Chapter 13 Flashcards
(165 cards)
What is the primary requirement for movement to take place in strength training?
Internal Torque must exceed the External Torque.
What must increase for movement to occur in strength training?
Muscle Force (Internal) must increase.
In free exercises, what factors change the external torque?
The position of the body as a whole and the positions of the active limbs.
What muscles are needed to exert torque of the upper body during a Trunk Curl Sit-up?
Rectus Abdominis, External & Internal Obliques, Psoas, Iliacus, Adductors, Gracilis.
What is the plane and axis involved in a Trunk Curl Sit-up?
Sagittal Plane / ‘x-axis’.
What happens to the External Moment Arm (d1) at Stage One of a sit-up?
The External Moment Arm decreases.
Where is the most strenuous part of the sit-up?
Just after the start of the motion when the External Moment Arm – d1 is the longest.
How can we increase the difficulty of a sit-up?
Increase the external moment arm.
What occurs to the External Torque during Stage Two of a sit-up?
The External Moment Arm gradually decreases.
Which muscles rotate the upper body about the hips to an upright sitting position during a sit-up?
Hip Flexors.
What happens to the moment-arm of the hip flexors if the legs remain extended during a sit-up?
The moment-arm of the hip flexors remains unchanged.
What is the advantage of performing a Bent-leg Sit Up?
It makes it easier to initiate the sit-up due to increased moment-arm length of the hip flexors.
Why can Leg Raises be prescribed if the abdominals and hip flexors are incapable of initiating a sit-up?
Leg Raises have a moment arm of the weight of the leg that is approximately the same as the upper body during the trunk curl.
What percentage of body weight does the weight of the leg represent?
Approximately 16% of body weight.
What causes lower back injuries during sit-ups?
Excessive anterior pelvic tilt increases lumbar curvature.
What is the key alignment during a push-up?
Head, trunk, & legs are held in alignment.
What joints and muscles constitute the ‘mover’s’ in the push-up lever system?
G.H. Joint and Elbow.
What external moment arm is involved in the push-up?
From ankle joint to the point of location of the Body Weight (W).
What happens to the external moment arm as the angle of inclination increases in a push-up?
The external moment arm derived from body weight increases.
How can you reduce the external moment arm in a push-up to make the progression easier?
Use the knees as a fulcrum.
List the active muscle groups during a Half Squat.
Hip Extensors, Knee Extensors, Ankle Plantar Flexors.
How does the external moment arm impact the demands on muscles during squats?
A larger external moment arm makes greater demands on the muscles.
In which position do the Hip Extensors need to work harder: inclined or erect?
Position 1: Inclined.
In which position do the Knee Extensors need to work harder: inclined or erect?
Position 2: Erect.