Influence of Shaving Behavior on Skin PhysioIogicaI Properties and Sensory Discomfort of Chinese Men

Xia Xue, Ilyoung Kwack, Jin Yan, Zhang Ping, He Quanquan, Jaeho Yeon

Amore-Pacific (Shanghai) R & I Center Co., Ltd., China

Introduction

Male skin properties is different from females skin in properties such as stratum corneum thickness, integrity recovery rate, sebaceous secretion, roughness, elasticity,etc.,[1,2]and the underlying mechanism would be hormone regulation, environmental stress and male behaviors.[3]To date, male skin studies mainly emphasized on phenotype difference identification,[4,5]while very few have noticed the influence of male behaviors on skin physiology.

The effect of shaving, as a distinct male behavior,on skin properties is worth studying. Currently studies mainly focus on shaving device optimization and shaving biomechanics[6～9], while how shaving behaviors affect skin physiological properties or cause skin sensory discomfort has not been systematically investigated. Furthermore, as typical Asian skin type, beard hair texture, growth rate and distribution of Chinese males is different from other ethnic groups,[10,11]so the preferred shaving device, frequency and shaving care habits also varied, which will also induce the variation of skin physiological properties.

Moreover, it is believed that shaving care product usage can help relieve shaving damage.[3,7,12]However,researchers mainly concentrated on product efficacy testing or a skin improvement mechanism explanation,[10,13,14]while whether the general shaving care habits would be effective to relieve shaving induced skin physiological properties is still unknown.

Skin research was carried out in healthy Han nationality males residing in Shanghai, China. Instrumental tests and sensory questionnaire investigation were performed to investigate how the shaving process affected skin physiological properties and cause skin sensory discomfort,and whether the general shaving care habits would be helpful for shaving damage relief. The information obtained would be useful for deeper understanding of shaving influence on skin properties and be beneficial for a specifically design shaving care product for Chinese male consumers.

Material and methods

Subjects

A total of 45 healthy Chinese males aged 20 to 35 years (mean age ± standard deviation: 28.2 ± 3.5 years)with Han nationality and residing in Shanghai were recruited. All subjects were indoor office males so as to avoid the interference of sun damage and other factors.Men having facial hair on non-shaved cheek area or have very few beard hairs on typical shaved chin area, as well as have visible scars, moles or pimples were excluded. Apart from this, subjects with shaving frequency lower than 2 to 3 times a week were excluded, so as to exclude from the panels individuals with very low beard hair growth rate. Subjects were asked not to shave 1 day before the test, and bring their usual shaving device to the test site for immediate shaving. All subjects were asked to sign the information consent form before the test.

Study design

Subjects were asked to wash their face with the mild facial cleanser and stay quietly in a controlled temperature and humidity room (25 °C ± 50% humidity) for 30 min before their first round of test. As shown in Figure 1, skin hydration,melanin, erythema, sebum and pH were measured on chin(1) and cheek (3), while TEWL, pore and wrinkle degree were measured on chin (2) and cheek (4) area to avoid probe interference. Then, they were asked to shave with their usually used shaving device. Among the panels, 24 subjects used electric shaver and 21 subjects selected manual blade, respectively. After shaving, the second round of tests immediately began. All parameters were measured only at the chin area, as which is directly influenced by shaving for all the subjects. Then they were asked to complete the questionnaires about sensory discomfort and shaving care habits.

The immediate effect of shaving was investigated in electric shaver users and manual blade users, respectively.The before and after shaving skin parameters in the chin area were compared in both groups to study how the two shaving methods immediately affect skin condition. In addition, how shaving accumulatively effects skin was also investigated through the comparison of the first-round test data between the chin and the cheek area. For Chinese males, beard hairs grow on the chin, and very few hairs are present on the cheek,and the comparison of skin parameters at shaved (chin) and unshaved (cheek) area would be a feasible method to study the long-term effect of shaving.[10]To study the effect of shaving care habits, the first round of test data in the chin area was compared between two panel groups with or without shaving care habits, and each group contained 15 subjects.The selection of panels was according to their questionnaire answers.

Figure 1. Facial areas for instrumental measurement.1, Left chin; 2, Right chin; 3, Left cheek; 4, Right cheek.

Non-invasive measurement

Skin hydration, sebum, melanin, erythema and pH were measured by series of probes attached to Cutometer®dual MPA 580 (Courage + Khazaka electronic GmbH,Cologne, Germany). Skin hydration was measured by Corneometer®CM 825, each test site was measured in triplicate to get the average value. Sebum was tested by Sebumeter®SM 815. As sebum was taken away by each measurement, this value was only measured once on each site, and the second round of tests was carried out in the opposite position of the chin to avoid repeated measurement. Melanin and Erythema were simultaneously detected by Mexameter®MX 18, and values were an average of triplicate test. For pH value, it was measured by Skin-pH-Meter®PH 905, the data was recorded when it reached constant level.

Measurement of skin pore and wrinkles was conducted by Skin Touch (Amore-Pacific Corp., Seoul,Korea), as shown in Figure 2. The principle was similar to dermatoscope in that pictures were taken in the test area by different light sources, and built-in image analysis software automatically calculated the degree of skin pore and wrinkle, and presented data on the connected computer. The diameter of measurement area was about 17 mm. Transepidermal water loss (TEWL) was measured by VapoMeter SWL (Delfin Technologies Ltd., Kuopio,Finland), a closed chamber instrument. The measurement was taken 3 times per test site to obtain the average value.

Figure 2. Device picture of skin touch that was used to measure skin pore and wrinkle degree.

Questionnaire investigation

A 5-point scale was built up to evaluate the discomfort degree after immediate shaving and long terms of shaving separately. The scale of 1 to 5 was set as non-discomfort,slightly discomfort, moderate discomfort, discomfort and strong discomfort. The evaluated items include itching, stinging, burning, skin darkness, dryness, pore enlargement, blotch, skin lesion and skin thickening.

The scores of both short term and long-term discomfort degree were collected from the 45 panelists to study the specific sensory feelings related to shaving.

Data analysis

All data were processed using IBM® SPSS® Statistics Version 22 (IBM Corp., New York, US). Shapiro-Wilk method was applied to test the normality distribution of all test data. Comparison of skin parameters at different test sites, and the comparison of two groups with or without shaving care habits were conducted with onefactor ANOVA test. Comparison of skin parameters before and after shaving, as well as long term and short term sensory evaluation were tested by paired t-test.Statistical significance was determined at p ＜ 0.05 for all these tests. (*p＜ 0.05; ** p＜ 0.01).

Results

The influence of immediate shaving on skin physiological properties

The skin parameters in the chin area of both electric shaver group and manual blade group were shown in Figure 3. In the electric shaver group, sebum dramatically decreased 40% after shaving, while other parameters remained steady. In the manual blade group, both skin hydration and sebum level decreased. The decreased water or sebum content may partially explain the dryness feelings after shaving. For TEWL, the indicator of skin barrier integrity, as well as melanin and erythema, the pigment index, maintained unchanged in both groups.The pH values significantly increased in the manual blade group, which may be altered by cleansing foam used during shaving.

Skin pore and wrinkle degree were tested by image processing method. Higher value indicates poorer skin condition. In manual blade group, the two parameters significantly decreased 25.6% and 17.8%, respectively.There was also significant difference between electric shaver and manual blade in regard to before-shaving data,suggesting the manual blade shaving would be beneficial for skin smoothness.

Figure 3. The comparison of skin physiological properties before and after immediate shaving in electric shaver group and manual blade group. A, Skin hydration; B, TEWL; C, Sebum; D, pH value; E, Melanin index; F, Erythema index; G, Pore; H,Wrinkle. (Filled column represents skin parameters before shaving, empty column represents skin parameters after shaving.)

The influence of long term shaving on skin physiological properties

Skin parameter comparison between shaved and unshaved area was shown in Figure 4. Water content was lower in the chin area, similar to the immediate effect of shaving. However, TEWL was significantly higher(26.2%) in the chin area, indicating poorer skin barrier integrity. Sebum and pH value, which were altered after immediate shaving,remained similar at different test sites. Skin pigmentation parameters value, melanin and erythema indexs were 52.5%and 12.9% higher in the chin area, respectively. Skin pore and wrinkle analysis were reduced by 19.7% and 28.4% in the chin area, respectively, suggesting the better pore and wrinkle condition in the chin area.

Self-evaluation of short term and long term sensory discomfort related to shaving

Figure 4. The skin physiological parameters at different facial sites. A, Skin hydration; B, TEWL; C, Sebum; D, pH;E, Melanin; F, Erythema; G, Pore; H, Wrinkle.

Self-evaluation proved to be capable of properly reflecting real skin condition.[8,13]The questionnaire results of sensory discomfort degree after immediate and long-term shaving were shown in Table 1. In this study, about 30% of panelists reflected moderate to a high degree of discomfort to items of itching, stinging,burning, as well as skin dryness and pore enlargement.According to the questionnaire, panelists were prone to score higher discomfort degree for long-term evaluation than immediate assessment. Especially for burning and dryness sensation, the score after long term shaving was significantly higher. Skin darkness is not considered as a major problem after shaving in hat only around 10% of panelists scored 3, 4 or 5, and higher discomfort degree was also observed in long term evaluation.

To some extent, blotch, skin lesion and thickened skin are considered to be serious skin problems, and can hurtself-esteem and affect quality of life. In this study, more than 30% of subjects reported the concern of blotch after shaving, and the cumulative damage was significantly severer than the immediate effect. Skin lesions were only assessed in short term, which described skin worn or bleeding after shaving, and the score of 3 or above is 18.7%. Meanwhile, as a manifestation of long term irritation induced skin incrassation and cornification, skin thickening is only evaluated as a long-term issue, and 18.8%of panelists have responded to this skin problem.

Table 1. Sensory evaluation of skin discomfort degree

The effect of shaving care habits on skin in the shaved area

The previous results suggested that long-term shaving can cause a significant alteration on skin physiological status. Thus, it is meaningful to investigate whether the shaving care habits of Chinese males would be helpful to relieve the skin damage caused by long-term shaving. The comparison of skin parameters in the chin area between shaving care group and non-care group was shown in Figure 5. Skin hydration was significantly higher in the shaving care group, indicating the relief of dryness caused by long-term of shaving. TEWL was also 19.5%lower in the shaving care group, suggesting barrier recovery. Accordingly, for sebum and pH level, which was not altered by long-term of shaving, remained similar between the shaving care group and non-care group. Furthermore, melanin and erythema indexs decreased 16.8% and 10.1% in the shaving care group,respectively. For skin pore and wrinkle degree, although better on chin than cheek, it was further improved by shaving care habits.

Figure 5. The comparison of skin physiological properties for shaving care group and non-care group.A, Skin hydration; B, TEWL; C, Sebum; D, pH; E, Melanin; F, Erythema; G, Pore; H, Wrinkle.

Discussion

Skin hydration and TEWL are very important skin physiological indicators that represent stratum corneum water content and barrier integrity of skin, respectively,which varied among ethnic groups, individuals or even facial locations.[15]In previous skin research on females,the chin has a higher hydration level and lower TEWL compared to the cheek area,[16,17]that proved the poor skin condition in male chin area is caused by long terms of shaving rather than original site difference. Shaving has long been considered to disrupt the skin barrier integrity.[18,19]There is no difference in TEWL after immediate shaving, but a change in TEWL after long-term shaving. These results indicate that skin barrier is more affected in the long term than short term. Fortunately, the shaving care habits proved to be capable of repairing the impaired barrier function, as the moisturizers would increase the waterbinding capacity of the stratum corneum to maintain barrier integrity and good barrier function conversely help to prevent skin water loss.[20,21]Moreover, skin barrier function is further regulated at the nerve, protein and genetic level.[22～24]These parameters are worth studying to thoroughly understand how shaving affects skin physiology.

Sebum is an oily substance secreted by sebaceous glands, which can provide protective layers and maintain water content.[25,26]In this study, sebum level greatly decreased immediately with after shaving has been found to be either electric shaver or manual razor,while it remained similar from shaved and unshaved area. According to Crowther, the sebum level of each individual is constant that will return to its original level after removal,[25]which may explain why long term shaving and shaving care habits can change the sebum content. In addition, the lack of water or sebum will result in the feeling of dryness. Based on our investigation, the dryness discomfort is severer after long term shaving, it is caused by a lack of water not sebum. It implied dryness feelings may be affected by water loss. Furthermore, loss of water and changes in sebum will also affect other skin physiological properties through alteration of the microbial distribution on the skin surface.[27]

Skin health is closely related to pH level, which is influenced by many factors.[26,28]Normally, facial pH level is with a range of 4.0 to 6.0,[29]and the acid status is essential for skin barrier maintenance.[11,30～32]In this study, after manual blade shaving, the pH level increased from 4.65 to 5.20. However, it is reported the normal pH level of males is below 5.0,[4]the elevated skin pH may not be beneficial to skin health. This change may be created by the shaving foam, because no pH level change was observed after electric shaving or long term shaving, no change by shaving care habits. According to Blaak et al., a pH 4 emulsion improved epidermal barrier structure, enhanced ceremide levels and changed skin lipid ordering,[33]suggesting the importance of acid pH maintenance at the skin surface.

Climate change, air pollution, as well as other environmental factors greatly affect skin condition.[24,30,34～36]Besides, males are also suffering from sensitive skin.[7]Itching, stinging and burning are three main factors indicating skin sensitivity.[37]In the sensory evaluation, about 30% of panelists reported the above response, indicating that shaving would be another factor inducing sensitive skin. Razor burn is a common problem related to shaving,[14,38]and the burn is an immune response prevent microorganisms get into the body through a wound caused by phyical injury of the skin during shaving,[7,8]which in turn will cause skin sensitivity in the long run.[14,39]The results shown that the burning sensation for long term shaving is significantly higher than short term. Additionally, in our study, there are still some severer skin problems such as blotch, lesion and thickening. It is known that some preservative,fragrances and surfactant ingredients may lead to skin irritation, nerve stimulation, inflammation and other unexpected skin problems.[8,40～42]Thus, consideration should be given to barrier recovery, nerve sedation and anti-inflammation efficacy when developing shaving care products.[24]In an American survey, 90%of responders agreed that the selection of shaving products was important for men with sensitive skin.[37]With the male cosmetic market growing in China,more Chinese males gain the awareness to choose proper shaving devices and shaving products.

Melanin and erythema indexs are two major parameters reflecting skin pigmentation and redness. Skin pigmentation is determined by the types and amounts of melanin,melanosome distribution and its transfer,[43～45]which would be affected by skin irritation, inflammatory factors as well as oxidative stress.[34]As for the erythema index, it is directly related to skin inflammation, microcirculation and stratum corneum thickness.[46]Since shaving is believed to cause skin irritation,[6～8]the pigmentation and redness issues are worth further investigation. Unexpectedly, neither melanin nor erythema index changed after immediate shaving, suggesting the irritation is not capable of immediately altering skin color. However, in the long term, the melanin and erythema indexs are significantly higher in the shaved chin area than unshaved cheek area, even if the cheek received more sun damage.[5,46]It implies the skin pigmentation and redness may form through cumulative irritation rather than immediate exposure, which is in accordance with sensory evaluation that panelists scored higher darkness degree after long term shaving. Furthermore, shaving care habits turn out to relieve skin darkness and redness:this efficacy may be generated by ameliorating skin dryness, and strengthen skin barrier.[47]

In this study, skin pore and wrinkle conditions were improved after shaving. According to the P&G research, skin flakes are removed after shaving, which make skin smoother and more delicate,[10]and it may partially explain our image analysis data of pores and wrinkles. Additionally, enlargered pore is an indication of heightened sebum secretion,[28]reducing sebum level may be improve skin pore condition. However, it is reported that low hydration and sebum content, as well as high TEWL and pH level would accelerate wrinkle formation[48]. In our case, wrinkle condition seems not to be damaged by these factors. Nevertheless,there still remains the possibility that the good pore and wrinkle condition in the chin area is the original states rather than the effect of shaving, as the cheek was expected to suffer severe elastic fiber loss by sun damage.[49]Moreover, Hara et al. considered dry skin can lead to wrinkles,[50]the shaving care habits may help provide water and sebum supply to maintain skin moisture so as to prevent wrinkle formation.

Conclusion

This study characterized the skin physiological properties and sensory feelings after shaving. The results indicated that immediate with a manual razor may cause dehydration and skin pore and wrinkles improvement,while the electric shaver only affects skin sebum level.For long term shaving, besides the above factors, the skin barrier is damaged and pigmentation as well as redness are observed. Compared to immediate shaving, long term shaving more dominantly influences skin properties.Sensory evaluation also indicates higher skin discomfort degree after long term shaving implies the correlation with skin sensitivity as well.

Furthermore, shaving care habits can help relieve the skin damage caused by long term shaving and improve the skin pores and wrinkles. The information obtained would be helpful to comprehensively understand how shaving affects skin physiology, so as to provide clues for the further research of shaving products specifically designed for Chinese male consumers.

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