THER EX: Exam II Flashcards
Types of muscular strength
- Absolute
- Relative
- Dynamic
- Static
Absolute = force produced by a muscle
Relative = strength normalized by body weight (usually kg)
– Ideally would use lean muscle mass
– Used to compare among people of different sizes
Dynamic = muscle shortens/lengthens with contraction (joint moves)
– Concentric or eccentric
– Ability to move an object
– Work performed (force x distance)
Static = muscle contracts with no change in muscle length
– Isometric
– No work performed but tension generated in muscle
Components of muscle performance
- Strength
- Power
- Endurance
Strength
= Ability to generate force against a resistance
– Ability of contractile tissue to produce tension
– Greatest measurable force generated by muscle during single max effort
KEY: High intensity
Examples: gripping a handrail, pushing open a door
Power
= Ability to produce force quickly
– Work produced by a muscle over a period of time
– (Force x Distance)/Time = Force x Velocity
KEY: Low intensity, high velocity
Examples: throwing shotput, sprinting
Endurance
= Ability to maintain force during repeated muscle contractions
– Ability to resist fatigue and generate/sustain tension over extended period
KEY: Low intensity, high repetitions (e.g., >15)
Examples: yoga, standing, putting 100 cans on a shelf
Characteristics of muscle power
- Short burst
- Multiple burst
– Methods for improving power
NOTE: Power = Work/Time
= Force x Distance/Time = Force x Velocity
Single burst activity = Single, rapid, explosive action
- Examples:
- Throwing shotput
- Lifting heavy piece of luggage
Multiple burst activity = Repeated burst of power
- Examples:
- Biking very fast
- Sprinting
Increase power:
(1) Increase FORCE produced during fixed amount of time
(2) Decrease TIME it takes to move a given force (increase VELOCITY)
- - Key characteristic = LOW intensity at HIGH velocity
- - Increased force = Decreased velocity
- - High training velocities promote power development
- - Keep intensities lower to allow higher velocities
Health benefits of resistance training
Demonstrated effects:
- Enhanced muscle performance
- Increased strength of CTs (e.g., ligaments, tendons)
- Greater bone mineral density or less bone demineralization
- Decreased stress on joints during physical activity
- Reduced risk of soft tissue injury during physical activity
- Enhanced physical performance during ADLs, work, recreation
- Improved body composition (decrease fat, increase LBM)
- Enhanced feeling of physical well-being
Possible effects:
- Improved perception of disability and quality of life
- Improved capacity to repair soft tissue (tissue remodeling)
- Improved balance
Adaptations to resistance training
– Neural
Time: First 2-4 weeks
– account for most initial strength gains
Effects:
(1) Increased motor unit recruitment
- - More fibers recruited = more force production
(2) Increased motor unit synchronization
(3) GTO inhibition
- - Some Inhibition of protective reflex mechanism (relaxation)
- - Increases ability to generate force
Adaptations to resistance training:
- Muscular adaptations
- Increases
- Decreases
Time: 4-8 weeks
Increases:
- Muscle fiber size (XSA) (= muscle hypertrophy)
- Transition from Type IIb to IIa fibers (= fatigue resistance)
- Glycolytic and high energy phosphate enzymes (= ATP production)
- Resting ATP and PCr (= capacity)
- Fiber pennation angle (= better line of pull)
Decreases:
– Body fat (limited evidence)
– Mitochondria volume and density
– Capillary density
NOTE: Muscle mass increases in greater proportion to mitochondria and capillary density
– RELATIVE decrease (ratio of mitochondria/capillary # to mass)
– Minimal effect (positive or negative) on aerobic capacity
– ACSM recommends training aerobic before resistance (do both)
NOTE: No evidence for new fibers made (hyperplasia) in humans
- Likely a very low contribution to overall strength gains
- Likely varies with type of exercise
Overload principle
- Definition
- Progressive resistance exercise
- FITT
- Strength overload
- Endurance overload
- General recommendation
- Recovery and maintenance
= Physiological adaptations occur only when muscle is challenged
Progressive resistance exercise (PRE)
= Incrementally increasing muscle load over time by varying resistance parameters
– Intensity (resistance) or volume (reps, sets, or frequency)
– Overall increased strength occurs as muscle is challenged
– Interspersed with periods of rest/recovery (decreased intensity)
Examples:
– FITT principle: Variables to manipulate
– Frequency (# sessions)
– Intensity (resistance or muscular tension)
– Type or mode (# exercises)
– Time or duration (reps, sets, rest)
– Strength overload = Incrementally increase resistance (intensity)
– Endurance overload = Incrementally increase reps
General recommendation:
= Increase resistance by 2-10% when all reps/sets completed w/o significant fatigue
Recovery and maintenance:
- Muscle must be given time to adapt and recover before load or reps are increased
- Performance maintained if demands remain constant after muscle has adapted
Specificity principle
- Definition
- Variables
- Transfer of training
= Adaptive effects of training highly specific to training method
- Critical that rehab mimics desired functional goals (task specific)
- Due to morphological, metabolic, and neural adaptations to training stimulus
Variables:
- Endurance, strength, or power
- Type of contraction
- Mode of exercise
- Velocity of exercise
- Joint angle and movement patterns
- Single vs. multi-plane movements
Transfer of training (= “Crossover” or “Overflow”)
- Minimal carryover between
- Exercises (for same muscle)
- Contraction types
- Body parts (cross-training)
- Muscular performance parameter (e.g., strength vs. endurance)
- Some overflow from
- Exercised to non-exercised contralateral limb
- Strength to endurance (not vice versa)
Individuality principle
- Definition
- Reason
- Significance
= Identical training regimen may not benefit everyone equally
- Numerous variables confound response
- Baseline fitness
- Fatigue status
- Muscle properties of individual
- Age
- Disease
- Genetic potential
- Responders vs. nonresponders
- Polymorphism = greater increase in lean muscle mass with resistance training
- Must focus training on individuals’ needs and capacities
Reversibility principle
- Definition
- Timeframe
- Factors
= Adaptations are transient unless regularly used
– Functional ADLs or maintenance program
– Detraining or deconditioning of strength, power, size, and BMD
= Reduced muscle performance after stopping resistance ex (e.g., injury)
Timeframe:
– Begins in 1-2 weeks (very quick)
– Continues until training effects are lost
Factors:
- Larger drops in inactive and older individuals
- Less drop in recreationally active individuals
- Minimal activity level required to maintain adaptations (neural and muscular)
- 1 time per week at high intensity may be adequate
NOTE: Important to emphasize program that individual can do on their own
– Incorporate muscle performance activities into daily life
Types of muscle contractions
- Dynamic
- Concentric
- Eccentric
- Static
- Isometric
– Dynamic = Muscle changes length (joint moves)
– Concentric = muscle shortened
– Force of contraction > external force
– Accelerate body parts
Example: Bicep curl
– Eccentric = muscle lengthened
– External force > force of contraction
– Decelerate body parts
Example: Walking downhill (quads); decelerating baseball throw (triceps)
– Static
– Isometric = no change in muscle length
– Force of contraction = external force
Example: Holding heavy book
Components of resistance exercise program
- Warm-up/Cool down
- Task-specific exercises
- Alignment
- Stabilization
- External
- Internal
Warm up:
– Increase blood flow and activate enzymes
– Muscle more responsive
Cool down:
– Blood pools in limbs when exercise stops
– Light intensity redistributes blood flow to vital organs
Task-specific:
– Design exercises to closely mimic functional or recreational needs
Alignment:
– Target muscle groups by aligning with pull of fibers
– Increasing intensity by aligning action against gravity
Stabilization:
– External = Outside supporting structure (e.g., PT, chair, wall, machine)
– Allows for pure muscle action (minimizes substitute motions)
– Internal = Adjacent muscle groups stabilize muscle being targeted (e.g., abs for SLR)
– Weak surrounding muscles may prevent ability to perform exercise
Recommendations for resistance exercise
- Exercise order
- Velocity
Exercise order:
– Large muscle groups > small muscle groups
– Multijoint > single joint exercises
– High intensity > low intensity
NOTE: More challenging first to minimize injury risk due to fatigue
Velocity:
- Early to advanced rehab = slow then fast
- Allows less trained individuals to learn movement
- Training velocities should match functional needs (little transfer)
- BUT many functional activities performed at much higher velocities
- Control velocities with isokinetic dynamometer
Recommendations for resistance exercise program
– Frequency
Frequency:
- Early rehab = 2-3 times per week
- Advanced rehab = 3-4 times per week
- Split upper/lower body or muscle groups (e.g., 2 days UE, 2 days LE)
- Factors:
- Intensity and volume (higher = less frequent/longer recovery)
- Health status (weaker = less frequent/more rest)
NOTE: Too frequent exercise is one main cause of overtraining
Recommendations for resistance exercise program
- Intensity
- Submaximal loading
- Maximal loading
= Amount of external resistance
Submaximal loading (50% of 10 RM or 30-40% 1 RM)
- Early stages of soft tissue healing
- Following prolonged immobilization
- Children and older adults
- Unfamiliar with correct form and technique
- Muscle endurance goals (30% 1 RM)
Maximal loading (100% 10 RM of 70-75% 1 RM) -- Advanced stages of rehab
