Biomechanical Concepts
Each lever in the body has 3 components (abbreviated as F, A, R). What do these abbreviations stand for and what are examples of them in the human body
Force (muscle), Axis (joint), Resistance (external load)
Is excessive external rotation of the shoulder in a baseball pitch beneficial or harmful for pitching performance? Explain
Helpful, because it increase the length of the lever which increases force which results in faster ball velocity
Which movement at the knee is the strongest and why?
Extension is stronger than flexion because the volume and size of the extensors.
What percentage of the gait cycle is spent in the stance phase?
~60%
What effect does the length of a lever have on torque?
The longer the lever the more torque
What is the equation for Velocity
Velocity (m/s) = Displacement (m) ÷ Change in Time (s)
A server at a pizza restaurant is holding a pizza, with one hand, above their head to avoid running into customers, what position is their wrist in (the one that is holding the pizza)
Hyperextension
With a straight leg, which is stronger at the hip, external or internal rotation?
External rotators are stronger than internal rotators (UNLESS the hip is flexed then the internal rotators are slightly stronger.)
When a concave surface moves on a stable convex surface the sliding motion happens in the same direction as the lever.
When a convex surface moves on a stable concave surface the sliding motion happens in the opposite direction as the lever.
Increase the speed at which they throw, or increase the distance that they travel
L(kg.m/s) = mass (kg) x velocity (m/s)
Which structures do Tennis Elbow and Golfer's Elbow effect?
Tennis: Common extensor tendon
Golfer: Common flexor tendon
Which muscles at the knee are key in the deceleration phase of kicking?
Knee flexors: popliteus & hamstrings: semimembranosus, semitendinosus, biceps femoris
In foot flat, what is the joint action at the ankle and what muscles are responsible for that action?
Plantar flexion, controlled by the dorsiflexors
Describe what it means for a joint to be in a closed packed position.
The joint surfaces have maximum contact with each other, are tightly compressed and are difficult to separate. Near the end ROM where a joint is vulnerable to injury
What is arthokinematics?
What are the 3 types of arthokinematics?
What is one joint that has all 3 arthokinematics?
The adjoining joint surfaces moving on each other in osteokinematic movement.
Roll, Spin, Glide
Knee
What are the 4 RTC muscles, and which is the most commonly injured and why?
What is the supraspinatus? The only superior stabilizer, passing through small subacromial space
Which muscles belong to the posterior deep crural compartment
Tibialis posterior, flexor digitorum longus, flexor hallicus longus
If a person starts by standing on both limbs, then steps out with their left foot, and takes 5 steps.
How many steps are they taking on each limb?
How many strides are they taking on each limb?
Left, Right, Left, Right, Left = 5 steps total 3 steps on the left, 2 steps on the right
2 strides on the right and 2 strides on the left
What is the Force-Velocity Relationship? Provide an example
The faster a muscle contracts concentrically the less force it can produce. 1RM squat vs Vertical Jump
Identify how the strength of two joint muscles is impacted when active on both joints that it effects as opposed to a single joint.
Two joint muscles when active at BOTH joints, strength is decreased.
Two joint muscles when active at only ONE joint, strength at that joint is increased.
What are 2 reasons why baseball pitchers get Tommy John's surgery from a ruptured UCL?
Decelerators are not strong enough to dissipate force. Increase in valgus torque. The amount of force going through the elbow increases with different pitches.
Name 3 reasons why female soccer players are at a higher risk of ACL injuries compared to their male counterparts.
Someone who has an anterior pelvic tilt has imbalanced between muscles. Which muscles are hyperactive and which are underactive? Give actual muscle names not just groups
underactive: Gluteus maximus, rectus abdominis
hyperactive: iliopsoas, erector spinae
Trendelemberg gait is a result of what muscle imbalance?
Gluteal weakness causing the standing hip to 'dip' which results in circumducted gait