Biomechanics Test 1
Both professors cited in the article claimed that the force resulting from two football players colliding could reach up to _________, and is equal to the impact force from a fall from a ________.
- 1500 pounds - 13 foot ladder
A collision between two football players: - Each man exerts about _______ of force, or ______ of a ton, on the other
- 1500 pounds - three quarters
Stability and center of gravity/mass: - The CG of an object is that _________ about which the mass is centered - CG represents the point in an object where the sum of all of the forces acting on the object ________ - CG can be located ________ of the object. - CG changes with the change in the ______ or body parts - CG in the average mature male is located at approximately ____% of the body's height measured from the floor. - CG in a mature female is approximately _____% of height from the floor - CG in infants and small children is located at a point closer to the _______
- 3 dimensional point - equal 0 - Outside (ex. human in the piked position or a donut) - position of a body - 56% - 53% - head
Jump of a 13-foot ladder and land on your feet. You would be traveling approximately ______ per second, which is about _____ an hour. It would hurt but bending your knees would absorb most of the energy, so it doesn't sound too bad. But football players do not collide feet first. Now imagine diving off a 13-foot ladder and landing on the ground head and shoulders first.
- 8.81 meters - 20 miles -
If you are using the metric system gravity is pulling at _________. If you are using the US system it is?
- 9.8 m/s^2 - 32.2 ft/s
What is an example of genetic influences on physical performance?
- ACTN3: male and female elite sprinters have higher frequencies of this specific gene allele - they generate forceful contractions at high velocity
____ and the ______ affect rotational responses
- Anatomical mass - distribution of this mass
Examples of friction within and outside the body: - ______ are small fluid-filled sacs located at anatomical sites throughout the body where tendon, ligament and muscle come in contact with bony protuberances. The bursae serve to __________ and _______ Synovial fluid, Bursa sacs, oil
- Bursae - reduce friction - disperse forces
Anthropometics: Measurements and description of the physical components of the body - As far back as the Roman civilization, humans have been documenting the antrhropometrics of the human body. This documentation continued as physicians and artists recognized the value of these descriptions. - What is an example of an artist who recognized the geometric characteristics of the body?
- Di Vinci's Vitruvian Man
What are some statistics about hip fractures
- Females incur 2-3 times more hip fractures then do men - 1/2 of women reaching age 90 will fracture a hip - only 25% of patients make full recovery - 1 in 4 patients with hip fractures will die within one year as a result of conditions related to the fracture
What are some examples of cultures that changed a physical component of their body?
- Incas: elongated skulls - Asians: bind feet - Tribe in south american that climbed trees so over the years their feet changed
Why do we have cartilage in our joints?
- Joints possess various forms of cartilage - The cartilage surface area dictates force absorption capabilities at the joint site. - Ex. The distal ends of the femurs and the proximal end of the tibia are coated with a layer of articular cartilage approximately 3mm in thickness. Thus these cartilages play a significant role in regulating compression forces within the knee joint.
_________ and ___________ not only dictate force generation but also determine how well muscle fibers use oxygen to produce energy
- Muscle fiber types - muscle firing patterns
Are there any anatomical changes with age that affect torque production? - __________ can cause the finger extensors to relocate in a less advantageous location, thus leading to a decrease in torque
- Rheumatoid arthritis
The distal ends of canes and walker legs are often equipped with _______. These stoppers are designed to create enough friction to prevent the leg from slipping on the surface. With age these rubber stoppers become dry. This dryness changes the surface property of the rubber and can lead to decreased friction. Tennis balls are often used to _______ friction
- Rubber stoppers - Reduce
Mass= ____________
- Weight/ gravity
A person with a more ______ muscle insertion site will generate more torque. - this additional torque can lead to a greater vertical jump and an increase in the number of pushups a person can perform
- advantageous (We can conclude that muscle insertion sites help dictate the amount of torque generated by a muscle contraction)
Example of impact concerns: Pediatric committee issues warning on youth soccer: "In the Norwegian study of 106 former and still active professional soccer players, 81% were found to have impairment of their ________, _______, ________ and ________ that ranged from mild to severe. The more recent U.S. study compared 60 young adult soccer players with a smaller group of non-players found that ______ and ______ deficits were significantly more common among those who "headed" the ball most often." Neuroscientists are demonstrating that lasting brain injury can happen even when a victim does not lose consciousness or suffer a concussion, and that the brain can be harmed over time by small repeated stresses
- attention, concentration, memory, and judgment - attention and concentration
Applying _________ and conducting ______ are important parts of the overall process of learning movement patterns
- biomechanical principles - biomechanical analyses
Muscles originate on, and attach to _________. Often these muscles cross at least _________. The insertion sites are located at a distance away from the ______ or ________ of the joint about which ________ takes place.
- bone - one joint - fulcrum or center point - movement
Hip fractures: - with aging, ________ decreases - who is most susceptible to hip fractures? - As abilities lessen, the likelihood of ________ increases - Alterations to home environments may increase force absorption in the event of a fall, such as ______
- bone density - females - falling - falling on carpet verses hardwood or tile floors
- Movement can be affected by internal factors relating to _________________ - External factors such as ____________ affect the way humans move as well.
- bone, muscle, connective tissue, and neurological tissues - physical stress and fluid mechanics
The ability to rotate a body is directly related to the spacial relationship between a person's _______________ and the person's _____________.
- center of mass - distribution of mass
What is an example of an effort to control external friction: - Gymnasts try to maintain a consistent amount of friction by using ________. - Blisters result from too much ________
- chalk (not to much or it will tear chunks of skin off, and not too little because then you will swing off the bars) - friction
What are external examples of force absorption
- crash mats - air bags - helmets - padded undergarments - shoes
Moment of inertia and performance: Baseball players have been known to bore out the barrel of a wooden bat in order to ____________. The mass has been _______ and the center of mass have moved ________. The circumference of the barrel has not been affected. This type of alteration will allow the hitter to ____________, thus allowing the hitter to wait a little longer before making the decision to swing. This is illegal to alter a wooden bat to decrease its moment of inertia.
- decrease the bat's moment of inertia - reduced - towards the handle of the bar - accelerate the bat more quickly
Moment of inertia.... - an object where the mass is concentrated close to the axis of rotation is _____ to spin than an object of identical mass with the mass concentrated ______ from the axis of rotation.
- easier - far
A person would weigh less at the _______ than at the ________
- equator, poles (person would also jump higher at the equator)
How can certain disease states affect motor control: Humans face many diseases, such as ALS, multiple sclerosis, and polio that affect the CNS and/or the PNS, causing muscle function to become _____________________
- erratic and leading to deterioration of motor control (are losing the ability to contract the muscles)
What are internal examples of force absorption
- fibrocartilage - articular cartilage - muscle and tendons - fatty pads - bone stress and strain properties - joint flexion movements
Force absorption can be affected by the type of ________ found in homes and work sites. Carpeting will increase ___________ and lessen the ________.
- flooring - absorption time - impact force
When designing __________, it is important to consider how the components of ______________ may impact the user of these ramps. The steepness of each section of the ramp, as well as the radius of all turns will come into play
- handicap-accessible ramps - centripetal force
The bat retains the same diameter and length, but gives up mass and now has a center of mass closer to the ______. So the hitter can more rapidly accelerate this bat due to a __________.
- handle - reduced moment of inertia
How do changes in anatomical arrangements affect performance? Anatomical factors dictate the ___________
- height of a child's center of mass
This learning process starts in __________, and through a series of trials and errors, humans eventually learn to ____________ the number of motor units needed to accomplish a task. Sometimes our predictions, often determined by visual inspection of an object, are in error and result in the recruitment of too few of too many motor units.
- infancy - subconsciously predict
Other effects of MOI: A patient who has changed the type of shoe they are wearing has changed the moment of inertia of the ________. Patients with balance problems may have difficulty adjusting to the change in moment of inertia. Adding weight to the distal end of a limb will _______ the MOI of that limb. This change in MOI may affect the temporal elements of a motor skill.
- lower limbs (ex. flip flops compared to snow shoes) - increase -
Assessment of rolling walkers used by older adults in senior-living communities: Many observational studies have associated rolling walker use with an increased risk of falling. Lack to consult a _________ when obtaining an RW, incorrect _______, poor ________ and _______ were problems commonly identified. This knowledge could assist medical professionals in implementing strategies to address these problems.
- medical professional - rolling walker height - rolling walker maintenance - forward leaning posture
A motor unit consists of a _________ and all the _________ that are innervated by the nerve
- motor nerve - muscle fibers
Can we do things that may jeopardize the selection and modification of these motor programs? - Baseball players often use a weighted bat to warm up. But they will not use this weighted bat while batting. Theoretically, the parts of the ________ that involve _________, as well as the temporal elements, will possibly be affected by the use of the weighted bat. It is suggested that when preparing to hit, 5 warm-up swings with either a light or normal bat will allow a player to achieve the greatest velocity of their normal bat.
- motor program - motor unit recruitment
How do we coordinate a movement such as walking or playing the piano? Motor control research indicates that as we develop skills, ____________. These programs can be rapidly accessed, and to a certain degree, can be modified, speed up or slowed down. We often use feedback from _____________ to perform these modifications. This feedback can be biomechanically generated.
- motor programs are formed - internal and external sources
Myostatin: Research intended to help people with muscle-wasting diseases could be about to launch a new era in performance-enhancing drugs: " The research has produced several muscle- building drugs now being tested in people with medical problems, including ________, _____, _____. The drugs all work by blocking a substance called ______ that normally produces to keep muscle from getting too big."
- muscular dystrophy, caner, and kidney disease - myostatin ( when you get rid of the myostatin gene entirely, you see more muscle fibers, and then you get bigger muscle fibers)
Mutations in the MSTN gene cause ______________. - MSTN gene provides instructions for making a protein called _______, which is active in muscles used for movement (skeletal muscles) both before and after birth. This protein normally _________
- myostatin-related muscle hypertrophy - myostatin - restrains muscle growth, ensuring that muscles do not grow too large.
Objects such as bicycles and wheel chairs will often modify the composition of the wheel in order to adjust the MOI of the wheel. Hollow wheels have most of their mass _______. Solid wheels will have their center of mass _______. Given the same amount of mass, the solid wheel will have a _____ MOI and will be _____ to accelerate.
- out by the rim - closer to the axis of rotation - lower - easier
Fast twitch muscle fibers are very good at _________, but are not very good at utilizing ___________
- rapidly contracting - oxygen to produce ATP
What is the production of force dependent on?
- recruitment (the number of motor units used) - rate coding (the rate at which these units fire) - muscle firing patterns (synchronous and asynchronous firing) - fiber type (slow and fast twitch)
Moment of Inertia (Newton's laws applied to angular motion): "Mass is a measure of how difficult it is to get something to move in a ________ or to change an object's _______. The more mass something has, the harder it is to ________. Similarly, the moment of inertia of an object is a measure of how difficult it is to __________ or _______
- straight line - straight-line motion - start it moving or stop it once it has started - start it spinning, or to alter an object's spinning motion
Force absorption becomes more efficient if we increase the ________ and/or increase the _________
- time - surface area
Bones alter their ability to respond to additional stresses by becoming stronger in the direction of the most common loading forces. However, too much exercise combined with ______________ can cause the cells that break down old bone and produce new bone to lose their synchronicity, leading to ___________ that often results in stress fractures. This demineralization of the bone is part of the _______, a condition related to females possessing __________, which, in turn, causes ______ to become weaker.
- too little body fat - weaker bone structure - female triad - to little body fat - bones
Myostatin prevents us from becoming _______. There is excessive muscularity if there is a _______
- too musclular and tells the body to store more fat - defect in myostatin
" New research suggests that even in the absence of a concussion, blows to the head during a single season of football or ice hockey may affect the brain's __________ and ________, or ______ and _______ abilities
- white matter - cognition - memory - thinking
does .05 or .10 have more absorption time
.05
Football-type collisions are associated with absorption times of _________
.05-.10 seconds
Friction is depended on what three things
1. Force pushing the surfaces together 2. Physical properties of the surfaces 3. Generally, independent of surface area (so not a factor in friction)
What are the four factors affecting stability
1. Height of the CG: the lower the CG the more stable 2. Position of the CG within the base of support. The closer to the center of the base of support the more stable 3. Size of the base. The larger the base of support, the more stable 4. Weight of the object. The heavier the object, the more stable
What are the four factors affecting the speed of a motion
1. Muscle fiber type (fast twitch fibers increase speed) 2. Muscle anatomy: longer sarcomeres increase speed 3. Muscle attachment site: short moment arm can increase speed of lever 4. Moment of Inertia: low moment of inertia will increase speed of lever
What are the two factors affecting force absorption
1. Time over which the force is absorbed 2. Surface area
1. The greater the mass of an object, the ______________ 2. The greater the speed, the ____________ 3. The smaller the radius, the ____________
1. greater the force needed to keep the curved path 2. greater the force needed to maintain the curved path 3. greater the force needed to maintain the curved path
The muscles of world class sprinters have been found to have as much as _____ percent fast twitch fibers
80%
World class distance runners have as much as _____ percent of their muscle fibers functioning as slow twitch fibers
85%
_________: The study of the structure of the body
Anatomy
Pressure = _________ - measured in?
F/A - pascals (Pa)
What is an example of ergonomic assessment of a work space
Ball chairs - but they only work if you have perfect posture
What was the example given of an animal that possessed a defective gene that is responsible for the regulation of myostatin
Belgium blue breed of cattle
__________: The study of internal and external forces acting on a living organism.
Biomechanics
Give an example of correct practice makes perfect
Ex. Divers practice when it is quiet because that is how it is when they compete
"______ makes perfect"
Correct practice
Do custom mouth guards or over the counter mouth guards reduce football have a greater percentage of reducing concussions
Custom mouth guards
What is the falling bodies formula
Distance = 1/2 gravity x t^2 D= 1/2 g X t^2
Memorize the Metric and US standard graph on page 18
Do we need to know these?
_________: is the science of making a home, play and work environment safer and more comfortable through the use of design principles and anthropometric data
Ergonomics
What does F, t, m, and Vi stand for
F: force t: absorption time m: mass Vi: instantaneous velocity
F= Momentum=
F= m * a Momentum= m * v
Sex differences in head acceleration during heading while wearing soccer headgear: _______ soccer players exhibited greater head accelerations than their _____ counterparts when wearing headgear. Our results are important clinically because they indicate that soccer headgear may not be an appropriate head injury prevention tool for all athletes.
Female, male
Do males or females have better fine motor skills
Females
Who tends to have a lower center of gravity
Femals compared to males
What is an example of when you would use the law of acceleration formula
For the calculation of impact forces such as the resulting force from a fall on the hip to a collision on the football field
_________: Causes a change in the state of motion of an object.
Force - Is needed to start, stop, slow down, speed up or change the direction of an object
Impulse-momentum formula = _________
Ft=m(Vi)
_________: The study of the biochemical nature of genes and heredity
Genetics
Examples of external forces:
Gravity, friction, recoil
The weight room may be unnecessary, say FASEB jounal: muscle growth is controlled by "Hulk" protein Grb10: " Australian researchers have found that by blocking the function of a protein called ________ while mice were in the womb, they were considerably stronger and more muscular than their normal counterparts." - what is that an example of?
Grb10 - gene manipulation
What is an example of two different things that have comparable skeletal systems and musculature
Great apes and humans
What is an example with a sport that requires a small moment of inertia
Gymnastics, diving - will be easier to angularly accelerate
_________: A body's resistance to a change in linear acceleration
Inertia
Wheel chair designs are dictated by the environment in which they will be used. For example a basketball wheel chair will be different than a tennis wheel chair. There will be a change in height and base of support.
Just a note
Women are not just smaller men, and medicine is waking up to that fact: Medicine has traditionally treated women as if they were merely smaller men. Women's bodies are different than men's and these differences affect disease risk, symptoms, diagnostic sensitivity and specificity and responses to therapy
Just a note
________: The study of time and space characteristics of movement
Kinematics
________: The study of the forces affecting movement
Kinetics
__________: A body will remain at rest or in motion, traveling in a straight line, unless acted upon by a force. Thus, a force is needed to cause an object to travel in a curved path
Law of Inertia (1st law)
___________: The change in momentum of an object is proportional to the force and inversely proportional to the mass
Law of acceleration (2nd law)
_________: for every action there is an equal and opposite reaction
Law of action/reaction (3rd law)
Mass is measured in what in the US and metric system. Force?
Mass: Metric= kiliograms (kg) US= slugs Force: Metric: Newtons US: pounds
________: A body's resistance to a change in angular acceleration
Moment of inertia
____________: the study of the neuromusclular mechanisms involved in the facilitation of movement.
Motor control
__________: The study of motor behavior across the life span
Motor development
___________: The study of the acquisition and refinement of motor skills
Motor learning
________ laws of motion help explain how an object behaves in space
Newtons
Bone responds to stress by building more bone, however with ______ it builds up too much bone on the tibia and it really hurts
Osgood schlatters
Give an example of a motor skill
Performing surgery
_________: The study of the function of the body
Physiology
_______ is an essential element of the motor learning process
Practice
__________: The study of human behavior
Psychology
What is an example of a force transducer technology to measure impact forces?
Smart mouth guard - The firm has developed a mouth guard able to pair with a mobile app, to inform players of head trauma received during games. It records information related to the direction, force, and location of impact. When the impact exceeds a predetermined threshold, a light on the monitor turns red, and trainers or caregivers are alerted so the player can be removed from the game and be assessed for a possible concussion.
Examination of balance and thickness of shoe soles: - " Some researchers who study loss of stability in older people point to diminished sensitivity in the feet as a potential contributing cause of falling"
So maybe use thin soled shoes because they give more sensory feedback
Define anthropometrics
Study of physical characteristics (measurements and descriptions of the physical components of the body)
What is the equation for torque
T= muscle force multiplied by the perpendicular distance from the fulcrum to the application of a force
Metal baseball bats outperformed wooden bats in Brown study - Metal baseball bats are inherently unsafe for youth games because the ball comes off them much faster than from wooden bats.
The center of mass is different and will change the inertia - "The average speed of a hit off the fastest bat, a metal model, was 93.3 mph; the average off the slowest bat, a wooden model, was 86.1 mph"
What can great apes not lock out
Their knee joints - This makes standing and bipedal locomotion difficult for the apes
People in the US are at a disadvantage in that the U.S is one of only 3 countries to use the ______ system of weights and measures. All other countries use the _______
US standard - metric system
The greater the mass the harder it is to __________
accelerate angularly
Canes and walkers are designed to create a more stable base of support. The rubber stoppers located on the base of the devises _________
alter friction
_______: study of physical characteristics
anthropometrics
___________ can establish correct practice
biomechanical analysis
The tendency for an object to want to travel in a straight line is commonly referred to as ________
centrifugal force (it is not really a force, it is simply inertia)
The force needed to keep an object in a curved path is referred to as ________
centripetal force
When looking at a photo of a muscle stain what does the dark color indicate and what does the white color indicate
dark= oxidative slow twitch white= non-oxidative fast twitch fibers
Rheumatoid arthritis can _________________
deform joints, making movement difficult
EMG measures the amount of ___________ in a muscle. This activity is indicative of the number of motor units being recruited, as well as the rate at which these units fire.
electrical activity
Force platforms are commonly used to assess _____________
foot strike forces when walking or running
cartilage surface area dictates ________
force absorption response
______________: these devices measure the amount of force that is present
force transducers and force platforms
________ is the resistance created when two or more surfaces come together
friction
Anthropometric data describes variances across ____________
gender, ethnicity, and elite athletes are readily available
You can _____ to see if an individual is more susceptible to something
genetic profile
Sport performances are affected by the differences in _______ and _______
gravity and altitude
What is the instantaneous velocity formula
gt (gravity x time)
Young children have a lot of mass towards their _____
heads - higher center of gravity (which = less balance) - ex. riding a bike at 3 vs riding a bike at 7
Foot-strike pattern and performance in a marathon: "1991 runners were classified by foot-strike pattern, revealing a _______ relevance of 93.67%
heel-strike
Do orthotics help or harm athletes who use them: Shoe inserts or orthotics may be _______________, preventing injuries in some athletes. But it is not clear how to make inserts that work. The idea that they are supposed to correct mechanical alignment problems does not hold up.
helpful as a short-term solution
Due to a larger head in relation to the rest of the body, a young child will have a ______________ when compared to an adult. - So standing, walking, running and balancing on a bike are more difficult due to the decreased stability caused by the raised center of mass.
higher relative center of mass
We can use the ______ formula to generate an estimate of the force occurring in each of these situations
impulse-momentum
______: An object's resistance to angular acceleration
inertia
Force that affect motion can be _______ and _______
internal and external
As a peron moves around the planet, the gravitational pull of the earth will vary due to the change in stance from the person to the center of the earth's mass
just a note
Ex. of force absorption principles: "Ala. window washer survives 13-story fall down the side of an Alabama hospital tower, landing in newly planted bushes and mulch, which helped break his fall.
just a note
When you have a loss in cartilage and it has degraded to the point where bone is directly contacting bone then the pressure forces occurring at the joint site change. The pressure increases.
just a note
Barefoot running was different to all shod conditions. barefoot running changes the amount of work done at the ___ and _____ and this may have therapeutic and performance implications for runners
knee and ankle joints
Divers and gymnasts will alter their moment of inertia by assuming various body positions. The _______ the moment of inertia, the more difficult the dive becomes.
larger (therefore if a diver pulled her knees in closer to her torso her moment of inertia would be smaller)
Why do we have a patella? - It serves as a __________ by as much as 40 percent
lever that increases the amount of quadriceps torque (so it changes the torque)
_______ moment of inertia will increase speed of lever
low
Effect of hip protectors, falling angle and body mass index on pressure distribution over the hip during simulated falls: Interpretation: our results indicated that the hip protector we tested had a much stronger protective benefit for _____ than _____ body mass index individuals
low, high
What is the formula for moment of inertia
m * K^2 (mass times radius of gyration squared)
Centripetal force=
m * V^2/r
Force= ____________
mass X acceleration
weight=
mass X acceleration of gravity
Gravity is dependent on the ___________
mass of the objects being attracted to each other
With an increase in mass or an increase in radius of gyration, it becomes ________
more difficult to angularly accelerate an object
A ____________ records movement through the use of reflective markers placed at various anatomical sites.
motor analyzer
Examples of internal forces:
muscle contraction, joint friction, bone articulation
Arthroscopic Partial Meniscectomy versus Sham Surgery for a Degenerative Meniscal Tear: "Arthroscopic partial meniscectomy is one of the most common orthopedic procedures, yet rigorous evidence of its efficacy is lacking" In this trial involving patients without knee osteoarthritis but with symptoms of a degenerative medial meniscus tear, the outcomes after arthroscopic partial meniscectomy were ________________ after a sham surgical procedure.
no better than those
Efficacy of a hip protector to prevent hip fracture in nursing home residents: "Hip protectors, as currently designed, are ________ for preventing hip fracture among nursing home residents"
not effective
Because muscle force is transmitted to a bone at the insertion site, the muscle force is referred to as an ___________, or a _______
off-axis force, or torque
The study of anatomy includes the examination of the ________ and _____ of our muscles
origins and insertions
In the knee, when you have a meniscus breakdown between the medial condyle and the tibial plateau pressure is dramatically increased at this site. This increased pressure can lead to ________ and/or _________. With progression, this patient may need a knee replacement at some point in time.
osteoarthritis and/or avascular necrosis
Mutations that reduce the production of functional myostatin lead to an ___________
overgrowth of muscle tissues
What is an example of fine motor control
picking up a pen
Slow twitch fibers do not rapidly contract, but are very good at _______.
producing ATP (produce more energy, excelent capacity to store O2 to form APT, more myoglobin, don't contract very rapidly but can go for a long time)
Force transducers are often imbedded into ____________ and record forces occurring at the traducer site
shoes, gloves, etc
If the mass is more closely located to the center of the mass, the object, or body, is said to have a __________
smaller moment of inertia - They will require less rotational force to accomplish a rotational movement.
White matter is brain tissue that plays an important role in the ___________
speed of nerve signals
Bones respond to _____
stress
The higher the center of mass= _________
the less stable an object becomes
Muscle insertion sites help dictate the amount of __________
torque generated by a muscle contraction
A defect in the myostain gene will cause you to look ______
very muscular with little body fat (This can damage the internal organs)
EMG can identity _________
which muscles are being used in the movement
