have you ever wondered what applied biomechanics is well you're in the right place because this video is the first in the series explaining all about biomechanics and in this video we'll cover not only the definition of the word but also how biomechanics relates to other fields within kinesiology okay dr. good and here and in this video as I said we'll be discussing an introduction to biomechanics so what is biomechanics bio meaning life and mechanics referring to machines how does it all come together and more importantly how does it fit within the umbrella of other kinesiology disciplines let's dive right into the content alright here we are in the slides for today and a big question we're addressing is what is biomechanics biomechanics is simply the science of movement of the living body so you see we have bio body biology life and mechanics movement machines etc now to break it down even further biomechanics is the physics of motion exhibited or produced by biological systems and if we want to get even more specific it's a highly integrated field of study that examines forces acting upon within and produced by the body so external forces that would be forces acting upon internal forces that would be forces within the body so forces ground reaction forces that are traveling up the shank and into the femur for instance or produced by the body via muscles now biomechanics integrates biological characteristics with traditional mechanics hence bio and mechanics but what is mechanic's so most of us in kinesiology we may not be brushed up on the physics so mechanics is the of physics it's a specific branch in physics that's specifically concerned with the effective forces and energy on the motion of bodies so if you recall Newton's three laws which we'll go over in another video those would be within the realm of mechanics and within mechanics we have both statics and dynamics now statics is the study of systems in a state of equilibrium so this could be at rest or in a constant state of motion think of somebody doing a handstand for instance a gymnast doing a handstand that would be an example of statics but so would a runner traveling at a constant speed or a cyclist or a swimmer now dynamics on the other hand is the study of systems in a state of accelerated or changing motion so now we want to think of a gymnast who is doing a tumbling routine or who is or maybe a soccer player who's not running at a constant speed but now they're cutting and decelerating and accelerating in different directions so when we perform a biomechanical analysis and we'll do that later in this course in other videos we can perform it from two different perspectives the first is kinetics and this is the study of forces like gravity or friction that inhibit cause facilitate or modify motion of the body so what is the effect of gravity on a javelin that you're throwing or what is the effect of friction on artificial turf as compared to grass I mean kinematics is the study of spatial and temporal characteristics of motion so these are things like velocity speed displacement here we have a picture of Usain Bolt traveling at high velocities and we're not when we're looking at kinematics were not so much concerned with the forces as much as we are on the displacement and the rate of displacement now typically we think of biomechanics in sport there's so many examples of biomechanics in sport is easy to come up with them in this case where the example is a basketball player might injure her ankle while landing from a layup from a kinematic perspective how fast was that player moving at the moment of injury so we want to know the velocity how fast was she running when she planted her foot 2bath how fast was she moving when she impacted the ground and was it single leg or double leg from a kinetic perspective we want to ask the question how much force was absorbed by the body upon landing so we might want to consider the stress and strain relationship of her lower leg we might want to consider how much force she was capable of absorbing the last time she was tested on a force plate but outside of Sport biomechanics is important as well so think about the normal gait cycle scientists in the realm of motor development mode of learning and motor control might necessity Panzi as far as their stride characteristics go so from a kinematic perspective what's the length or the distance of these strides from a kinetic perspective we might ask why do they walk with these particular characteristics so just imagine a baby in a chimpanzee walking they tend to walk with their arms up high out to their side short steps toes turn outwards for balance how does the force produce differ between the infant and chimpanzee or how is it the same now I mentioned in the intro that biomechanics is a field that's highly related to other fields within kinesiology here we have a list it's not a complete list but biomechanics is all about movement and so are things like economic physical therapy occupational therapy and so on down this list all of these sub disciplines within kinesiology have a biomechanical component so for instance biomechanics and exercise physiology what is the relationship there well if biomechanics is about movement exercise physiology is about movement that is caused by the contraction of skeletal muscle so in this case we're focused on what's the physiology of that muscular contraction that causes force and if you recall that force is going to be within under that umbrella of kinetics or a kinetic analysis within biomechanics what about motor control so your biomechanics is about movement while motor control is about the mechanisms used by the nervous system to control and coordinate the movements of the musculoskeletal system within motor control we also have motor development and motor learning so the maturation throughout the lifespan and the motor learning is experience and/or practice how do we modify these movement patterns with practice now this brings us to two important concepts the first is an open loop skill an open loop skill is a skill that occurs at a faster rate than feedback can change so think of a a clean and jerk in Olympic style weightlifting in the clean-and-jerk you that a flea needs to accelerate the barbell off the ground hit a series of very specific positions on the way up through the first and second and third poles meet the bar at its apex and catch it and then stand up with it and this is not a light bar but this happens so fast it all happens within a second or two so the athlete often doesn't have time to reevaluate if they think oh the bar path was out you know the bar was traveling out in front of my knees I need to pull it back by the time you think that the bar is already up and you're into your third pole and it's too late to correct a closed loop skill on the other hand is a skill that can be changed while in motion as a result of feedback so let's say that you're a runner and you're running along maybe you're out on a 10-mile run it's supposed to be a tempo run at a nice steady pace maybe around your marathon pace and as you're running your your foot strike every single foot strike that you feel is giving you proprioceptive feedback as is the feeling in the muscles of your legs as is the carriage of your arm swing and a runner often a good one will intuitively know if their stride is off if they're feeling clunky or if they're feeling kind of stompy as they run maybe they're over striding maybe they're feeling flat and slow because of fatigue but they can use that feedback to then correct with every step that they take to get better running economy as they're running and that would be an example of a closed loop skill you can correct it as you go now in these three examples that I just gave the neuromuscular system is really the link between these disciplines between exercise phase motor control and biomechanics if we think of muscles as many metabolic machines these little machines can actually cause motion of the skeletal system so therefore these muscles are actually the kinetic factors force producing factors that affect kinematic values he produced force in the muscle and then it results in change in the body force produced by the muscle results in displacement of bones around joints and muscles are under the control of the nervous system so it's really that nervous system that links at all to with us off ergonomics so this takes us again outside of the realm of sport so if you consider if you even look at the chair that I'm sitting in right it has some cushion on the back has these arm rests you can adjust the height the back feels pretty good you know I can lean back and it doesn't hurt too much I can sit in this for a decently long time without feeling any pain in my joints the one thing though that I have noticed working at this desk during quarantine is that I tend to get wrist cramps because the desk might be a little bit high when I'm typing on my keyboard so all of these things that I'm mentioning are related to economics it's it's the attempt to make the human machine interface while you're working or on the job site as fluid as possible so we want to design a better human machine interface that doesn't lead to these chronic overuse injuries or workplace pain that would not only result in decreasing work output but in decreasing quality of life for the workers this sometimes is also called occupational biomechanics now physical therapy this is something that often comes to people's mind when they think of biomechanics and it is maybe one of the most integrated practical fields with biomechanics so physical therapy is obviously dedicated to preventing evaluating and treating movement abnormalities most of us have been to a physical therapist at some point in our lives disordered movement whether that's caused by injury disease imbalance congenital conditions you know whether it's learned or due to an injury these can all lead to injury and a decrease in quality of life it can lead to pain and so a physical therapist has to be familiar with biomechanical principles to really recognize and diagnose underlying causes of disordered movement and then they have to be able to design an appropriate intervention maybe somebody comes in and they're having you know right knee pain on the patellar tendon and so the physical therapist might watch them walk they might assess their gait they might do manual muscle testing to see if their gluteus medius and minimus are activating well they might take a look at their lumbar spine to check and see if they're in alignment or not they might look at their leg length to see if there's a discrepancy there they may evaluate their landing mechanics from a jump or from you know stepping off of something and then landing to see if they have an eval gist or if their knees are coming way too far over their toes causing undue stress that their quads don't have the capacity to absorb all that force within sports medicine we have athletic trainers who are focused on for preventing and then immediately treating injuries that occur in sports so these methods may require things like bracing and taping and these can both affect normal human motion so we might use biomechanics and to understand how an ankle brace for instance affects than normal pattern of cutting that an athlete might take as they go through an agility test you know does that ankle brace decrease performance more importantly does it lead to some sort of maladaptive pattern of movement that could lead to injury further up the kinetic chain biomechanics can help us answer these questions pedagogy so this is relating to how we teach people how to move so both teaching and coaching this begins with an understanding of motor behavior as well as comprehensive knowledge in the content area so in the sport that you're coaching in or in the discipline that you're teaching in but biomechanics can help us to provide better feedback for the type of learner their level of proficiency and whether we need to give frequent feedback or no feedback at all perhaps and finally we have adaptive motion this is a growing field and for a good reason more and more these days people who have disabilities are challenging themselves and the whole concept of what a disability means by continuing to pursue sport and exercise at a high high level but we also have to keep in mind that there are individuals who are just trying to navigate the world with some sort of a disability so these disabilities can be due to a loss of sensory function whether visual tactile auditory proprioceptive perhaps loss of limb perhaps some challenge for understanding instructions and selecting efficient motor patterns and all of these all of these various levels of ability have with them biomechanical implications how do we change the pedagogy that dewar delivering how do we change the equipment that we're using for these athletes and for those these people how do we modify the closed versus open loop nature of certain movements so that we can we can get movement outcomes for these individuals so to recap biomechanics is the physics of motion exhibited or produced by biological systems it deals with not only kinetics the forces acting on or produced by a biological system but also with kinematics which is movement through spatial and temporal domains biomechanics also relates highly to other disciplines in kinesiology like exercise physiology motor behavior pedagogy etc because all of these domains require human movement and biomechanics is all about analyzing that movement to ensure better movement outcomes [Music]