M.Sc Thesis

M.Sc StudentPolovinets Olga
SubjectWrist Biomechanics During Dynamic Loading
DepartmentDepartment of Mechanical Engineering
Supervisors PROF. Alon Wolf
DR. Ronit Wollstein
PROF. Anath Fischer
Full Thesis textFull thesis text - English Version


Push-ups are a basic sport activity used for multiple purposes such as military physical training, rehabilitation after injury, and martial arts. The wrist is an important joint in this activity, transferring the force to the upper limbs. The biomechanics of the wrist is not yet completely understood. The purpose of this study was to compare the forces in the wrist during push-ups on a hyperextended wrist and during push-ups performed on a straight wrist. We hypothesized that force transmission in the wrist differs between these two push-up methods.

Fourteen healthy right-handed male volunteers performed two sets of push-ups on a neutral wrist and two sets on a hyperextended wrist. The push-ups were performed in a gait analysis laboratory using a Vicon motion capture system and 26 reflector markers to follow the kinematics of the exercise. The force vectors were measured and computed using two AMTI force plates. An ultrasound machine was used to determine the capitate bone location. Statistical analysis using IBM SPSS software on the forces, the force angle and marker position was performed.

In both methods of push-ups, the force was not uniform throughout the exercise task. The force patterns did not change and the dominant hand was loaded with a higher force, regardless of the type of push-up. In addition, the distance between the force vector and the shoulder marker on average was greater than the distance between the force vector and elbow markers. In all push-ups, the right and left upper extremity moved equally in the vertical plane. Neutral wrist push-ups had a more uniform force, the angle of force distribution was smaller and a capitate marker had smaller location distribution. Furthermore, the elbow marker had a smaller movement in the laboratory space. In the hyperextended push-ups, the horizontal distance between the capitate bone location and force origin was smaller. Moreover, the force origin was closer to the ulna marker and the force passed more dorsally to the joint.

Thus, it was found that forces through the wrist are distributed differently during the different types of push-ups. In the hyperextended wrist, the forces are more dorsal, ulnar and have a wider distribution. It seems that while in the neutral position the force is less diffuse, this compensation can be seen in elbow movement and force transmission.

Three-dimensional computer model of a healthy wrist posed in a working position was built, using Computer Tomography scan and a custom written MatlabTM program. Meshing was performed within ScanIP? software. Typical example of force measured during biomechanical analysis was on the model using finite elements analysis.

The measured force applied to the wrist included shear forces that shifted forces to a volar side of forearm bones. Moreover, correspondence between cartilage material properties and stress distribution was found.

Future research should include biomechanical analysis of shoulder and elbow joints and refinement of wrist model. Tracking hand position during the exercise in biomechanical laboratory and preforming online registration of the forces to personalized computer model, could helpful for athletes and rehabilitation purposes.