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Toe walking: muscular demands at the ankle and knee
Jacquelin Perry1, Judith M Burnfield, JoAnne K Gronley
1Pathokinesiology Laboratory, Rancho Los Amigos National Rehabilitation Center, Downey, CA 90242, USA. pklab@larei.org
Objective:
To compare the relationship between electromyographic activity and internal moment in heel-toe and toe walking.
Design:
Simultaneous recording of stride characteristics and kinematic, kinetic, and intramuscular electromyographic data; paired t tests identified significant between-condition differences.
Setting:
Gait laboratory.
Participants:
Ten able-bodied subjects.
Interventions:
Not applicable.
Main Outcome Measures:
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.