Motor and Sensory Nerve ConductionAre Affected Differently by Ice Pack,Ice Massage, and Cold WaterImmersionEsperanza Herrera, Maria C. Sandoval, Diana M. Camargo, Tania F. Salvini
Background. It is well known that reducing tissue temperature changes sensoryand motor nerve conduction. However, few studies have compared the effect ofdifferent cold modalities on nerve conduction parameters.
Objective. The purpose of this study was to compare the effects of ice pack, icemassage, and cold water immersion on the conduction parameters of the sural(sensorial) and tibial motor nerves.
Design. An experimental study was conducted in which the participants wererandomly assigned to 1 of 3 intervention groups (n�12 per group). Independentvariables were cold modality and pre- and post-cooling measurement time. Depen-dent variables were skin temperature and nerve conduction parameters.
Methods. Thirty-six people who were healthy, with a mean (SD) age of 20.5 (1.9)years, participated in the study. Each group received 1 of the 3 cold modalities,applied to the right calf region for 15 minutes. Skin temperature and nerve conduc-tion parameters were measured before and immediately after cooling.
Results. All 3 modalities reduced skin temperature (mean�18.2°C). There alsowas a reduction in amplitude and an increase in latency and duration of the com-pound action potential. Ice massage, ice pack, and cold water immersion reducedsensory nerve conduction velocity (NCV) by 20.4, 16.7, and 22.6 m/s and motor NCVby 2.5, 2.1, and 8.3 m/s, respectively. Cold water immersion was the most effectivemodality in changing nerve conduction parameters.
Limitations. The cooling area of the ice massage and ice pack was smaller thanthat of the cold water immersion. The examiner was not blinded to the treatmentgroup. The population included only participants who were healthy and young.
Conclusions. All 3 modalities were effective in reducing skin temperature andchanging sensory conduction at a physiological level that is sufficient to induce ahypoalgesic effect. The results suggest that cold water immersion, as applied in thisstudy, is the most indicated modality for inducing therapeutic effects associated withthe reduction of motor nerve conduction.
E. Herrera, PT, MS, is a PhD stu-dent in the Program of Physiolog-ical Sciences, Federal University ofSao Carlos, Sao Carlos, Brazil, andTitular Professor, Department ofPhysical Therapy, Universidad In-dustrial de Santander, Ciudad Uni-versitaria, Carrera 27 Calle 9, Bu-caramanga, Santander, Colombia.Address all correspondence to MsHerrera at: [email protected].
M.C. Sandoval, PT, PhD, is Associ-ate Professor, Department ofPhysical Therapy, Universidad In-dustrial de Santander.
D.M. Camargo, MS, is AssociateProfessor, Department of PhysicalTherapy, Universidad Industrial deSantander.
T.F. Salvini, PT, PhD, is Titular Pro-fessor, Department of PhysicalTherapy, Federal University of SaoCarlos.
[Herrera E, Sandoval MC, Ca-margo DM, Salvini TF. Motor andsensory nerve conduction are af-fected differently by ice pack, icemassage, and cold water immer-sion. Phys Ther. 2010;90:581–591.]
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April 2010 Volume 90 Number 4 Physical Therapy f 581
Cryotherapy is the therapeuticapplication of a substance toremove body heat, resulting
in diminished tissue temperature.1,2
It often is used in sports and rehabil-itation settings during the immediateand rehabilitative phases of injurymanagement.3 Reduced tissue tem-perature, blood flow, and cellularmetabolism are some of the physio-logical effects of cryotherapy.2–8
Cryotherapy also reduces nerve con-duction velocity (NCV) in the sen-sory and motor nerves9,10 and has acontroversial effect on musclestrength (force-generating capaci-ty).11–13 These physiological changeslead to some therapeutic effectssuch as a reduction in pain and mus-cle spasm and the prevention ofposttraumatic edema.1–13
Various modalities are frequentlyused to deliver cryotherapy treat-ment. The efficacy of cooling de-pends on the method, applicationtime, and treatment area and the in-dividual’s physical activity level im-mediately before or after the inter-vention.14 Overall, crushed ice pack,ice massage, and cold water immer-sion are considered the most effec-tive clinical modalities for reducingtissue temperature.14–17 The efficacyof the cryotherapy modalities hasbeen assessed by comparing their ca-pacity to decrease intramuscular,18
intra-articular,19 and skin tempera-ture10,14–17,20,21 and to maintain thetemperature changes. Skin tempera-ture measurement has been widelyused because it is a simple and non-invasive procedure. Some authors,
based on skin temperature measure-ments, have hypothesized that skintemperature changes are closely re-lated to changes in subcutaneousand intramuscular temperature.10,15–17
However, the study by Jutte et al,22
which used a multiple regressionmodel, showed that skin tempera-ture was a weak predictor of intra-muscular temperature because itexplained only 21% of temperaturevariance within the muscle. The in-fluence of subcutaneous and muscu-lar tissue thickness on the coolingof deeper tissues also has beendebated.23,24
A more precise way of analyzing theefficacy of cryotherapy modalitieswould be to compare their effects ondeep tissues directly associated withclinical intervention using quantita-tive, direct, and reliable measure-ment. For example, nerve fibers aretargeted for cryotherapy interven-tion to reduce muscle pain andspasm,3 and the changes attributedto cooling can be identified throughnerve conduction studies (NCS) inwhich reliability has been estab-lished previously.25
Prior electrophysiological studieshave determined a direct linear rela-tionship between skin temperatureand NCV and an inverse relationshipwith latency, amplitude, and dura-tion of compound action poten-tial.26–30 Nevertheless, this relation-ship varies according to the type ofnerve fiber. Sensory nerves can showa reduction of 1.4 to 2.6 m/s forevery degree of skin temperature re-duction, whereas motor NCV can de-crease by 1.1 to 1.5 m/s/°C.1 Thereare other factors that affect the rela-tionship between skin temperatureand NCV, such as the depth of thenerve, the amount of surroundingsubcutaneous tissue, age, range oftemperature variation,27–30 and pos-sibly the type of modality used toalter skin temperature.
In the literature, there is a lack ofstudies comparing the effects of thedifferent cold modalities on motorand sensory nerve conduction pa-rameters. We found only one study31
that established a greater effect ofcold packs compared with gel packson reducing ulnar motor NCV. How-ever, this study did not analyze theeffect of these modalities on sensorynerve conduction. Therefore, it isimportant to compare the effective-ness of the different cryotherapy mo-dalities on motor and sensory nerveconduction to provide physiologicalparameters that contribute to the in-dication of the most adequate modal-ity according to the desired thera-peutic effect.
Considering that each cold modalityhas a different capacity to cool theskin and subcutaneous tissues andthat nerve fiber conduction is af-fected by skin temperature changes,the hypothesis of this study was thatcryotherapy protocols with differentcharacteristics should have differenteffects on sensory and motor nerveconduction. The purpose of thisstudy was to compare the effects of 3commonly used therapeutic coldmodalities (ice pack, ice massage,and cold water immersion) on theconduction parameters of the suralnerve and tibial motor nerve in par-ticipants who were healthy.
MethodResearch DesignAn experimental study was con-ducted with 3 randomly assigned in-tervention groups. The independentvariables were cold modality type(ice pack, ice massage, and waterimmersion) and measurement time(pre- and post-cooling). The depen-dent variables were skin tempera-ture (degrees Celsius) and nerve con-duction parameters: NCV (meters persecond), latency and duration (milli-seconds), amplitude of compoundmuscle (millivolts), and sensory ac-tion potentials (microvolts).
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Cold Modalities and Nerve Conduction
582 f Physical Therapy Volume 90 Number 4 April 2010
ParticipantsThe participants were informed ofthe experimental procedures andthe risks involved with the study andsigned a consent form. Thirty-sixparticipants who were healthy (18women and 18 men) were enrolledin this study. The participants’ mean(SD) age, mass, height, and bodymass index were 20.5 (1.9) years,60.2 (8.4) kg, 1.63 (0.1) m, and 22.4(1.6) kg/m2, respectively.
The sample size for each cold modal-ity group was determined throughthe application of the sampsi com-mand of Stata 9.0 software.* The fol-lowing design specifications weretaken into account: ��.05; (1��)�0.9; ratio�1:1; and method ofcalculation�analysis of covariance(ANCOVA) for repeated measure-ments, with a baseline measurementand a final measurement. The corre-lation between the initial and finalmeasurements was r�.2. Thismethod defined a sample of 10 to 12participants for each cold modalitygroup.
All participants filled out a healthquestionnaire that indicated thepresence of any of the following ex-clusion criteria: history of alcoholismor smoking, peripheral vascular orcardiovascular disease, diabetes,neurological or skeletal muscle dis-orders, recent trauma or injury to theright leg, local hot or cold insensitiv-ity, cold adverse reactions, Raynaudphenomenon, and pregnancy. Addi-tionally, the participants were askedto avoid eating and drinking anystimulants (eg, alcohol, caffeine,chocolate) 2 hours before the inter-vention and to not exercise for atleast 4 hours before intervention.These exclusion criteria and recom-mendations were considered accord-ing to previous studies.10,31
InstrumentsSkin temperature was measured us-ing an infrared thermometer (RaytekST PRO†) that displays a precisionof 1°C, high reliability (intraclass cor-relationcoefficient�.97), validity (r�.92), and responsiveness (change in-dex�4.2). Nerve conduction measure-ments were acquired using a NicoletCompass Meridian System‡ and stan-dard surface electrodes from thesame manufacturer. The selection ofcold modalities was based on theirhigh effectiveness in reducing skintemperature and their frequent ap-plication in the clinical setting.14–17
The ice pack consisted of 279 g ofcrushed ice in a plastic bag of 18 � 8cm without air. Ice massage was ap-plied by using an ice block of 279 gwith dimensions of 8 � 10 � 5 cm.Water immersion was conducted inan acrylic container of 20 � 35 � 30cm, filled with water and crushed iceuntil the water temperature reachedapproximately 10°C, as reported pre-viously.17,20 The temperature of thismodality was measured throughoutthe intervention, showing an initialmean of 8.9 (1.0)°C and a final meanof 7.8 (1.2)°C.
ProcedureThe participants were randomly as-signed to 1 of 3 cold modality groupsby using a computer-generated ran-dom number sequence.32 Further-more, to minimize the influence ofthe circadian cycle on body temper-ature regulation, all participants re-ceived the cold modality at the sametime (eg, 2–6 PM). The interventionand measurement procedures wereperformed on the right calf of eachparticipant. Given that the post-cooling measurement had to betaken immediately after the coldmodality application, the same roomwas used for the application of inter-
vention and for the measurementprocedures. Room temperature wasmaintained at 24 (0.08)°C, and therewere no significant variations duringthe tests (P�.29).
Before the experimental protocol,the participants were asked whetherthey had followed the recommenda-tions regarding stimulant intake andexercise. Their height and weightwere recorded to calculate the bodymass index. The participants woreT-shirts and shorts and, for acclima-tization, assumed the prone positionon the standard examining table for15 minutes. During the acclimatiza-tion time, the treatment area to becooled was determined and the elec-trodes for NCS were placed.
Cold modalities. The cold modal-ities were applied for 15 consecutiveminutes by the same trained physicaltherapist (M.C.S.). This duration isfrequently used for treatments be-cause it is sufficient to achieve ther-apeutic effects and it avoids compli-cations from cold modalities.21,33
The ice massage and the ice packwere applied to a previously deter-mined rectangular area (18 � 8 cm)on the calf (Fig. 1). The ice pack wasapplied directly to the skin and with-out compression. The ice massagewas applied by continuous longitudi-nal displacements. For the cold wa-ter immersion, the participants re-mained seated while immersing theright leg as far as the top border ofthe rectangle determined for the pre-vious modalities (Fig. 1). At the endof intervention, the leg was quicklydried without friction, and the par-ticipant returned to the prone posi-tion for the post-cooling measure-ment. All participants completed theexperimental protocols without ad-verse reactions to the cold.
Skin temperature measurement.Skin temperature was measured im-mediately before (pre-cooling) andafter (post-cooling) the cold modal-
* StataCorp LP, 4905 Lakeway Dr, College Sta-tion, TX 77845.
† Raytek Corp, 1201 Shaffer Rd, Santa Cruz,CA 95061.‡ Nicolet Biomedical Co, 5225 Verona Rd #2,Fitchburg, WI 53711-4497.
Cold Modalities and Nerve Conduction
April 2010 Volume 90 Number 4 Physical Therapy f 583
ity application. The temperature wasmeasured at the center of the previ-ously defined rectangle (Fig. 1) withan infrared thermometer placed in aperpendicular position and kept asclose as possible to the skin withouttouching.
Nerve conduction measurement.Compound action potentials result-ing from stimulation of the posteriortibial motor and sural nerves wererecorded twice, before and aftercooling, according to standardizedtechniques described by Oh.34 These
nerves were selected because theyare located within the treatmentarea. Furthermore, the posterior tib-ial nerve has a high quantity of motorfibers, and the sural nerve is a puresensory nerve,26,34 allowing the as-sessment of the cooling effects inboth motor and sensory fibers.
Nerve conduction studies were ob-tained by the same examiner (E.H.).In order to reduce technical varia-tions, the stimulation and record-ing sites were delimited with apermanent ink marker during the
pre-cooling measurement, and therecording electrodes were not re-moved during the intervention, ex-cept in the participants who re-ceived cold water immersion. In thiscase, the recording electrodes wereremoved after the pre-cooling mea-surement and replaced at the sitespreviously marked for the post-cooling measurement.
Before the NCS measurement, theparticipants were instructed to avoidleg movements. The sural nerve re-cordings were obtained with abandwidth of 20 Hz to 3 kHz, a gainof 20 �V per division, and a sweepspeed of 1 millisecond per division.The surface bar recording electrodewas placed immediately behind thelateral malleolus and the stimulat-ing electrode, was placed about14 cm proximal to the active re-cording electrode, just lateral to themidline of the width of the calf mus-cle34 (Fig. 2A). Stimuli were 100-microsecond rectangular pulses, withamplitude adjusted slightly higherthan needed to ensure a maximumresponse. The nerve signals were ob-tained by averaging 20 responses.The following sensory nerve param-eters were measured: NCV, peak la-tency, peak-to-peak amplitude, andduration (onset to end of negativewave) of the compound sensory ac-tion potential.
The tibial motor nerve recordingswere obtained with a bandwidth of2 Hz to 10 kHz, a gain of 2 mV perdivision, and a sweep speed of 2 mil-liseconds per division. The activedisc recording electrode was placedover the abductor hallucis muscle,and the reference disc recordingelectrode was placed at the base ofthe big toe. The ground electrodewas positioned on the calf muscle.The distal stimulation site was on theankle immediately behind the medialmalleolus, and the proximal stimula-tion site was on the knee on themedial aspect of the knee crease34
Figure 1.Cooling area. Ice pack and ice massage were applied to the same rectangular areadefined according to the following procedure: (a) measurement of the length of the legbetween the head of the fibula (1) and the lateral malleolus (2); (b) definition of themidpoint between the head of the fibula and the lateral malleolus (3); (c) projection ofa perpendicular line to the posterior part of the leg, marking the midpoint of the calf(4); and (d) placement of the center of an acetate mold in the midpoint of the calf tomark a rectangle (18 � 8 cm) where the ice pack and ice massage would be applied.For the cold water immersion, the participants immersed their right leg in a cold watertank as far as the top border of the rectangle (5).
Figure 2.Stimulation and recording electrode sites for the sural nerve and tibial motor nerveconduction studies. (A) Sural nerve: antidromic technique was performed. (B) Tibialmotor nerve: distal stimulation on the medial malleolus and proximal stimulation on themedial aspect of the knee crease (not shown). S�stimulation site, R�recording site, andG�ground electrode.
Cold Modalities and Nerve Conduction
584 f Physical Therapy Volume 90 Number 4 April 2010
(Fig. 2B). The following motor nerveparameters were measured: NCVfor the nerve segment between an-kle and knee, distal latency, ampli-tude, and duration of the negativewave of the compound muscle ac-tion potential.
Intrarater reliability of sural andtibial motor NCS. Before data col-lection, we assessed intrarater reli-ability of the tibial motor and suralnerve recordings in 20 participantsfollowing the same recording tech-niques described above. The sameexaminer who performed the assess-ments of the current study testedeach participant twice on 2 separatedays with a minimum 8-day lapse be-tween the measurements.25
Statistical ProceduresIntrarater reliability of nerve conduc-tion parameters was evaluated usingthe Bland-Altman method.35 Datawere reported as mean difference(95% limits of agreement). For thepresent study, descriptive statisticswere used to summarize the charac-teristics of the population, the skintemperature, and nerve conductiondata, which are presented as mean(SD). The baseline characteristics ofthe cold modality group participantswere compared using analysis ofvariance (ANOVA) and a chi-squaretest, depending on the scale of mea-surement of each variable.32 Themeasurements obtained before andafter cooling were compared using apaired t test because the normal dis-tribution of all variables was provenby the Shapiro-Wilk test.32,36 In addi-tion, an ANCOVA37 compared the ef-fects of the 3 modalities of skin tem-perature and the nerve conductionparameters using the ice massagegroup as reference. For the statisticalanalysis, the Stata 9.0 software wasused, with a significance level of��.05.
ResultsIntrarater Reliability of NCSThe intrarater analysis showed meandifferences close to zero, and therewas no evidence of systematic error.The mean differences (95% limits ofagreement) for the sural nerve pa-rameters were: latency�0.17 milli-second (�0.73, 1.07), NCV��0.07m/s (�4.48, 4.33), amplitude��2.9�V (�20.73, 14.95), and dura-tion�0.04 millisecond (�0.3,0.37).25 Respective data for the tibialmotor nerve parameters were: laten-cy�0.23 millisecond (�1.10, 1.56),NCV��0.32 m/s (�6.20, 5.53), am-plitude��0.1 mV (�4.30, 4.10),and duration�0.36 millisecond(�0.91, 1.63) (unpublished data).
Effects of Cold Modalities onSkin Temperature and NerveConduction ParametersA total of 39 potential participantswere assessed for eligibility; 2 didnot meet inclusion criteria, and 1was not assisted to the experimentalsession. Twelve participants wererandomly allocated to each experi-mental group (Fig. 3). There were nosignificant differences in baselinecharacteristics among the cold mo-dality group participants (P�.05)(Tab. 1). There was a decrease inskin temperature after the applica-tion of the 3 modalities (P�.0001)(Tab. 2). The ice massage caused agreater decrease in skin temperaturecompared with the ice pack(��3.03, P�.001) and the cold wa-ter immersion (��9.36, P�.0001).All 3 modalities induced an increasein latency and duration of the com-pound action potential of the suraland tibial motor nerves (P�.05).There also was a reduction in theamplitude of the potentials and theNCV (P�.05) (Tabs. 3 and 4). Theeffect of the cold water immersionon all motor nerve parameters, aswell as on amplitude and duration ofsural nerve potential, was differentand greater compared with the ef-fect of ice massage (Tab. 5). There
were no differences between the ef-fects of the ice pack and ice massageon the motor and sensory conduc-tion parameters (P�.05) (Tab. 5).
DiscussionThe 3 cold modalities resulted in sig-nificant changes in every sural nerveparameter, except cold water im-mersion in amplitude (Tab. 4). Meandifferences among parameters deter-mined before and after cooling weregreater than those determined inthe intrarater reliability analysis. Theeffects of ice massage and ice packon the tibial motor nerve parameterswere more subtle (Tab. 3). Althoughlatency and duration differenceswere statistically significant for theeffect of ice pack intervention on thetibial motor nerve, mean differenceswere lower or similar to those deter-mined in the intrarater reliabilityanalysis for this nerve. However, it isimportant to note that assessmentsafter ice pack and ice massage pro-tocols did not require the removal ofelectrodes, which usually is the mainsource of error in NCS. Mean differ-ences in tibial motor nerve parame-ters from cold water immersionwere greater than those determinedin the intrarater reliability analysis.Therefore, we believe that the motorand sensory nerve conductionchanges determined for each modal-ity were a real consequence of cool-ing rather than error in measurementmethods.
The results of this study support theproposed hypothesis because thecold modalities applied have differ-ent effects on motor and sensorynerve conduction. The modality ofcold water immersion, as applied inthis study, had the greatest effecton the conduction parameters, espe-cially of the tibial motor nerve(Tab. 5). The modalities of ice packand ice massage, as applied in thisstudy, differed substantially from thecold water immersion. First, the icemassage and ice pack were applied
Cold Modalities and Nerve Conduction
April 2010 Volume 90 Number 4 Physical Therapy f 585
to the same calf area (44 cm2),whereas the area/volume covered bycold water immersion was muchgreater, including the calf, ankle, andfoot regions where the nerve be-comes more superficial and thus
more susceptible to cooling. Second,these modalities also have thermo-dynamic differences: in the ice mas-sage and ice pack modalities, heatexchange occurs by conduction,whereas cold water immersion in-
volves conduction and convectionprocesses.1 Our results can be ex-plained mainly by the differences inthe area/volume, and this parameterof the cold modalities may contrib-ute to a greater cooling effect on the
Figure 3.Flow of participants through the study.
Table 1.Demographic Characteristics of the Participantsa
Body mass index (kg/m2) 22.2 (1.6) 22.3 (1.4) 22.6 (1.7) .81
a Data are presented as mean (SD), except for the number and percentage of female participants.
Cold Modalities and Nerve Conduction
586 f Physical Therapy Volume 90 Number 4 April 2010
subcutaneous tissues, including theperipheral nerve. Future studies areneeded to compare the effects of thecold modalities on nerve conductionwith different thermodynamic prop-erties applied to an area of similarmagnitude.
Paradoxically, cold water immersionwas the modality that caused theleast skin temperature reduction(Tab. 2), possibly due to the fact thata greater area received the treat-ment, leading to a faster activation ofthe thermoregulatory responses thatprotect the body from abrupt tem-perature changes.38 Consequently,skin temperature was quickly stabi-lized and did not adequately reflectthe effects of cooling on subcutane-ous tissues.22
The cooling induced by the 3 modali-ties was effective in reducing the NCVand prolonging the latency and dura-tion of the compound muscle and sen-sory action potentials (Tabs. 3 and 4).The effects of temperature reductionon nerve conduction parameters arewell described in the literature27–30
and may result from the changes in thestructure of the axonal membrane39
and from the conductance of thevoltage-sensitive sodium and potas-sium channels.27 Therefore, the coldreduces the nerve membrane current,which lengthens the refractory peri-ods following a stimulus; as a result,the duration of the nerve action poten-tial increases and the rate of impulsetransmission decreases.
In the scientific literature, the rela-tionship between the amplitude ofcompound action potential and tem-perature remains a controversial is-sue. Some studies that analyzed theeffect of temperature changes onconduction parameters showed anegative relationship,40,41 whereasother authors did not identify thisrelationship.27 In the present study,cold water immersion significantlyreduced the amplitude of compoundmuscle action potential (Tab. 3).Similarly, the ice massage and the icepack reduced the amplitude of sen-sory compound action potential(Tab. 4). Perhaps the differences be-tween the results of the presentstudy and those of previous stud-ies27,40,41 are due to the differencesin the skin temperature changes. Inprevious studies,27,40,41 skin temper-ature decreased only from 33.6°C to22.5°C, whereas in the present study,the cooling induced by all modalitieswas greater (from 31.6°C to 4°C).
The amplitude of the compound ac-tion potential represents the numberof nerve fibers that responds to anappropriate electrical stimulus.34
Therefore, the reduction of this pa-rameter after the cold modality appli-cation could suggest an increase in theactivation threshold of some nerve fi-bers, as well as a block of the fibersthat are more sensitive to cooling. Ad-ditionally, the increase in the durationof the compound action potential is anindicator of alteration in the dischargesynchronization of nerve fibers.34
The physiological mechanisms of thehypoalgesic effect of cryotherapyhave not yet been completely eluci-dated. Different hypotheses havebeen proposed: (1) closing of thepain gate, (2) counter-irritant effectthat activates inhibitory controlmechanisms, (3) increase in the acti-vation threshold of nociceptors, and(4) participation of descending path-ways of the central nervous systemthat modulate pain by releasing en-dogenous opiates. It also has beensuggested that the hypoalgesic effectof cryotherapy could be related to anincrease in pain threshold and paintolerance associated with a decreasein NCV.9 We suggest that the inacti-vation of some nerve fibers, which isevident in the decrease in compoundaction potential amplitude, as well asthe change in the synchronizationresponse of these fibers could beother important physiological mech-anisms for the hypoalgesic effect ofcryotherapy. Studies are needed toinvestigate this hypothesis.
Although the present study did notinclude specific pain measurements,the results for the 3 modalities sug-gest that the hypoalgesic effect ofcryotherapy may be producedmainly by the reduction in sensoryfiber conduction because the cool-ing effect on the conduction param-eters was usually greater in the sen-sory nerve than in the motor nerve(Tabs. 3 and 4). Ice massage, icepack, and cold water immersion re-duced sural NCV by 37.9%, 31.9%,
Table 2.Skin Temperature in Participants Submitted to Different Cold Modalitiesa
Cold water immersion 31.55 (0.89) 13.32 (1.33) �18.23 (1.46)c
a Data are presented as mean (SD).b Difference�post-cooling � pre-cooling.c P�.0001.
Cold Modalities and Nerve Conduction
April 2010 Volume 90 Number 4 Physical Therapy f 587
Tab
le3.
Para
met
ers
ofTi
bial
Mot
orN
erve
Con
duct
ion
Befo
rean
dA
fter
Col
dM
odal
ityA
pp
licat
iona
Ner
veC
on
du
ctio
nP
aram
eter
Ice
Mas
sag
eIc
eP
ack
Co
ldW
ater
Imm
ersi
on
Pre
-co
oli
ng
Po
st-c
oo
lin
gD
iffe
ren
ceb
Pre
-co
oli
ng
Po
st-c
oo
lin
gD
iffe
ren
ceP
re-c
oo
lin
gP
ost
-co
oli
ng
Dif
fere
nce
Late
ncy
(ms)
3.47
(0.4
3)[3
.19,
3.74
]3.
62(0
.46)
[3.3
2,3.
91]
0.15
(0.1
7)c
[0.0
4,0.
26]
3.82
(0.6
0)[3
.44,
4.21
]4.
02(0
.63)
[3.6
1,4.
42]
0.19
(0.1
4)c
[0.1
0,0.
28]
3.61
(0.5
5)[3
.26,
3.96
]6.
99(0
.93)
[6.4
0,7.
58]
3.38
(0.7
3)d
[2.9
2,3.
85]
Mot
orne
rve
cond
uctio
nve
loci
ty(m
/s)
49.6
7(3
.31)
[47.
56,
51.7
7]47
.17
(3.1
1)[4
5.20
,49
.14]
�2.
50(1
.31)
c
[�3.
34,
�1.
67]
49.5
8(3
.73)
[47.
21,
51.9
5]47
.50
(2.8
1)[4
5.71
,49
.29]
�2.
08(1
.56)
d
[�3.
08,
�1.
09]
49.0
0(3
.59)
[46.
72,
51.2
8]40
.67
(2.8
4)[3
8.86
,42
.47]
�8.
33(2
.19)
c
[�9.
72,
�6.
94]
Am
plit
ude
(mV)
14.9
(4.0
0)[1
2.36
,17
.44]
14.0
4(3
.98)
[11.
51,
16.5
7]�
0.86
(1.7
7)[�
1.99
,0.
27]
16.7
2(2
.70)
[15.
00,
18.4
3]16
.12
(2.8
0)[1
6.12
,14
.34]
�0.
60(1
.04)
[�1.
26,
0.06
]15
.63
(3.0
4)[1
3.69
,17
.56]
12.5
3(3
.06)
[10.
58,
14.4
7]�
3.09
(3.2
0)c
[�5.
13,
�1.
06]
Dur
atio
n(m
s)5.
39(0
.50)
[5.0
7,5.
70]
5.74
(0.5
8)[5
.37,
6.11
]0.
35(0
.26)
c
[0.1
8,0.
52]
5.63
(1.0
4)[4
.96,
6.29
]6.
00(1
.01)
[5.3
6,6.
64]
0.38
(0.1
6)d
[0.2
7,0.
48]
5.46
(0.6
7)[5
.03,
5.88
]8.
64(1
.49)
[7.7
0,9.
59]
3.18
(1.3
7)c
[2.3
1,4.
05]
aD
ata
are
pre
sent
edas
mea
n(S
D)
[95%
confi
denc
ein
terv
al].
bD
iffer
ence
�p
ost-
cool
ing
�p
re-c
oolin
g.c
P�.0
5.d
P�.0
001.
Tab
le4.
Para
met
ers
ofSu
ralN
erve
Con
duct
ion
Befo
rean
dA
fter
Col
dM
odal
ityA
pp
licat
iona
Ner
veC
on
du
ctio
nP
aram
eter
Ice
Mas
sag
eIc
eP
ack
Co
ldW
ater
Imm
ersi
on
Pre
-co
oli
ng
Po
st-c
oo
lin
gD
iffe
ren
ceb
Pre
-co
oli
ng
Po
st-c
oo
lin
gD
iffe
ren
ceP
re-c
oo
lin
gP
ost
-co
oli
ng
Dif
fere
nce
Late
ncy
(ms)
2.93
(0.2
7)[2
.76,
3.11
]4.
62(1
.21)
[3.8
5,5.
39]
1.68
(1.0
4)c
[1.0
2,2.
35]
3.17
(0.3
3)[2
.96,
3.38
]4.
50(0
.71)
[4.0
5,4.
95]
1.33
(0.6
0)d
[0.9
5,1.
71]
3.08
(0.3
8)[2
.84,
3.32
]5.
39(0
.70)
[4.9
5,5.
83]
2.31
(0.3
8)d
[2.0
7,2.
55]
Sens
ory
nerv
eco
nduc
tion
velo
city
(m/s
)53
.92
(2.8
4)[5
2.11
,55
.72]
33.5
0(5
.76)
[29.
84,
37.1
6]�
20.4
2(5
.96)
c
[�24
.20,
�16
.63]
52.4
2(4
.27)
[49.
70,
55.1
3]35
.67
(6.9
1)[3
1.28
,40
.05]
�16
.75
(5.5
3)c
[�20
.26,
�13
.24]
54.0
8(4
.56)
[51.
18,
56.9
8]31
.50
(2.7
1)[2
9.78
,33
.22]
�22
.58
(2.3
5)c
[�24
.08,
�21
.09]
Am
plit
ude
(�V)
39.2
9(1
2.18
)[3
1.55
,47
.03]
18.9
5(1
1.30
)[1
1.77
,26
.13]
�20
.34
(9.5
4)d
[�26
.40,
�14
.28]
39.9
7(1
1.31
)[3
2.78
,47
.15]
24.8
6(1
2.32
)[1
7.03
,32
.69]
�15
.11
(11.
10)c
[�22
.16,
�8.
05]
40.7
9(1
4.85
)[3
1.36
,50
.22]
44.1
8(1
4.49
)[3
4.97
,53
.39]
3.39
(7.9
9)[�
1.69
,8.
47]
Dur
atio
n(m
s)1.
26(0
.10)
[1.2
0,1.
32]
1.40
(0.1
7)[1
.30,
1.50
]0.
14(0
.14)
c
[0.0
5,0.
23]
1.38
(0.1
5)[1
.28,
1.47
]1.
53(0
.19)
[1.4
0,1.
64]
0.15
(0.1
1)c
[0.0
8,0.
22]
1.33
(0.1
4)[1
.23,
1.42
]2.
68(0
.20)
[2.5
5,2.
80]
1.35
(0.1
7)d
[1.2
4,1.
46]
aD
ata
are
pre
sent
edas
mea
n(S
D)
[95%
confi
denc
ein
terv
al.
bD
iffer
ence
�p
ost-
cool
ing
�p
re-c
oolin
g.c
P�.0
5.d
P�.0
001.
Cold Modalities and Nerve Conduction
588 f Physical Therapy Volume 90 Number 4 April 2010
and 41.8%, respectively. In contrast,these modalities reduced tibial mo-tor NCV by only 5.0%, 4.2%, and17.0%, respectively. It is difficult tocompare these results with those ofprevious studies9,31 because of thedifferent intervention protocols andanalyzed nerves. Algafly and George9
applied an ice pack for a mean timeof 26 minutes and obtained a skintemperature of 10°C and a 33% re-duction in sensory plantar NCV.McMeeken et al31 used an ice packfor 15 minutes and obtained a skintemperature of 5.6°C and an approx-imate reduction of 13% in ulnar mo-tor NCV. Even though these studiesmeasured different nerves, in a broadsense they corroborate the results ofthe present study, which demon-strated a greater cooling effect onthe sensory fibers than on the motorfibers. The greater sensibility of thesensory fibers to cooling may be dueto their more superficial locationcompared with the motor fibers,which would explain why the func-tional effects of cryotherapy on sen-sibility42 are more pronounced thanthe effects on muscle function.12
The depression of sensory and motorNCV derived from cooling modalitiesalso may indicate the risks of delete-rious effects associated with pro-longed icing, such as skin burn andsuperficial nerve damage. Previousstudies33,43 have shown cases ofnerve palsy resulting from ice appli-cation near the subcutaneous course
of nerves. The consequent disabilitywas transient (1–4 days) or pro-longed (4–6 months), with all pa-tients eventually reaching full recov-ery. The application of cryotherapyis typically safe and beneficial if theprotocol is appropriate and suffi-ciently monitored. However, clini-cians must be aware of the locationof major peripheral nerves, the thick-ness of the overlying subcutaneousfat, the method of application, theduration of tissue cooling, and thesurface area covered.33,43
The results of the comparison ofthe effects of the 3 cold modalitieson conduction parameters show thatthe cold water immersion protocolused in this study, although neitherthe most comfortable modality forthe participant nor the easiest to ap-ply, may be the most indicated forgreater therapeutic effect mediatedby the change in motor conduction(eg, in muscle spasm and spasticity[hypertonicity]). In contrast, the hy-poalgesic effect could be inducedby any of the 3 assessed modalities.Cold water immersion was more ef-ficient in changing some parametersof sensory conduction, but the appli-cation of the 3 modalities loweredskin temperature to less than 13.6°Cand reduced NCV by more than10%. As suggested in previous stud-ies,10,17 these changes could be asso-ciated with the hypoalgesic effect ofcryotherapy.
The present study had some method-ological limitations that restrict thegeneralization of the results. Thecooling area of the ice massage andice pack was small compared withthat of the cold water immersion andpossibly smaller than those used inthe clinical setting. The study samplecomprised only young participantswho were healthy, and the responsesmight have been different in olderadults and individuals with clinical dis-orders. The time used for each modal-ity (15 minutes) also may have beeninsufficient to induce greater effectson the motor nerve, especially in thecase of the ice pack and the ice mas-sage, which were applied to restrictedareas. Considering that the nerve con-duction evaluations were taken imme-diately before and after the cold mo-dality application, the examiner wasnot blinded to the treatment group.This fact may limit the internal validityof the study. Subsequent studies areneeded to determine the functionalrelevance of changes in nerve conduc-tion induced by the cold modalities onsensibility and muscle strength, as wellas the clinical importance of thesechanges. The present study contrib-utes to the literature because, to ourknowledge, it is the first study compar-ing the effect of 3 modalities fre-quently used in clinical practice on theparameters of motor and sensorynerve conduction.
Table 5.Effects of Cold Modalities on Nerve Conduction Parameters (Analysis of Covariance, Using the Ice Massage Group as Reference)
Parameter
Tibial Motor Nerve Sural Nerve
Ice Pack Cold Water Immersion Ice Pack Cold Water Immersion
April 2010 Volume 90 Number 4 Physical Therapy f 589
ConclusionsIce massage, ice pack, and cold wa-ter immersion were effective in re-ducing skin temperature and chang-ing most of the motor and sensoryconduction parameters, with greatereffects on the sensory nerve. Coldwater immersion, as applied in thisstudy, was the most effective modal-ity in changing nerve conduction,especially in the tibial motor nerve.Our results can be considered clini-cally relevant and contribute to theinformed choice of a cryotherapymodality based on the desired phys-iological and therapeutic effects.
All authors provided concept/idea/researchdesign, writing, and consultation (includingreview of manuscript before submission).Ms Herrera and Dr Sandoval provided datacollection. Ms Herrera, Dr Sandoval, and MsCamargo provided data analysis. Ms Herreraprovided project management and partici-pants. Dr Salvini provided facilities/equipment.
The study protocol was approved by the In-stitutional Ethics Committee of UniversidadIndustrial de Santandar. The study followedthe Declaration of Helsinki.
Ms Herrera acknowledges Coordenacao deAperfeicoamento de Pessoal de Nıvel Supe-rior (CAPES, Brazil) for providing her doc-toral grant.
This article was received April 22, 2009, andwas accepted December 6, 2009.
DOI: 10.2522/ptj.20090131
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