Kinematics
Rate of change of displacement is called
velocity
Your pediatric patient has suffered a right elbow dislocation and fracture due to fall from riding a bike. They needed a surgery and a cast. As their PT, you recognize that their center of mass would shift towards which side?
Center of Mass will shift towards right side due to added weight on the right side
Due to the mechanical disadvantage of the muscles, they will need to produce _________ (greater or lesser) force compared to the external force.
greater
Which immobilized position could result in increase in number of sarcomeres in the muscle tissue?
Lengthened position
The area under the stress-strain curve till failure point is defined as __________ of a material and the slope of the stress-strain curve in the elastic zone is called ________ of a material.
strength; stiffness
What is the direction of roll you would expect during closed chain hip flexion?
posterior to anterior
To produce an isometric force that only causes rotational moment, what should be the angle between the line of action of the force and moment arm?
90 degrees
The ground reaction force vector (GRF) is posterior to the frontal axis at the knee joint and anterior to the frontal axis at the hip joint in the sagittal plane. The GRF produces what moments at the knee and hip?
Flexion moment at both the knee and the hip
When lowering your body during lunge, your lower extremity muscles are undergoing __________ contraction while __________ power
eccentric; absorbing
Compared to the cortical bone, cancellous bone is _______ stiffer but has ________ compliance.
less; higher
You want to try if a new exercise intervention is beneficial for your patient with Parkinson's disease. As part of the assessment, you want to measure their gait speed in the clinic. But you will need to do it in a hallway. What would be the best way to measure the gait speed of your patient in the hallway using a stop watch?
Have enough space to allow them to speed up and slowing down as you measure their gait speed over a known distance outside the speeding up and slowing down phases
A toddler transitioning from crawling to walking will find the task progressively challenging and less stable because _________ and ___________
decreasing base of support and higher location of the center of mass
Performing 30 degrees of hip flexion while lying supine is harder compared to performing 30 degrees of hip flexion when standing. This is because _________
The moment arm of the body weight from the hip joint center is longer while lying supine compared to while standing.
During your assessment, you notice that your patient is walking with a shorter step length as well shorter foot clearance (step height). Even though you don't have access to a biomechanics lab with 3D motion capture system that includes force plates, what might be happening in terms of ground reaction force production during gait cycle?
lower propulsive force in both the antero-posterior and the vertical directions
Focal loading to joint cartilage can occur with excessive wear on the cartilage creating a larger surface for loading and therefore, increasing the stress on that area. (True/False)
False
If your patient performs shoulder extension and external rotation simultaneously, in which direction would you expect the glide to occur?
posterior to anterior
Your patient had a recent fall and sustained hip injury. Due to the fall episode, their fear of falling has increased. This increased fear of falling is evident when you observe them walk with limited hip flexion and shorter steps, as well as excessing hip abduction and wider steps. They are exhibiting these cautious gait characteristics because ______________
They are trying to enhance their stability by maintaining their line of gravity closer to the center of the base of support as well as within wider base of support.
Your volleyball athlete jumped up to hit a spike and landed awkwardly on his right leg causing him to collapse and sprain his ACL. When talking to him, he says that he wished he could stop himself immediately once he landed on his right leg and that would have prevented the collapse and subsequent injury. With your knowledge of biomechanics, which Newton's law would you use to explain to him why it would have been hard to stop himself from collapsing.
Newton's 2nd law; Takes a lot of force to quickly stop an accelerating body.
When your patient actively tries to contract their quadriceps to extend the knee during straight leg raise (while flexing at their hip), but are unable to do so effectively, it could be because of __________ insufficiency of the quadriceps
active
Tensile strength of ligaments is relatively ________ than that of tendons; Also, ligaments ______ (can or cannot) withstand forces in other directions relatively better than tendons
lesser; can
Inferior glide
If the line of action of a muscle shifts from being superior to inferior to the sagittal axis in the frontal plane, and its line of action also shifts from being anterior to posterior to the longitudinal axis in the transverse plane. Which of the following is true about the change in action of the muscle as the movements (and subsequent shift of the line of action) occur?
The muscle shifts from abducting and medially/internally rotating to adducting and laterally/externally rotating
The muscle shifts from adducting and laterally/externally rotating to abducting and medially/internallyaterally/externally rotating
The muscle shifts from abducting and medially/internally rotating to adducting and laterally/externally rotating
You have an athlete who is recovering from an unilateral ACL tear and subsequent surgery on their left side. As part of their return to sport, you assess their gait mechanics and have them walk across the force plates. On which side (injured or uninjured) do you expect the peak force and peak knee flexion angle to be greater during the weight-acceptance phase?
Peak force and peak knee flexion will be greater on the uninjured leg (right leg) during weight-acceptance phase
When working with your patient who is undergoing rehabilitation with running-related injury, you notice that their tibialis anterior muscles (dorsiflexors) are weak. You also know that during walking gait cycle, while going from initial contact to foot flat (loading response phase), the ground reaction force vector lies posterior to the coronal axis at the ankle joint in the sagittal plane. This would mean that they will have trouble during the loading response phase of the walking gait cycle because ___________
Their dorsiflexors will have to eccentrically generate enough dorsiflexion moment to counter the plantar flexion moment created by the ground reaction force vector. Since their dorsiflexors are weak, they may have trouble generating enough dorsiflexion moment eccentrically.
Based on SAID principle, certain tissues behave better when there is little to no loading whereas other tissues behave better when there is too much loading compared to an optimal amount of loading (True or False)
False