Elsevier

Journal of Thermal Biology

Volume 65, April 2017, Pages 41-47
Journal of Thermal Biology

Individualising the exposure of −110 °C whole body cryotherapy: The effects of sex and body composition

https://doi.org/10.1016/j.jtherbio.2017.01.014Get rights and content

Highlights

  • Mean body temperature and local site specific Tsk were different between sexes.

  • Females have a tendency for a greater insulative response to whole body cryotherapy.

  • Sexually dimorphism is not accounted for when attempting to optimise WBC treatments.

  • The use of tympanic temperature measurements should not be used with whole body cryotherapy treatments.

Abstract

The purpose of this study was to investigate the effects of whole body cryotherapy (WBC) on a range of thermoregulatory measures. We also sought to examine the influence of sex and body composition. A convenience sample of 18 healthy participants (10 males and 8 females) (27±6 yr) volunteered for this study. Temperature (core, tympanic, skin and mean body), heart rate, blood pressure, and thermal comfort and sensation were recorded pre- and post- (immediately and every 5 min until 35 min post) exposure to a single bout of WBC (30 s at −60 °C, 150 s at 110 °C). Anthropometric data (height, weight, body surface area, body mass index, fat mass and fat free mass) were also recorded. No significant differences in temperature (core, tympanic, skin and mean body), heart rate, blood pressure, or thermal comfort / sensation were observed between male and females at baseline. Immediately post WBC mean body (male:31.9±0.8 °C; female:31.0±0.9 °C; ∆ mean body temperature:0.9±0.1 °C; P≤0.05, d=0.64) and mean skin (male:22.1±2.2 °C; female:19.6±2.8 °C; ∆ mean skin temperature:−2.5±0.6 °C; d=0.99, P≤0.05) temperature was significantly different between sexes. Sex differences were also observed in regional skin temperature (male thigh, 20.8±1.1 °C; female thigh, 16.7±1.1 °C, ∆ mean thigh skin temperature:−4.1 °C; d=3.72; male calf, 20.5±1.1 °C; female calf, 18.2±1 °C, ∆ mean calf skin temperature:−2.3±0.1 °C; d=3.61; male arm, 21.7±1 °C; female arm, 19±0.4 °C, ∆ mean arm skin temperature: −2.7±0.3 °C; d=3.54; P≤0.05). Mean arterial pressure was significantly different over time (P≤0.001) and between sexes (male 0 mins:94±10 mmHg; female 0 mins:85±7 mmHg; male 35 mins:88±7 mmHg; female 35 mins:80±6 mmHg; P≤0.05). Combined data set indicated a strong negative relationship between skin temperature and body fat percentage 35 min’ post WBC (r=−0.749, P≤0.001) and for core temperature and body mass index in males only (r=0.726, P≤0.05) immediately after WBC. There were no significant differences between sexes in any other variables (heart rate, tympanic and perceptual variables). We observed sex differences in mean skin and mean body temperature following exposure to whole body cryotherapy. In an attempt to optimise treatment, these differences should be taken into account if whole body cryotherapy is prescribed.

Introduction

Whole body cryotherapy (WBC) involves a short exposure to cold air, which is growing in popularity with athletes and coaches (Hausswirth et al., 2011, Costello et al., 2012a). The majority of protocols repeatedly expose individuals to extremely cold air (−110 °C to −140 °C) in an environmentally controlled chamber for short periods of time (2–4 min) (Costello et al., 2012b). WBC has been claimed to treat depression (Rymaszewska et al., 2003), rheumatic conditions (Hirvonen et al., 2006), ankylosing spondylitiis (Banfi et al., 2010), and exercise induced muscle damage (Hausswirth et al., 2011) in both athletic and clinical populations (Hammond et al., 2014). A range of claims based on thermoregulatory responses have been stated about the benefits of WBC, however, the evidence supporting these claims is limited in both quality and statistical power (Costello et al., 2012b).

During WBC, the interaction between the cold environment and the body mainly occurs at the skin. The heat lost at the skin represents the balance of heat loss of metabolically active tissue to the environment (Cholewka et al., 2012). Both core temperature and skin temperature have specific responses to a cold environment, and the magnitude in response is determined by the change in skin or core temperature (Kakitsuba et al., 2007). Thermo afferent signals from the core to the periphery are integrated centrally to establish normothermia by means of skin vasoconstriction and increasing metabolic rate via shivering (Kakitsuba et al., 2007). Tissue cooling and the transfer of heat from the body depends on several factors including relative mass, size of contact area, difference in starting temperatures and the relative heat capacity and rewarming of metabolically active tissue (Zhang et al., 2001). Skin temperature has been shown to reduce significantly after WBC, with concomitant decreases in core and muscle temperature (Costello et al., 2012b, Selfe et al., 2014). Despite what is known about WBC, there is still a paucity of data regarding WBC treatment times, optimal temperatures, and how these relate to sex differences.

Metabolic rate and heat production have been reported to be significantly reduced in overweight, compared to lean, participants during mild air cooling (15 °C) and a rewarming period after cooling (Ooijen et al., 2006). Given that WBC uses vastly cooler temperatures (typically less than −100 °C) and that higher fat mass/adipose tissue impacts upon cooling time, metabolic heat production may be amplified with leaner, compared to overweight, participants. Larger skin folds have been shown to require longer ice exposure than smaller skin folds to elicit similar reductions in deep tissue temperature (Otte et al., 2002), and differences in the degree of skin temperature cooling experienced have been reported between high and low body mass index in individuals following WBC (Cholewka et al., 2012). Consistent with the link between body mass index and cooling, there have been a number of attempts to examine the impact of WBC on skin temperature (Cholewka et al., 2006, Cholewka et al., 2012, Klimek et al., 2011, Hammond et al., 2014) along with core temperature (Westerlund et al., 2003, Costello et al., 2012b), heart rate and blood pressure (Westerlund et al., 2004, Westerlund et al., 2006), but with little attention paid to sexual dimorphism, morphological and protocol differences. It is surprising that sexual dimorphism has received relatively little attention in WBC research, especially as WBC has been used in a wide variety of populations, with varying results, in both clinical and well trained individuals. Given that sexual dimorphism such as adiposity (Jutte et al., 2012) and the menstrual cycle (Coyne et al., 2000) are likely to alter core and tissue cooling, understanding the effectiveness of WBC is of paramount importance to clinicians, athletes and coaches. In addition female participation is vastly underrepresented in sport and exercise science based research (Costello et al., 2014) and even more so in thermoregulatory based areas such as WBC. The effects of this short duration WBC exposure (~3 min) and sex differences in thermoregulatory and cardiovascular measures has not been studied in depth.

Therefore, this investigation sought to examine the role of sex differences on thermoregulatory and cardiovascular responses following WBC. It was hypothesised that greater reductions in tissue temperature would be observed in females. Additionally, in an attempt to establish a best practice for individualised WBC treatments a secondary aim was to explore predictive equations (Hammond et al., 2014) for the reduction in skin temperature following exposure.

Section snippets

Participants

A convenience sample of 18 untrained participants (10 males and 8 females) volunteered for this study. A summary of anthropometric characteristics of the participants can be seen in Table 1. The study was approved by the Moulton College Human Research Ethics Committee and, in accordance with the Declaration of Helsinki, participants were informed of the requirements of the study prior to signing a consent form. Each participant also completed a medical consent form and declared that they were

Core temperature

There was no significant interaction between sex and time for core temperature however a significant effect over time following WBC exposure was observed (F(1,16)=83.578, P<0.001, d=3.14), but no difference between sexes was evident (F(1,16)=0.278, P=0.605). Baseline core temperature was similar between sexes (male:37.3±0.1 °C; female:37.3±0.2 °C; P=0.932). Core temperature reduced to a minimum of 36.7 °C and 36.3 °C at 35 min after exposure respectively for males and females. However, there was

Discussion

The purpose of this study was to investigate the impact of sex differences on thermoregulatory and cardiovascular responses to cold exposure after WBC. Additionally, we investigated the accuracy of predictive equations to help explain the variability in skin temperature after WBC. Our data suggested that there are differences between male and female mean body temperature, simultaneously with regional skin temperature when using 3-min exposure of WBC. Specifically, females demonstrated lower

Conclusion

To our knowledge this is the first study to investigate the role of sex differences on change in body heat content, core, and mean body temperature following WBC. Our data suggests that sex related differences do have an influence on thermoregulatory responses after WBC. Female participants experienced a greater reduction in skin temperature than their male counterparts, which may provide tentative support for a greater insulative response to WBC. In addition, in this study it was demonstrated

Conflict of interest

The authors declare they have no conflict of interest on the content of this paper.

Acknowledgements

We would like to acknowledge the help of Mr Jon Meyler and support of the staff at the Chris Moody Centre (Moulton College) and for the participants who volunteered for the study. The investigations comply with current laws of the UK. This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.

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