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Female development includes significant size changes across the breast. Yet, whether differences in breast surface area (BrSA) modify breast sensitivity to warm, cold and wetness, and the associated epidermal properties (skin thickness and surface roughness) remain unclear. We investigated the relationship between BrSA and thermal and wetness perception, as well as epidermal properties, in 21 females (28±$\ \pm $10 years) of varying breast sizes (BrSA range: 147–502 cm2), at multiple breast sites (i.e., nipple, above and below the nipple, and bra triangle). Associations between BrSA and the perceptual and epidermal variables were determined via correlation analyses. Differences across test sites were assessed by repeated‐measures ANOVA. Our results did not support the hypothesis that larger breasts present reduced thermal and wetness sensitivity, except for the above nipple site, which presented reduced warm sensitivity with increasing BrSA (r = −0.61, P = 0.003). We also found a heterogeneous distribution of cold, but not warm or wetness, sensitivity across the breast, with the above nipple site presenting lower cold sensitivity than any other site (P < 0.015). Our findings did not indicate any association between BrSA and epidermal properties (thickness and roughness), nor any site‐dependent variation in these anatomical parameters (P > 0.15). We conclude that, while some skin‐site (i.e., above the nipple) and perceptual modality‐dependent (i.e., warm sensitivity) differences were observed, BrSA‐dependent variations in thermal and wetness sensitivity were not a generalised feature of the skin covering the breast. These observations advance our fundamental understanding of breast sensory function, and they could inform the design of user‐centred clothing such as bras. [ABSTRACT FROM AUTHOR] more...

Female development includes significant morphological changes across the breast. Yet, whether differences in breast surface area (BrSA) modify breast skin stiffness and tactile sensitivity at rest and after exercise in the heat remain unclear. We investigated the relationship between BrSA and skin stiffness and tactile sensitivity in 20 young to middle‐aged women (27 ± 8 years of age) of varying breast sizes (BrSA range: 147–502 cm2) at rest and after a submaximal run in a warm climatic chamber (32C${\mathrm{C}}$ ± 0.6C;${\mathrm{0}}{\mathrm{.6C;}}$ 53% ± 1.7% relative humidity). Skin stiffness above and below the nipple and tactile sensitivity from the nipple down were measured. Associations between BrSA and both skin stiffness and tactile sensitivity at rest were determined via correlation analyses. Effects of exercise and test site were assessed by a two‐way ANOVA. Skin stiffness was positively correlated with BrSA 3 cm above the areola edge (r = 0.61, P = 0.005) and at the superior areola border (r = 0.54, P = 0.016), but not below the nipple (P > 0.05). The area 3 cm below the areola was also significantly stiffer than all other test sites (P < 0.043). Tactile sensitivity did not vary with BrSA (P > 0.09), but it varied across the breast (i.e., the area 3 cm below the areola was more sensitive than the inferior areola edge; P = 0.018). Skin stiffness and tactile sensitivity across the breast decreased after exercise by ∼37% (P < 0.001) and ∼45% (P = 0.008), respectively. These findings expand our fundamental understanding of the mechanosensory properties of the female breast, and they could help to inform sportswear innovation to better meet the support needs of women of different breast sizes at rest and following exercise. What is the central question of this study?How do differences in breast surface area impact skin stiffness and tactile sensitivity in healthy women before and after running in the heat?What is the main finding and its importance?We found a new relationship between breast morphology and skin stiffness, such that skin stiffness increased linearly with breast surface area in the upper breast. Furthermore, skin stiffness and tactile sensitivity decreased after exercise in the heat. These findings expand our fundamental understanding of breast mechanosensory properties and they could help to inform sportwear innovation to meet the support needs of women of different breast sizes better. [ABSTRACT FROM AUTHOR] more...

Female development includes significant morphological changes across the breast. Yet, whether differences in breast surface area (BrSA) modify sweat gland density and output remains unclear. The present study investigated the relationship between BrSA and sweat gland density and output in 22 young to middle‐aged women (28±$\ \pm \ $10 years) of varying breast sizes (BrSA range: 147–561 cm2) during a submaximal run in a warm environment (32 ±$ \pm \ $0.6°C; 53 ±$ \pm \ $1.7% relative humidity). Local sweat gland density and local sweat rate (LSR) above and below the nipple and at the bra triangle were measured. Expired gases were monitored for the estimation of evaporative requirements for heat balance (Ereq, in W/m2). Associations between BrSA and (i) sweat gland density; (ii) LSR; and (iii) sweat output per gland for the breast sites were determined via correlation and regression analyses. Our results indicated that breast sweat gland density decreased linearly as BrSA increased (r = −0.76, P < 0.001), whereas sweat output per gland remained constant irrespective of BrSA (r = 0.29, P = 0.28). This resulted in LSR decreasing linearly as BrSA increased (r = −0.62, P = 0.01). Compared to the bra triangle, the breast had a 64% lower sweat gland density (P < 0.001), 83% lower LSR (P < 0.001) and 53% lower output per gland (P < 0.001). BrSA (R2 = 0.33, P = 0.015) explained a greater proportion of variance in LSR than Ereq (in W/m2) (R2 = 0.07, P = 0.538). These novel findings extend the known relationship between body morphology and sweat gland density and LSR, to the female breast. This knowledge could innovate user‐centred design of sports bras by accommodating breast size‐specific needs for sweat management, skin wetness perception and comfort. What is the central question of this study?How do differences in breast surface area impact sweat gland density and output across the breast of healthy women during running in the heat?What is the main finding and its importance?There was a novel relationship between breast morphology and sweat gland density and output such that gland density and local sweat rates decreased linearly as breast surface area increased. Furthermore, the breast had lower sweat gland density and output than the bra triangle. This knowledge could inform user‐centred design of sports bras through a better understanding of breast size‐specific thermal needs. [ABSTRACT FROM AUTHOR] more...

Women continue to be under‐represented in thermoregulatory research despite their undergoing unique physiological changes across the lifespan. This study investigated the biophysical, thermo‐physiological, and perceptual determinants of cool‐seeking behaviour during exercise in younger and older women. Eleven younger (25 ± 5 years; 1.7 ± 0.1 m; 63.1 ± 5.2 kg) and 11 older women (53 ± 6 years; 1.7 ± 0.1 m; 65.4 ± 13.9 kg) performed a 40‐min incremental cycling test in a thermoneutral environment (22 ± 1.7°C; 36 ± 4% relative humidity). Throughout the test, participants freely adjusted the temperature of a cooling probe applied to their wrists to offset their thermal discomfort. We continuously recorded the probe–wrist interface temperature to quantify participants' cool‐seeking behaviour. We also measured changes in participants' rate of metabolic heat production, core and mean skin temperatures, and skin wetness. Finally, we body‐mapped participants' skin heat, cold and wetness sensitivity. Our results indicated that: (1) older and younger women exhibited similar onset and magnitude of cool‐seeking behaviour, despite older women presented reduced autonomic heat‐dissipation responses (i.e., whole‐body sweat losses); (2) older women's thermal behaviour was less determined by changes in core temperature (this being a key driver in younger women), and more by changes in multiple thermo‐physiological and biophysical parameters (i.e., physical skin wetness, temperature and heat production); (3) older women did not present lower regional skin thermal and wetness sensitivity than younger women. We conclude that predictions of female cool‐seeking behaviours based on thermo‐physiological variables should consider the effects of ageing. These findings are relevant for the design of wearable cooling systems and sports garments that meet the thermal needs of women across the lifespan. What is the central question of this study?How does cool‐seeking behaviour during exercise and its underlying biophysical, thermo‐physiological and perceptual determinants change with ageing in women?What is the main finding and its importance?Younger and older women exhibited similar onset and magnitude of cool‐seeking behaviour, despite older women presenting reduced autonomic heat‐dissipation responses. Furthermore, older women's thermal behaviour was less determined by changes in core temperature, and more by changes in multiple thermo‐physiological and biophysical parameters. These findings are relevant for the design of wearable cooling systems and sports garments that meet the thermal needs of women across the lifespan. [ABSTRACT FROM AUTHOR] more...

Women are a group of individuals that undergo unique anatomical, physiological and hormonal changes across the lifespan. For example, consider the impact of the menstrual cycle, pregnancy and menopause, all of which are accompanied by both short‐ and long‐term effects on female body morphology (e.g., changes in breast size) and temperature regulation, heat tolerance, thermal sensitivity and comfort. However, empirical evidence on how skin thermal and wetness sensitivity might change across the lifespan of women, and the implications that this has for female‐specific thermal behaviours, continues to be lacking. This paper is based on a symposium presentation given at Physiology 2023 in Harrogate, UK. It aims to review new evidence on anatomical and physiological mechanisms underpinning differences in skin thermal and wetness sensitivity amongst women varying in breast size and age, in addition to their role in driving female thermal behaviours. It is hoped that this brief overview will stimulate the development of testable hypotheses to increase our understanding of the behavioural thermal physiology of women across the lifespan and at a time of climate change. [ABSTRACT FROM AUTHOR] more...