Lab Test 1 (lab 1) Flashcards
This is often used to evaluate performance
muscle strength
Strength
the amount of force or tension a muscle or muscle groups can exert against a resistance in one maximal effort
Reasons to test strength 4
predict performance
implement a training program
measurement of rehabilitation
identify a muscle imbalance
Two reason to predict performance
comparison to normal values
use certain tests to estimate fiber type composition
reason to test strength to implement a training program
periodization
two reasons to get a measurement of rehabilitation 2
post-trauma (surgery) muscle strength decreases: atrophy
stages of recovery based upon the muscle’s ability to produce force
Identifying a muscle imbalance is done doing this
agonist vs antagonist ratios
one reason to identify a muscle imbalance
comparison to norms
muscle imbalance: knee extension and knee flexion
quads/hamstring ratio
hamstring/quads ratio
hamstrings are typically this percent as strong as the quads
65-75%
The strength difference in the hams vs the quads is due to
size of two muscle groups
Ideal ratio hams vs quads
65%
Hamstrings should be at least this % as strong as quads to prevent injury
58%
3 ways to measure muscle strength
Isometric
Isotonic
Isokinetic
A contraction (or muscle action) with tension, but there is no change in external muscle length. AKA static contraction (or muscle action)
Isometric
A muscular contraction (or muscle action) in which a muscle shortens with varying tension while overcoming or lifting a constant resistance through the ROM (range of motion)
Isotonic
Maximal tension (force or torque) developed in all joint angles throughout the full ROM. Speed (or velocity) is constant (regardless of how much force is produced, the speed stays the same). There is accommodating resistance at a controlled speed of movement.
Isokinetic
THis measure of muscular strength uses an accommodating resistance at a controlled speed of movement
isokinetic
4 advantages to isometric testing
inexpensive (not much equipment needed)
time efficient
useful in rehabilitative settings
most facilities/people can do it
4 disadvantages to isometric training
joint angle specific
does not reflect increase in strength across an entire ROM
strength values do not relate to a dynamic moment
there is no mathematical work done
4 advantages to isotonic testing
better than an isometric muscle action
related to performance/athletics
psychological aspect of seeing the bar or stack move
relatively inexpensive
3 disavantages to isotonic testing
measures the weakest point in the ROM
unable to measure strength at any controlled speed
trial-and-error method to attain max
DCER
dynamic constant external resistance
3 advantages of isokinetic testing
measures strength/force/torque at different joint angles
1-500 x s^-1
they are fancy
2 disadvantages of isokinetic testing
expensive (>= $45000)
must know how to operate an isokinetic dynomometer (cant be computer illiterate)
3 ways to express strength results
absolute terms
relative terms
strength / lean body weight
A limited value in expression of strength results
absolute terms
This is a strength-to-weight ratio. A relative value also allows for comparison between individuals
relative terms
provides information regarding strength per unit of muscle mass
strength/lean body weight (LBW)
2 points on absolute strength results
cannot compare different people with absolute strength or power values
units of foot pounds or newton meters
formula for relative strength results
strength value (ft.lbs) / BW (lbs) = relative strength ratio
converting ft.lbs to Nm
Strength value (ft.lbs) x 1.3588 = strength value in Nm
Relative strength terms do this
takes into account variables
Strength / lean body weight allows for this
gender comparisons
The cybex II can be used to measure this
concentric flexion and extension for the lower and upper body
The cybex II cannot be used to measure this
eccentric movements
Isokinetic strength testing can measure peak force production at these joint angles.
various
Isotonic strength testing can measure peak force here
at the weakest point in the range of motion
This type of strength testing cannot measure the maximal force which can be produced by a muscle and speed of contraction cannot be predetermined
Isotonic
Torque vs # of reps
negative slope
torque vs ROM
Upside down U shaped slope
Torque vs velocity
negative slope
Torque vs time
Negative slope
sprinters have a faster drop off
Long distance runners have a slower drop off
Peak strength relative to body weight =
Initial peak torque (ft.lbs) over weight (kg)
% decline =
(initial peak torque - final peak torque) / initial peak torque all X 100%
% fast twitch =
% decline - 5.2 all over 0.9
