Transcript Sock Material and Warm-Up Effects on Foot

Sock Material and Warm-Up Effects on Foot Temperature
during Treadmill Running
1
Patel,
2
Oestreich,
2
Post,
1
Ross,
2
Schmidt,
Tej M.
Nicholas J.
Mitchell L.
Brandon J.
Alyssa C.
Brent T.
Julie E. Smith,4 Travis L. Stinson,2 Nickolas Van Roekel,1 Rachel M. Barkley,1 David S. Senchina5
3
Shelton,
1Biochemistry,
Cell, and Molecular Biology Program; 2College of Business & Public Administration; 3College of Education;
4College of Pharmacy & Health Sciences; 5Biology Department, Drake University, Des Moines, IA, 50311
ABSTRACT:
Manufacturers market a variety of athletic socks to runners with varying claims of
comfort and ergogenic properties. This study (approved by Drake IRB ID 200910088) investigated how foot temperature during running was modulated by
different socks. Additionally, the influence of a short warm-up period prior to data
collection was investigated. Sixteen male subjects (21.3  1.4 yrs) completed four
10-minute running trials at self-selected but constant speeds in four different
socks: cotton, synthetic, a cotton/synthetic blend, and a combination of the blend
sock plus a calf compression sleeve. Eight subjects performed a 5-minute warmup at approximately 75% of their trial treadmill speed and eight did not warm up
whatsoever. Foot temperature was recorded for the 10 minutes during running
and 5 minutes immediately after. Heart rate and subjective ratings of perceived
comfort and heat were recorded throughout. There were no significant differences
in foot temperature across socks during or after running. Subjects perceived their
feet as being warmer in the cotton and blend socks compared to the synthetic
sock or the blend sock plus the sleeve. There were no differences in comfort
perception across trials. Expectedly, there was a trial order effect for subjects who
didn’t warm up such that foot temperature was higher in later trials compared to
earlier trials. These results suggest that (a) socks of differing materials may
transfer heat similarly, (b) wearing a calf compression sleeve influences
perceptions of foot temperature, and (c) subjects’ perceptions of foot temperature
may not coincide with actual temperature.
Sock Type
Manufacturer
Composition
Cotton
S.A. Gear
(TSA, Inc.)
Adidas Climalite
(Adidas, Inc.)
100% cotton
Blend
Synthetic
Calf Compression
Sleeve
53% polyester, 37% cotton, 8% olefin,
1% natural latex, 1% spandex
Heatgear
98% polyester, 2% spandex
(Under Armour, Inc.)
Zoot Active
70% polypropylyene, 30% spandex
(Zoot, Inc.)
Table 1—Type and composition of socks used in this study.
Figure 2 (left to right)—(a) Socks
used including cotton (top), blend
(middle), and synthetic (bottom)
with sleeve shown rightmost. (b)
Subject with compression sleeve.
(c) Asics GT-2110 running shoe.
• Since 70% of sweat production occurs on the upper foot (and hence the bulk of
evaporative cooling; [5]), it is the best location for measuring foot temperature.
• The few studies available suggest that cotton content of a sock is unrelated to its
heat transfer properties (1) and that, under previous experimental conditions, foot
temperature is not influenced by cotton vs. synthetic socks (1,2,4).
METHODS:
Procedures were pre-approved by the Drake University Institutional Review Board (ID 2009-10088) . Sixteen males
(21.3  1.4 yrs; stature = 181.9  1.6 cm, 73.8  2.4 kg) who could exercise in size 11.5 shoe, could run for 30 min,
and have no precluding medical conditions participated. Subjects visited the lab for one experimental session
involving four 10-min treadmill runs (Sole, Inc.) spaced by sitting 10-min rest periods. Trial order was
counterbalanced and subjects had to run the same self-selected speed for all 4 trials (average 7.4  0.3 mph).
Flexible thermistors (thermometers; YSI, Inc.) were attached to the upper right foot, lateral side midway across the
arch using electrical tape, one against the skin and one at the same site between the sock and the shoe (Figure 1).
Temperature was recorded from both sites during the 10-min run and the first 5-min of sitting rest. All subjects ran
in a pair of Asics GT 2110 running shoes throughout the session (Figure 2b) This shoe has a mass of 411.2 g, as
compared to the runners’ own average running shoe mass of 363.1  8.9g. Runners wore the same shoes under
4 different sock conditions (Table 1): cotton, blend, blend + compression sleeve , and synthetic. Heart rate was
recorded throughout but no significant changes were documented and the data is not shown. Subjects’ self-rated
perceptions of comfort and stability were assessed independently via 10-cm visual analogue scale (3) where
subjects placed a mark along the scale where they perceived foot temperature or comfort, accordingly (see Table 2
for more explanation). Subjects were allowed water ad libitum.
Tables 4 and 5—There were significant differences in subjects’ perceptions of
foot heat by sock regimen in the warm-up group (p=0.051) but not in the no warmup group (p=0.101). Subjects in the warm-up group perceived their feet as being
cooler when wearing the blend + sleeve as compared to wearing the blend alone
(p=0.034) or the cotton (p=0.026). There was also a trend for subjects to perceive
their feet as being significantly cooler when wearing the synthetic sock as
compared to the cotton (p=0.058) or blend alone (p=0.076). Similar effects,
though not significant, were seen in the no warm-up group.
There were no differences in comfort ratings by sock for either the warm-up group
(p=0.789) or the no warm-up group (p=0.669) (Tables 4 and 5).
INTRODUCTION:
• The ability of a sock to dissipate foot heat generated during running may impact
on performance in long-distance events and foot health over weeks of training.
• Because these studies were limited in their scope, the purpose of our
investigation was to examine the influence of sock material under more rigorous
conditions with co-factors such as warm-up or presence of a compression sleeve.
RESULTS:
Tables 2 and 3—The change in foot temperature during running and rest was not
significantly different between the different sock regimens in either the warm-up or
the no warm-up groups (all p 0.504). However, there was a significant trial order
effect in the no warm-up group for change in skin temp 0-10 min (p=0.033);
expectedly, the effect was such that the change in foot temperature decreased
with increasing trial number.
Cotton
Blend
Blend + Sleeve
Synthetic
Skin, 0-10 min
2.06  0.33
2.23  0.33
2.68  0.32
2.14  0.32
Sock, 0-10 min
1.95  0.39
2.35  0.38
3.15  0.38
2.84  0.6=38
Skin, 10-15 min
-0.33  0.25
-0.07  0.25
-0.41  0.24
-0.4  0.24
Sock, 10-15 min
0.37  0.15
0.33  0.14
0.11  0.14
0.15  0.14
Tables 2 (above) and 3 (below)—Foot temperature change (expressed as C, mean 
standard error) at both skin and sock thermometer sites. Data for the warm-up group is shown
in Table 2 (above) and data for the no warm-up group is shown in Table 3 (below).
Cotton
Blend
Blend + Sleeve
Synthetic
Skin, 0-10 min
2.19  0.3
2.53  0.29
2.44  0.3
1.91  0.27
Sock, 0-10 min
2.25  0.38
2.88  0.37
3.09  0.39
2.35  0.35
Skin, 10-15 min
-0.05  0.17
-0.26  0.16
-0.04  0.17
0.12  0.16
Sock, 10-15 min
0.67  0.17
0.4  0.17
0.5  0.18
0.6  0.16
Cotton
Blend
Blend + Sleeve
Synthetic
Comfort
4.0  1.4
4.2  1.3
5.0  1.3
5.7  1.3
Heat
5.9  0.7
5.8  0.6
3.7  0.6
4.0  0.6
Tables 4 (above) and 5 (below)—Subjects’ perceptions of comfort and heat and assessed
via a 10-cm visual analogue scale. A “0” indicates most uncomfortable/hot imaginable and a
“10” indicates most comfortable/cool imaginable. Values are mean  standard error. Data
from the warm-up group is shown in Table 4 (above) and from the no warm-up group in
Table 5 (below).
Cotton
Blend
Blend + Sleeve
Synthetic
Comfort
6.2  0.9
4.7  0.8
5.4  0.9
5.7  0.8
Heat
5.9  0.6
5.9  0.6
4.3  0.6
3.8  0.6
DISCUSSION:
• Sock type was not a significant factor in running-induced changes in foot
temperature (Tables 2 and 3). For a 10-minute run, the sock’s composition is not
likely to impact on actual foot temperature. Whether this holds true for longer runs
(more typically seen in runners) remains to be shown.
• Despite the lack of difference in actual foot temperature across trials, subjects in
the warm-up group perceived the blend + sleeve combination and synthetic sock
as reducing foot temperature more than the blend alone or cotton (Table 3). Other
researchers have similarly reported that actual foot temperature and subjects’
perception of foot temperature may not coincide (4). Since we did not see
differences in comfort ratings, other factors must be influencing these results.
REFERENCES:
 Figure 1—Thermometer set-up (left to right). (a) “Skin thermometer” placed on
the dorsal surface of the right foot arch, slightly lateral. (b) “Sock thermometer”
placed next to the skin thermometer. (c) Both attached thermometers plus shoe.
(1)
(2)
(3)
(4)
(5)
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