Mm strength and endurance testing (chap 6) Flashcards
Loss of function and aging
- Sedentary populations
- Athletes
- Bed rest
- Rate of 2% / year
- Rate of 5% / year
- 12% lost w/ week bed rest (3-5 weeks lose 50%)
Frailty barrier
When 70% loss of function has occurred
- a lack of activity to counteract, it happens much faster in all populations
- PT must have realistic expectations, motivate pt, and be able to edu on the negative effects so pt understands importance of moving
- age + injury = faster decline
- Force
- Torque
- Power
- Work
- Mass x acceleration
- Force x perpendicular distance from axis
- Work / time
- Force x distance
Muscular strength
Force output of a contracting mm or mm group
- directly related to the amount of tension a contracting mm can produce
- eccentric control top priority with majority of injuries
Mm strength influencers
- cross section of mm (myosin and surface area)
- lever arm
- neuromuscular factors (timing, motor learning)
- psychological factos (belief, understanding, **pain)
Measuring strength
- MMT (0-5 scale)
- Cable tensiometry: mechanical measurement of either pull or push, force in lbs but quick movements gives inaccurate number
- dynamometer: measures isometric contraction
- isokinetics: data include force production, torque, power, and work. $$ used in research mainly and can isolate specific movement or mm group for entire range for both concentric and eccentric
Mm endurance
Ability to perform repetitive or sustained activities over a prolonged period of time
- local endurance
- **ability of a mm to contract repeatedly against an external load, generate and sustain tension, and resist fatigue over an extended period of time
- usually increase strength means increased endurance
Cardiopulmonary endurance
Total body endurance
- repetitive, dynamic motor activities envolving large mm groups (walking, cycling)
Mm power
Related to strength and speed of movement as is defined as the work (F x D) produced by a mmm per unit of time (F x D / time)
- rate of performing work
- biggest variable is speed
Mm power determinants
- number of fibers recruited
- size of fiber
- slow twitch vs fast twitch
- body composition
- efficiency / economy of movement
- joint ROM
- coordination
- speed
- age (peaks 20s and decreases 6% / 10y)
- sex
- heredity
SAID
Specific adaptation to imposed demands
- to improve a specific mm performance element, the resistance program should be matched to that elements constructs
- to increase mm power the exercise program should consist of interventions that increase work demands while decreasing the time that work is accomplished
Endurance vs strength training
- strength training program: the amount of external resistance applied to the mm is incrementally and progressively increased
- endurance training: emphasis is placed on increasing the time a mm contraction is sustained or the number of reps performed rather than the amount of external resistance
Physiological adaptations to resistance ex
- Neural adaptations
- Skeletal mm adaptations
- Vascular and metabolic adaptations
- Mm fiber type adaptation
- Adaptations of connective tissues
Neural adaptations
- initial rapid gain in tension-generating capacity of skeletal mm is due to neural responses (mm memory)
- increase recruitment in the number of motor units firing as well as an increased rate and synchronization of firing (coordination)
- some cross over with training of unaffected side to affected side
- bilat exercises or start ex on unaffected side to get understanding
- see overall improvements in motor learning
Skeletal mm adaptations: hypertrophy
Increase in the size of individual mm fibers due to increased myofibrillar volume
- increased cross-sectional area and increased protein (actin and myosin) synthesis and decreased protein degradation
- usually occurs after 4-8+ weeks of CONSISTENT training, responsible for secondary growth gains
- IIB mm fibers appear to increas in size most readily with resistance training
- occurs in 6-8 weeks with mod resistance training and 2-4 with high
Skeletal mm adaptations: hyperplasia
- not highly accepted theory
- a portion of the increase in mm size that occurs with heavy training is due to mm fiber splitting.
- seems insignificant if real
Vascular and metabolic adaptations
With high intensity, low volume resistance training, there is a relative decrease in capillary bed density due to an increase in the number of myofilaments per fiber
Mm fiber type adaptation
- Type I: slow twitch (endurance and postural mm)
- Type II: fast twitch (power, strength, and speed)
- transformation of type IIB to IIA is common with endurance training and early weeks of heavy resistance training, making them more existent to fatigue. (Little to no evidence that type II become type I with training)
* *first activated slow - fast IIA - fast IIB
Chart
Chart
Adaptation of connective tissue
Increased collagen content =
- increased tendon and ligament outs strength
- connective tissue in mm thickens
- bone density increased (9-12+ months)
Training principles
- Overload
- Progressive
- Specificity
- SAID
- DOMS
- Reversibility
Overload principle
For performance and porphological change, a stimulus must progress and exceed the normal functional capabilities of the mm trained
Progressive overload
Once the body adapts to the stress, intensity of the stimulus must be increased to maintain overload and continue adaptations
Specificity of training
There are specific and predictable adaptations that occur at specific motor units that are trained
- train what you want to improve
DOMS
Delayed onset muscle soreness
- normal!
- due to skeletal mm microdamage, NOT lactic acid build up
- generalized pain, low grade ache
- low intensity exercise, ice, hydration, and anti-inflammatory meds can help to relieve soreness
- lasts 24-72 hours, peaks 24-48 hours
- eccentric > concentric
Reversibility principle
Adaptive changes are transient unless training-induced improvements are regularly used or unless the individual participants in maintenance program
- within 1-2 weeks
- transfer training of unaffected side?
1 RM
It is the maximum amount of weight one can lift in a single repetition for a give exercise, moving though a full ROM, with proper form and without compensation
- used as guidance to parameters
- not functional and not accurate cu most ppl need training to engage proper mm and coordination
Mode of exercise
Multi-factorial
- type of mm action
- type of strengthening exercise
- type of resistance
- open vs closed chain exercise
Isometric contraction
No change in mm length
- usually used in early phase of rehab
- stabilization and early rehab strengthening exercises
Concentric contraction
Mm fibers shortening
- usually 1-2”
- usually used in later phases of rehab
Eccentric contraction
Mm fibers are elongating (control)
- 3-4” contraction
- eccentric strength training will carry over to concentric phase
- overuse injuries respond well to therapy
- reduce weight; most control, less energy
- prepare for activities
Isotonic
Constant resistance though ROM, speed is variable strengthening exercise
Isokinetic
Contact speed, variable resistance strengthening exercises
Manual resistance
+ easily modified, good for early rehab, when movement needs to be controlled, modified in trining for functional activity
- limited by strength of clinician and not measurable
Open chain exercise
Distal segment moves freely in space
- used to strengthen and isolate specific, weakened mm prior to applying a WB load
Closed chain exercise
Distal portion of exercising system is fixed
- motion at one joint will produce motion at all other joints in the system in a predictable manner
- good for strengthening connective tissues as well. More benefit on entire body, including neuro
Duration of exercise TO GAIN STRENGTH
No in time increment but reps, sets, and rest time.
- 6- reps
- 2-3 sets
- 2-5 min rest between sets
- 80% 1 rep max
- usually used in later rehab phases for power, speed, agility (sport specific)
TO GAIN STRENTH AND HYPERTROPHY
- 6-12 reps (clinically 8-12)
- 3-4 sets
- 30-120 sec rest
- 70-80% 1RM
- *do not give ranges, give firm number
TO GAIN ENDURANCE
- 12-20+ reps
- can also use time (hold)
- 3+ sets
- 20-30 sec rest
- 50-70% 1RM
- usually what we train first in early phases of rehab
- distal strength by proximal endurance
Progression of strength training activities
- if 2 reps over goal on 2 consecutive treatments, PROGRESS
- always increases reps before weight
- once goal achieved, increase weight by 5-10% and decrease reps
Common errors
- Valsalva
- INADEQUATE REST (increases inflammatory response and decreases healing)
- Progressing too quickly
- IMPROPER FORM
Precautions
- local fatigue
- general fatigue
- disease fatigue (increase rest or decrease resistance)
- osteoporosis or fractures (change type or placement of resistance)
- avoid over work (lower motor neuron disease may not feel fatigue observe it)
Contras
- cleared for exercise
- uncontrolled HTN, arrythmias, severe CHF, severe myopathy, severe carditis (unless referred by physician)
- recent MI or CABG must wait 6-8 weeks
- severe joint or mm pain during - 24+ hrs after (decrease resistance or eliminate exercise)
- increased inflammation from previous visit
