The Effects of Cryotherapy Applied Through Various Barriers

Journal of Sport Rehabilitation, 1997, 6,343-354
O 1997 Human Kinetics Publishers, Inc.
The Effects of Cryotherapy Applied
Through Various Barriers
Kavin K.W. Tsang, Barton P. Buxton, W. Kent Guion,
A. Barry Joyner, and Kathy D. Browder
The purpose of this study was to investigate the differences in skin temperature during ice application through a dry towel and a dry elastic bandage compared to application on bare skin. Nine subjects completed a 30-min treatment
session that consisted of 0.68 kg of cubed ice applied under three conditions:
through a dry towel, through a dry elastic bandage, and directly on the skin
(control). Following the removal of the ice, all subjects were monitored for
20-min for skin temperature (S temp). There was a significant interaction in S
temp between the control (12.50 f 4.39 "C) and dry towel (23.48 2.88 "C)
conditions, the control (12.50 4.39 "C) and dry elastic wrap (27.47 2.36
"C) conditions, and the dry towel (23.48 f 2.88 "C) and dry elastic wrap (27.47
f 2.36 "C) conditions. The findings indicated that using a barrier (dry towel or
dry elastic bandage) limits the temperature-reducing capacity of the ice and
therefore its potential physiological effects.
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Cryotherapy has become the most widely accepted method of treating acute
athletic injuries (8, 11, 12, 20, 23). Although injuries may vary in severity, the
most common characteristics of trauma or injury are pain, inflammation, and loss
of function. Due to the characteristics of acute trauma, cryotherapy is often used in
conjunction with various compression or immobilization techniques, dressings, or
bandages (1 1, 12,27,28).
Cryotherapy can be used as an effective tool in the management of musculoskeletal injuries, both in the immediate care of trauma and during rehabilitation.
The application of cooling agents is specifically indicated in the treatment of pain
(acute, subacute, and chronic), muscle spasm, spasticity, edema, inflammation,
and fever and for the control of bleeding (11, 12,28.)
The term cryotherapy indicates a broad range of therapeutic applications of
ice or cold agents. Knight described cryotherapy as the "therapeutic application of
The authors are with Georgia Southern University, Department of Health & Kinesiology, Statesboro, GA 30460. Direct correspondence to Barton P. Buxton.
Tsang, Buxton, Guion, ef al.
344
any substance to the body which results in the withdrawal of heat from the body"
(11, 12). The ability of ice to remove heat is referred to as heat abstraction or
cooling. Therefore, the application of a cooling agent will significantly lower temperatures of the skin and underlying tissues (3, 11, 12, 14,26,3 1).
This mechanistic response to cooling decreases the metabolism (i.e., decreases the need for oxygen) of the underlying tissue, which reduces secondary
hypoxia, increases the healing rate, and facilitates a quicker recovery (11, 12, 22,
27,28). Cooling also reduces (analgesic) or potentially eliminates (anesthetic) the
conductive velocities of sensory and motor nerves (11, 12, 22, 27, 28), thus providing pain relief.
According to Starkey (28), the therapeutic application of cold ranges in temperature from 0 to 18.3 "C (32-65 OF). However, the literature indicates that the maximum decreases in localized blood flow can occur at temperatures ranging from 12.83
"C (9) to 15 "C (13). Furthermore, the literature supports a range of 13.6-15.6 "C for
optimal analgesic effects (3). To accomplish cooling within the "therapeutic range,"
most practitioners commonly employ ice bags (crushed or cubed), commercial ice
packs, ice cups (ice massage), cold water baths (immersion or whirlpool), and
vapocoolant sprays (10-12, 19,22, 23, 27, 28). With advances in technology, other
forms of cold application such as the Cryo CuPM or controlled cold therapy (CCT)
units (5,6, 11, 12, 19) are being developed for use in various settings.
Although the rationale for using cryotherapy is understood and universally
accepted, a wide range of application techniques are often practiced. Whether cold
agents should be applied directly to the skin or through some barrier is debated in
the literature. Urban and Knight (30) studied the effects of ice applied directly to
the skin versus that applied over frozen, wet, and dry elastic wraps. After 30 min of
ice application, the skin temperature was 3.2 1.1 "C for the control (directly on
the skin), 8.9 f 2.3 "C for the wet elastic wrap, 10.8 f 2.6 "C for the frozen elastic
wrap, and 19.5 2.3 "C for the dry elastic wrap.
In their clinical manual for nursing practice, McCaffery and Beebe (18) recommended applying a damp towel or single layer of wet elastic wrap as a barrier.
Metzman et al. (21) measured skin temperature after a crushed ice pack was applied to the surface of plaster and synthetic casts. Skin temperature decreased to a
minimum temperature of 19.7 "C for synthetic casts and 18.7 "C for plaster casts.
In a similar study by Weresh et al. (32), average skin temperatures of 16.5 "C and
18.8 "C were measured after 90 min of ice pack application for plaster and synthetic casts, respectively.
Other researchers (1, 5, 15) have looked at the effects of ice application on
skin temperature when applied over other barriers. Culp and Taras (5) found ice
pack application to be of minimal effect on skin temperature when applied over
bulky postoperative hand and wrist dressings. Belitsky and colleagues (I) found
the greatest decrease in skin temperature when ice wrapped in cotton terry cloth
was applied directly to the skin, in comparison to applications of ice in a plastic
bag or a commercial cold pack wrapped in cotton teny cloth. La Velle and Snyder
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Cryotherapy Through Barriers
345
(15) found a significant decrease in skin temperature with use of a damp washcloth, a dry washcloth, and an Ace wrap.
Because cryotherapy is commonly used in conjunction with various compressive or immobilization wraps, dressings, or bandages, and since the amount of
cooling or heat abstraction could be directly affected by properties or characteristics of the barrier, further research is needed concerning the effects of cryotherapy
through standard compressive dressings and "comfort" barriers. Therefore, the
purpose of this investigation was to examine the differences between skin temperature during a cryotherapy treatment using a dry towel, a dry elastic wrap, and
ice applied directly on the skin.
Methods
Subjects
Nine university students with a mean age of 22 (k1.0) years volunteered to participate in this investigation.Arepeated-measures, three by three, balanced Latin Square
design was employed to ensure random assignment of subjects to treatment groups.
Therefore, each treatment group had a representation of n = 9. Prior to the study,
all subjects read and signed an informed consent form approved by the University
Institutional Internal Review Board.
Instrumentation and Procedures
Each subject completed three treatment sessions over a 3-day period, with 24 hr
between each treatment session. Treatment sessions consisted of a 10-min pretreatment period used to standardize skin temperature, a 30-min treatment period
in which 0.68 kg of cubed ice was applied, and a 20-min posttreatment period in
which the ice was removed. Each 30-min treatment period consisted of the application of ice over one of three different treatment conditions: dry towel, dry elastic
wrap, and control (applied directly to the skin). The dry towel treatment consisted
of a single layer of a standard, white, 100% cotton towel. The dry elastic wrap
treatment consisted of a 3-in. MBM EconowrapBelastic bandage wrapped in a
sequential distal-to-proximal pattern. The wrap was applied so that it covered onehalf of the bandage on each circumferential application.
During the 60-min treatment session, all subjects were assessed for sitespecific skin temperature (S temp). The S temp was measured using a YSF Incorporated Model 43 TD telithermometer and YSF Series 400 surface skin temperature probe and was recorded every 2.5 rnin.
Prior to the first treatment session, all subjects were assessed for height (Ht),
weight (WE),site-specific skinfold (Skf), site-specific girth (G),and sum of three
skinfolds (SSF). All skinfolds were measured using HarpendenTMskinfold calipers. Two measurements were taken at each site, and if the variation was less than
1 rnm, the average of the two measurements was used to represent the skinfold
Tsang, Buxton, Guion, eta/.
346
thickness of each site. The SSF measures were taken using the three-site technique
described by Harrison et al. (7) The Skf measure was taken at the midforem,
equidistant from the medial epicondyle of the humerus and the radial styloid process (site of skin telithermometerprobe). Girth measurements were obtained with
a centimeter tape measure, using a technique described by Callaway et al. (4), and
were taken at the same midforem point as the Skf measurement. A11 anthropometric and body composition measures were performed by the same investigator
using standard anthropometric techniques (16).
All treatment sessions began with the subject sitting and resting for 10 min
(pretreatment period) to allow for standardization of body temperature. The YSI@
surface skin temperature probe was placed at the midforearm site on the
nondominant arm. After 10 rnin, we began the treatment period by placing the ice
bag and barrier over the probe. The ice bag was shaken every 5 min to prevent a
temperature gradient from developing (17). After 30 min of application, the ice
pack was removed and S temp was continually recorded for another 20 min
(postapplication period). Atmospheric conditions were measured every 2.5 min
with a Vista Scientific Corporation Heat Stress Computer Model 858.
Statistical Analysis
Descriptive statistics (mean f SD) were employed on all anthropometric data for
each subject. To test for differences in skin temperature between treatment conditions, a two-way ANOVA with repeated measures (within subject over time) was
performed. The independent variable was the treatment condition with three levels
(dry towel, dry elastic wrap, and control), and the dependent variable was skin
temperature recorded at 2.5-min intervals over 60 min. Tests of within-subjects
contrasts were employed to determine if differences existed between treatment
groups (for skin temperature) and between time intervals (for skin temperature).
An alpha level of p < .05 was set for all statistical procedures.
Results
Table 1 presents the means (+SD) of the anthropometricdata for all subjects. Table
2 presents the mean (+SD) skin temperatures recorded over time and between the
three treatment conditions (barriers). The ANOVA with repeated measures (tests
of within-subjects contrasts) revealed significant interactions ( p < .05) between
mean skin temperature and the three treatment conditions over time.
During the pretreatment period, the mean (+SD) skin temperature for the dry
towel group was 3 1.19 f 0.93 "C, for the dry elastic wrap group 30.72 1.86 "C,
and for the control group 3 1.52 1.12 "C. Mean ( S D ) skin temperature during
the treatment period for the dry towel group was 23.84 f 2.88 "C, for the dry
elastic wrap group 27.47 2.36 "C, and for the control group 12.50 4.39 "C.
During the posttreatment period, the mean (fSD) skin temperature for the dry
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Cryotherapy Through Barriers
347
Table 1 Means ( S D ) of Anthropometric Data
Height (cm)
Weight (kg)
Site-specificskinfold (mm)
Site-specificgirth (em)
Body fat (%)
Mean
SD
172.06
7 1.49
6.63
23.09
18.39
8.31
16.28
1.83
3.33
4.96
Table 2 Mean Scores ( S D )of Skin Temperature ("C) Over Time
Dry towel*
Time (min)
M
SD
Dry elastic wrap*
M
SD
Control*
M
*Significant difference (p < .05) in skin temperature between barriers. ?Significant
difference (p < .05) in skin temperature from preceding time internval.
SD
Tsang, Buxton, Guion, et a/.
348
towel group was 26.99 Jr 2.56 "C, for the dry elastic wrap group 27.5 f 2.80 "C,
and for the control group 21.86 f 3.85 OC.
The ANOVA with repeated measures further revealed significant differences
0, <.05) in skin temperature between time intervals within each treatment condition. Table 2 reflects the significant differences in skin temperature between time
intervals and their preceding time (i.e., Time Reading 2 vs. Time Reading 1).
Mean (SD)atmospheric room temperatures over the three days of testing
were 21.90 2 2.50 "C for the first day, 21.53 2.11 OC for the second day, and
2 1.96 f 1.92 "C for the third day.
Figure 1 presents the mean skin temperature of each treatment condition
plotted over time. The data reflect a significant decrease (p < .05) in skin temperature during the treatment period for all treatment conditions (Figure 2). After 30
min of ice bag application through the different treatment conditions, the mean
skin temperature had decreased from 3 1.19 0.93 "C to 20.9 2.29 "C for the dry
towel, from 30.72 1.86 "C to 25.67 f 2.42 "C for the dry elastic wrap, and from
31.51 f 1.12 "C to 10.12 f 2.65 OC for ice applied directly to the skin.
Figure 2 presents the mean skin temperature between treatment conditions
within the treatment session. The data revealed that significant differences 0, <
.05) existed between all treatment conditions during the treatment period of the
treatment session. Significant differences (p < .05) were also observed between
the dry towel condition and control condition and between the dry elastic wrap
condition and the control condition during the posttreatment phase. No significant
differences were found during the pretreatment period.
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Discussion
The use of cryotherapy in the management of musculoskeletal injuries is universally understood and accepted. A barrier used in conjunction with the cold agents
is introduced with varying application techniques. The purpose of this study was
to examine the effects of cryotherapy, more specifically an ice bag, applied over a
dry towel, over a dry elastic wrap, and directly to the skin.
Relationships in Skin Temperature Through Barriers
The results from the present study support the findings of La Velle and Snyder
(15), who measured the effects of an ice bag application over an Ace wrap, a padded Ace wrap, a dry washcloth, and a damp washcloth as well as directly to the
skin. After 30 min of ice bag application, La Velle and Snyder (15) observed significant (p < .05) reduction in temperature with all barriers except the padded Ace
group. The mean skin temperature prior to the ice bag application was 30.8 OC for
the dry washcloth, 30.6 "C for the Ace wrap, and 30 "C for the no-barrier condition. Mean skin temperatures after the 30-min application were 20.5 "C, 17.8 "C,
and 10.8 "C, respectively, for the Ace wrap, the dry washcloth, and the no-barrier
Cryotherapy Through Barriers
35
11
Yle
treatment
1 2 3 4
1
~nautent
Post-treatment
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
T i e Readings ( 2 5 min interval)
Figure 1 -Mean skin temperature of treatment conditions plotted over time.
Figure 2 -Mean skin temperature between treatment sessions and treatment conditions.
Tsang, Boxton, Guion, et a/.
350
conditions. The lowest mean skin temperature, however, was found with the damp
washcloth condition, 9.9 "C. These results are similar to the present investigation,
in which the mean skin temperature for the direct application of the cold agent to
the skin was lower than the temperatures for the dry towel and dry elastic wrap
(Figure 2). Another similarity is that the dry elastic wrap resulted in the highest
mean temperatures of the three barriers (Figure 2).
The use of a damp washcloth as a barrier was examined by Belitsky et al.
(I), who used flaked ice, an ice bag, and a commercial gel pack, all of which were
wrapped in a damp terry cloth towel prior to application. After 15 min of cold
application, the group using an ice bag (wrapped in a damp towel) had a mean skin
temperature of 20.1 "C (a decrease of 9.4 "C). In the present study we found a
mean skin temperature of 23.82 1.36 "C at 15 min of application through a dry
cotton towel, which represents a decrease of 7.52 "C. This comparison seems to
indicate that the use of a damp cotton towel allows for more rapid heat abstraction
and cooler skin temperatures.
The application of cold to the skin can decrease the underlying blood flow and
therefore affect localized metabolism. In cold applications ranging from 20.56 to 12.83
"C, Ho and colleagues (8,9) observed a significant Cp < .05) decrease in blood flow as
compared to the control condition when assessing arterial, soft tissue, and skeletal
blood flow in the knee using a triple-phase bone scan with technetium-99m. They
further indicated that maximum decreases (29.5%) in soft tissue blood flow occurred
at a skin temperature of 12.83 "C and a maximum decrease (33.8%) of arterial blood
flow occurred at 16.33 "C. Knight and colleagues (13) reported a 25% decrease in
forearm blood flow as compared to a control condition at a temperature of 15 "C.
These findings demonstrate that to affect localized blood flow in underlying tissues,
superficial skin temperatures should be between 12 and 16 "C.
Therefore, in the present study, the only treatment condition capable of altering localized blood flow was the control condition (cold applied directly to the
skin). This treatment condition elicited a skin temperature of 12.92 f 3.17 "C after
10 min of application and maintained that temperature (or lower) until the ice was
removed. Interestingly, within 2.5 min after removal of the ice, the skin temperature was 16.59 3.28 "C, which, based on the findings of Knight et al. (13), indicates that localized blood flow may have decreased. The results of the present
study revealed that within the 30-min treatment period, the mean skin temperatures in the dry towel and dry elastic wrap conditions were not low enough to
decrease blood flow and affect pain as previously discussed. The lowest mean skin
temperature for the dry towel condition was 20.9 2.29 "C and for the dry elastic
wrap condition 25.67 2.42 "C.
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Relationship in Skin Temperature Over Time
In the present study there were several significant differences (p < .05) in temperature over time interval readings (Table 2). This finding suggests that when a dry
towel is used, heat abstraction does not occur with a significant effect until ap-
Cryotherapy Through Barriers
351
proximately 5 min after application of ice. This implies that the barrier helps to
maintain skin temperature and also "insulates" the skin from the cold agent. However, from approximately 5 min after ice was applied to 15 min into treatment, the
skin temperature decreased significantly from the previous reading five times. Significant changes in skin temperature between intervals were not observed again
until 5 min after the ice bag was removed from the dry towel. The skin temperature
readings with the dry elastic wrap indicate that the majority of the significantchanges
between intervals did not occur until the later stages of ice application (Table 2).
This suggests that the barrier helped to insulate the skin and prevent major heat
abstraction until approximately 10 min into the treatment.
The differing results of time interval skin temperature readings between the
two barriers and the control group are dramatic. In Figure 1, the slope of each line
represents the rate at which skin temperature change occurred for that particular
treatment. For the control group, skin temperatures decreased quickly during the
first 10 min of treatment and then leveled off at about 11 "C for the remaining 20
min of treatment. In contrast, the dry towel and dry elastic wrap groups experienced a slower rate of skin temperature change with no indication of leveling off.
Therefore, the length of treatment time was too short, and the temperature could
have continued to decrease into the 12-16 "C range had a longer treatment time
been employed. The dry elastic wrap group exhibited the slowest rate of temperature decrease. When a line was fitted to the last four data points for this group (the
last 10 min of the treatment period), the following equation was produced: y =
-0.11~+ 30.2, where y represents the skin temperature in degrees Celsius and x
represents time in minutes (r = .99). Using this equation, we calculated that when
a dry elastic wrap was used as a barrier, it would take approximately 151 min for
the skin temperature to reach 13 "C, if skin temperature change continued at this
rate.
A similar procedure was used for the dry towel group and the following
equation was determined: y = - 0 . 1 1 ~+ 25.5. Using this equation, we calculated
that when using the dry towel as a barrier, approximately 109 min would be required for the skin temperature to reach 13 "C. This suggests that it may be possible to decrease skin temperature when a barrier is used during ice application;
however, the time of application has to be extended well beyond 30 min.
In 1975, Bugaj (3) investigated the cooling, analgesic, and rewarming effects of ice massage applied to the gastrocnemius for 10 min. The findings indicated that within the first minute of cold application, skin temperature decreased
14.8 "C followed by a 5.7 "Cdecrease during the second minute. At the conclusion
of the 10-min treatment period, a skin temperature of 5.8 "C was recorded. In
comparison to the present study, the findings of Bugaj (3) suggest that ice massage
can decrease skin temperature more rapidly than the application of an ice bag.
These findings are also supported by Zemke (33), who studied the effects of subcutaneous tissue temperature differences when using an ice bag versus ice massage. However, the Zernke (33) study indicated no significant differences in cool-
Tsang, Buxton, Guion, et a/.
352
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ing (29.67 1.4 "C for ice massage and 29.67 1.7 "C for ice bag), only in the rate
of cooling (17.8 f 2.4 min for ice massage and 28.21 f 12.5 min for the ice bag).
Many authors have advocated the use of cold agents in the treatment of
acute and recurrent pain (1-3,5, 10, 14, 15, 19-21,23,25,29,32,33). Brandner
et al. (2) found a significant decrease in morphine consumption with lumbar spine
surgery patients using cryotherapy. The patients who used a cooling pad set between 7.2 and 10 "C in conjunction with their patient-controlled analgesia (morphine) pump during their postoperative pain management significantly decreased
( p < .05) morphine consumption. Bugaj (3) found an analgesic effect when skin
temperature decreased to 13.6 "C, and this effect terminated during rewarming at
approximately 15.6 "C. The findings of the present study indicated that to achieve
an analgesic effect in a 30-min treatment, the cold application could not be used
with a dry barrier. In the present study, skin temperatures low enough to gain such
an analgesic response were obtained within 7.5 min of direct ice application to
the skin (control) and were maintained until the ice was removed. This finding
suggests that the analgesic effects of ice application are at a maximum when the
ice is applied directly to the skin and begin to decrease immediately upon removal.
Conclusion
The findings from the present study and previous research (1,5, 11,12, 15,18,21,
22, 24, 27, 28,30, 32) indicate that the use of a barrier in conjunction with a cold
agent does allow for a reduction in skin temperature. The findings also indicate
that the rate of heat abstraction is possibly related to the properties or contents of
the barriers used. The results also reveal that the use of a dry towel allows for more
heat abstraction than a dry elastic wrap. The rubber and nylon found in dry elastic
wraps give the wrap its compressive qualities but may act as insulators, thereby
inhibiting the abstraction of heat from the body. These findings further indicate
that in order for a cryotherapy treatment to affect local metabolism, blood flow,
and nerve conduction velocity for an analgesic response, a dry towel or dry elastic
wrap should not be used in treatment times of 30 min or less. Finally, to achieve a
temperature within the range of 12-16 "C, treatment must be continuous, with the
cold agent directly applied to the skin for 10 min or longer.
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