Week 5 - Resistance Training

Frequency

# of exercise sessions per day/week

Stabilization

-Helps reduce compensatory patterns -Ex: Treatment table, wall, pt's body weight -Proximal attachment; sometimes distal

Force increases occur by:

-Increasing rate of discharge -Graded recruitment of higher threshold motor units

Progressive loading muscle by manipulated:

-Intensity of exercise -Vol. of exercise

Internal Stabilization

-Isometric contraction of adjacent muscle group. -Only effective if adjacent muscles are strong enough or not fatigued. (ex: bilateral straight leg raise, abs contract isometrically to stabilize pelvis & lumbar spine.)

Exercise Order; General Guidelines:

-Large muscle groups before smaller groups -Multi-joint muscles before single joint -High intensity before low intensity exercises CLINACALLY, not always possible or reasonable

Isotonic Contractions: Eccentric

-Lengthening muscle contraction -Decelerate body segments (running: HS eccentrics right before heel strike)

Improve Endurance

-Many reps against submax. load -30-70% 1 RM -Use of isometric contractions

Hypertrophy cont.

-Time frame dependent on intensity -Usually 8 weeks, sometimes 2-3 w/high intensity training. -BF resistance allows venous pooling & works muscle anaerobically for gains in muscle size & strength w/LOWER resistance. -Greatest increases associated w/high-volume, moderate-resistance exercise (eccentrically)

To Improve Strength

-Use of load that causes fatigue after 6-12 months -60-80% 1 RM -Increase resistance when no fatigue after target # of reps

Resistance level; Clinically:

Choose a resistance level & document # of reps before muscles fatigue.

Length-Tension Relationship

Greatest amount of resistance occurs at midrange of muscle contraction.

Factors Influencing Tension Generation: Muscle Architecture

High force production = short fibers w/pinnate & multipinnate design (quads, gastroc, deltoid, biceps) Low force production = long, parallel design in fibers; fast rate of shortening but less force production (sartorius, lumbricals).

Selective recruitment of fiber types is predicted more on:

Intensity

Power

Produced over brief or extended periods of TIME - Work = F x D -Power = Work/Time Ex: Lifting a box onto shelf, or climbing stairs. To improve power: Increase work, or decrease time.

Type IIA & IIB Force:

Rapid fatigue and rapid, high force production

Duration

Remember to increase strength. A program must be at least 6 weeks long.

SAID Principle

Specific Adaptations to Imposed Demands -Framework, which guides therapists in determining exercise prescription/parameters that will create specific training effects to best meet functional needs & goals.

Muscle Fatigue (Local)

Temporary & gradual decline in the force-producing capacity of the neuromuscular system, leading to a decrease in muscle length.

Muscle Fatigue

The diminished response of muscle to a repeated stimulus. -Normal and Reversible

Muscle Strength

The greatest measurable force that can be exerted by a muscle or muscle group to overcome resistance during a SINGLE max effort.

Connective Tissue; High Load, Low Rep Adaptations:

Thickens & tensile strength of tendons, ligaments & bone increase to improve strength or power.

Factors Influencing Tension Generation: Type & Speed of muscle contraction

Type: Force output from greatest to least: eccentric > isometric > concentric. Speed: -Concentric contraction: increase speed and force production decreases. -Eccentric contraction: increase speed and force production increases.

Endurance

ability to perform low-intensity, repetitive, or sustained activities over a prolonged period of time. Types: -Cardiopulmonary or Muscle Endurance

Motor Unit consist of:

-A motor neuron -Its Axon -Muscle fibers supplied by motor neuron

Muscle Fatigue: Type I (slow twitch)

-Aerobic Metabolism -Slow speed of contraction -Low level muscle tension, but can sustain contraction for a long time (endurance/postural muscles)

Muscle Fatigue: Type II (fast twitch)

-Anaerobic Metabolism -Type IIa & Type IIb -Great amount of tension in short period of time. Fatigue quickly, type IIb even faster than type IIa.

Force Velocity Curve: Eccentric

-As velocity of active muscle lengthening increases, force production increases, but quickly levels off. -Initial increase in force may be a protective response. -Used during shock absorption or rapid deceleration of limb.

Vascular/Metabolic; High Load, Low Rep Adaptations:

-Capillary bed density decreases due to an increase of myofilaments per fiber.

Muscle Fatigue Causes

-Decreased energy stores, insufficient oxygen, etc. -Protective inhibitory influences from CNS -Decrease in conduction of impulses or reduced excitability at neuromuscular junction

Cardiopulmonary Fatigue (General)

-Diminished response of entire body as a result of prolonged physical activity. -Associated w/endurance training -Caused by: decrease in BG, decrease in glycogen stores, & depletion of potassium.

Factors Influencing Tension Generation: Recruitment of Motor Units & Frequency of Firing Motor Units

-Greater # and synchronization of motor units firing = more force produced. -Higher frequency of firing, the greater the tension.

Factors Influencing Tension Generation: Fiber-type Distribution

-Higher % of Type I fibers = low force production, slow rate of max force development and resistant to fatigue -Higher % of Type II fibers = rapid force production and rapid fatigue

Dynamic Muscle Action

-Involves movement -Also referred to as isotonic -Also, isokinetics

Key Parameters of Endurance Training:

-Low load -High rep -Prolonged Period of Time Muscle adapts to endurance training by increases in their oxidative & metabolic capacities, which allows better delivery & use of oxygen.

Factors that influence muscle performance:

-Muscle -Neurological -Biochemical influences -Metabolic -CV/Respiratory -Cognition/Emotion

Isotonic Contractions: Concentric

-Shortening muscle contraction. -Accelerate body segments (running: quad contracts during swing phase)

3 Key Elements of Muscle Performance

-Strength -Power -Endurance Factors that can effect these 3 Elements: -Injury -Disease -Immobilization & Disuse -Inactivity

Signs/Symptoms of Muscle Fatigue

-Uncomfortable sensation in muscle, pain, & cramping -Unintentional slowing of movement w/ successive repetitions of an exercise -Active movements become jerky -Inability to complete movement through full ROM -Substitute motions (compensation patterns) -Inability to continue low intensity physical activity.

Reversibility Principle

-Use it or lose it -Detraining, reflected by reductions in muscle performance, a week or two after cessation of resistance exercises. -To overcome, give pts a maintenance program.

Muscle Endurance (Local endurance, Aerobic Power)

Ability of a muscle to contract repeatedly against external load, generate & sustain tension, & resist fatigue over an extended period of time. -Maintenance of balance & proper alignment the body segments require endurance of the POSTURAL muscles.

Functional Strength**

Ability of neuromuscular system to produce, reduce or control forces during functional activities in a smooth, coordinated manner.

SAID Principle: Specificity Training

Adaptive effects of training are highly specific to training method employed -Exercises should mimic anticipated function. -Must incorporate optimal mode or joint angle.

Precaution w/ Overload Principle**

Always consider underlying pathology, age, stage of tissue healing, & pt's response, & overall abilities & goals of pt. Give muscles & body systems time to adapt to demands of increased intensity or volume before subsequent increases.

Intensity:

Amount of external resistance imposed on muscle.

Volume

Amount of repetitions, sets, frequency of exercise. For endurance training, emphasis placed on increasing the time a muscle contraction is sustained or # or reps performed.

Intensity

Amount of resistance; training load or exercise load

Force

An agent that produces, or tends to produce, a change in the state of rest or motion of an object. Mass x Acceleration

Power can be differentiated into:

Anaerobic or Aerobic

Resistance Exercise/Training

Any form of active exercise in which a dynamic or static muscle contraction is resisted by an outside force. Outside Force: manual or mechanical

External stabilization

Applied manually by therapist. Use of belts, chairs

Force-Velocity Curve: Concentric

As velocity of muscle shortening increases, the force that the muscle can generate decreases. -May not have sufficient time to develop muscle tension. -E.g. Isokinetics. Fast speed = lower forces

Cardiopulmonary Endurance (Total body endurance):

Associated with repetitive, dynamic motor activities, such as walking, cycling, swimming, or UE ergometry. (All involve large muscles.)

Muscle Strength**

Broad term referring to ability of contractile tissue (muscle) to produce tension & resultant force. -With adequate strength, the contractile tissue generates enough force to meet the physical & functional demands placed on the system.

Recovery From Exercise:

Build into exercise program: Active Recovery: Light exercise; i.e. jogging after a sprint. More rapid recovery. Passive Recovery: Total rest; standing after sprint

Muscle Performance

Capacity of muscle to do work. - W = F x D

SAID Principle: Transfer of Training

Carryover of training effects from one variation of exercise/task to another. -More evidence on strength vs. endurance.

Articular Cartilage; Tissue Specific Exercises:

Compression/distraction in a weight bearing or functional position. Ex: thousands of reps - put a pt on total gym for 10 min.

Recovery Period

Dependent on intensity & volume of exercise. -Higher intensity, longer rest interval required

Henneman Size Principle

During activation of motor neurons, those w/smallest axons have the lowest thresholds & are recruited first, followed by larger cells w/ higher thresholds.

Tissue Specific Exercises:

During tissue repair, low loads & high reps.

Endurance Training vs Strength Training

Endurance has a more positive impact on improving function compared to strength training. Endurance also minimizes adverse forces on joints, produces less irritation to soft tissues, & is more comfortable for the pt.

Tendon/Ligament Tissue Specific Exercises:

Ex: exercise for 30 sec. at a time & rest for 5-10 sec. & repeat for minutes. Must be pain free w/slow speeds.

Resistance Level

Greatest amount of weight a muscle can move through full available ROM w/control a specific # of time before fatiguing.

Parallel fiber arrangement (AKA strap or fusiform) muscles can have:

High rates of shortening, but produce less force

Short or fibers arranged obliquely to a muscle's long axis (think feather) are:

Higher force producing muscles

Training Zone

If pt is sedentary or untrained, a % of 30-40% of rep max is enough to induce adaptation in strength, but for someone who is trained it may be >80%

Submaximal Loads

Immobilization-articular cartilage may not be able to withstand large compressive forces or there may be demineralization.

Hyperplasia

Increase in # of muscle fibers due to longitudinal splitting of muscle fibers. (So far only found in animals)

Hypertrophy

Increase in size of individual muscle fiber -Generally type IIB

Static Muscle Action

Isometric: force developed in muscle without any motion about an axis; no work done.

Factors Influencing Tension Generation: Cross Section & Size of Muscle

Larger muscle diameter, the greater tension producing capacity.

Threshold for fatigue:

Length of time a contraction is maintained or the # of reps that can be performed.

Type I Force:

Low force production, resists fatigue, slow rate of max force development

Factors Influencing Tension Generation: Moment Arm

Moment arm between muscle force vector & axis of joint. -Greater tension produced w/longer moment arm.

Eccentric Contractions Cont.

More important component of functional movement -Stand-to-sit; descending stairs; setting down an object

Overload Principle

Muscle must be challenged to perform at a greater level than that to which it is accustomed. Must be challenged to increase instead of just maintain.

Factors Influencing Tension Generation: Length-Tension Relationship

Muscles produce the most tension when at or near the physiological resting length at the time of contraction.