This study explored whether anthropometric measures influence magnitude of skin cooling following exposure to whole body cryotherapy (WBC). Height, weight, body fat percentage, and lean mass were measured in 18 male and 14 female participants. Body surface area, body surface area to mass ratio, body mass index, fat-free mass index, and fat mass index were calculated. Thermal images were captured before and after WBC (−60°C for 30 seconds, −110°C for 2 minutes). Skin temperature was measured at the chest, arm, thigh, and calf. Mean skin temperature before and after WBC and change in mean skin temperature
Whole body cryotherapy (WBC) involves a short exposure to very cold air whilst wearing minimal clothing. It has been used in both clinical and sporting populations for treatment of depression [
Therefore the aims of this exploratory study were to examine the relationship between anthropometric measures and magnitude of skin cooling following exposure to WBC; explore whether anthropometric measures can be used to predict magnitude of skin cooling following exposure to WBC; compare skin cooling responses to WBC in males and females.
Thirty-two recreationally active participants (males:
Height and weight were measured using laboratory scales and stadiometer. Body composition was measured using bioelectrical impedance (BIA) at a frequency of 50 kHz (Biostat 1500, Isle of Man) yielding information on body fat percentage and lean mass. From the anthropometric measures taken, height and weight, BMI, body surface area using the Du Bois equation [
Anthropometric characteristics of study participants.
Males | Females | |||
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Mean | SD | Mean | SD | |
Height (cm) | 179.2 | 6.2 | 164.6 | 6.5 |
Mass (kg) | 80.6 | 9.4 | 64.1 | 12.4 |
BMI (kg/m2) | 25.0 | 2.3 | 23.7 | 4.6 |
FFMI (kg/m2) | 21.1 | 1.4 | 16.8 | 1.2 |
FMI (kg/m2) | 4.0 | 1.3 | 6.9 | 3.8 |
BSA (m2) | 2.0 | 0.1 | 1.7 | 0.2 |
Lean mass (kg) | 67.7 | 6.2 | 45.7 | 4.9 |
Body fat percentage (%) | 15.6 | 4.0 | 27.4 | 8.8 |
BSA : Mass (cm2/kg) | 2.0 | 0.1 | 3.0 | 0.3 |
Skin temperature was measured by taking thermal images using a factory calibrated FLIR Thermal Imaging Camera (E40BX FLIR systems, Danderyd, Sweden). The thermographs were taken according to the standard protocol for infrared imaging in medicine [
Cryotherapy exposures took place in a liquid nitrogen cooled cryogenic chamber at The Chris Moody Sports Injury and Rehabilitation Centre in Northamptonshire, United Kingdom. The unit was purpose-built and temperature controlled (Juka, Poland), comprising two chambers (−60°C and −110°C) connected by an internal door.
Participants were instructed to abstain from consuming caffeine, smoking, or taking part in exercise on the day of testing and had not consumed food within 2 hours of WBC exposure. They were asked to remain hydrated. Height and weight were first measured; then participants acclimated for 20 minutes to ambient room temperature. Four-electrode BIA was undertaken and connected at two sites (wrist/hand and ankle/foot).
In preparation to enter the cryotherapy chambers, participants undressed to shorts (males) and shorts and vest (females). Protective garments worn by the participants included gloves, socks, clogs, tubular bandages to cover elbows and knees, headband to cover the ears, and surgical mask over the mouth. Glasses, jewellery, and piercings were removed before entering the chamber. Thermally inert markers were attached using adhesive tape to eight sites on the participants’ bodies to create ROI for temperature analysis, in a similar fashion to that described by Costello et al. [
Following a safety briefing from the cryochamber operators, participants (in pairs) entered the antechamber for 30 seconds at
Descriptive analysis of pre- and post-WBC temperatures for each of the ROI and
The mean temperatures of all body regions
Mean temperature of body regions (°C) before and after exposure to WBC.
Males | Females | Combined | |||||||
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Before WBC (°C) | After WBC (°C) |
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Before WBC (°C) | After WBC (°C) |
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Before WBC (°C) | After WBC (°C) |
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33.58 ± 0.76 | 25.45 ± 1.97 | 8.13 ± 1.57 | 34.15 ± 0.73 | 25.25 ± 2.98 | 8.90 ± 2.48 | 33.83 ± 0.79 | 25.3 ± 2.42 | 8.47 ± 2.02 |
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31.17 ± 1.14 | 21.20 ± 2.00 | 9.98 ± 1.81 | 31.52 ± 1.07 | 20.40 ± 2.40 | 11.13 ± 1.84 | 31.33 ± 1.10 | 20.85 ± 2.22 | 10.48 ± 1.88 |
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31.47 ± 1.14 | 20.50 ± 2.56 | 10.97 ± 2.36 | 31.23 ± 0.86 | 17.38 ± 1.76 | 13.85 ± 1.21 | 31.36 ± 1.02 | 19.14 ± 2.72 | 12.23 ± 2.41 |
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32.20 ± 0.57 | 19.54 ± 3.28 | 12.66 ± 3.06 | 31.50 ± 0.76 | 15.05 ± 2.04 | 16.46 ± 1.96 | 31.9 ± 0.74 | 17.57 ± 3.57 | 14.33 ± 3.2 |
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For combined male and female data, a highly significant moderate relationship was observed between body fat percentage and
Males | Females | Combined | ||||
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BMI | .590 | .010 | .402 | .154 | .286 | .113 |
FFMI | .622 | .005* | .653 | .009 | −.013 | .478 |
FMI | .380 | .118 | .288 | .315 | .444 | .010 |
BSA | .115 | .649 | .417 | .138 | −.216 | .234 |
Body fat % | .326 | .187 | .313 | .276 | .516 | .002* |
BSA : Mass | −.512 | .030 | −.501 | .068 | −.137 | .455 |
Significant association between body fat percentage and
Nonsignificant association between FMI and
Association between FFMI and
Simple linear regression of the significantly associated variable of body fat percentage with
Similarly, FFMI can be used as a predictor of
The response of individuals to WBC appears to depend upon sex and anthropometric variables, with body fat percentage demonstrating a significant positive correlation with
FFMI was significantly associated with
Skin temperatures recorded at the different anatomical sites sampled for combined sexes showed a trend that is also in agreement with previous work in this area.
Like many studies of WBC, skin temperature was measured by infrared thermography in this study. Infrared cameras have the advantage over other methods of assessing skin temperature (such as thermocouples, thermistors, or wireless sensors) that they do not require contact with the skin and therefore do not create any local area of insulation [
BIA is a popular commercial method for measuring body composition and has been shown to be reliable and valid when compared to skinfold analysis and hydrostatic weighing [
Skin temperature is clearly an important parameter in influencing internal cooling following WBC [
One issue that was not accounted for in female subjects was potential variation in basal body temperature according to the phase of the menstrual cycle that individuals were in at the time of testing. Some attempt was made by the research team to quantify the cycle phase to explore whether it was confounding; however three-quarters of the female participants were using hormonal contraception, and consequently some participants had not experienced menses for some time. Therefore it was not possible to examine any potential effects of this variable. The effects of this on the findings are likely to be minimal and, however, should be taken into consideration when interpreting the female portion of the data presented here.
The sample size used for this study is greater than many studies that have explored the effects of WBC; however at 32 it was still relatively small when considering a heterogeneous group of people. The female dataset was more heterogeneous than the male dataset, with large standard deviations observed for mass, BMI, and body fat percentage. A larger number of participants would result in a more representative study population, and further research with much larger numbers of participants is needed to validate the findings presented here. A larger sample size would also facilitate performing multiple regressions on the data to explore whether multiple anthropometric predictors exist for skin cooling following WBC; this was not possible in this data set as the test would be underpowered for 6 predictors in 32 participants. Further research should also examine whether the same effects occur in athletic populations, where anthropometric characteristics are diverse and where WBC has become a popular tool for recovery [
The findings of this study appear to suggest that individuals with different anthropometric characteristics receive different therapeutic effects in terms of changes in skin temperature from identical doses of WBC, with individuals with higher adiposity cooling more at the skin than thinner individuals. Similarly, males and females appear to respond differently to WBC exposure, and this should be considered when designing and interpreting research studies and determining commercial treatment protocols for WBC. These findings could have implications for the individualisation of dosage for WBC. Personalised medicine is becoming an increasingly popular model of healthcare and these findings lend support to the idea of individualising dosage, although more research would be needed to determine a multitude of parameters in order to achieve this. As well as application for medical usage, this may have important implications in determining WBC dosage in elite athletic populations, for those that have access to cryotherapy chambers. Performance margins are very small in elite sport, so individualising a dose of WBC may assist in creating optimal effects in individual elite athletes. Manipulating the parameters of time and temperature of exposure adjusts the therapeutic dose given to users, but the question of “what are the optimal modality, temperature, and duration required to elicit the required physiological response?” posed by Costello et al. [
Whole body cryotherapy took place at The Chris Moody Sports Injury and Rehabilitation Centre which is a commercial arm of Moulton College, an educational institution. Authors S. Cuttell and J. Meyler are employed on academic contracts at Moulton College and are not involved in commercial activity.
The authors thank the technical staff at The Chris Moody Sports Injury and Rehabilitation Centre for operating the whole body cryotherapy chamber. The authors also thank the anonymous reviewers for their constructive comments on this paper.