BIOMECHANICS UNIT 2 EXAM Flashcards
Which type of muscle functions to decelerate ballistic contractions?
a. Agonists
b. Neutralizers
c. Antagonists
d. Local stabilizers
C - Antagonists usually serve to oppose the action of the prime movers, as seen in the biceps and triceps muscle groups, respectively; therefore, they help to decelerate the movement. During ballistic contractions the antagonists for the action performed must function effectively to limit the risk for injury and over-stretching of the working muscles or connective tissues involved.
Which of the following serve to control neutral joint positions?
a. Global stabilizers
b. Local stabilizers
c. Global neutralizers
d. Local mobilizers
B - Local stabilizers are essential for joint stability and the maintenance of neutral joint positions. They are often smaller, internally located and do not produce joint movement themselves. Global stabilizers on the other hand function to control the inner and outer range of motion for a given movement and tend to contract eccentrically for low-load deceleration and rotational control. Mobilizers and neutralizers do not serve to increase local muscle stiffness or neutral joint positioning.
Improper activation or poor endurance within which of the following muscles will often result in posterior rotation of the pelvis and place the spine in a compromised position during loaded squat exercises?
a. Thoracolumbar fascia
b. Pelvic floor
c. Iliopsoas
d. Gluteus medius
B - The pelvic floor aids to stabilize the spine by capturing force within the inner unit. When it is weak or lacks adequate endurance, the rectus abdominals take over its stabilizing role and rotate the pelvis during loaded conditions. Emphasis on proper contraction of the pelvic floor during squats can greatly improve inner unit activation and therefore optimize spinal and pelvic stability/positioning.
- An athlete with lower-cross syndrome will likely experience motor unit inhibition during which of the following actions?
a. Hip flexion
b. Hip extension
c. Knee extension
d. Plantar flexion
B - An athlete with lower-cross syndrome will experience (reciprocal) inhibition during actions that involve glute-driven hip extension such as squats. Lower-cross syndrome presents as visible lumbar lordosis (excessive) and chronic anterior tilting of the pelvis. The calves, hip adductors, erector spinae and hip flexors are commonly overactive while the gluteals, hamstrings, abdominals, and spinal stabilizers are commonly underactive. Lower-cross syndrome often results in hamstring strains, groin strains and lower back pain.
- What is the most likely problem if the knees move inward during landing activities?
a. Weakness in the gluteals
b. Excessive strength in the hip abductors
c. Weakness in the hip flexors
d. Excessive strength in the hip adductors
A - If an athlete has notable weakness in their gluteals, specifically their gluteus maximus and gluteus medius (hip abductor), the femurs may cave inward during landing activities. If the hip extensors abductors do not activate appropriately for eccentric control, the hips can move in the opposite direction – namely through adduction. This creates the inward knee positioning upon landing, which greatly increases the risk for knee injuries; especially among those athletes with larger Q angles (females).
- The most common error during programs aimed at improving kinetic chain function is:
a. Excessive emphasis on technique
b. Insufficient loading
c. Excessive use of unilateral exercises
d. Limited use of closed-chain activities
B - Functional training does not necessarily warrant lighter loading. Functional activities must still prepare the body for traditional compound and Olympic lifting and should be loaded to form. The most common error during training aimed at improving kinetic chain function is the use of light loads. The strength coach should understand that once proper technique has been mastered, functional exercises can be loaded for higher-intensity efforts in the same manner as traditional resistance training activities as long as the emphasis remains on quality movements.
- Closed kinetic circuits are used to:
a. Increase stability for loading
b. Increase range of motion
c. Decrease reciprocal inhibition
d. Decrease movement velocity
A - Closed kinetic-circuit exercises include those where both limbs must manage a single load such as a barbell press. This reduces the individual stability requirements of the lift at each respective joint because the limbs work together. This increases the potential for loading when compared to using an open kinetic-circuit - or a separate load for each limb (dumbbells). This is easily understood when one considers the difference in loading potential between exercises such as a bench press and dumbbell chest press, or military press and standing dumbbell overhead press. Closed kinetic circuits will potentially reduce the range of motion.
- Which limiting factor would dictate the quantity of repetitions used for a set of dumbbell step-ups to unilateral overhead press?
a. Quadriceps fatigue
b. Shoulder fatigue
c. Trunk stabilizer fatigue
d. Triceps fatigue
C - During a unilaterally-loaded combination exercise that incorporates use of the lower and upper body across the trunk, the prime or assistive movers will most likely not be the limiting factor for dictating the quantity of repetitions performed. Rather, the trunk stabilizers will be challenged during each aspect of the lift, and serve double-time due to the unilateral loading that forces the movement to be repeated with both sides of the body. This would make trunk stabilizer fatigue the limiting factor for setting a repetition range for an exercise such as dumbbell step-ups to unilateral overhead press. Stabilizer fatigue leads to faulty movement so exercises should be programmed based on the duration the stabilizers are stressed.
- Which of the following is a potential consequence of myofascial deformation?
a. Increased muscle relaxation
b. Increased stretch shortening responses in a given muscle
c. Lack of coordinated activation
d. Lack of blood flow due to restriction
C - Myofascial deformation is associated with pain, motor dysfunction, disordered movement, restricted ROM, and unbalanced muscle activation. A coach should use dynamic/static stretches, foam roll techniques, and acupressure for trigger points to help remedy the issue. Of the selections provided, only a lack of coordinated activation would be a consequence of myofascial deformation.
- ______________________ involve applying force to a distally-fixed position and require the body to stabilize segments so that the transfer and acceleration of force can be facilitated to accomplish the task.
a. Closed kinetic chain exercises
b. Open kinetic chain exercises
c. Machine-based exercises
d. Physioball exercises
A - Closed kinetic chain exercises involve applying force to a distally-fixed position and require the body to stabilize segments so that the transfer and acceleration of force can be properly facilitated to accomplish the task. During open kinetic chain exercises the resistance is moved around a distally-fixed body position which is usually well stabilized, consequently reducing stability and activation requirements.
- Which of the following would be the most useful corrective exercise for an athlete with tight hamstrings?
a. Step-ups
b. Front squat
c. Split-stance goodmorning
d. Buddy (Nordic) hamstrings
C - The split-stance goodmornings would be a highly-effective corrective exercise for an athlete with hamstring tightness. A standard goodmorning in itself places a significant stretch upon the hip extensors (upper hamstrings) as the participant descends during the eccentric phase; often forcing an increase in knee and hip flexion. The split stance variation would provide an even greater stretching response as the lead leg starts in a greater degree of hip flexion with added pelvic stability. This exercise must be performed under control and with proper form to elicit an optimal response.
- Lateral band squats would be useful for an athlete who struggles with which of the following movement compensations during the back squat?
a. Posterior pelvic tilting
b. Overactive adductors
c. Anterior tibial translation
d. Excessive forward leaning
B - Lateral band squats would be useful for an athlete with overactive and/or tight hip adductors. The athlete will be forced to abduct the hips under load which presents lateral resistance. This will increase hip abductor activation, which will help reciprocally inhibit the overactive hip adductors.
- Which of the following would be an effective corrective exercise for an athlete with tight calves?
a. Goodmorning
b. Bench hip extension
c. Single-leg opposite reach
d. Seated plantar flexion
C - Single-leg opposite reaches would be the best corrective activity out of the options provided for an athlete with tight calves. The unilateral anchoring combined with the reaching action creates an elongated kinetic chain which places a notable stretch upon the entire lower limb (posterior chain), including the calf musculature. This stretch upon the calves would be greater than provided during the bilateral movements because some of the force is absorbed within the upper body due to the axial loading, and the kinetic chain is not as elongated (shorter lever arm).
Resisted overhead Y-reaches are commonly used to:
a. Increase anterior trunk stability
b. Increase ROM in the scapular plane
c. Increase activation in the mid-lower trapezius
d. Increase ROM in the external rotators
C - Resisted overhead Y-reaches are commonly used to improve activation in the middle and lower trapezius. The overhead pull performed with fully extended arms in the “Y position” will force the middle and lower trapezius to activate to maintain proper positioning of the scapula against the ribcage. Many athletes suffer from overactive cervical flexors with weakness and laxity in the middle and lower fibers. This reduces shoulder complex efficiency and force transfer through the upper body as well as increases the risk for a number of injuries and postural distortions (upper-cross syndrome, rotator cuff dysfunction).
. An athlete’s plank with T-reach can be used to:
a. Stretch the anterior deltoid and activate the posterior deltoid
b. Strengthen the serratus anterior and pectoralis minor
c. Activate central and peripheral stabilizers while stretching the chest
d. Activate the posterior chain while training the scapular plane
C - An athlete’s plank with T-reach is a challenging activity which can serve a number of functions, including improved central-peripheral stability and ROM in the pectorals and internal rotators of the shoulder. Any plank activity with dynamic reaching will challenge the coordinated activity of central and peripheral stabilizers to maintain proper form and pelvic/spinal alignment, while the T-reach pattern will specifically stretch the chest.
