DISCUSSION
In the current study, we found that between the pre-swing and the mid-swing the flexion peak and the external rotation
peak of the knee joint and the plantarflexion peak of the ankle joint significantly increased with the increase of the gait speed.
These results imply that there is a need for greater power generation at higher gait speeds for propelling
the body forward, and it is accompanied by coupling motion of the external rotation of the knee joint.
Gait speed has an important influence on the kinematic parameters of the lower extremity joints.
In particular, the kinematic parameters of the knee and ankle joints have a positive relationship with gait speed13, 15, 16).
In this study, the knee flexion peak during pre-swing and mid-swing significantly increased with the increase of gait speed.
The knee flexion angle in the gait cycle has a significant positive correlation with the gait speed, according to previous
studies13, 16), indicating that the angle of the knee flexion increases with increase of gait speed.
It is possible that this is due to the need for greater shock absorption at higher speeds.
In addition, our findings show that the external rotation peak of the knee joint significantly increased with increase of gait
speed.
Previous studies have reported that one joint segment of the lower extremities affects the others during the gait.
These relationships are described as coupling motion16, 17).
Therefore, we think that gait speed is affected by coupling motion of the lower extremity.
Our present findings support the findings of other studies of gait mechanism.
The plantarflexion peak of the ankle joint significantly increased with increase of gait speed.
This result is in agreement with other studies that have suggested that plantarflexion of the ankle joint is closely related to gait speed.
In addition, the ankle joint plays an important role in changing gait speed, and it has been suggested that plantarflexion is a strong predictor of step length and gait speed18–20).
In conclusion, we examined the changes in the lower extremity joints at different gait speeds using a 3-dimensional
motion analysis system.
Our results suggest that coupling motion of the knee joint and plantarflexion of the ankle joint significantly increase with increase of the gait speed.
These results provide important insights into the gait mechanisms underlying speed regulation in walking and provide a foundation on which to investigate the influence of walking speed on various measures of interest in pathological populations.
In this study, we restricted recruitment to males of standard height and weight to negate the effects of external factor.
Therefore, further studies involving a larger population are suggested.