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Eadric Bressel
Brad J. Larson ABSTRACT Perineal trauma is a common problem
in bicyclists, and manufacturers have strived to create seats that provide
comfort and still optimize function.
In women, bladder infections and painful skin breakdown are common,
and women complain of perineal problems as their number one bicycling
injury. In men, perineal
compression can lead to sterility along with pain.
Typical road positions, especially with lower handlebars, cause
greater pressure to be placed on the perineum.
Subjects with low back pain are often told to increase their
anterior pelvic angle to decrease strain on the posterior spinal tissues,
but this position causes more perineal pressure and weight absorption,
which can also lead to pain. These authors decided to test both
experienced cyclists and novice cyclists to determine how they tilt their
pelvis when riding a street bike with their arms in the upper and lower
positions on three different saddles:
standard, partial cutout, and complete cutout. Also, they wanted to see how the subjects rate the comfort of
these saddles, and also to use EMG to assess triceps activity (which would
help determine how much weight they are using to lean forward with). The study group was comprised of 10
experienced cyclists (riding more than 50 miles per week) and 10 novice
cyclists. Each rode 8 minutes
on a seat, half in the upper position, half in the lower position.
An inclinometer was used to assess pelvic position, which was
verified for reliability and validity with radiographic study.
Markers were placed at the acromion, ASIS, PSIS, and greater
trochanter to measure the amount of anterior pelvic tilt, and surface
EMG’s were placed on the long head of the triceps muscle. Results for pelvic angle response
revealed no difference between experienced and novice riders, and anterior
tilt increased 8% with partial cutout saddle riding, and 16% with complete
cutout. Both groups averaged
a 77% increase in pelvic angle as they went from the high handlebar
position to the low position. Pelvic
angle was measured between the horizontal and a line connecting the ASIS
to the PSIS. Trunk angle response also did not
change with the level of experience, that there was minimal change between
the saddle types, and there was an 11% increase in the trunk angle as the
participants went to the lower handle bar position. Trunk angle was measured via the line that goes from the
acromion to the trochanter (when viewed from the side) and the horizon. Overall, 55% of the subjects
preferred the partial cutout seat as the most comfortable, and 30% ranked
the standard seat. The
complete cutout was not favored. EMG data for the triceps revealed a
16% increase with complete cutout saddle use, and 10% more with incomplete
cutout. In addition, those
using the complete cutout saddle had greater triceps activation when in
the upper handlebar position than in the lower position. The data indicates that partial
cutout saddles result in increased pelvic angles regardless of hand
position, and this position can reduce low back strain.
The triceps EMG activity backs up the angles measured, and the fact
that the partial relief saddle was rated most comfortable indicates that
this type of seating may reduce perineal injury while benefiting other
factors. COMMENTS As we approach spring and everybody
takes to the roads on their bikes, we need to be prepared to educate and
treat this patient population. A
great marketing tool is to advertise a clinic where cycling education,
ergonomics, and even simple exercise can be taught. Tomorrow’s update will be a large grouping of cycling tips
and ideas for those interested. The sample size used was small, and
there was not a great descriptive outline for exact positioning of the
cyclist, but I think the data still has value and validity.
Unfortunately, they did not perform this study on hybrid or
mountain bicycles, which are far more used nowadays than the older style
road bike. There is some important information
to be gained from the study. Patients
with a history of low back pain often have difficulty riding when their
pelvis is more posteriorly placed, which causes more spinal curvature and
therefore more strain on the posterior structures.
Placing the body into a more anterior tilt causes increased
perineal pain, which is avoided by many people.
The new seats with partial cutouts, grooves, and other adaptations
permit increased anterior pressure without increased discomfort.
This also permits the rider to use lower handlebar positions or
lower bars in general for increased efficiency and lower wind resistance,
without fear of exacerbation. Another method to further reduce
perineal pressure is to tilt the saddle downward. Also, the complete cutout saddle is not offered in the
catalogs I have listed (at least from what I can see), but is often
offered in Harriet Carter and similar catalogs.
It may be beneficial to purchase one for your clinic cycles and
place on an extra post, so that rapid switching can be performed for those
patients that need the relief. The
complete cutout saddle removes the long stem that usually protrudes
between the cyclist’s legs, which is actually used to facilitate
steering and maintain balance. This
may be the reason why the study participants did not prefer that type of
saddle. This ideal position may not be for
all patients, however. Those
with carpal tunnel, wrist problems, shoulder impingement, cervical
degeneration, and even HNP of the cervical spine may benefit more from the
upright position. This
requires elevation of the handlebars, and thus more posterior angle of the
pelvis. These patients may
not find the cutout saddle as comfortable, as they are not placing as much
pressure on the perineum. However, this position can lead to increased spinal flexion,
and they should be advised to maintain a lordotic curve.
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