1. PTA 130 – Fundamentals of Treatment I

2.  Introduction to muscle performance  Discuss anatomical considerations of muscle  Describe various types of resistance training  Describe muscle adaptation to resistance training

3.  The capacity of a muscle to do work  W = force x distance  A complex component of functional movement and is influenced by all of the body systems  Key elements of muscle performance include: ◦ Strength ◦ Power ◦ Endurance

4.  Muscle tissue is made up of contractile and noncontractile tissues  Connective tissue structures are: ◦ Endomysium (innermost layer) ◦ Perimysium ◦ Epimysium (envelops the entire muscle)

5.  Individual muscles are composed of muscle fibers  A single muscle fiber is made up of many myofibrils  Each myofibril is composed of the smallest contractile units known as sarcomeres  Sarcomeres are composed of overlapping myofilaments of actin (thin) and myosin (thick)  What happens to the actin-myosin filaments when a muscle actively shortens?

7.  Sarcomere = from Z-disc to Z-disc  Contraction is triggered by a stimulatory nerve impulse that causes an action potential to spread across the sarcomerenerve impulseaction potential  The action potential stimulates the sliding of filaments to occur  A change in muscle length results

9.  A functional structure consisting of a motor neuron and the muscle fibers it innervates  Larger muscles are made up of more muscle fibers ◦ Produce less specific movements  Smaller muscles are made up of fewer muscle fibers ◦ Produce very specific movements  Examples: ◦ A motor unit inside the eye will usually contain two to three fibers, with only three to five motor units residing in the entire eye. ◦ The calf muscle can have between 1,000 and 2,000 motor fibers per motor unit.

10.  Dependent upon many factors: ◦ Biological ◦ Neurological ◦ Metabolic ◦ Biomechanical factors ◦ Energy stores available to muscle ◦ Influence of fatigue and recovery from exercise ◦ Age ◦ Gender

11.  The diminished response of muscle to a repeated stimulus  Occurs during exercise when a muscle repeatedly contracts statically or dynamically against an imposed load  Muscle fatigue is normal and reversible  The rate at which muscle fatigue occurs is also dependent upon the type of muscle fibers involved

12.  Affects how resistant the muscle is to fatigue  Two broad categories: ◦ Type I  Slow-Twitch ◦ Type II  Fast-Twitch

13.  Type I fibers  Tonic, slow-twitch  Generate low level of muscle tension  Can sustain the contraction for a long period of time  More resistant to fatigue  For prolonged, sustained aerobic activity  What muscle(s) are composed primarily of Type I fibers?

14.  Type II fibers  Generate a great amount of tension within a short period of time  For brief, intense anaerobic activity  More force production possible because of greater muscle fiber numbers in motor unit  What muscle(s) are composed primarily of Type II fibers?

16.  Muscles are composed of both slow- and fast-twitch fibers  Ratios of each type vary from muscle to muscle and from person to person

17.  Irritability: ◦ Stimulation is required to produce a response. ◦ Threshold = minimum stimulation required for a response  Contractility: ◦ Ability to contract = twitch. ◦ One contraction occurs with each stimulus ◦ Sustained contractions: require repeated stimuli

18.  Excitability ◦ Capacity of muscle to respond when stimulated by nerve impulse  Extensibility (stretchability) ◦ Capacity of muscle to stretch beyond its relaxed length  Elasticity ◦ Ability to return to original length after contraction or stretching

19.  Extensibility and Elasticity: ◦ As muscle is stretched, it becomes more extensible ◦ Inactivity produces stiffness ◦ Stiffness can be overcome with active exercise (which increases temperature, decreases viscosity, and improves extensibility)

20.  Muscle Contracture: ◦ The failure of a muscle to relax; it is normal for muscle to relax after contraction ◦ Fatigue reduces the ability to produce maximum contraction and to completely relax ◦ It is important to stretch after activity since fibers do not resume normal length with fatigue ◦ Muscle contracture is not the same as orthopedic contracture (connective tissue shortening) or muscle spasm

21.  Fatigue: ◦ Related to contracture ◦ From exhaustion of muscle with activity or from inadequate circulation to provide nutrients needed for continued activity ◦ Lactic acid: builds up with inadequate amount of oxygen to metabolize it ◦ Endurance proportional to tolerance of pain produced by lactic acid buildup:  tolerance   endurance

22.  Fatigue: ◦ Lactic acid production varies:  Untrained muscles produce more lactic acid than trained muscles  Type II muscle produce more than type I muscle  High intensity exercises produce more than low ◦ Sustained isometric exercises: block blood flow to increase lactic acid buildup  fatigue (e.g., carrying suitcase: grip)

23.  The type of resistance training selected for a therapeutic exercise program are dependent on many factors: ◦ Cause and extent of impairments ◦ Stage of tissue healing ◦ Condition of joints ◦ General abilities of the patient ◦ Patient’s goals and intended functional outcomes

24.  Static ◦ Isometric  Dynamic ◦ Isotonic ◦ Isokinetic

25. ◦ Force produced in muscle without a change in the muscle’s length; no visible joint motion ◦ Advantages:  Strengthen muscle without undue stress (no change in position)  Can start early (e.g., surgery, fracture)  Appropriate when muscle is too weak for active range of motion against gravity, isotonic, or isokinetic exercises

26.  Muscle – setting exercises ◦ Quad sets ◦ Glut sets ◦ Hamstring sets  Stabilization exercises ◦ Core stabilization ◦ Rhythmic stabilization

27.  Intensity of muscle contraction ◦ Exercise intensity load of 60-80% of a muscle’s force  Duration of muscle activation ◦ 6-10 second hold during contraction  Repetitions performed depends upon ◦ Muscle’s condition ◦ Ability of part to move ◦ Healing phase of tissue

28.  Precaution - Valsalva maneuver: ◦ Breath – holding commonly occurs during isometric exercise ◦ Causes a rapid increase in blood pressure ◦ It is important to emphasize exhalation during the contraction

29.  Causes joint movement and a change in length of muscle tissue  Concentric Contraction – ◦ Muscle contracts and shortens  Eccentric Contraction – ◦ Muscle lengthens under tension  Concentric and eccentric contractions are involved in most activities

30.  A form of dynamic muscle loading where tension in a muscle develops and physical shortening of the muscle occurs as an external force (resistance) is overcome  Example?

31.  Involves dynamic loading of a muscle beyond its force-producing capacity, causing physical lengthening of the muscle as it attempts to control the load  Example?

32.  Both types of exercise have value in rehabilitation programs  A combination of both concentric and eccentric activities occur in our daily life  Are concentric or eccentric exercises more difficult to perform?  Why?

33.  Type of dynamic activity  Velocity of muscle shortening or lengthening is maintained, but force varies through range of motion  The term isokinetic refers to movement that occurs at an equal velocity  Also known as accommodating resistance exercise  Offers reciprocal training of agonist and antagonist