Class: BE210
Group: W3
Members: FACILITATOR
...
.. Joshua Kachner
TIME & TASK KEEPER
. Devjani Saha
SCRIBE ... Vail Miller
PRESENTER .. Ronit Morris
ENGINEER . Sang Lee
Date:May, 2001
Abstract:
The EMG activity in two major muscles of the lower leg gastrocnemius
and soleus- was studied as a function of speed and grade during normal
human walking. Integrated EMG data recorded using BioPac Pro software was
analyzed using Multiple Linear Regression techniques to determine a relationship
between %RVC (percent reference voluntary contraction); and subject, speed
and grade, given by the following equation: % RVC = b0 + b1*Subject + b2*Grade
(slope) + b3*Speed (mph). The equation for the gastrocnemius was: % RVC
= -14.52+/-14.79 + -6.325+/-2.202*Subject + 9.236+/-1.061*Grade (slope)
+ 40.29+/-3.875*Speed (mph) and for the soleus was: % RVC = 12.03+/-9.321+
-9.149+/-1.388*Subject + 2.747+/-0.669*Grade (slope) + 40.49+/-2.442*Speed
(mph). The coefficients b1 for the gastrocnemius and soleus muscles were
significantly different from zero, indicating that subject as a variable
had a significant influence on the data. The values for b2 were positive
and significantly different from zero, indicating that grade had a positive
influence on EMG activity in both muscles during walking. Also, b2 for
the gastrocnemius was higher than for the soleus, which indicates that
the slope more significantly affects the EMG activity of the gastrocnemius
than that of the soleus. The b3 values were also positive and different
from zero, indicating that EMG activity increased with increasing speed
for both muscles. The b2 values for the gastrocnemius and soleus muscles
were not significantly different; therefore, they were both influenced
equally by increased speed. A significant difference in time at peak activity
for the gastrocnemius and soleus as a percentage of total stride time was
not established.