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