It has been shown that changes to kinematics occur during running when alternating footwear. However, lower extremity muscle changes over longer distances has yet to be observed.
PURPOSE: To examine muscle activities occurring while barefoot running and in different footwear.
METHODS: The current study compared EMG activity while running one mile while wearing minimalist shoes (MIN), zero-drop shoes (ZD), standard shoes (ST), and barefoot (BF). Participants ran at self-selected paces for 1 mile for each of the 4 conditions. Muscle activity in the Gastrocnemius (GA), Soleus (SO), Rectus Femoris (RF), Vastus Lateralis (VL), Vastus Medialis (VM), Biceps Femoris (BF), Erector Spinae (ES), and Rectus Abdominis (RA) were collected with the Delsys Trigno 16 channel wireless EMG system (Boston, MA). EMG data were analyzed using a root-mean square (RMS) method. All data were analyzed using a repeated measures ANOVA (α=0.05).
RESULTS: Significantly decreased average muscle activity for the SO in ST (M=68.85±11.1 (BF), 73.1±12.0 (MIN), 71.6±15.3 (ZD), M=45.51±11.1* (ST); p<0.001*) and GA (M=74.14±22.91 (BF), 74.62±21.8 (MIN), 68.9±18.3 (ZD), and 49.87±9.2** (ST); p=0.001**) was observed. Additionally, decrease in VM for ST was observed (M=137.0±75.6 (BF), 123.9±59.7 (MIN), 144.2±64.0 (ZD), and 115.9±58.0*** (ST); p=0.048***).There were no other significant differences.
CONCLUSIONS: This study provides evidence of similar muscle activity between the BF, MIN and ZD conditions. A decrease in VM may indicate incomplete knee range of motion combined with decreased muscle activity in SO and GA may decrease efficiency during the propulsive phase in ST, however phases of the running gait remain unanalyzed and it is still unclear as to the nature and timing of the activity. Further examination is needed to further understand muscle activity during the running stride.