Introduction: During the sit-to-stand (STS) motion, thigh push-of (TP) is frequently used, yet the biomechanical advantage for the upper extremity, is relatively unknown. In this thesis, the STS motion is analyzed for three different techniques; TP, armrest push-off (AP), and no arm aid (NA). The aim of this study is to determine the biomechanical advantage of the TP strategy through examining the joint moments (JM), and muscle forces (MF). Furthermore, the study aims to find whether age or gender affects the JM and MF generated in the TP, AP, and NA strategies. Method: Time to stand (TTS), JM and MF exerted on the upper extremity were examined for TP, AP and NA strategies for 34 participants across 3 groups: EM, elderly female (EF), and young males (YM). The metrics were obtained through inverse kinematic (IK), inverse dynamic (ID), and static optimization (SO) simulations in a 3D musculoskeletal model. Results: The time-to-stand (TTS) in elderly participants is significantly longer in the TP strategy than in the AP and NA strategies. For elderly people, the TP strategy results in upper extremity JM lower than during AP and equal as in NA. Similarly, the TP strategy results in significantly lower MF than the AP strategy, and equal MF as in the NA strategy. Conclusion: The TP strategy takes longer than AP and reduces the JM and MF for elderly participants. Moreover, the TP strategy does not yield higher JM and MF than the NA strategy for any participant group. Thus, the biomechanical advantage of the TP strategy for elderly people, are lowered JM and MF in the upper extremity