Research on complementary underwear

doi:10.21203/rs.3.rs-1313085/v2

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Research Article

Research on complementary underwear

https://doi.org/10.21203/rs.3.rs-1313085/v2

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Purpose

The main changes in women's body shape due to aging include the descent of the breasts, tension in the abdomen, descent of the hips, increase in fat from the waist to the pelvis, and loss of waist definition. We adopted a system in which skilled body fitters correctly fitted subjects with underwear of different functions made based on the corrective underwear step system.

Design/methodology/approach

This study was designed to use a three-dimensional (3D) body scanner to examine (1) the effects of aging and other factors on body shape changes, and (2) the status of the effect of moving and fixing fat flowing to the axillae and back to improve body shape.

Findings

The results of the 8-month study have suggested that the system affected changes in the body shape, especially in the breasts.

Originality

By using this method, not only the body line can be expected to improve.

Corrective underwear

Three-dimensional (3D) body scanner

Quality of life

Step system

A woman's body shape changes with age. The main changes in body shape due to aging include the descent of the breasts, tension in the abdomen, descent of the hips, increase in fat from the waist to the pelvis, and loss of waist definition (Song et al., 2022) (Wren et al., 2014).

The breasts are mainly composed of mammary gland tissue and adipose tissue, and the Cooper’s ligament wraps around the tissue, supporting and rounding the breasts (Gefen and Dilmoney, 2007) (Riggio et al., 2000). With we age, the skin loses its elasticity and flexibility (Lavker et al., 1987) (Escoffier et al., 1989), weakening the ability to support the breasts, and when the Cooper’s ligament is stretched by gravity, it is no longer able to support the breasts, causing the entire breasts to drop (Filipea et al., 2015). In addition, the fatty tissue in the breasts flows from the armpits to the back (Sato and Demura, 2009). Once the Cooper’s ligament is stretched, it cannot return to its original position, since it is not a muscle, it cannot be strengthened exercise (Filipea et al., 2015) (Chan et al., 2015).

For woman, underwear is something she wears every day, and in order to maintain her figure, it is important to choose the right underwear for her (Lim and Cho, 2013). Since underwear is in direct contact with the skin, it can help prevent changes in body shape due to aging and other factors by supporting breasts and hips that have dropped due to physical factors. Currently, underwear designed to help women maintain their shape and correct their body lines are available from various manufacturers. There are various types of supplementary (corrective) underwear depending on the time of day when they are worn and the desired effect.

However, there are no standards for the supplementary (corrective) effects of individual products, and many aspects of their effects on body shape changes when not worn have not been verified. Adopting the right underwear for the wearer and wearing it in the right way are also considered to be factors that affect the body shape after wearing.

In this study, we defined the "prosthetic underwear step system" as a system in which a body fitter correctly fits products according to the wearer's physical condition and the conditions of time and place, and changes the underwear step by step over a long period of time. Prosthetic underwear with different functions made based on the prosthetic underwear step system was worn in the manner described above.

In addition to dividing the participants into age groups and investigating the effects of supplementary underwear according to age, we also divided them into groups according to whether or not they had ever breastfed, a factor that influences changes in women's body shape, and examined the effects of supplementary underwear according to the wearer's situation.

Ethical review

This study was conducted in the spirit of the Declaration of Helsinki (Fortaleza Amendment, October 2013) and in compliance with the “Ethical Guidelines for Medical and Health Research Involving Human Subjects (December 22, 2014, partially amended on February 28, 2017, Ministry of Education, Culture, Sports, Science and Technology and Ministry of Health, Labour and Welfare)” and the Protocol. Furthermore, this study was approved by the Clinical Trial Review Committee of Medical Corporation Association Ouryokukai Nihonbashi Sakura Clinic and registered at the University Hospital Medical Information Network Clinical Trials Registry before its implementation.

Study participants

The subjects of this study were Japanese women who met the inclusion criteria and did not meet the exclusion criteria. The inclusion criteria were as follows: (1) women between 20 and 49 years of age during consent, (2) subjects with a body mass index (BMI) of ≥18.5 kg/m², (3) subjects with a body fat percentage between 20% and 35%, (4) subjects with a weight change of ≤10% between the weight during enrollment and that on the day of observation 1 month later, and (5) subjects have consented in writing to participate in this study The exclusion criteria were as follows: (1) subjects who were wearing supplementary (corrective) underwear, (2) subjects who had undergone breast reconstruction surgery, (3) subjects who have undergone breast augmentation surgery, (4) subjects who were taking contraceptive pills (regardless of dose), (5) subjects who were taking supplements for slimming or breast enhancement, (6) subjects who had undergone liposuction surgery, and (7) subjects with a history of surgery that would affect the evaluation of this study.

Adequate written and oral explanations were given to the subjects beforehand, and voluntary written informed consent was obtained from each subject.

Study design

This was a prospective observational study conducted at a single institution. Subjects were recruited via the Internet, and written informed consent was obtained. One month after consent was obtained, the subjects wore normal underwear without using any prosthetic underwear as the introduction period. The weight and other measurements of the subjects were measured on the observation day after the end of the introduction period, and those whose weight were within ±10% of their weight at the time of enrollment and on the observation day one month later began wearing corrective underwear. Those whose weight change exceeded ±10% were dropped out of the study. The values measured on the observation day were used as the baseline, and the period from the observation day one month later to the observation day eight months later was defined as the period of wearing the underwear, and the weight and other data were measured on the observation day eight month later.

In this study, a body fitter selected and provided prosthetic underwear according to the subject’s body shape. During the wearing period, the body fitter conducted fittings every two weeks to a month, checked the condition of the subjects’ breasts, and changed the underwear according to the subject’s conditions if necessary.

The prosthetic underwear used was the “Bradelis” series from Gold Flag Co. It was manufactured based on the “prosthetic underwear step system,” and the features of the prosthetic underwear at each step were as follows:

(1) Breasts

Stage 1: Use a bra with a wide wire contour to gather the underarm, back, and breast flesh into the correct position and create a border under the bust.

Stage 2: Use a bra with a narrower wire contour and more space in the bust to gather the flesh to the center and create cleavage from the border under the bust. Use a night bra at bedtime.

(2) Hips

Stage 1: Use a pair of shorts that are three-dimensionally cut with stretchy and breathable material to wrap around the hips from the waist to restore the roundness of the buttocks.

Stage 2: Use a soft long girdle that can support and pull up from the thighs to the buttocks without constricting the groin area due to the material and three-dimensional cutting.

In addition, the same body fitter was available for all study subjects throughout the study. This person was familiar with the product and system, and was skilled in teaching them how to wear the product correctly, choose the correct size of underwear, and determine when to change from stage 1 to 2.

During the observation period, all study subjects were instructed not to diet or do muscle training, but to maintain the same frequency of diet and exercise as before the study began.

Evaluation items

The background of the study subjects was ascertained at the time of enrollment. Body weight and BMI were measured at the time of enrollment, on the observation day after 1 month, and on the observation day after 8 months. Body fat percentage was measured using the bioimpedance method at the aforementioned measurement periods. Body sizes, including the top breast, under breast, waist, and hips, and the distance between the nipples and the center of the clavicle, were measured at enrollment, on the observation day after 1 month, and on the observation day after 8 months.

The subjects were photographed using a 3D body scanner (Bodyline Scanner 3D Ligament Measurement System C9036, Hamamatsu Photonics KK, Shizuoka, Japan) on the observation days of 1 months and 8 months, respectively. The upper body was photographed without any clothes, and the lower body was photographed wearing only non-Bradelis panties.

The following items were obtained from the quality of life (QOL) questionnaire:

On the observation day after one month

Shoulder stiffness, dissatisfaction with underwear, expectations for corrective underwear, etc.

On the observation day after 1 and after 8 months, respectively

Comfort of bra, comfort of panties, degree of improvement in stiff shoulders, degree of improvement in dissatisfaction with underwear, and feeling of using corrective underwear

In addition, the wearing status of the corrective underwear was obtained.

Endpoints

The primary endpoint of this study is the changes in the area ratio of the back flesh as it moves to the chest, as measured by cross-sectional views using a 3D body scanner. For each subject, the value on the observation day after 8 months was compared with the baseline values on the observation day after 1 month. In the chest cross-sectional view, the ratio of the front to the back was divided into 2:8, and the area ratio was measured using the chest side as the chest circumference (2/10) and the back side as the chest girth (8/10).

The secondary endpoints were breast size, underbust size, distance from nipple and clavicle center, waist size, hip size, and QOL assessment, and the values at the 8-month observation day were compared to the baseline values at the 1-month observation date.

Statistical analysis

In the statistical analysis of this study, subjects whose percentage of change between the 1-month and 8-month observation dates of the breasts, using the 3D body scanner exceeded ±10% were excluded because of possible measurement inadequacies at the time of measurement.

For each endpoint, paired t-test was used to compare the values at the 1-month observation day with those at the 8-month observation day. For the primary endpoint, stratified analysis was performed by age and breastfeeding experience. For age, each groups was compared using analysis of variance, and Bonferroni’s multiple comparisons were performed when significant differences occurred. For breastfeeding experience, Student’s t-test was used to compare the groups. The significance level was two-sided and was set at 5%. R version 3.6.2 (R Core Team, Vienna, Austria) was used for statistical analysis.

Of the 91 subjects who agreed to participate in this study, 90 underwent measurements on the observation day one month later. The number of subjects included in the final analysis was 67 and 48 on the observation days after 1 and 8 months, respectively. Nineteen people did not visit after 8 months.

The overall change in chest circumference measured using the 3D body scanner was −0.105 ± 0.213 [m²], and the rate of change was −1.9% ± 3.9%, indicating a significant change (p < 0.05). In the chest circumference (2/10), the change was −0.017 ± 0.081 [m²] with a change rate of −1.0% ± 6.1%, whereas in the posterior chest girth (8/10), the amount of change was −0.088 ± 0.152 [m²] and the rate of change was −2.2% ± 3.7%. In terms of area ratio, the anterior change was 0.2 ± 0.9 [m²] with a rate of change of 0.9% ± 3.7%, while the posterior change was −0.2 ± 0.9 [m²] with a rate of change of −0.2% ± 1.2%.

On the observation day 8 months later, both body weight and abdominal girth decreased compared to the baseline values, with a significant difference in the abdominal girth (p < 0.001).

The breast circumference, nipple distance, nipple–clavicle distance, and upper-hip circumference showed a decreasing trend compared with the baseline values. On the other hand, hip and top-hip circumferences was observed.

In this study, the results were obtained from 42 of 48 subjects (response rate = 87.5%). For the rate of wearing underwear, 35 respondents reported wearing underwear almost every day. The remaining seven respondents also indicated wearing underwear ≥3/4 of the time during the period. The percentage of respondents who answered “very good” or “good” for comfort of wearing corrective underwear throughout the period of use was 90.5% and 76.2% for the bra and panties, respectively.

Stratified analysis by age showed a significant decreases in chest circumference and girth (8/10) compared to baseline in women in their 20s and 30s, but not in women in their 40s. A significant decrease in the abdominal girth compared to the baseline value was seen only in subjects in their 30s. According to the breastfeeding experience, significant decreases in chest circumference and girth (8/10) compared with the baseline values were found in the group that had never breastfed.

Wearing corrective underwear was terminated on the day of observation 8 months later, and body sizes were measured again after 11 months. Four participants were measured on the observation day 11 months later. Comparing the rate of change in the area ratio of chest circumference (2/10) and chest girth (8/10) with that measured on the observation day eight months later, the rate of change in chest circumference (2/10) tended to decrease and the rate of change in chest girth (8/10) tended to increase, indicating that the body shape that had changed by wearing corrective underwear and completing the adaptation of the system had changed in the direction of returning to the original shape.

In this study, we examined the effect of a system in which a skilled body fitter correctly fits underwear with different functions made based on the corrective underwear step system according to the time, place, and situation and changes the underwear in stages according to long-term wear, on changes in the body shape using a 3D body scanner.

On the observation day 8 months later, there was a decrease in the chest circumference compared to the baseline value. This is thought to be due to the decrease in chest circumference that accompanied the decrease in body weight. Although the subjects in this study were instructed not to change their diet or exercise during the wearing period, this may be because the subjects became aware of their body shape through periodic measurements.

The change in the area ratio of each part of the 2:8 divisions of the chest circumference cross-section showed a decrease in the posterior side and an increase in the anterior side. The corrective underwear used in this study was intended to collect fat that had flowed to the chest, and the results showed that the fat flowing to the armpits and back was returned to its original position (chest side). Furthermore, the distance between the nipple and clavicle decreased, indicating that the breasts were lifted to the clavicle side by corrective underwear. These results suggest that wearing corrective underwear that fits the body type continuously in stages can affect the shape of the breasts.

Although the upper hip circumference significantly decreased, no significant differences in the top-hip and hip circumferences were observed with an increasing trend. These findings indicate that the increase in capacity was due to the moving of fat from the upper hips to the top-hips area, suggesting that wearing corrective underwear can affect the shape of the hips.

After the termination of wearing corrective underwear, these changes were not lasting forever and changed toward returning to the original shape in a few months, suggesting that it is desirable to continue wearing the corrective underwear.

According to the results of the QOL questionnaire, only a few subjects felt changes in their overall body shape, such as clothing size, and more than half of the subjects felt changes in their breasts and hips. This suggests that some subjects were able to confirm the changes indicated by the measurements.

Stratified analysis by age and breastfeeding experience showed a significant decreases in the number of corrective effects in the age groups of 20s and 30s and in the group who had never breastfed. Age and breastfeeding experience affected the magnitude of the effects of corrective underwear, but there was no significant difference was found among the groups in their 40s or those who had breastfed. These may be due to the influence of the skin texture of each age group. There was no significant difference in the chest circumference (2/10), and there was an increasing trend in those in their 20s and 30s, but no change in those in their 40s, suggesting that the magnitude of the effects of wearing corrective underwear is influenced by skin type. However, the trend of change was similar to that of the other groups, suggesting that the fitting system used in this study can change body shape through the continuous wearing of corrective underwear, regardless of age or breastfeeding experience.

One of the limitation of this study is that although we provided guidance on diet and exercise, we did not conduct in-depth interviews with the study subjects about the content of their diet and exercise.

We adopted a system in which skilled body fitters correctly fitted subjects with underwear of different functions made based on the corrective underwear step system, according to the time, place, and occasion, and then changed the underwear according to the stage of change as the subjects wore the underwear over a long period of time. The results of the 8-month study have suggested that the system affected changes in the body shape, especially in the breasts. During the measurements, the subject wore nothing on her upper body and only panties, not corrective one, on her lower body. Therefore, the changes in the wearer’s body shape was maintained even after the support of the corrective underwear was removed. By using this method while wearing the corrective underwear that fits the body shape over time, not only the body line but also the awareness of the wearer can be expected to improve.

Funding details

For single agency grants: This work was supported by the GOLD FLAG Co.,Ltd.

Disclosure statement

No potential competing interest was reported by the author.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author, YY, upon reasonable request.

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Version 2

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Research on complementary underwear

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Abstract

Introduction

Materials And Methods

Results

Discussion

Declarations

References

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