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.