Definitions
The study of observable changes in movement
Kinematics
Type of motion where the entire system moves as one unit
Linear movement OR Translation
Can be thought of as squeezing force, pulling force, and a force that acts parallel to a surface
Compression, tension, and shear
Many joints in the human body have the presence of bursae, which exude synovial fluid. What is the purpose of synovial fluid in biomechanical terms.
To reduce friction of the articulating surfaces thereby protecting articular cartilage.
While observing somebody with knee pain perform a squat, you see that they have a tendency to overpronate (collapse their arch). How would this be linked to their knee pain
Increased foot pronation facilitates knee valgus which puts increased stress on the medial knee structures, as well as affects patellar tracking, potentially affecting anterior superior knee structures.
The tendency of objects to maintain its current state of motion, or lack thereof
Inertia
Type of motion where both linear movement and angular movement are present
General motion
Bone tissue has better tolerance to this type of force
Compressive
changes in bone strength and growth is directly linked to the magnitude and direction of forces
Wolff's law
You are doing standing hamstring curls as part of a rehab protocol. You learn that trying to actively extend your hip and flex your knee leads to cramping, why is this.
Active insufficiency of the hamstrings.
Statics
Visualization (human eyes)
This occurs when a muscle fiber sustains maximal tension leading to fatigue and progressive decline in force output
Tetanus
Explain why the lumbar vertabrae have greater resistance to compressive forces compared to the cervical vertabrae
Due to the size of the vertebral body and presence of trabecular bone in the body, it can sustain higher compressive forces due to the increased surface area.
During stretching of your hip, you find that you cannot extend your hip and flex your knee to their full range, why is this?
Occurs as a product of force and a moment arm
Torque
Alternative method to movement analysis - first used on horses
Video analysis
According to the force-velocity relationship, as this variable increases, the concentric velocity will slow to zero. A further increase in this variable, the eccentric velocity willl increase
Force
The intervertebral disc has 15-20 concentric layers of collagen oriented 30 degrees to each other. What is the importance of this
Increases resistance to compressive, tensile, and to a certain degree shearing forces
Low back pain is very common, for various reasons. One common reason is intervertebral disc health. You find that when there is more movement throughout the day, the discs are healthier and contribute less to back pain, why is this?
The intervertebral discs act as pump. Loading = loss of water within the disc, unloading = reabsorption of water. The presence of proteoglycans within the disc help increase the reabsorption.
Having the ability to shorten over time
Viscoelasticity
This structure has 5 involved joints and is easily the most complex movement system of the human body
Shoulder girdle
Eccentric muscle activity followed immediately by concentric muscle activity leads to greater force development
Stretch shorten cycle
Explain osteoporosis and its effects on loading.
Due to the decreased bone density, the bones have less compressive strength and will reach the point of deformation faster, in this case a fracture.
You are watching somebody perform lateral raises for shoulder strengthening, they first start by applying resistance at the elbow and can lift 15 kg for 15 reps. They then move the resistance to their hand and find they can only lift 15 kg for 3 reps. Explain the reasoning for the change
Change in moment arm distance leads to greater torque output by the muscles, and quicker muscle fatigue.