1.    Introduction
Walking is a common part of an exercise routine, and muscle mechanical power is a crucial biomechanical factor in analyzing human gait performance. This parameter describes the energy flow that initiates or controls each movement. Muscle power can be calculated as the product of joint torque and angular velocity, providing an estimate of the combined muscle activity of each joint. This approach indirectly determines the performance of muscle groups (specifically, extensors and flexors) that pass over the joint, both eccentric and concentric (1). The interaction between muscle power in the gait of healthy individuals reflects specific driving and control functions related to each organ (2), as joint power determines the role of muscle groups in movement production and control (3). Currently, no study has investigated and compared the muscle mechanical power among different joints of each limb, particularly the dominant leg. Therefore, this study aims to compare the three-dimensional mechanical power of the dominant leg joints during walking.
2.    Methods
Thirty female participants walked barefoot at their self-selected speed while being recorded by motion analysis cameras and force plates. This setup allowed for the capture of three-dimensional mechanical power of each joint in the lower limb. External markers were used to assess joint coordinates for kinematic calculations, and the center of rotation for each subject's joint was estimated. Following each gait cycle, data on the subjects' right leg was extracted from the cameras, and ground reaction forces from the force plates were analyzed. Instantaneous muscle power (P) in each joint (j) and in each plane (k) was calculated using the product of joint moment (M) and its angular velocity (ω), as described in Equation 1 (5, 4).
Pj,k = Mj,k. ωj,k                   equation 1

One-way analysis of variance (ANOVA) and Bonferroni's post hoc test were used to compare the values of upper limb mechanical muscle power variables at a significance level of P≤0.05.
3.    Results
The results of the one-way analysis of variance are shown in Table 1. It is evident that the peak of mechanical muscle parameters both within and between groups is significant.
The highest peak of lower limb mechanical power belongs to A2S, while the lowest belongs to K2T. Among various parameters, H1S shows the most significant difference in averages compared to other peaks, while H2F and H1T have the lowest average differences. In the thigh's sagittal plane, there is a noteworthy relationship between the average peaks of H1S and H2S and most other mechanical power peaks, but this relationship is not observed with H3S. There is no significant relationship between the average power peak of H3S and the peaks of the thigh in the frontal and transverse planes, or between the knee and ankle in the transverse plane. In the knee's sagittal plane, the K1S peak is the only one that did not show a significant difference with the other peaks (K2S, K3S, and K4S) of mechanical power in the knee. Finally, in the ankle, the peaks in the sagittal, frontal, and horizontal planes show the most significant relationships with other peaks of mechanical power in the dominant leg.

4.    Conclusion
The ankle joint plays a crucial role in forward propulsion (6) by creating significant plantar flexion during the push-off phase (7). This movement is essential for forward motion, particularly during walking. The hip joint's abduction and adduction in the frontal plane contribute to stability and maintaining dynamics during single-leg support. During heel strike, the thigh's involvement in controlling the forward movement of the trunk helps with propulsion and trunk rotation. The knee extensors, especially at the peak of mechanical power, aid in preparing the body for push-off. The knee's movements in the frontal and transverse planes are not as significant, but they play a role in power generation during impact-absorbing positions.
From the results of this research, we can conclude that there is a variation in the peaks of mechanical power of the thigh, knee, and ankle joints in the lower limb. Among these peaks, the second peak of the ankle has the highest mechanical power, while the knee has the lowest. Therefore, specialists in biomechanics, rehabilitation, and therapy should consider that the ankle joint plays the most important role in propulsion during walking and muscle strengthening activities. The knee primarily has a stabilizing and controlling role.

Ethical Considerations
Compliance with ethical guidelines
All steps of the protocol for this research were approved by the ethics committee of Karazmi University's Movement Sciences Research Center (code 103.1000). Additionally, all participants were informed about the details of the test process and signed an informed consent form to participate in the research.
Funding
This research did not receive any grants from funding agencies in the public, commercial, or non-profit sectors.
Authors' contributions
All authors contributed equally to preparing the article.
Conflicts of interest
The authors declared no conflict of interest.