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Electromyography
for the evaluation of
handicapped swimmers
L. Maes, J. P. Clarys, and P. J. Brouwer
In the literature many authors recommend the use of a specific swimming
technique for supporting and/or strengthening certain muscles or muscle
groups. Very few of these recommendations are based on scientific experiences. Lorenzen (1970) mentioned the strengthening of the extensors of the
back during the backcrawl. Vis (1971) indicated the breaststroke was the
most effective way to develop the back musculature. According to Duffield
(1969) the extensors are generally used in back and front crawl. The flexors
are utilized in breaststroke and butterfly.
Experimental investigations on the function of muscles during swimming
are limited. Ikai et al (1964) compared the electromyogram (EMG) of an
Olympic champion with a University champion in breaststroke, front, and
back crawl. Lewillie (1968, 1971, 1973) studied the triceps brachii, the
biceps brachii, and the quadriceps femoris at different speeds using the four
competitive strokes.
Clarys et al. (1973) investigated the biceps brachii, the brachia radialis,
the flexor carpi ulnaris, and the triceps brachii in subjects executing the front
crawl stroke in competition and in water polo. In this study the electrical
potentials (EMG) of five preselected muscles were studied during three
swimming techniques: a) breaststroke, b) back crawl, and c) front crawl. The
results were related to the "normal" and the disabled swimmer.
PROCEDURES
The EMG technique used for the measurement of muscle potentials during
swimming has been previously described by Lewillie (1968, 1971). The
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Electromyography of handicapped swimmers
269
recordings are made by means of a telemetric apparatus. The electromyograms are synchronized with 16-mm mm.
The 13 male subjects (mean age 21 years) in this study were all-around
swimmers and water polo players. We realized that eventual style differences
were due either to an individually different motor learning process or to
anatomical differences. In a previous study, no significant differences were
found in swimming motions between swimmers and certain water polo
players (Clarys et al., 1973).
The muscle selection was made according to several criteria.
1. Most of the superficial muscles, mentioned in the literature, were photographed on ten cadavers and a scale was developed. The relative subdermal
surface of each muscle was measured by means of a planimeter (OTT 113).
All muscles with a relative subdermal surface less than 10 cm2 were omitted
because of the possibility of faulty recordings.
2. The different muscles were classified according to their location and
anatomical function.
3. Finally, a group of five flexors were selected that met the criteria of
sufficient surface and location on each body part: the biceps brachii, the
flexor carpi ulnaris, the rectus abdominis (under and above the umbilicus),
the biceps femoris, and the tibialis anterior. The biceps brachli was used as
the control muscle because of the possibilities for comparison with previous
studies.'
Data were recorded for each of the following items: a) the total relative
myoelectrical activity developed by the muscle and its quantitative irnportance in relation to the activity developed during a maximal (isometric)
contraction (Table 1); b) the relative maximal intensity reached and its
quantitative importance in relation with the activity during a maximal isometric contraction (Table 1); c) the location of the different peaks in the
EMG pattern in relation to the movement pattern.
RESULTS AND DISCUSSION
The recordings of the biceps brachii and the flexor carpi ulnaris in the front
crawl were similar to the results reported by Qarys et aL (1973).
Biceps brachli
In the breaststroke ten subjects showed a double-peaked EMG pattern with a
maximum at the beginning of the pull of the arm cycle and at the end of the
push phase of the arm cycle, respectively. Ikai et al. (1964) mentioned only
one peak in their study.
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Table I.
--
Total (relative)* electrical activity (%)
(Relative) maximal intensity reached(%)
Breaststroke
Front crawl
Back crawl
Breaststroke
Front crawl
Back crawl
Biceps brachii
29.3
48.7
33.7
61.5
94.5
66.6
Flexor carpi
ulnaris
45.4
43.1
31.8
59.0
62.4
53.0
Biceps femoris
27.2
32.5
27.3
62.6
57.4
54.2
Tibialis anterior
33.3
22.7
16.9
80.4
38.7
24.8
Rectus abdominis
(under umbilicus)
13.0
21.0
19.9
30.9
29.2
36.8
Rectus abdominis
(above umbilicus)
22.5
31.4
25.1
42.4
52.1
38.4
-
Muscle
*The relative 100% =the individual isometric maximum for a specific muscle over a time period of 0.2 sec.
,....
"
Electromyography of handicapped swimmers
271
In the back crawl, all subjects showed a double-peaked pattern, but the
film analysis revealed little resemblance among the different cycles. These
results differ from the findings of Ikai et al. (1964 ). (It should be noted that
Ikai and his associates did not record the activity of the arm flexors during
the primary pull and push phases of the arm cycle.)
Flexor carpi ulnaris
During the breaststroke, ten subjects showed a double-peaked pattern with
highest values near the time of maximal extension of the arm and in the
middle of the pull and push phases. During the maximal extension of the arm
Ikai et al. (1964) also found one peak.
In the back crawl, eight subjects showed a double-peaked EMG, pattern
but in three cases only one peak was found. The double-peaked electromyograrns reached a maximum a) between the middle of the recovery phase
and the glide phase and b) between the entry in the water and the middle of
the pull and push phases (in this region the single peak maximum was also
found). Ikai et al. (1964) described one peak during the cycle at the same
point in the stroke cycle as was found in this study.
Biceps femoris
The biceps femoris showed single-peaked pattern during the breaststroke in
ten cases. Three subjects showed a double-peaked EMG. (See Figures 1-3.)
The maxima occurred: a) in the middle of the counter movement of the leg
and b) between the complete extension of the leg and the middle of the knee
flexion (at approximately 1/4 of the knee flexion).
In the front crawl, eight subjects showed a triple-peaked pattern. The
different peaks were not very pronounced. Because of inadequate synchronization between the rhythm of the arm and leg movements, it was not possible
to locate the peaks in relation to the movement pattern. A similar situation
existed in the cases of the biceps femoris in the back crawl and the tibialis
anterior in both back and front crawl.
During the back crawl, nine subjects had triple-peaked EMG patterns,
with marked individual differences in durations and amplitudes.
Tibialis anterior
All subjects in the breaststroke showed one very clear and pronounced peak
in the EMG pattern, with a maximum at the end of the recovery movement
of the legs. These findings are similar to those reported by Ika1 et al. (1964).
In the front crawl, sLx swimmers showed a minimal electrical activity
compared to the other muscle patterns. The amount and the form of the
272
Maes et al.
0. TIBlAL!S
A~TERIDR
Figure I. EMG patterns of the breaststroke.
peaks seem to indicate an important variation. Ikai et al. (1964) found one
peak during the leg cycle in the front crawl. A minimum of myoelectrical
activity was found in this muscle during the back crawl by eight subjects.
There were also important irregularities in the form and the amount of the
peaks.
The EMG results derived from subjects who swam the breaststroke seem
very relevant. Therefore, we suggest the use of the tibialis anterior as a
control muscle in future EMG investigations of leg movements.
Rectus abdominis (under the umbilicus)
During the breaststroke, six swimmers showed a rounded single-peaked pattern, while six others had an EMG indicating minimal myoelectrical activity.
Electromyograp hy of handicapped swimmers
273
Figure 2. EMG patterns of the back crawl.
In one case, a rounded double-peaked pattern was found. The 16-mm film
analysis indicated a maximum when the arm reached the middle of the
recovery phase. At the same moment, the legs were almost at maximal flexion
at the hip joint.
In the front crawl, six subjects showed identical patterns without pronounced peaks. One had an electrical maximum when the arms reached the
middle of the pull phase. If a second peak could be seen, the maximum was
found during the glide phase.
In the back crawl, six subjects showed a small pronounced single-peaked
EMG pattern. No electrical activity was found in five cases. The peaks only
reached the maximum during the pull and push phases of the arm.
Rectus abdominis (above the umbilicus)
In the breaststroke, a single-peaked pattern was found in seven swimmers, a
double-peaked pattern in one case. Four subjects showed a constant form of
myoelectrical activity without pronounced peaks. In the mono-peaked EMG,
the maximum was located at the end of the push phase. In this position the
legs were in maximal flexion at the hip joint.
274
Maes et al.
Figure 3. EMG patterns of the front crawl.
In the front crawl, a similar form of electrical activity with small peaks
was found in nine patterns. OI1Jy one swim.mer had a regular mono-peaked
EMG. This peak was found halfway through the pull phase of the arm.
During the back crawl, very irregular patterns for most of the subjects
were apparent: one little peak per cycle for three subjects, two peaks per
cycle for five subjects, constant electrical activity in the case of two subjects,
and no electrical activity for two subjects.
In the case of the mono-peaked patterns the maximum was found at the
start of the pull phase of the arm. In the double-peaked patterns, the maxima
were located at± Ij4 and 3/4 of the same phase.
The fact that the percentages of the rectus abdominis (above the umbilicus) were always markedly higher than those of the rectus abdominis (under
the umbilicus) seems to support the theory that the part of this muscle above
the umbilicus cooperates in an active way in the total movement. During the
propulsive phase of these three swimming techniques, this part will contribute
to the intensity of the pull and push phase of the arms, while pulling the ribs
toward the fixed pelvis. While swimming front and back crawl the two parts
of the rectus abdominis would assist in augmenting the arm movement.
Electromyography of handicapped swimmers
275
CONCLUSION
The assumption is made that the results of this study may be related to most
handicapped cases, on the one hand. The recordings of the biceps brachii and
the flexor carpi ulnaris were similar to those of Clarys et al. (1973 ). Therefore, in relation to the handicapped swimming, we presume that those two
muscles can be strengthened and/or supported in all three swimming techniques. On the other hand, both measurements of the rectus abdominis
showed little activity during swimming movements.
The biceps femoris and the tibialis anterior are important in Lhe breaststroke but none or only a small amount of activity was found during the back
and front crawl, in contradiction to the findings of Lorenzen (1970) and
Duffield (1969 ).
REFERENCES
Clarys, J. P., J. Jiskoot, and L. Lewillie. 1973. A kinematographical, electromyographical and resistance study of waterpolo and competition front
crawl. In: S. Cerquiglini, A. Venerando, and J. Wartenweiler (eds.), Biomechanics Ill, Medicine and Sport, Vol. 8, pp. 446-452.-Karger, Basel.
Duffield, M. H. 1969. Exercise in Water. London.
Ikai, M., M. Miyashita, and K. Ishii. 1964. An electromyographical study of
swimming. Jap. Res. J. Phys. Educ. 7: 4.
Lewillie, L. 1968. Telemetrical analysis of the electromyogram. In: J. Wartenweiler, E. Jokl, and M. Hebbelinck (eds.), Biomechanics I, Medicine and
Sport, Vol. 2, pp. 147-148. Karger, Base!.
Lewillie, L. 1971. Quantitative comparison of the electromyogram of the
swimmer. In: L. Lewillie and J. P. Clarys (eds.), First International Symposium on Biomechanics on Swimming, pp. 155-159. Universite Libre de
Bruxelles, Brussels.
Lewillie, L. 1973. Muscular activity in swimming. In: S. Cerquiglini, A.
Venerando, and J. Wartenweiler (eds.), Biomechanics HI, Medicine and
Sport, Vol. 8, pp. 44Q--445. Karger, Basel.
Lorenzen, H. 1970. Behinderte Schwimmen. H. Putty Verleg, Wuppertal.
Vis, W. P. M. 1971. Swemmem els therapis. Lernniscaat, Rotterdam.