Article

Overweight children demonstrate biomechanical differences during gait; however it
is not known if these differences occur within active or passive tissue. The
purpose of this study was to examine differences in lower extremity muscle
activation patterns of children with different body mass during three walking
speeds. Twenty children (8-12 years) were recruited and classified as overweight
(OW), normal-weight (NW), or underweight (UW). Electromyography was recorded for
vastus lateralis, semitendinosus, gastrocnemius, and tibialis anterior while
participants walked on a treadmill at slow (SP), self-selected (SSP), and fast
(FP) speeds. Differences in group and walking speed were analyzed for duration of
muscle activation (presented as a percentage of stride, stance, or swing phases).
Compared to OW, UW experienced greater duration of vastus lateralis and tibialis
anterior activation during the swing phase. OW had greater duration of
gastrocnemius activation during stride than UW. Increased walking speed resulted
in greater duration of vastus lateralis activation for all groups. NW also
exhibited greater duration of tibialis anterior activation at faster walking
speeds. During FP, OW had greater duration of gastrocnemius activity during
stance, but lower duration during swing. These findings are consistent with the
idea that children with greater mass adopt a more passive gait strategy during
swing to maximize energy recovery. Increased duration of gastrocnemius activity
during stance also provides greater stability and stronger propulsion, which
corroborates previous research. These findings help to understand the
neuromuscular mechanisms associated with previous biomechanical findings in
children's gait.
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