1. MUSCULAR STRENGTH, ENDURANCE AND POWER
Returning the athlete to competitive and functional level following injury

2. Definitions Muscular Strength
Ability to generate force against some resistance
Important to maintain normal levels of strength for normal healthy living
Measure with 1 RM –
In rehab 1 Rm too difficult for weak or injured muscles
Could use a 10 RM – weight not as stressful

3. Definitions Muscular Endurance
Ability to perform repetitive muscular contractions against some resistance ( less than max load)
Depends on energy systems
As strength increases, endurance increases

4. Definitions
Power
Strength applied over a distance for a specific amount of time
P=Fxd/T
Ability to generate force quickly
Combination of strength and speed
Performance is limited without power
Speed depends on coordination , efficiency of movement and timing
Power is developed after strength ( in rehab)

5. Fiber Types Slow Twitch Fibers Fast Twitch Fibers
Type I or slow oxidative
Resistant to fatigue
Primarily associated with long duration, aerobic type activities and postural muscles
Fast Twitch Fibers
Type IIa (fast oxidative glycolytic) IIb (fast glycolytic)
Produce quick, forceful contractions by tendency to fatigue

6. Fiber Types Cont’d Ratio in Muscle Fiber changes due to training
Both fiber types exist in individual muscles
Ratio varies by muscle and by individual
Genetically determined
Fiber changes due to training
Enhanced metabolic capabilities through specific training
Can fiber type change?

7. Muscle Strength and Muscle Endurance
High intensity and low reps at one end of continuum – strength gains
Low intensity and high reps at other end of continuum – muscle endurance gains
Strength gains can be achieved with high rep and as can endurance gains with low reps but not as well – good to remember for rehab ….
General rule a thumb
Strength – 10 reps
Endurance reps

8. Muscle Strength and Muscle Endurance
Berger 1962 – sets – three sets beneficial for strength training
This study has not been replicated
ACSM- one set of reps to fatigue to increase strength
Recovery times vary for type of exercise
Isometric – 1 minute
Isotonic – 30 sec to a minute
Isokinetic – 2-4 minutes

9. Types of Contraction Isotonic contraction
Dynamic involves a change in the muscle length
Concentric contraction
Muscle shortens
Eccentric Contraction
Muscle lengthens
20-40 % more force can be produced
More likely hood of DOMS
Isometric contraction
Contraction that produces muscle tension but no change in muscle length

11. Types of Contraction Isokinetic
Velocity is controlled ( speed is unchanged) where as the resistance is changed
Often called accommodating resistance

12. Factors That Determine Levels of Strength, Endurance and Power
Size of Muscle
Proportional to cross-sectional diameter of muscle fibers
Hypertrophy
Increase in muscle size
Atrophy
Decrease in muscle size
Can occur in as little as 48 hours
Consistent exercise essential to prevent

13. Factors Continued Number of Muscle Fibers
Strength is a function of the number and diameter of muscle fibers
Number of fibers is inherited characteristic

14. Factors Continued Neuromuscular Efficiency
Strength is directly related to efficiency of the neuromuscular system
Initial increases in strength during first 8-10 weeks are attributed to neuromuscular efficiency
Enhanced strength in 3 ways
Increase motor unit recruitment
Increase in firing rate
Enhance synchronization of motor unit firing

15. Evaluating Muscle strength
Isokinetic devices, cable tensiometers , isometric strength
Manual Muscle test
The basis of this test is assessment of the muscles ability to move a joint through a ROM
Muscle strength is graded from 0-5
Always remember ACTIVE ROM first
Resistance testing – isometric , mid range provide stabilization

16. Strength equipment
Varies greatly due to availability and cost , size of room
Manual resistance – resistance force applied by therapist or by patient
Advantage – no equipment required, cost , hands on , immediate feedback , can easily modify resistance applied , can modify speed and can be easily incorporated in to a program
Disadvantages- requires one on one work – time consuming , manual resistance nor measurable , not a consistent force
Body weight – use of patient’s own weight
Advantage- no equipment , performed anywhere , cost , functional activities , performed independently
Disadvantage – no guarantee doing right when not supervised ,can not tolerate weight bearing ex

17. Strength equipment
Rubber tubing /bands – dynamic resistance – lots of different weights
Advantage – cost is low, ex at home , not bulky can be taken on road trips ,can make progressions , can mimic functional exercises
Disadvantage – performed independently – unsure of technique, resistance greater at end when stretched , easier to use for upper than lower body
Free weights – cuffs , bar bells
Advantage – variety of free wts available, measurable changes ,can be used in functional activities
Disadvantages – safety , training supervision using too much weight, boring

18. Strength equipment Isotonic machines – constant load during exercise
Advantage- safety , readily available in gyms , multi station units , can work more unsupervised
Disadvantage – weight restrictions due to muscle strength , boring , cost
Isokinetic machines – accommodating resistance machines - biodex and cybex
Advantage- constant speed and accommodating resistance , max and sub max outputs, patterns , measurable results ( computer charts graphs )
Disadvantage- cost $40,000, exercises are mostly OKC

19. Exercise Progression No Pain , during , after , next day ( DOMS)
No inflammation
Make attainable goals yet challenging
Progressive overload – loads must increase progressively – overload principle
Cross training – training contralateral side – can be used when limb movement is restricted

20. Strength Four principles SNAP Specific exercise No Pain
Attainable goals
Progressive overload

21. Physiological Adaptations Summary
Improved neuromuscular efficiency
Muscle hypertrophy
Number of muscle fibers does not increase
Increased size and number of myofilaments Actin and myosin
Increased number of capillaries
No new capillaries
Increase in dormant capillary activity to meet needs of muscle

22. Strength of non-contractile structures
Tendons and ligament increase
Increased bone-mineral content
Improved oxygen uptake
If resistance training is high enough to elicit a cardiovascular response/adaptation
Increased metabolic enzymes
Increased ability to withstand metobolic wastes

23. Overtraining Imbalance between exercise and recovery
Training exceeds physiological and psychological capacity of individual
Can have negative effect on strength training
May result in psychological or physiological breakdown
Injury, illness, and fatigue can be indicators

24. Open and Closed Kinetic Chain
Open Kinetic Chain
Distal segment ( hand or foot ) moves freely in space
Movements in other segments within the chain are not predictable
Kicking , throwing open kinetic chain
Advantage – ex not delayed if can not weight bear
Closed Kinetic Chain
Distal segment is weight bearing
Foot/hand meets resistance, movement of more proximal segment occurs in predictable pattern
Running , handstands
Less shear force with CKC- safer to use especially in early rehab program

26. Girth Measurments
Often girth measurements are taken prior to the development of the rehab program to provide the therapist with a starting point.
Measurements are repeated a intervals on the program to be used as a way to monitor progress
Increases and decreases in girth size are thought to be related to muscle strength

27. Girth measurements
To ensure accurate and reliable measurements the therapist should use the same anatomical landmarks when performing the measurements.