Movement Analysis: Squat Thrust

HMB 274: Functional Anatomy
Movement Analysis: Squat Thrust

Movement Analysis: Phases
Drive Phase Image 1 Image 2
Figure 1 Images 1 & 2 show the commencement and finish of the drive phase of the squat thrust
Thrust Phase Image 3 Image 4
Figure 2 Images 3 & 4 show the commencement and finish of the thrust phase of the squat thrust.

Table 1 Movement analysis for the squat thrust (Phase 1 - drive Phase)
Joint or Body Segment

Observed Movements
Muscles Active
Contraction Type

Joint Action Tendencies of Outside Forces
Undesired Action(s) of Recruited Muscles
Explanation for Absence of Undesired Action(s)
Wrist (Radiocarpal Joint)
None (Used as stabilizers throughout exercise)
Extensor Carpi Radialis Brevis (ECRB)
Isometric
Gravity is a motive force to extend the wrist

Momentum is a motive force to extend the wrist
None

Extensor Carpi Radialis Longus
(ECRL)
Isometric

None

Extensor Carpi Ulnaris (ECU)
Isometric

Adducts the wrist and hand
ECRL acts as a helping synergist to ECU by preventing adduction of the wrist and hand
Elbow
(Elbow Joint)
None (Used as stabilizers throughout exercise)1
Biceps Brachii (BB)
Near Isometric1
Gravity is a motive force to flex the elbow.

Momentum is a motive force to flex the elbow.
Supination
PT & PQ act as true synergists to BB by preventing supination of forearm

Pronator Teres (PT)
Near Isometric1

None

Brachialis (B)
Near Isometric1

None

Triceps Brachii (TB)
Near Isometric1

None

Brachioradialis (Br)
Near Isometric1

None

Pronator Quadratus (PQ)
Near Isometric1

None

Shoulder (Glenohumeral Joint)
Mostly Stabilization.
Upward Rotation
Pectoralis Major (PMx)
Isometric
Gravity is a motive force to retract the shoulder.

Momentum is a motive force to flex the arms.
Adduction & Medial rotation
DA, DL and Muscles of the Rotator Cuff Group (SITS) act as true synergists to PM by

References: Ploutz-Snyder, L.L., Convertino, V.A., & Dudley, G.A. (1995). Resistance exercise-induced fluid shifts: change in active muscle size and plasma volume. The American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, 269: 536-543. Ohkoshi, Y., K. Yasuda, K. Kaneda, T. Wada, and M. Yamanaka. (1991) Biomechanical analysis of rehabilitation in the standing position.Am. J. Sports Med. 19:605-610. Chris K. Rhea, J. Gualberto Cremades and Erica, O., (2005)., A Comparative EMG Analysis: Abdominal Crunches Performed on a Stable Versus Unstable Surface, American Alliance for Health, Physical Education and Recreation, 76: 1 Isear, J., Erickson, J., Worrell, T., (1997)., EMG analysis of lower extremity muscle recruitment patterns during an unloaded squat, Medicine & Science in Sports & Exercise, 24:532-539.