The Long & Short
of It
(eccentric & concentric)
of It
(eccentric & concentric)
This type of contraction occurs in the biceps during the extension of serving /facing front
What is Eccentric - the biceps are lengthening while controlling the motion.
The agonist (prime mover) arm muscle in the curl part of a biceps curl
Agonist: Biceps brachii
Antagonist: Triceps brachii
Explanation:
The biceps brachii is responsible for elbow flexion (the active movement), making it the agonist. The triceps, which performs elbow extension, relaxes and lengthens - making it the antagonist
In which plane of motion does a biceps curl occur?
Sagittal plane
Explanation:
A biceps curl involves flexion and extension of the elbow - classic sagittal plane movement, which moves the body forward and backward.
This muscle is commonly referred to as the “six-pack”
Rectus abdominis
Is something wrong?
Exercise: Roll-up
Phase: Rolling over with spinal flexion
Agonist: Rectus abdominis
Antagonist: Erector spinae
Erector spinae is: contracting concentrically
❌ False
Explanation: The erector spinae are antagonists here and are lengthening under tension - that’s eccentric, not concentric.
During the push out phase of pelvic lift, the quadriceps are contracting this way?
What is Concentrically - the quads are shortening to extend the knee.
Agonists (prime movers) muscles during the elevation portion of bridge
Agonists: Gluteus maximus and hamstrings
Antagonists: Hip flexors (e.g., iliopsoas)
Explanation: As the hips lift into extension, the glutes and hamstrings shorten and generate force (agonists). The hip flexors, which oppose hip extension, lengthen under tension (antagonists).
What plane of motion are you primarily working in during side-lying leg lifts?
Frontal (coronal) plane
Explanation:
Side leg lifts involve hip abduction and adduction - movements away from or toward the midline - which occur in the frontal plane.
This muscle forms the bulk of the calf and helps with plantar flexion
Gastrocnemius
Is there something wrong?
Exercise: Swan
Phase: Lifting the chest into spinal extension
Agonist: Erector spinae
Antagonist: Rectus abdominis
Erector spinae is: contracting concentrically
✅ True
During the pull back of chest expansion, this contraction occurs in the triceps
What is Concentric - the triceps are shortening to control elbow flexion.
Agonist muscle during the spinal flexion phase of a roll-up
Agonist: Rectus abdominis
Antagonist: Erector spinae
Explanation:
The rectus abdominis contracts to flex the spine forward (agonist), while the erector spinae - which extend the spine - lengthen and resist the movement (antagonist).
In which plane does spinal rotation occur during an exercise like Spine Twist?
Transverse plane
Explanation:
Spinal rotation - turning right or left - happens around the vertical axis of the spine, which is characteristic of the transverse (horizontal) plane.
This deep core muscle wraps around the abdomen like a corset and stabilizes the spine
Transversus abdominis
Is something wrong?
Exercise: Side-lying leg lift
Phase: Lifting the top leg into hip abduction
Agonist: Gluteus medius
Antagonist: Adductors
Gluteus medius is: contracting eccentrically
Answer: ❌ False
Explanation: Gluteus medius is the agonist lifting the leg, which requires concentric contraction - it's shortening, not lengthening.
During the descent of Roll-down, the abdominals are performing this type of contraction
What is Eccentric - they’re lengthening under tension to control spinal flexion.
Antagonist muscle during the lift of side-lying leg lift
Antagonists: Adductors (inner thigh muscles)
Agonist: Gluteus medius
Explanation:
The gluteus medius contracts to lift the leg away from the midline (abduction). The adductors, responsible for drawing the leg inward, act as antagonists by opposing this movement.
Which plane is used when performing scooter?
Sagittal plane
Explanation:
Movements like scooter with flexion/extension patterns (rolling forward and back, hip and knee movement) occur in the sagittal plane, which divides the body into right and left halve
This muscle runs along the back and helps extend the spine during Swan or prone work
Erector spinae
Is something wrong?
Exercise: Shoulder Bridge
Phase: Lifting the pelvis off the mat
Agonist: Gluteus maximus and hamstrings
Antagonist: Hip flexors
Gluteus maximus is: contracting concentrically
Answer: ✅ True
Explanation: The glutes shorten to extend the hips upward - classic concentric action in this phase of the bridge.
When lifting into a single-leg bridge, the hamstrings on the working leg are contracting in this way
What is Concentrically - the hamstrings are shortening to extend the hip and lift the pelvis.
Agonist muscle during extension in Swan
Agonists: Erector spinae
Antagonist: Rectus abdominis
Explanation:The erector spinae group actively contracts to extend the spine (agonist). The rectus abdominis, which would normally flex the spine, opposes this action and is lengthened (antagonist). Hip flexors may contribute as antagonists depending on pelvis position, but the core focus here is spinal movement.
Pulling straps (T), primarily take place in which plane of motion?
Frontal (coronal) plane
Explanation:
Any lateral movement away from or toward the midline (like side arm arcs or leg lifts to the side) is happening in the frontal plane. Jumping jacks are a perfect example - both arms and legs abduct/adduct in the frontal plane.
This muscle stabilizes the pelvis and abducts the hip during single-leg standing work or side-lying leg lifts
Gluteus medius
Is something wrong?
Exercise: Spine Twist
Phase: Rotating the torso to the right
Agonist: Left external oblique and right internal oblique
Antagonist: Opposing obliques and spinal stabilizers
Right external oblique is: the prime mover contracting concentrically
: ❌ False
Explanation: In right rotation, the right internal oblique and left external oblique are the primary movers. The right external oblique would act more as a stabilizer or antagonist in this direction - it is not the prime mover.