1st Joint ESMAC-GCMAS Meeting - Análise de Marcha

O-47
AVERAGED EMG PROFILES IN RUNNING COMPARED TO WALKING
Hof, At, Dr Ir 1,2 , Gazendam, Marnix, Drs 2
1 Laboratory of Human Movement Analysis, University Medical Center
2 University of Groningen, Center for Human Movement Sciences,
Groningen, The Netherlands
Summary/conclusions
EMGs were collected of 14 muscles with surface electrodes in 10 subjects during walking and
running. The EMGs were rectified, interpolated in 100 % of the stride, and averaged over all
subjects to give an average profile. Muscles could be divided into a quadriceps, hamstrings,
calf and gluteal group, with largely identical profiles within the group. Many muscles show a
similar profile in running as in walking. The most notable exception is the calf group, which
shows activation in early stance( 86-25%), together with quadriceps, instead of in late stance
(25-55%) as in walking.
Introduction
In a previous paper [1] a method was presented to quantify the ‘profiles’ of averaged rectified
EMGs for human walking in a range of walking speeds. It turned out that the timing of the
profiles, when expressed as a fraction of the stride duration, was usually invariable, while their
amplitude could vary with speed. The profiles of each muscle could be composed into a limited
set of basic patterns, which they had in common within their functional group: calf, quadriceps,
hamstrings and gluteal. The aim of the present paper is to make a similar analysis for running.
Statement of clinical significance
When EMG recordings are made in an analysis of pathology in running, these can be compared
to the average profiles for healthy young people, as presented here.
Methods
Ten healthy male subjects (age 20.8 ± 1.2 years, mass 71.3 ± 6.3 kg, stature 1.84 ±0.07 m, leg
length 0.99 ± 0.05 cm) were included. They walked and ran on a treadmill (ENRAF Entred) at
speeds from 1.25 up to 2.25 m.s -1 (walking) or 4.5 m.s -1 (running). EMGs of fourteen leg
muscles of the right leg were recorded. The smoothed (24 Hz) rectified EMGs were linearly
interpolated to 100 points per stride, triggered by the right heel contact. Heel contact was
obtained from the recording of vertical ground reaction force. At every speed an average over
all subjects was obtained[1].
Results
On the basis of their EMG profiles, muscles could be divided in the same functional groups as
in walking.
The vasti group (vastus medialis and lateralis) showed the same pattern as in walking: one
peak from shortly before heel contact (80%) up to 15%. When changing from walking into
running at the same speed, there is a 40% increase in amplitude, Figure 1A. At higher running
speeds the amplitude increases only little.
The hamstrings (biceps femoris, semimembranosus, semitendinosus) showed a pattern with
two peaks in late swing and early stance, similar to walking, but some 10% earlier, Figure 1B.
The amplitudes of the two peaks changed with speed quite differently for the three muscles.
The muscles of the calf group (soleus, gastrocnemius medialis and lateralis, peroneus longus)
had a pattern markedly different from walking. In running, activity started shortly before heel
contact (86%) and ending before toe-off at 25%, Figure 1C. In walking toe-off is much later
(57%) than in running (37%) and peak calf muscle activity is later as well, from 25-55%.
In the gluteal group (gluteus maximus and medius) the EMG showed peaks from 88-18% and
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