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.
