The influence of glove and hand position on pressure over the ulnar nerve during cycling

Abstract

Chronic ulnar nerve compression is believed to be the primary cause of sensory and motor impairments of the hand in cyclists, a condition termed Cyclist's Palsy. The purpose of this study was to quantitatively evaluate the effects that hand position and glove type can have on pressure over the ulnar nerve, specifically in the hypothenar region of the hand.
Thirty-six experienced cyclists participated. Subjects rode at a constant cadence and power output on a stationary bicycle with their hands in the tops, drops and hoods of a standard drop handlebar. A high resolution pressure mat was used to record hand pressure with no gloves, unpadded gloves, foam-padded gloves and gel-padded gloves. Wrist posture was simultaneously monitored with a motion capture system. Laser scans of the subject's hand were separately acquired to register pressure maps onto the hand anatomy.
Average peak hypothenar pressures of 134-165kPa were recorded when cyclists did not wear gloves. A drops hand position induced the greatest hypothenar pressure and most extended wrist posture. Padded gloves were able to reduce hypothenar pressure magnitudes by 10 to 28%, with slightly better pressure reduction achieved using thin foam padding.
The hand pressure magnitudes and loading patterns seen in steady-state cycling are of sufficient magnitude to induce ulnar nerve damage if maintained for long periods. Wearing padded gloves and changing hand position can reduce the magnitude and duration of loading patterns, which are both important to mitigate risk for Cyclist's Palsy during extended rides.

Full text

The influence of glove and hand position on pressure over the ulnar nerve
during cycling
Josh Slane
a,c
, Mark Timmerman
d
, Heidi-Lynn Ploeg
a,b,c
, Darryl G. Thelen
a,b,
⁎
a
Department of Mechanical Engineering, University of Wisconsin–Madison, United States
b
Department of Biomedical Engineering, University of Wisconsin–Madison, United States
c
Materials Science Program, University of Wisconsin–Madison, United States
d
School of Medicine and Public Health, University of Wisconsin–Madison, United States
abstractarticle info
Article history:
Received 21 October 2010
Accepted 1 March 2011
Keywords:
Cyclist's Palsy
Dynamic pressure mapping
Wrist posture
Hypothenar pressure
Road cycling
Background: Chronic ulnar nerve compression is believed to be the primary cause of sensory and motor
impairments of the hand in cyclists, a condition termed Cyclist's Palsy. The purpose of this study was to
quantitatively evaluate the effects that hand position and glove type can have on pressure over the ulnar
nerve, specifically in the hypothenar region of the hand.
Methods: Thirty-six experienced cyclists participated. Subjects rode at a constant cadence and power output
on a stationary bicycle with their hands in the tops, drops and hoods of a standard drop handlebar. A high
resolution pressure mat was used to record hand pressure with no gloves, unpadded gloves, foam-padded
gloves and gel-padded gloves. Wrist posture was simultaneously monitored with a motion capture system.
Laser scans of the subject's hand were separately acquired to register pressure maps onto the hand anatomy.
Findings: Average peak hypothenar pressures of 134–165 kPa were recorded when cyclists did not wear
gloves. A drops hand position induced the greatest hypothenar pressure and most extended wrist posture.
Padded gloves were able to reduce hypothenar pressure magnitudes by 10 to 28%, with slightly better
pressure reduction achieved using thin foam padding.
Interpretation: The hand pressure magnitudes and loading patterns seen in steady-state cycling are of
sufficient magnitude to induce ulnar nerve damage if maintained for long periods. Wearing padded gloves
and changing hand position can reduce the magnitude and duration of loading patterns, which are both
important to mitigate risk for Cyclist's Palsy during extended rides.
© 2011 Published by Elsevier Ltd.
1. Introduction
Sensory and motor impairments of the hand are common among
both amateur and experienced bicyclists (Black et al., 2007;
Braithwaite, 1992; Capitani and Beer, 2002; Eckman et al., 1975;
Haloua et al., 1987; Hankey and Gubbay, 1988; Kalainov and Hartigan,
2003; Maimaris and Zadeh, 1990; Noth et al., 1980; Patterson et al.,
2003; Woischneck et al., 1993). This condition, termed Cyclist's Palsy,
most often presents as numbness and/or paresthesia in the fifth and
ulnar aspect of the fourth finger, sometimes accompanied with
weakness in the abductors or adductors of these fingers (Kennedy,
2008; Richmond, 1994). For example, Anderson and Bovim (Andersen
and Bovim, 1997) interviewed 169 cyclists after completion of a
540 km race and found sensory symptoms present in 40% of riders
while 19% exhibited motor symptoms. The duration of Cyclist's Palsy
varies widely among riders, persisting anywhere from several days to
months (Akuthota et al., 2005; Cherington, 2000; Mellion, 1991).
Further, the condition can occur as either bilateral or unilateral
neuropathy, with the dominant hand being more frequently involved
in unilateral cases (Cherington, 2000).
Persistent ulnar nerve compression is believed to be the primary
cause of Cyclist's Palsy (Kalainov and Hartigan, 2003; Woischneck
et al., 1993). The ulnar nerve passes into the hand ulnarly to the
pisiform and radially to the hamate, via Guyon's Canal (Akuthota et al.,
2005). Upon exiting the canal, the nerve bifurcates into superficial
sensory and deep motor branches. The sensory branch provides
sensation to the fifth finger and half of the fourth finger while the
motor branch innervates the hypothenar muscles as well as several
other small muscles groups in the hand (Kennedy, 2008). Guyon's
Canal is located relatively superficially, making the ulnar nerve
susceptible to compression when pressure is placed over the
hypothenar region (Fig. 1) of the hand (Black et al., 2007; Richmond,
1994). Because of this, measures to prevent Cyclist's Palsy, such as
wearing padded gloves and frequently changing hand position, are
typically aimed at reducing the magnitude or duration of hypothenar
loading (Capitani and Beer, 2002; Kennedy, 2008; Patterson et al.,
2003; Richmond, 1994). The effect of these preventive measures on
Clinical Biomechanics xxx (2011) xxx–xxx
⁎Corresponding author at: Department of Mechanical Engineering, University of
Wisconsin–Madison, 1513 University Avenue # 3039, Madison, WI 53706, United States.
E-mail address: thelen@engr.wisc.edu (D.G. Thelen).
JCLB-03297; No of Pages 7
0268-0033/$ –see front matter © 2011 Published by Elsevier Ltd.
doi:10.1016/j.clinbiomech.2011.03.003
Contents lists available at ScienceDirect
Clinical Biomechanics
journal homepage: www.elsevier.com/locate/clinbiomech
Please cite this article as: Slane, J., et al., The influence of glove and hand position on pressure over the ulnar nerve during cycling, Clin.
Biomech. (2011), doi:10.1016/j.clinbiomech.2011.03.003

ulnar nerve loading has not been determined. Aside from direct
hypothenar loading, maintaining an extended wrist posture may also
contribute to Cyclist's Palsy symptoms by inducing tension on both
the ulnar nerve (Patterson et al., 2003) and the median nerve within
the carpal tunnel (Mogk and Keir, 2008).
The purpose of this study was to evaluate the effects that hand
position and glove type have on wrist posture and pressure over the
hypothenar region of the hand. Specifically, we considered tops, drops
and hoods hand positions used by road cyclists. We also compared
gloves that were padded with either gel or foam materials located
over the metacarpals, hypothenar eminence and thenar eminence.
Our primary hypothesis was that padding would act to reduce
pressure, with the greatest amount of pressure reduction found when
using a compliant material. Our secondary hypothesis was that
putting the hands in the drops would result in an extended wrist
position and also induce the greatest load on the hypothenar region of
the hand, due to the large amount of body weight that is shifted
forward in this position (Potter et al., 2008). The information obtained
in this study can provide a scientific basis for evaluating interventions
that diminish the potential for Cyclist's Palsy to occur.
2. Methods
2.1. Participants
Thirty-six experienced cyclists, evenly divided into males (age,
40.2 years (SD 13.8); height, 180 cm (SD 8); mass, 82 kg (SD 14)) and
females (age, 37.1 years (SD 12.7); height, 170 cm (SD 7); mass, 80 kg
(SD 5)), were recruited from local cycling groups. All subjects were
actively road bicycling for three or more hours per week for at least
one year prior to participating in the study. Subjects had no history of
cardiovascular, pulmonary, neurological or musculoskeletal impair-
ments, and had no prior orthopaedic surgery performed on either
upper extremity. Participants gave written informed consent in
accordance with a protocol approved by the University of Wisconsin's
Social and Behavioral Sciences Institutional Review Board.
2.2. Procedures and instrumentation
An adjustable stationary bicycle was configured to match the
dimensions (seat tube angle, saddle height, handlebar height, reach
and width) of each subject's personal road bicycle. The bicycle was
outfitted with a gender-specific saddle (Bontrager inForm RL, Trek
Bicycle Corporation, Waterloo, WI, USA) that was leveled to ground.
For a subset of subjects (N =18), the saddle was mounted on a three-
dimensional load cell (JR3, Woodland, CA, USA) which recorded the
net saddle forces throughout testing. Gender-specific drop handle-
bars, the same width as those on the subject's personal cycle, were
mounted on the bicycle (males: Race 31.8, females: VR 31.8,
Bontrager, Trek Bicycle Corporation, Waterloo, WI, USA). An instru-
mented rear hub (PowerTap Pro, Saris Corp, Madison, WI, USA) on the
bicycle provided subjects with real-time feedback of power output
and pedaling cadence. Subjects warmed up for 5 to 10 min at a self-
selected cadence and trainer resistance that they deemed equivalent
to a typical 1 to 2 hour tempo ride. The resistance level, cadence and
corresponding power output was recorded and maintained for all
subsequent cycling trials in which data was collected. Cadence and
average power output were 80 rpm (SD 12) and 159 W (SD 47) for
male subjects, and 84 rpm (SD 10) and 116 W (SD 43) for females.
Hand pressure distributions were monitored at 50 Hz using a
piezo-capacitive pressure mat (Elastisens-FO44; Novel GmbH,
Munich, Germany). The mat consisted of 229 sensors (4.4 mm per
side) arranged in a rectangular grid. Laser scans of the hand with and
without the pressure mat attached were taken to relate pressure
profiles to the underlying anatomy (Fig. 1). We first performed a
three-dimensional laser scan (y-axis resolution of 0.5 mm) of the
ventral aspect of their dominant hand (ShapeGrabber A1300; Shape-
GrabberTM Inc, Ottawa, Ontario). An impression of the dorsal aspect
of the hand was made in modeling compound (Play-Doh, Hasboro
Fig. 1. Subjects rode a stationary bicycle at a constant cadence and power output while glove type and hand position were randomly varied. A piezo-capacitive pressure mat recorded
pressure distributions over the hypothenar eminence of the subject's dominant hand. A three-dimensional laser scanner was used to obtain the surface coordinates of the subject's
hand with and without the pressure mat attached. The origin and axes of the pressure mat were visible in these laser scans, allowing for the calculation of a transformation matrix
relating the coordinates of each individual sensor within the pressure mat to the hand reference frame. Finally, the collected pressure data was co-registered with the laser scans in
order to relate pressure distributions to the underlying anatomy. Peak pressures were quantified in four regions of interest (RoIs) that encompassed the hypothenar region of the
hand, which is indicated by the outer bounding box within the figure.
2J. Slane et al. / Clinical Biomechanics xxx (2011) xxx–xxx
Please cite this article as: Slane, J., et al., The influence of glove and hand position on pressure over the ulnar nerve during cycling, Clin.
Biomech. (2011), doi:10.1016/j.clinbiomech.2011.03.003

Inc., Pawtucket RI, USA) to ensure consistent positioning during the
scan. The pressure mat was then secured over the hypothenar
eminence of the dominant hand via adhesive tape, such that the mat
origin was located above the pisiform bone and the edge of the mat
was aligned with the medial aspect of the palm (Fig. 1). Subjects then
re-positioned their hand in the impression and a second laser scan of
the hand was obtained with the mat in place.
Each subject performed a series of cycling trials in which glove type
(Table 1) and hand position (Fig. 3) were randomly varied. Subjects rode
with no gloves, unpadded gloves, two foam-padded gloves (3 and 5 mm
thickness) and two gel-padded gloves (3 and 5 mm thickness). Padding in
the gloves was positioned over the thenar eminence, hypothenar
eminence and metacarpal heads. Glove size was determined based on
hand circumference measurement charts (S: 15–16.5 cm, M:
16.5–18 mm, L: 18–19.5 cm, XL: 19.5–21 cm). For each glove, subjects
rode with their hands in the tops, drops and hoods position (Fig. 3).
Average peak pressure distributions were obtained by averaging each
sensor's peak pressure measurement over twelve consecutive pedal
strokes. Co-registration of the pressure mat position on the hand was
achieved by digitizing the sensor origin and axes on the laser-scanned
hand-mat image. These digitized points were used to calculate the
transformation needed to align the mat with the hand reference frame.
The sensor coordinates were then projected onto the hand surface,
allowing us to display the sensor pressure data onto laser-scanned hand
images (Fig. 1).
Pressure data was summarized over a standardized anatomical
region-of-interest (RoI) that overlies the ulnar nerve and the
communicating branch between the ulnar and median nerves (Peter
et al., 2000). The RoI was defined on a subject's laser-scanned hand
image as the area enclosed by (1) pisiform/distal wrist crease, (2)
center of distal wrist crease, (3) distal palmar crease under radial
aspect of the fourth finger and (4) distal palmar crease under the ulnar
aspect of the fifth finger. The RoI was further subdivided into four,
equal sub-RoIs (Fig. 1). For each trial, the peak average pressure
within the RoI and sub-RoIs was determined. All pressure data and
image analysis was conducted in MATLAB (Mathworks, Natick, MA,
USA).
2.3. Kinematics
Wrist posture was monitored using an active motion-capture
system (Visualeyez VZ-4000, PhoeniX Technologies Inc, Burnaby,
British Columbia). Rigid marker plates, consisting of three markers
attached to a sheet of thermoplastic, were strapped to the subject's
hand and forearm. Marker positions were first acquired while the
subject held their arm in a relaxed position at their side, with the
lower arm and hand reference frames aligned with the lab reference
frame. Marker positions were then monitored at 100 Hz during the
cycling trials. Three-dimensional segment orientation at each frame of
the motion was determined using a singular value decomposition
approach (Soderkvist and Wedin, 1993). Joint angles between the
lower arm and hand were quantified via body fixed rotations, that
involved wrist flexion–extension followed by ulnar–radial deviation
(movement of ulnar aspect of hand towards medial side of forearm).
2.4. Statistical analysis
A three-way analysis of variance (ANOVA) was used to study the
effects of gender, hand position (tops, drops and hoods) and glove
condition (no glove, unpadded glove, and padded glove) on peak
pressure within the RoI and sub-RoI's, and on the average wrist joint
angles. We then performed a separate three-way ANOVA to assess the
influence of padding material (gel and foam), thickness (3 mm and
5 mm) and hand position on peak hypothenar pressure. For each
ANOVA, Tukey's Honestly Significant Difference (HSD) post hoc test
was used to conduct pair-wise comparisons of main effects. The
probability associated with Type I error was set at P= 0.05 for all
observations. All statistical analysis was performed using Statistica
version 6.1 (StatSoft Inc, Tulsa, OK, USA).
2.5. Materials testing
The elastic modulus of the gel and foam padding inserts (removed
from the glove) were determined using displacement controlled
compression tests performed on a materials testing machine (MTS
Insight, MTS Systems Corporation, Eden Prairie, MN, USA) with a 50 N
load cell. Standardized techniques were used for testing thin (5 mm)
samples of nearly incompressible (gel) and compressible materials
(foam). Gel samples were bonded to a steel mounting plate and then
indented at rates of 0.5 and 5 mm min
−1
to a maximum displacement
of 400 μm using a flat 10 mm diameter steel cylindrical indenter.
Applied force and displacement data were simultaneously recorded
and used to estimate the Poisson's ratio and Elastic Modulus of the gel
using the approach described by Zheng et al. (2009).
Foam padding inserts were machined into 15 mm diameter
cylindrical specimens, giving an effective aspect ratio of 3:1. Specimens
were loaded between lubricated steel compression platens and
compressed at rates of 1 and 3 mm min
−1
to a maximum displacement
of 800 μm. The size of the loading platens was larger than the specimen
diameter and their contact surfaces were polished to a mirror finish to
reduce the effects of friction. Elastic modulus was defined as the slope of
the initial linear region of the stress–strain plot obtained from these
tests. Eight gel and ten foam samples were tested and the modulus
values were averaged across samples for each material.
3. Results
3.1. Hand position effects
Peak hypothenar pressures were significantly greater (Pb0.05)
with the hands in the drops position (112–140 kPa), relative to those
found in the tops (36–135 kPa) and hoods (68–122 kPa) positions
(Figs. 2). Conversely, the percentage of body weight supported by the
saddle was significantly lower in the drops hand position (47% (SD
5)), than in the tops (51% (SD 5)) or hoods (51% (SD 5)).
Pressure distributions also varied significantly between hand
positions (Fig. 3). Hand pressure in the tops position was concen-
trated across the distal portion of the hypothenar region. Pressure in
the hoods hand position induced a more diagonal pressure pattern
extending from the proximal ulnar portion of the hypothenar region.
The drops hand position resulted in more even pressure measures
across all 4 sub-regions of the hypothenar area of the hand (Fig. 2).
Pressure magnitudes did not significantly vary between male and
female cyclists for any of the hand positions.
Table 1
Average (SD)peak pressure (kPa) over the entire hypothenar region(n =36) for padded
gloves. HE —hypothenar eminence, TE —thenar eminence, MC —metacarpal heads.
Padding
a
Thickness (mm)
b
Hand position
c
HE–TE–MC Tops Drops Hoods
Gel 3–3–3 123 (34) 147 (28) 114 (35)
Gel 5–5–3 113 (30) 142 (39) 103 (34)
Foam 3–3–3 108 (33) 133 (33) 104 (28)
Foam 5–5–3 113 (28) 128 (27) 96(32)
a
Foam padding significantly reduced pressure relative to gel padding.
b
For gel padding, a 5 mm thickness resulted in significantly lower pressures relative
to 3 mm. This effect was not observed with foam padding, where thickness was
non-significant (P=0.095).
c
The drops hand position resulted in pressures significantly higher than tops and
hoods, which were found to be equivalent.
3J. Slane et al. / Clinical Biomechanics xxx (2011) xxx–xxx
Please cite this article as: Slane, J., et al., The influence of glove and hand position on pressure over the ulnar nerve during cycling, Clin.
Biomech. (2011), doi:10.1016/j.clinbiomech.2011.03.003

3.2. Glove effects
Hypothenar pressure magnitudes were not significantly different
between the no-glove and un-padded glove conditions. However,
significantly lower hypothenar pressures were observed in the padded
glove conditions, which reduced pressure relative to the no-glove
condition by 19%, 21% and 29% for the tops, drops and hoods positions,
respectively (Fig. 4). The use of foam padding resulted in significantly
(Pb0.05) lower peak pressure than gel padding. Increasing padding
thickness from 3 to 5 mm resulted in significant pressure reduction for
the gel, but had no effect when using the foam (Table 1).
3.3. Padding material properties
Compression testing revealed that the foam padding inserts were
approximately 60% more compliant than the gel inserts. Specifically,
Fig. 2. Significant variations in hypothenar pressure distributions were observed with hand position (*Pb0.05). The drops hand position resulted in the highest pressures in RoIs 1, 3
and 4. Pressure in the tops was more focused in the distal RoIs, while pressure in the hoods was concentrated in RoIs 1, 2 and 4. Data presented here is from the no glove condition.
Fig. 3. Three handpositions commonlyused by road bicyclistswere tested in this study;tops, drops and hoods.The drops position resultedin the highest averagepeak pressure magnitude
over the hypothenar eminence. Wearing padded gloves did not substantially vary the pressure profiles, but did diminish peak pressures as seen graphically in these images.
4J. Slane et al. / Clinical Biomechanics xxx (2011) xxx–xxx
Please cite this article as: Slane, J., et al., The influence of glove and hand position on pressure over the ulnar nerve during cycling, Clin.
Biomech. (2011), doi:10.1016/j.clinbiomech.2011.03.003

foam and gel inserts were found to have elastic moduli of 121.9 kPa
(SD 8.2) and 308.7 kPa (SD 32.0), respectively. Elastic modulus did not
significantly vary (foam: P=0.55, gel: P=0.34) between the two
strain rates used.
3.4. Wrist posture
Wrist extension was significantly higher with the hands in the
drops hand position (54°), compared to the hoods (36°) and tops
hand positions (23°). Ulnar wrist deviation was significantly higher
(37°) with the hands in the tops position, compared to the drops (22°)
and hoods (4°) hand positions (Fig. 5). Wrist angles did not vary
significantly with gender or glove type.
4. Discussion
One of the most common recommendations for preventing
Cyclist's Palsy is the use of padded gloves. However to our knowledge,
this is the first study that has actually assessed the effect of gloves on
hand pressure distributions in cyclists. We measured peak pressures
of 134–165 kPa over the hypothenar region of the hand when cyclists
did not wear gloves, with the highest pressures occurring in a drops
hand position. The higher hypothenar pressure in the drops likely
reflects a more flexed riding posture, which required subjects to
support more of their upper body weight with their hands and less
with the saddle. As hypothesized, padded gloves significantly reduced
peak hypothenar pressure. Reductions of 10 to 29% were achieved,
with the greatest pressure reductions occurring when wearing a glove
that had 3 mm foam padding. Interestingly, increasing the foam
padding from 3 to 5 mm provided no significant additional pressure
reduction. This result is not consistent with the common recommen-
dation for cyclists to wear thick padded gloves (Maimaris and Zadeh,
1990; Richmond, 1994). Gel padding was found to be slightly less
effective than foam padding in reducing pressures. The difference in
performance between the two padding materials seems to be
attributable to the greater compliance of the foam that was used.
Cyclist's Palsy can present clinically in four different manners
dependent upon the location of ulnar nerve compression (Capitani
and Beer, 2002). Type I occurs when compression takes place proximal
to Guyon'sCanal (before the nervebifurcates) and results in sensoryloss
and weakness of all ulnar innervated hand muscles (Fig. 6). Type II
involves compression of the deep motor branch of the ulnar nerve distal
to Guyon's Canal and results in weakness of all ulnarhand muscles. Type
III also involves compression of the deep motor branch distal to Guyon's
Canal causing motor weakness of all ulnar innervated hand muscles
expect the hypothenar group. Finally, Type IV occurs when the
superficial sensory branch is compressed distal to Guyon's Canal
resulting in sensory loss only (Capitani and Beer, 2002). Although the
ulnar nerve only provides sensation to the fifth finger and the ulnar
aspect of thefourth finger, cyclistsoften report experiencing paresthesia
in all fingers(Akuthota et al., 2005).This observation could result from a
communicating branch that often exists near the mid-section of the
palm underneath the fourth finger that connects the ulnar and median
nerves (Bas and Kleinert, 1999; Peter et al., 2000). As a result, sensory
disturbances to the ulnar nerve could be potentially transferred to the
median nerve resulting in Cyclist's Palsy symptoms developing in the
remaining fingers of the hand.
Pressure distribution patterns varied significantly with hand
position, which could relate to the different types of Cyclist's Palsy
observed clinically. A tops hand position tended to induce pressure
concentrations nearer to the superficial sensory branch (Fig. 3), which
would more likely result in Cyclist's Palsy type III and IV. In contrast, the
drops hand position resulted in a relatively large pressure concentration
that extended distally from Guyon's Canal along the ulnar nerve. Thus,
there wouldseem to be the potential for a dropshand position to induce
any of the four Cyclist's Palsy types. Moving from the drops to the hoods
Fig. 4. Statistical analysis revealed that the no-glove and un-padded glove conditions were equivalent. Conversely, padded glove conditions significantly reduced hypothenar
pressure for all hand positions, relative to the no glove and unpadded glove conditions (*Pb0.05).
Fig. 5. Wrist postures varied significantly with hand position (*Pb0.05). In particular,
ulnar deviation was greatest with the hands in the tops hand position, while the largest
wrist extension was observed with the hands in the drops hand positions.
5J. Slane et al. / Clinical Biomechanics xxx (2011) xxx–xxx
Please cite this article as: Slane, J., et al., The influence of glove and hand position on pressure over the ulnar nerve during cycling, Clin.
Biomech. (2011), doi:10.1016/j.clinbiomech.2011.03.003

reduces pressure on the ulnar side of the hypothenar region (Fig. 3),
which could diminish risk for Cyclist Palsy types I, II and IV.
Surface pressure is recognized asone of the neurosensory inputs that
can contribute to hand discomfortand/or pain, which canin turn lead to
decreased fine motor control and function (Johansson et al., 1999). The
mean pain-pressure threshold for the palm and thenar region of the
hand are reported to be 494 kPa and 447 kPa, respectively (Johansson et
al., 1999).However, substantially lower externally applied pressures are
sufficient to induce nerve damage. Rudge et al. reported a severe/
complete conduction block of the anterior tibial nerve (after 90 min)
with an applied pressure of 157 kPa, a moderate/partial conduction
block with an applied pressure of 98 kPa and no effect with pressures
below 74 kPa. Additionally, they found that increasing the duration of
compression to 180 min resulted in wallerian degeneration that
required several weeks to months to heal (Rudge et al., 1974).
Hypothenar pressures recorded in this study (Table 1) are well below
the pain-pressure threshold, yet are sufficient to induce nervedamage if
maintained for long periods. This suggests that road bicyclists could
unknowingly induce localized nerve damage inthe hand. While padded
gloves wereeffective in reducing peak pressures, the magnitudes would
still seem to be sufficient to contribute tonerve damage. Hence, the use
of additional counter-measures, such as changing hand positions
(Capitani and Beer, 2002; Kennedy, 2008; Patterson et al., 2003;
Richmond, 1994), would seem prudent to mitigate risk of Cyclist's Palsy
in longer duration rides.
In addition to external pressure, wrist position is believed to affect
the internal loading on both the ulnar and median nerves (Capitani and
Beer, 2002;Mogk and Keir, 2008; Patterson et al., 2003). In particular,an
extended wrist posture can directly contribute to nerve tension
(Capitani and Beer, 2002). We observed the greatest amount of wrist
extension in the drops hand position (Fig. 5), which could exacerbate
the potential for nerve damage to occur when riding in the drops. The
tops hand position, which required the riders to places their hands on
the medial portion of the handlebars, resulted in ulnar deviation of the
wrist. Ulnar wrist postures can result in pressure on the median nerve
within the carpal tunnel, and potentially contribute to median
neuropathy (Keir et al., 2007).
The compliant, piezo-capacitive pressure mat used in this study
allowed us to obtain higher resolution information than has been
recorded in previous studies of bicycle interface pressures (Bressel and
Cronin, 2005; Lowe et al., 2004; Potter et al., 2008). We chose to attach
the pressure mat to the subject's dominant hand, which is the
commonly affected hand in individuals who present with unilateral
Cyclist's Palsy (Cherington, 2000). All subjects were fitted with new
gloves, such that our results do not reflect changes in padding material
properties that can occur with extended wear. We were only able to
measure pressure arising from normal forces onthe hand, though shear
forces may also play a role in the development of localized tissue
damage (Johansson et al., 2002). Also, we tested subjects on their own
bicycle geometry and at a self-selected cadence and power output,
rather than using a standardized fitting procedure and fixed cadence
and power (Bressel and Cronin, 2005; Potter et al., 2008; Sauer et al.,
2007). This was done so as to not introduce subjects to a novel bicycle
geometry, and to reduce the potential for fatigue to set in during the
testing. Finally, testing was conducted under steady-state conditions in
a laboratory environment. Future studies should consider dynamic
variations in hand pressureand wrist posture due to terrain, particularly
among mountain bikers who more often present with medial nerve
symptoms (Patterson et al., 2003).
5. Conclusion
We conclude that the hand pressure magnitudes and loading
patterns seen in steady-state cycling are sufficient to induce ulnar
nerve damage if maintained for long periods. Wearing a glove with thin
compliant padding over the hypothenar region can reduce peak
pressure by 10–29%. However, these pressures remain sufficiently
high that additional counter-measures, e.g. changing hand position,
seem necessary to mitigate the risk for incurring Cyclist's Palsy during
longer duration rides.
Acknowledgments
The authors thank Caitlyn Collins, Yvonne Schumacher, Jane Lee,
Ryan Gallagher, Jennifer Retzlaff, Kyle Gleason, Chris Carlson and Curt
Irwin, Ph.D., for their contributions. This study was supported by Trek
Bicycle Corporation, Waterloo, WI.
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Biomech. (2011), doi:10.1016/j.clinbiomech.2011.03.003

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7J. Slane et al. / Clinical Biomechanics xxx (2011) xxx–xxx
Please cite this article as: Slane, J., et al., The influence of glove and hand position on pressure over the ulnar nerve during cycling, Clin.
Biomech. (2011), doi:10.1016/j.clinbiomech.2011.03.003