anaerobic (glycolytic) capacity and motor unit strength  Fast contractile speed (50 ms) and myosin ATPase Fast-Twitch (FT a ) Muscle Fibers  300–800 fibers per motor neuron  High sarcoplasmic reticulum development

22. The difference in force development between FT and ST motor units is due to the number of muscle fibers per motor unit, not the force generated by each fiber. Did You Know…?

23.  Genetics determine which motor neurons innervate our individual muscle fibers.  Muscle fibers become specialized according to the type of neuron that stimulates them.  Endurance training and muscular inactivity may result in small changes in the percentage of FT and ST fibers. What Determines Fiber Type?  Aging may result in changes in the percentage of FT to ST fibers.

24.  Frequency of Impulses The rate of action potentials going to a muscle fiber (Hz) -force increases with the frequency of impulses

25.  The more fatigue the less strength.  Is fatigue peripheral or central? Fatigue

26. Muscular Strength Tests n 1. Handgrip Dynamometer –static

27. Muscular Strength Tests n 2. 1RM –Protocol 1. Have subject complete 5-10 reps at 40-60% of perceived 1RM 2. 1 minute of stretching 3. 3-5 reps at 60-80% of perceived 1RM 4. Add small amount of weight - attempt 5. If successful, rest 3-5 minutes and add more weight - attempt

28. 1RM n Protocol 6. Continue “titrating” until subject is unsuccessful 7. 1RM should be determined within 3-5 maximal efforts 8. 1RM = the weight of the last successfully completed lift

29. Estimation of 1RM (submaximal) n Submaximally estimate 1RM –Advantage – don’t have to do max testing and not as likely to injure your athletes. n Epley Equation n 1RM = (((0.033*Reps) Rep Wt.) + Rep Wt.)

30. Muscular Strength Tests n 3. Isokinetic Dynamometers –leg extension strength at various velocities (velocity spectrum testing) –3 maximal muscle actions at each velocity –record the highest value of the three

31. Ways to Express Results n 1. Absolute n 2. Relative to BW n 3. Relative to FFW

32. Muscular Endurance n Ability of a muscle group to execute repeated contractions over a period of time sufficient to cause muscular fatigue, or to maintain a specific percentage of MVC for a prolonged period of time

33. Muscular Endurance n 1. Grip Endurance n 2. Sit-ups n 3. Push-ups n 4. Thorstensson

34. Grip Endurance n 1. Squeeze dynamometer for 1 minute maximally - record initial strength and final strength n 2. Squeeze dynamometer at a submaximal percent of MVC (ie., 60%) to fatigue

35. Sit-ups n Supine n Knees at 90º n Arms at side n Fingers reaching for masking tape 8-12 cm from resting n Metronome - 40 beats/min

36. Push-ups n Males in “up” position n Females in “knee” position n Hands shoulder width apart n Chin touches mat n As many as possible consecutively and without rest

37. Thorstensson n Endurance test that allows for the calculation of %FT n 50 Reps n 180 º/sec

38. Thorstensson n %Decline = ((Initial PT - Final PT) ÷ Initial PT ) x 100 n %FT = (% Decline - 5.2) ÷ 0.9

39. Muscular Endurance