How does muscle work with the skeleton?
Muscles function by pulling against bones that rotate about joints and transmit force through the skin to the environment.
A system of what enables the skeleton to move?
system of muscles
Macrostructure of muscle
entire skeletal muscle
microstructure of muscle
level of individual muscle fiber and the contractile mechanisms
Each skeletal muscle is what that contains what ?
organ that has muscle tissue, connective tissue, nerves, and blood vessels
This part of the muscle covers the body’s more than 430 skel muscles
fibrous connective tissue/ epimysium
motor unit/neuron and all the muscles fibers it innervates
What causes the release of calcium from the SR into the myofibril, which causes what in the muscle?
The discharge of an AP from a motor nerve signals the release of Ca++ from the SR into myofibril, causing tension development in the muscle.
The sliding-filament theory of a muscle contraction states what?
that the actin filaments at each end of the sarcomere slide inward on myosin filaments, pulling the Z-lines twd the center of the sarcomere and thus shortening the muscle fiber.
passive component of muscle
tendons/ elastic part
active component of muscle
What are the five phases of the sliding filament theory?
Resting Phase Excitation-Contraction Coupling Phase Contraction Phase Recharge Phase Relaxation Phase
What dictates the force production of a muscle?
of cross bridges that are attached to actin filaments at any instant in time
What two things are necessary for myosin cross-bridge cycling with actin filaments?
How is muscle activated?
arrival of AP at nerve terminal causes the release of ACh. Once a suffienct amt of ACh is released, an AP is generated across the sarcolemma, and the fiber contracts
Control of muscle depends on what?
number of muscle fibers within each motor unit
type IIa and IIx
motor neuron size of type 1 muscle fiber
nerve conduction velocity, contraction speed, and relaxation speed of type 1 muscle fibers
type 1 fatigue resistance is
Force production, power output, anaerobic enzyme content, for type one is
endurance, aerobic enzyme content, capillary size, myoglobin content, mitochondria density/size for type one is
fiber diameter for type one
color of type 1
motor neuron size, fiber diameter IIX
motor neuron size IIa
fiber diameter IIa
nerve conduction velocity, contraction speed, relaxation speed for type IIa and IIx
faitgue reistance, endurance, aerobic enzyme cotent for type IIA
power output type IIA
force production, cap density, mito size/density, fiber diameter type IIA
Fatigue resistance, endurance, aerobic enzyme content, cap density, mito size/density, Mb content are what for IIx
force production, power output, anaerobic enzyme content
color of type IIa
color of type IIx
What determines motor units’ functional capacity
Motor units are composed of muscle fibers with specific morphological and physiological characteristics that determine functional capacity
Motor unit recruitment patterns during exs; the force output of a muscle can be
varied through change in the frequency of activation of individual motor units or change in the number of activated motor units
Proprioception is information concerning what?
kinesthetic sense, or conscious appreciation of the position of body parts w.r.t gravity; and they are include the proprioceptors GTO and MS
Muscle spindles are what kind of receptors
length/stretch receptors and stimulatory
GTOs are what kind of receptors
force receptors and inhibitory
MS are proprios that consist of
several modified muscle fibers enclosed in a sheath of connective tissue
GTO are proprios located in
tendons near the myotendinus j(x)ction
GTOs occur in
series with extrafusal muscle fibers
Proprioceptors are what?
specialized sensory receptors that provide the CNS with info needed to maintain muscle tone and perform complex coordinated movements
maximal force that a muscle or muscle group can generate at a specified velocity
max force in muscle = and why?
torque since all muscles cross a joint
time rate of doing work; the product of force an object an the object’s velocity in the direction in which the force is exerted
Biomechanical factors in Human strength
Neural ctrl muscle CSA Arrangement of muscle fibers muscle length joint angle muscle contraction velocity joint angular velocity
Neural control (human strength): muscle force is > when:
a) more motor units are involved in a contraction
b) the motor units are greater in size
c) rate of firing is faster (rate coding fast)
MUSCLE CSA: the force a muscle can exert is related to what?
to its cross-sectional area (CSA) rather than its volume
Arrangement of muscle fibers impacts strength cuz . . . . .
variation exists in arrangement and alignment of sarcomeres in relation to the long axis of the muscles
At resting muscle length :
actin and myosin filaments lie next to each other; maximal number of potential cross-bridge sites are available; the muscle can generate the greatest force
When muscle is stretched:
a smaller proportion of the actin and myosin filaments lie next to each other; fewer potential cross-bridge sites are available; the muscle cannot generate as much force
When a muscle is contracted:
the actin filaments overlap; the number of cross-bridge sites is reduced; there is decreased force generation capability
Joint Angle impact on human strength:
Amount of torque depends on force versus muscle length, leverage, type of exercise, body joint in question, the muscles used at that joint , and the speed of contraction
Muscle contraction velocity
nonlinear, but in general, the force capability of muscle declines as the velocity of contraction increases
Joint Angular Velocity
3 types of muscle action:
The concept of specificity hold that training is the most effective when
R exs are similar to the sport activity in which improvement is sought (the target activity)
Exercises that use similar joint movements are then
emphasized in the resistance training program
What is used to power muscular activity?
energy stored in the chem bonds of ATP
LT begins @ what %-% in untrained individuals
LT begins @ what % range in trained athletes
The use of appropriate exercise intensities and rest intervals allows for the “selection” of what
specific energy sys’ during training and results in more efficient and productive regimens for specific athletic events w/ various metabolic demands.
The ion, stored in the SR, is released into the sarcoplasm to signal the beginning of the contraction process?
To which of the following structures do the cross-bridges attach during muscle action?
Which of the following muscle fiber types is the MOST beneficial for a marathon runner?
When throwing a baseball, an athlete’s arm is rapidly stretched just prior to throwing the ball. Which of the following structures detects and responds to that stretch by reflexively increasing muscle activity?
Which of the following shoulder movements and planes of action are associated with the upward movement phase of the side lateral shoulder raise exercise?
All else being equal, this type of muscle fiber arrangement will be associated with higher forces.
The length-tension relationship of muscle is based on the following fact:
As muscle lengthen, the tension changes and is highest at either the middle length (elastic/greg) or longest length (NSCA cscs answer)
Which of the following is the ultimate source of energy for a muscular contraction?
The primary substrate for a 50-meter sprint is
The predominant energy system used during a training session depends primarily on the
The predominant energy system used during a training session depends secondarily on the
The production of lactic acid results from the activation of which of the following energy systems?