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Weak Vastus Medialis Oblique

Issue: Knee or knees falls in above 90 degree or parallel during squat

VMO Function: Extends the knee and provides stability on ground contact

Corrective Exercise Methods: Peterson Step up, split squat, cyclists squat, 1 ¼ Squats, Backward Peterson sled drag

Common Problems when tight: low back pain, knee pain, knee instability, especially if tight and weak

Tight or Weak Adductors

Issue: As the subject descends in the squat the knees are widening

Function of the Adductors: Adducts and laterally rotate hip joint, adductors longus and brevis also flex the extended femur and extend the flexed femur

Corrective Methods: Inner-thigh stretching, massage, pausing in the deep position of the split squat, lateral sled work, leg adduction machines

Adhesion of the Adductor Magnus and Medial Hamstrings

Issue: The knees buckle in or out at the 90* point during squatting

Function of the Adductors: Adducts and laterally rotate hip joint

Function of the Medial Hamstrings: Flex the knee joint. Extend the hip. Semimembranosus and Semitendinosus also medially rotate (turn in) the lower leg when knee is flexed

Corrective Methods: Inner thigh stretching, massage

Tight or Weak Gluteus

Issue: Bending forward at the hip

Function: Extends and laterally rotates hip joint (force full extension as in running or rising from sitting) extends trunk, as in adduction of the hip joint

Corrective Methods: Good Morning, RDL, deadlifts, squats, lunges, split squats, all forms of Olympic lifting, pulls

Tight or Weak Quadratus Lumborum

Issue: Subject shifts the hips


  • Laterally flexes vertebral column
  • Helps stabilize the diaphragm
  • Helps extend the lumbar part of the vertebral column and provides lateral stability

Common problems: Referral pain to the hip and gluteal area and low back

Corrective Exercises: Side bends, side sit ups, side flexion w/ Swiss ball or bench

Glute Dominant or Weak Quads

Issue: Subject falls back during ascent or descent of squat, raises buttocks to help stand up out of the squat

Function of Quad: Vasti extend the knee joint

Rectus Femoris: Extends the knee joint and flexes the hip joint

Function of Glute: Extends and laterally rotates the hip joint (forceful extension in running or rising from sitting). Extends trunk, assists in adduction of hip joint

Corrective Methods: Peterson step ups, split squats, backwards sled drag, step ups, front squats

Glute Dominant – Tight Hip Flexors

Issue: Subject bends forward, raises buttocks on the way up

Corrective methods: Stretching, deep split squats

Tight Psoas

Issue: One foot is placed in front of the other, leans too far forward during squat, butt starts to stick out at 15*

Function: Main Flexor of the hip joint (flexes laterally, rotates thigh, as in kicking a football) Acting from it insertion, flexes the trunk as in sitting up from the position

Corrective Method: Stretch hip flexors

Common problems: When muscles are tight and shortened it may cause low back pain due to increase in lumbar curve (lordosis)

Tight IT Band

Issue: At 45 degree, knees buckle in and out briefly during squatting

Corrective Methods: perform IT Band stretches, soft tissue work

Tight Erector Spinae

Issue: During the squat there is a rounding of the lower back


  • Extends and laterally flexes vertebral column (i.e. bending backwards and sideways)
  • Helps maintain curvatures of the spin in erect and sitting positions
  • Steadies the vertebral column on pelvis while walking

Corrective Methods: Stretch lower back, posterior chain work, i.e. reverse hypers

Tight Piriformis

Issue: Below 90 degree the knees and feet turn out

Function: Laterally rotates hip joint, Abducts the thigh when hip is flexed, helps hold head of femur in socket

Corrective methods: Stretch piriformis

Tight Rectus Femoris

Issue: Subject has difficulty allowing the knees to traveling past their toes during squatting

Function: Extends the knee joint and flexes the hip joint

Corrective Methods: Quad and hip flexor stretching

Note: Ankle might be tight as well

Weak Flexor Hallucis Longus

Issue: Ankle turns out / supinates

Function: Flexes the great toe. Helps to plantarflex and invert the foot. Helps stabilize the inside of the ankle

Corrective methods: Standing and seated calf raises, tibialis anterior work

Weak Trapezius

Issue: Subject can’t hold bar fixed overhead


  • Upper fibres pull the shoulder girdle up (elevation) and help prevent depression of the shoulder girdle when the weight is carried on the shoulder or in the hand
  • Middle fibres retract (adduct) the scapula
  • Lower fibres depress the scapula
  • Upper and lower fibres act together to rotate the scapula, as in elevating arm above head

Corrective methods: Pulls of all kinds, shrugs, shoulder dumbbell and barbell pressing, chin-ups, dumbbell lateral raises, dips

Weak Rhomboids

Issue: Subject can’t retract and adduct scapula

Common problems: tight soreness between shoulder blades, over-stretched, rounded shoulders

Function: Retracts and adducts scapula, stabilizes scapula, slightly assists in outer range of adduction of arm (i.e from overhead to arm at shoulder level)

Corrective Methods: Dumbbell and barbell rowing, upright row, high pulls, behind the neck lat pull down, pulley shoulder adduction

Tight Coracobrahialis

Issue: Subject can’t fully extend arm in the overhead position; during squat subject will feel pain in the anterior deltoid complex

Function: Flexes and adducts the arm

Corrective Methods: stretching, treatment, massage

Key Muscles at Play During the Overhead Portion in the Muscle Snatch and Overhead Squat

Issue: Subject can’t hold / stabilize bar overhead. Tight or weak Deltoid, Supraspinatus, Infraspinatus, Teres Minor and Teres Major

Corrective methods: stretching, massage, external rotation work, muscle snatch and lateral raises



  • Protector of the shoulder joint
  • Anterior fibres act in flexion and medial rotation
  • Medial fibres abduction of the arm
  • Posterior fibres act in extension and lateral rotation

Rotator Cuff

  • Supraspinatus, Infraspinatus, Teres Major, Subscapularis
  • Collectively these four muscles surround and reinforce the glenohumeral joint on three sides
  • Their main function is to help keep the head of the humerus in the glenoid cavity during various movements, particularly abduction

Triceps Brachii

  • Extends (straightens) the elbow joint
  • Long head can adduct the humerus and extend it from the flexed position
  • Stabilizes the shoulder joint

Latissimus Dorsi

  • Extends the flexed arm
  • Adducts and medially rotates the humerus (i.e draws the arm back and inwards towards body)

Weak Rotator Cuff Muscles

Issue: Subject cannot externally rotate 20kg bar to the overhead position during the muscle snatch

Action: Please refer to Section: Key Muscles at Play During the Overhead Portion in the Muscle Snatch and Overhead Squat

Corrective Methods: muscle snatch, dumbbell and cable external rotations.

Tight Rotator Cuff Muscles

Issue: Subject can’t keep bar close to body during the concentric portion of lift

Action: Please refer to Section: Key Muscles at Play During the Overhead Portion in the Muscle Snatch and Overhead Squat

Corrective Methods: Stretching

Imbalance in Right or Left Rotator Cuff

Issue: Right or left elbow is uneven during the external rotation of the bar

Action: Please refer to Section: Key Muscles at Play During the Overhead Portion in the Muscle Snatch and Overhead Squat

Corrective Methods: Stretch rotator cuff muscles, dumbbell or cable external rotation work


The Body Moveable, by David Gorman
The Concise Book of Muscles, by Chris Jarmey
Anatomy of Movement by Blandine Calais – Germain
PICP Structural Balance Level 2


Athlete Activation System Inc.
Toronto, ON Canada

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