| dc.description.abstract | Introduction: Stairs are a frequently encountered obstacle in daily life. Due to their
abundance, the ability to ascend and descend stairs without difficulty or pain is
important to quality of life. The Consumer Product Safety Commission has reported
an estimated two million injuries and 1... deaths each year associated with stair
falls and in Australia stair and step fall injuries increased by over 7. percent during
the decade 1333/4 to 2..2/3. In the U.S., for falls involving stairways where the
location of the stairway is reported, °59 occur in residential settings. Many studies
have shown that stairs are among the main common factors involved in low (below
two meters) fall accidents.For ascent and descent, it would appear that larger riser
heights (e.g. height of each step) cause under stepping at the point of incident, and
this was the major design factor associated with stair accidents. The purpose of this
study was, therefore, to investigate the EMG activity of the leg muscles involved in
ascending and descending stairs with different heights.
Methods : Eighteen females with a mean age of 23 ± 5..2 year, height of 161.33 ±
4.3 cm, and body weight of 53.66 ± 5.57 kg, and with no history of neuromuscular
disorder and injury to the lower extremities participated in this study. Three heights
of stairs were specially designed and built for the purpose of this study. The custombuilt steel and wood staircase of 4 steps with the dimensions of 1° cm, 15.5 cm, 1.
cm (riser), 3. cm (tread), and 3. deg (the total slope of the stairs) were used. No
hand railings were available. Subjects were asked to ascend and descend a staircase
of four steps. They tested 3 sets of stairways with different riser dimensions, with the
order of presentation of the stair conditions randomized across the participants.
Muscle activity was measured using ME6... Biomonitor EMG System.EMG
recordings were made using a pair of surface electrodes(silver-silver chloride, 55
mm) placed over the Tbialis anterior(TA),Soleus(SOL), Rectus femoris(RF) and
Gluteusmaximus(G.MAX) muscles of the dominant leg. The data were analyzed
using SPSS version 15.5 Significantly different conditions between stairs were
included in subsequent analyses as covariance structure (linear mixed model).90
Results: The muscle activity levels of the SOL muscle were significantly higher than
those of the TA, RF and G.MAX muscles for both ascending and descending
conditions (p = .....). The results of the study also showed significant differences in
the muscle activity levels of the RF,G.MAX and SOL muscles between ascending
and descending conditions .(F(1,2..)=13.36,P<....1) F(1,133)=154.57, P<....1)
(F(1,21.)=1°.4.6, P<....1). However, the results showed no significant
difference in the muscle activity levels of the TA between ascending and descending
conditions (F(1,134)=2.22, p = ..3°.). The results showed significant effect of stair
height on the muscle activity levels of RF (F(2,172)=11.°2,P<....1) but no
significant effect of stair height on the muscle activity levels of SOL(F (2,122)
=...73,p = ..33.) or TA (F(2,156) =2.271,p = ..1.7) or G.max
)F(2,154)=..57,P=..6 ( muscles.
Conclusions: The main findings of the study were that the EMG activity of the SOL
muscle was significantly higher than the TA , RF and G.MAX muscles activity and
that the muscle activity level of the SOL , RF and G.MAX muscles was significantly
higher when ascending compared to descending condition, although the stair height
had no significant effect of the EMG activity of the TA, SOL and G.MAX muscles,
but the stair height had significant effect of the EMG activity of the RF muscle.
These findings provide an insight that how the muscles of the leg are influenced by
stair height during ascending and descending stairs | en_US |
