Toe walking: muscular demands at the ankle and knee.
OBJECTIVE
To compare the relationship between electromyographic activity and internal moment in heel-toe and toe walking.


METHODS
Simultaneous recording of stride characteristics and kinematic, kinetic, and intramuscular electromyographic data; paired t tests identified significant between-condition differences.


METHODS
Gait laboratory.


METHODS
Ten able-bodied subjects.


METHODS
Not applicable.


METHODS
Kinematic, moment, power, and electromyographic variables (ankle, knee).


RESULTS
Compared with heel-toe walking, toe walking showed greater plantarflexion during stance (P<.001), higher plantarflexor moments (peak, mean) during loading response (P<.001) and midstance (P<.001), lower mean plantarflexor moments during terminal stance (P=.002), premature soleus (P=.001) and gastrocnemius (P<.001) activity, and higher levels of mean soleus and gastrocnemius activity during stance. During toe walking, the peak internal knee extensor moment was lower in midstance (P=.002), and power absorption was reduced in loading response; however, vastus intermedius electromyographic activity was not reduced.


CONCLUSIONS
During toe walking, terminal stance soleus and gastrocnemius activity was greater, despite a lower mean internal plantarflexor moment. The dichotomy between internal moments and muscle effort (ie, electromyographic activity) was consistent with the reduction in force-generation capacity of the calf muscles when the ankle was in a plantarflexed position.
Perry
Jacquelin
J
Pathokinesiology Laboratory, Rancho Los Amigos National Rehabilitation Center, Downey, CA 90242, USA. pklab@larei.org
Burnfield
Judith M
JM
Gronley
JoAnne K
JK
Mulroy
Sara J
SJ
D000328:Adult; D000843:Ankle Joint / Q000502:physiology*; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D007866:Leg / Q000502:physiology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology