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Do Current Sports Brassiere Designs Impede Respiratory Function?

BOWLES, KELLY-ANN1; STEELE, JULIE R.1; CHAUNCHAIYAKUL, RUNGCHAI2

Medicine & Science in Sports & Exercise: September 2005 - Volume 37 - Issue 9 - p 1633-1640
doi: 10.1249/01.mss.0000177590.75686.28
Applied Sciences: Physical Fitness and Performance
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Purpose: Although sports brassieres are more effective in limiting breast motion and related breast pain when compared with standard fashion brassieres, some females do not wear sports brassieres during physical activity, as they perceive them to be too tight around the torso, possibly impeding their performance during physical activity. The purpose of this study was to determine whether breast hypertrophy, breast momentum, and/or wearing a sports brassiere impeded respiratory function at rest and during physical activity.

Methods: Twenty-two active women completed standard resting spirometry maneuvers while not wearing a brassiere. All subjects then completed maximal cycle ergometer testing in two breast support conditions (sports brassiere and no brassiere (NB)), followed by submaximal treadmill exercise tests under three breast support conditions (sports brassiere, no brassiere and fashion brassiere) while standard spirometry, brassiere pressure and comfort were measured.

Results: The sports brassiere imparted significantly more pressure on smaller breasted females’ torsos when compared with the fashion brassiere (0.861 ± 0.247 and 0.672 ± 0.254 N·cm−2, respectively), although this increased pressure did not appear to significantly affect measured lung volumes or brassiere comfort scores. Brassiere size affected maximal exercise ability (relative V̇O2peak: smaller breasted NB: 49.84 ± 6.15 mL·kg−1·min−1; larger breasted NB: 40.76 ± 4.47 mL·kg−1·min−1) as well as some temporal measures of resting and submaximal respiration. However, no significant difference was found between the no brassiere and brassiere conditions in regards to measured lung volumes.

Conclusions: As no significant restriction to exercise performance or respiratory mechanics was found when subjects wore sports brassieres, it was concluded that active females should wear a sports brassiere during physical activity to reduce breast motion and related breast pain.

1Biomechanics Research Laboratory, University of Wollongong, New South Wales, AUSTRALIA; and 2College of Sports Science and Technology, Mahidol University, THAILAND

Address for correspondence: Professor Julie Steele, Biomechanics Research Laboratory, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia; E-mail: julie_steele@uow.edu.au.

Submitted for publication August 2004.

Accepted for publication April 2005.

This research was funded by an Australian Research Council Strategic Partnership with Industry Grant with Berlei (Australia) as the Industry Partner. Berlei (Australia), however, were not involved in any data collection, data analysis, or the production of this article. Funding was also provided by the New South Wales Sporting Injuries Committee, and the custom novel pressure measuring strips were kindly donated by novelgmbh (Munich, Germany) for this experiment.

Sports brassieres have been shown to be more effective in limiting breast motion and related breast pain compared with other forms of external breast support (11). However, anecdotal evidence suggests that females are often deterred from wearing sports brassieres during physical activity, as they perceive sports brassieres to be too tight around their chest and, in turn, may impede their athletic performance. Although sports brassieres are typically restrictive around the torso in an attempt to limit breast motion and related breast pain (17), the effects of this restrictiveness on respiratory function and resultant physical performance has not been examined.

Although no research pertaining to the effects of brassiere design on respiratory function was located in the literature, several studies have investigated the effects of strapping the chest region on respiratory function (6,13,14). This previous research has provided evidence that strapping the chest wall can impede respiratory function by reducing functional residual capacity (FRC) and limiting inspiratory chest wall motion (6). Although the magnitude of the reported reduction in lung volume varies among studies, it is thought that the reduction in FRC may be primarily attributed to reductions in the expiratory reserve volume (ERV) (6), with several researchers suggesting poor ventilation in some regions of the lung as a result of chest strapping (6,13). O’Donnell et al. (14) have also reported finding significant decreases in resting lung volumes and exercise performance and significantly more shallow and rapid breathing patterns during exercise when chest strapping was applied to their subjects compared with exercise with no chest strapping.

In addition to the paucity of literature relating to brassiere design effects on respiratory function, no research was found investigating the effects of breast hypertrophy on respiratory function during physical activity or at rest. That is, it is not known whether momentum developed by female breasts during physical activity affects chest wall motion, which, in turn, impedes respiratory function, or whether the presence of large amounts of breast tissue imitates those results seen in the overweight and obese populations, with additional mass placed on the external chest. Obesity is associated with reduced lung volumes, especially reductions in ERV (4), vital capacity (VC) and forced expiratory volumes in 1 s (FEV1) (10). Babb et al. (4) suggested that the smaller ERV seen in obese individuals was due to a reduction in either the end-expiratory lung volume (EELV) or the FRC, although no such research has investigated whether similar reductions in lung volumes are observed in larger breasted women. Therefore, the purpose of this study was to determine whether the presence of breast hypertrophy, or the breast momentum developed by larger breasted women and/or wearing a sports brassiere impeded respiratory function at rest or during physical activity. Based on the reviewed literature it was hypothesized that an increase in the external pressure applied by a sports brassiere would be coupled with a decrease in respiratory function during physical activity in all subjects, relative to less restrictive breast support conditions. In addition, it was hypothesized that larger breasted subjects would display reduced respiratory function when compared with the smaller breasted subjects, both at rest and during physical activity.

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METHODS

Subjects.

After being professionally fitted for a brassiere by the Chief Investigator (K.-A.B.), 22 healthy active female volunteers (mean age = 25.14 ± 4.82 yr; height = 166.5 ± 4.5 cm; mass = 65.11 ± 9.2 kg) were recruited for this study from staff and students at the University of Wollongong. The women were allocated to one of two subject groups (11 per group) based on their brassiere size: (i) smaller breasted women (A cup brassiere) or (ii) larger breasted women (≫C cup brassiere). Subjects presenting with lower limb musculoskeletal disorders or cardiorespiratory problems, breast surgery/implants, or previous or current pregnancies were excluded from participating in the study.

After providing written informed consent, subjects completed a pulmonary function and physical activity questionnaire (7). All subjects then attended the laboratory on four separate occasions, each visit scheduled within 2 wk after the onset of their menses, at the same time each day, and with a minimum of 48 h between testing sessions (Table 1). At the commencement of the initial visit, each subject’s height and weight were recorded in triplicate to later calculate body mass index (BMI) and weight adjusted V̇O2peak.

TABLE 1

TABLE 1

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Brassieres.

Two brassiere styles were tested in this experiment, a fashion brassiere (Berlei Touched; made from Meryl nylon and white elastane; A cup with no underwire; C+ cup with underwire) and a sports brassiere (Berlei Ultrasport; made from white nylon, cotton, polyester and Lycra; A cup with no underwire; C+ cup with underwire). All brassieres, regardless of size or style, were encapsulating in design with structured brassiere cups. The subjects were fitted for the fashion brassiere and then provided with a sports brassiere of the same size. The chief investigator (K.-A.B.) assisted each subject to fit their brassieres for each trial, attaching each brassiere at the middle hook and eye on the rear fastener of the brassiere and adjusting the shoulder straps for individual subject comfort. Each subject wore new brassieres during their test sessions to ensure that there was no adverse effects of either wear or washing on the brassieres.

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Resting spirometry protocol.

To determine whether brassiere size affected resting respiratory function, spirometry measures were collected (50 Hz; DAS 1602, MetraByte; Keithley Data Acquisition, Taunton, MA) for each subject while she stood on a treadmill, wearing a nose clip and breathing into a Hans Rudolph low-resistance heated pneumotachograph (model 8430) via a mouthpiece connected to a spirometry filter. The pneumotachograph was connected to a differential pressure transducer (Validyne DP45-14, ±0.22 kPa; Validyne Corp., Northridge, CA), which was coupled to a carrier demodulator (Validyne CD19A; Validyne Corp.). Two sets of low-resistance two-way, nonrebreathing valves were attached to the respiratory system, next to the mouthpiece-pneumotachograph assembly to allow the subject’s inspired and expired laboratory air to be separated and to minimize apparatus dead space. Flow calibration was performed before commencing each session using a 3-L syringe pump, with volume standards applied at various flow rates (8). Expiratory, inspiratory, and tidal lung volumes were determined from the digital integration of respiratory flow signals, with all volumes corrected and expressed as body temperature and pressure saturated with water vapor (BTPS).

Resting spirometry measures, including static tidal volume (V̇T), were collected during relaxed spontaneous breathing, with other volumes and capacities derived from standard lung volume maneuvers (2). Both data sets were collected over 60 s. Maximum voluntary ventilation (MVV) and FEV1 were also performed to assess the dynamic function of each subject’s respiratory system. All maneuvers were completed in triplicate each day, with the three greatest volumes and flows achieved for each measure over the final 2 d of testing averaged and used for data analysis.

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Maximal exercise testing.

In an attempt to quantify whether perceived sports brassiere “tightness” impeded maximal exercise performance, maximal exercise tests were completed by the subjects in two breast support conditions: (i) while wearing a fitted new sports brassiere (SB), and (ii) while wearing no external breast support other than a loosely fitting T-shirt (NB).

Pilot testing established that running on a treadmill while wearing no external breast support resulted in breast pain severe enough to force some subjects to cease the exercise trial after as little as 5 min of exercise. Therefore, maximal exercise tests were completed on an electronically braked cycle ergometer. As breast motion during cycling was minimal, this cycle ergometer protocol also enabled the effects of brassiere “tightness” to be examined in isolation of any breast momentum effects.

Exhaled air during cycling was carried into the open-circuit gas analysis system (SensorMedics2900, Yorba Linda, CA) to calculate V̇O2 measures with the gas analyzers calibrated daily with two known gas concentrations (oxygen: 15.9–26.4%; carbon dioxide: 0–4.23%). During testing, subjects commenced cycling at 20 W for a 1-min warm-up, with resistance then increasing in a ramped protocol of 6–7 W·20 s−1 until exhaustion. Each subject completed three maximal exercise tests (Table 1), with results from the second and third day used for data analysis. During all exercise trials, each subject’s HR was monitored using a POLAR HR monitor (Polar Electro, Oy, Finland). To eliminate any chest wall restriction caused by the elastic belt of the HR monitor, while still enabling clear HR signals to be monitored, the chest strap of the monitor was removed and the monitor was attached to two electrodes, which were placed directly onto each subject’s torso below the level of breast tissue.

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Submaximal exercise testing.

In order to evaluate the effects of breast support on respiratory function during submaximal exercise and to determine whether breast momentum significantly impeded submaximal exercise performance, each subject completed submaximal exercise trials in three breast support conditions: (i) NB, (ii) SB, and (iii) wearing a fitted new fashion brassiere (FB). The submaximal exercise trials were completed on a treadmill as each trial was approximately 5 min in duration and breast bounce was required for these trials to determine whether breast momentum developed by larger breasted subjects impeded respiratory function compared with their smaller breasted counterparts.

For submaximal exercise trials, the subjects stood on a treadmill (Quinton Instruments, Model 18-60-1, Seattle, WA) while wearing the nose clip and spirometry mouthpiece, with a 15-cm section of 5-cm diameter flexible tubing inserted between the mouthpiece and the pneumatograph to allow the subjects to move more freely during the submaximal trials. The size of the inserted tubing was restricted to minimize any effect on the system’s dead space. Treadmill speeds during the submaximal exercise trials were individualized to achieve 70% of each subject’s V̇O2peak using the methods detailed in the American College of Sports Medicine’s Guidelines for Exercise Testing and Prescription (1). HR was monitored during each trial using the same procedures that were described for the maximal exercise testing.

Lung spirometry measurements during exercise commenced once the steady HR had been achieved at 70% of the subject’s V̇O2peak. These measures of dynamic V̇T are detailed in the resting spirometry protocol and were collected for 1 min via the mouthpiece-pneumotachograph assembly, immediately followed by standard lung volume maneuvers collected over an additional 1 min. If the target HR was not achieved or the target HR was surpassed before the HR stabilizing, the treadmill speed was adjusted accordingly.

To determine brassiere “tightness” during exercise, the external pressures that the brassieres applied to each subject’s chest region were quantified using two custom-designed pliance-sensor pressure strips (novelgmbh, Munich, Germany), which consisted of ten 1-cm2 sensors in parallel. The calibrated pressure strips were attached to each subject’s torso, using micropore tape, directly under the elastic strap of the brassiere gore (Fig. 1).

FIGURE 1— Pressure measuring strips attachment site.

FIGURE 1— Pressure measuring strips attachment site.

From the pressure strips, pressure data were collected (50 Hz) via a pliance mobile multiinterface box attached to a collection box (novelgmbh), interfaced with a personal computer. All data were collected via pliance Expert 8.2 online software (novelgmbh) with the sensor strips “zeroed” for each trial after they were attached to the subject. Pressure measurements were recorded for 15 s coinciding with the measures of VT, allowing simultaneous changes in the pressure signal and breathing cycle to be monitored. However, as the pressure and spirometry systems could not be time locked, no assumption can be made in regards to the exact temporal relationship between pressure and spirometry measures in this study.

Subjects were required to rest for 10 min between each submaximal exercise trial. To quantify the perceived comfort of each brassiere, the subjects were asked to indicate brassiere comfort, using a visual analog scale, immediately after the FB and SB trials. After all the submaximal trials were completed, each subject answered subjective questions to provide a qualitative assessment of the two brassiere styles.

Means and SD were calculated for the two subject groups for each of the variables. Independent samples t-tests were then performed on the resting spirometry values to determine whether there were any significant (P < 0.05) differences in these data between the two breast size subject groups. A two-way repeated-measures ANOVA design with one within factor (breast support condition) and one between factor (breast size) was then used to determine whether either brassiere design or breast size significantly (P < 0.05) affected the respiratory, pressure, or comfort data obtained during the submaximal exercise trials, or exercise performance during the maximal exercise tests. If a significant main effect was achieved, a Tukey’s post hoc test was applied to the data to identify where the difference lay.

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RESULTS

Resting spirometry protocol.

Descriptive statistics pertaining to the resting spirometry variables, the physical activity scores calculated from the questionnaire, and the BMI measures obtained for the smaller and larger breasted subjects are presented in Table 2. As can be seen in the table, there was no significant difference between the larger (≫C cup) and smaller breasted (A cup) subjects when assessing BMI (P = 0.12), suggesting that differences between the breast size groups could not be attributed to differences in overall height to weight ratios. In addition, there was no significant difference found between the estimated physical activity levels of the two groups (P = 0.82), suggesting that pretesting physical activity levels did not affect testing results. Although no significant differences were found between the two brassiere groups in regards to lung volumes, the larger breasted subjects tended to display lower ERV measures compared with their smaller breasted counterparts (Table 2), a finding that corresponds to previous research pertaining to obese individuals (3,4,15,16). In contrast, significant between-subject group differences were noted with respect to some of the temporal measures. That is, the larger breasted subjects had a significantly greater VT/time of inspiration ratio with a decreased time of inspiration/total time of breath ratio compared with their smaller breasted counterparts (Table 2).

TABLE 2

TABLE 2

No significant between-subject group difference was found when dynamic lung function was assessed (Table 2). The smaller breasted subjects tended to display nonsignificant greater MVV measures compared with their larger breasted counterparts, with the recorded measures for the larger breasted subjects being significantly lower than the predicted values for these subjects when using the equation suggested by McArdle et al. (12). With a decreased inspiratory time per total time ratio and with the greater VT per time of inspiration ratio found in the larger breasted subjects, it is likely that (i) this group consumed a greater VT within a similar inspiratory time or (ii) they took a shorter time to activate inspiration with the similar total respiratory time compared with the smaller breasted subjects (Table 2). Results obtained from VT, inspiratory time, and total time of breath and the duty cycle suggest that smaller breasted subjects were likely to take longer to activate their inspiratory muscles in order to acquire the similar VT (Table 2).

Resting V̇E values revealed that subjects in both groups consumed only 11 and 13% of their maximum reserved ventilation (see resting V̇E/MVV ratio in Table 2). Babb (3) suggested that the V̇E/MVV ratio gave an indication of the mechanical ventilatory constraints within subjects, with our results again demonstrating no significant difference between the two brassiere size groups at rest.

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Maximal exercise testing.

Descriptive statistics pertaining to the maximal exercise testing variables obtained for the smaller and larger breasted subjects are presented in Table 3. These results confirm that subjects in both groups exercised maximally as indicated by peak respiratory rates of 41–47 breaths·min−1, peak HR of 177–180 bpm, and a shift toward fat and carbohydrate metabolism as indicated by the RER (Table 3) (12). During maximal exercise, subjects in both groups also consumed approximately 82 and 90% of their maximal reserved ventilation at peak exercise (Table 3). However, no significant main effect of brassiere design was found during the maximal exercise tests when the data were pooled across subject groups (Table 3). A significant main effect of breast size was found on the relative V̇O2peak measures, when the data were pooled across breast support worn, with the smaller breasted subjects recording significantly higher relative V̇O2peak measures during maximal exercise testing.

TABLE 3

TABLE 3

Some trends were also seen in the data, with Table 3 illustrating an increase in the VT measures during the NB conditions compared with the SB conditions (P = 0.053) when the data were pooled across subject groups, suggesting that sports brassieres may cause some restriction to VT during maximal exercise. A strong trend was also seen between the breast size groups in regards to the cycle ergometer resistance level achieved during maximal exercise tests (P = 0.054), with the larger breasted subjects reaching lower Watts in the maximal exercise test when compared with their smaller breasted counterparts. Maximal oxygen consumption measures also showed a trend with the smaller breasted subjects recording greater V̇O2peak measures when compared with their larger breasted counterparts (P = 0.052).

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Submaximal exercise testing.

Descriptive statistics pertaining to the submaximal lung volume and submaximal HR data obtained for the smaller and larger breasted subjects are presented in Table 4. The smaller breasted subjects displayed a significantly greater ERV when they were wearing sports brassieres compared with the FB condition (P = 0.019), although there was no effect of brassiere design noted on these parameters for the larger breasted women. Although other lung volumes and capacities and the submaximal HR were not significantly different for the smaller breasted subjects when comparing the FB and SB trials, the ERV decrease was accompanied by nonsignificant increases in all inspiratory volumes and capacities in the FB condition (Table 4). These results suggest that, during submaximal exercise, the smaller breasted subjects tended to breathe at a lower lung volume during the FB trials compared with the SB trial. Because airways resistance is higher while breathing at lower lung volumes (20), the fashion brassiere may have a negative impact on the respiratory function of smaller breast females during exercise.

TABLE 4

TABLE 4

Consistent with the resting spirometry measures, the smaller breasted subjects recorded significantly greater time of inspiration/total time of breath ratios when compared with their larger breasted counterparts when the data were pooled across brassiere design conditions (P < 0.001, Table 2). These results suggest that, even during exercise, the inspiratory portion of respiration for the smaller breasted subjects contributed to a greater temporal proportion of the subject’s total breath when compared with the larger breasted subjects, irrespective of breast support worn.

Mean (± SD) maximum pressure data recorded under the brassieres during the submaximal exercise trials for the smaller and larger breasted subjects are displayed in Figure 2. No significant main effect of either breast size or brassiere design was found for the maximal pressure, mean pressure, maximal force, or area data. However, significant interactions were found between breast size and brassiere condition when assessing both the maximal pressure the brassiere applied to the wearer (P = 0.044) and the pressure–time integral data (P = 0.037). That is, significantly higher maximal pressures and higher pressures over time were applied to the torso of the smaller breasted subjects when wearing the sports brassiere compared with the fashion brassiere, although this brassiere design effect was not noted for their larger breasted counterparts.

FIGURE 2— Mean (± SD) maximum pressure data recorded under the brassieres during the submaximal exercise trials for the smaller (

FIGURE 2— Mean (± SD) maximum pressure data recorded under the brassieres during the submaximal exercise trials for the smaller (

When assessing the results from the visual analog scale, no significant main effect of either breast size or brassiere design was noted in the perceived comfort of the brassiere styles. However, 19 of the 22 subjects indicated that they would prefer to exercise while wearing the sports brassiere when compared with the fashion brassiere. Interestingly, three subjects indicated that the sports brassiere affected their ability to breath and two subjects stated that the sports brassiere affected their ability to exercise, as it was “tight.”

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DISCUSSION

A primary aim of this study was to determine whether breast hypertrophy impeded exercise capacity or respiratory function in all active and resting states. Interestingly, the only between-subject group difference noted in the resting spirometry measures was a temporal difference, which implied that larger breasted subjects breathed in faster than their smaller breasted counterparts, relative to the time of their total breath. Although no research could be found in the literature discussing such a change between obese and nonobese subjects, it could be suggested that the temporal difference found in this study may be a direct result of the additional mass on the chest of the larger breasted subjects, necessitating more muscular work to create the pressure gradient between the lungs and the external environment for inspiration to occur. This increased muscular work required by the larger breasted subjects may decrease the relative time required to fill the lungs for a normal breath.

Although no significant between-subject group difference was found in regard to dynamic lung function measures, the larger breasted subjects displayed lower MVV predicted values. As no significant difference was found between subject groups with respect to factors affecting the predicted values in the equations (standing height and age), it is speculated that breast size may affect MVV, with increases in breast tissue decreasing the amount of air subjects can maximally and repeatedly ventilate over a short period of time. However, as no significant differences were found between the smaller and larger breasted subjects in the resting state for both static lung volumes and dynamic lung function, it is thought that breast size does not impede lung volumes in a resting state. Therefore, although breast size does not appear to affect lung volumes in a resting state, it does appear to influence the temporal pattern of breathing.

Although brassiere style did not significantly influence maximal exercise capacity, results from this study implied that larger breasted subjects recorded significantly lower relative V̇O2peak when compared with their smaller breasted counterparts. Babb and associates (4) reported similar results for obese subjects whereby their obese subjects recorded significantly lower V̇O2peak·kg−1 measures when compared with their leaner counterparts. As there was no significant difference in the BMI of the two brassiere size subject groups and no significant difference between physical activity levels or intensity of physical activity between breast sizes (Table 2), it is suggested that larger amounts of breast tissue may imitate those results seen in the overweight and obese population in terms of restricting maximal oxygen consumption. Therefore, although wearing a sports brassiere does not appear to significantly affect maximal exercise performance compared with wearing no brassiere, breast size appears to affect maximal exercise performance, whereby females with a larger amount of breast tissue record lower maximal oxygen consumption readings, when corrected for body weight, compared with their smaller breasted counterparts. However, it is acknowledged that physical activity levels and intensity were assessed in the present study using questionnaire, which is limited by the need for self-reported responses. Therefore, possible between subject-group differences in physical activity may still have been a confounding factor and requires further investigation.

Although no literature could be found discussing the effects of tight brassieres on respiratory mechanics, Gehlsen and Albohm (9) reported that placing a 4-inch elastic wrap over the top of a supportive brassiere provided additional breast support compared with wearing the brassiere alone. Berger-Dumound (5) also stated that, in an evaluation of sports brassieres on the market, the most effective brassieres in limiting breast motion were not rated highly in comfort and that the most comfortable sports brassieres were among the worst performers in controlling breast motion. The author suggested that the brassiere’s ability to stretch had been compromised in the attempt to limit breast motion. In the present study, the pressure data confirmed that sports brassieres were “tighter” in that they caused significantly greater maximum pressure readings compared with the fashion brassiere, but only in the smaller breasted women. To explain this finding, the lengths of all brassieres used in the study were measured. Interestingly, in the smaller breasted brassiere size, the sports and fashion brassieres were very similar in length, with the sports brassiere measuring only 1 cm less in length when compared with the fashion brassiere. The increased pressures in this size brassiere group could therefore be explained by the more rigid fabrics used in the gore of the sports brassieres in an attempt to increase compression of the breasts against the torso to minimize breast motion. In contrast, there was a greater discrepancy between the lengths of the larger brassiere sizes, whereby the sports brassieres actually measured longer in these sizes, up to 5 cm in the 14C size. Therefore, although the more rigid material of the sports brassiere should provide increased support, its increased length would have negated any increase in pressure against the torso. This assumption was further supported by the fact that significantly greater pressure–time integrals were recorded for the smaller breasted subjects compared with their larger breasted counterparts and with the smaller breasted subjects generating significantly greater pressure–time integrals while wearing the sports brassieres compared with the fashion brassieres.

When assessing the spirometry data, it appears that the differences in brassiere lengths and the resultant differences in brassiere pressure were not sufficient to cause significant differences in most lung volumes during submaximal exercise. The only differences found between the brassiere size groups and the brassiere styles were ERV differences between the sports and fashion brassiere conditions for the smaller breasted subjects and time of inspiration/time of breath difference between the two breast size groups. Although no literature could be found assessing different lung volumes as a result of brassiere tightness, the literature pertaining to regional lung ventilation suggests that the lower regional alveoli are ventilated to a greater extent than the upper regions and that chest expansion is therefore greater in the lower region of the chest, probably more so than where a brassiere rests when fitted correctly. There are also suggestions that restrictions to chest expansion (mainly in disease) in the upper chest regions do not have as great an effect on respiratory function as would lower regional restriction (19).

The difference in the time of inspiration/time of breath between the breast size groups was consistent with the resting spirometry measures and suggests that, at both rest and during exercise, larger breasted subjects appear to breath in more quickly relative to the time of their total breath compared with their smaller breasted counterparts. As previously suggested, this may be due to additional muscular work during inspiration resulting in less time required for inspiration. However, the difference seen in the ERV between the fashion and sports brassiere trials for the smaller breasted subjects is more difficult to explain.

The significant decrease in the ERV during the FB trial for the smaller breasted subjects is coupled with nonsignificant increases in inspiratory volumes and capacities. This would suggest that during the FB trials, the smaller breasted subjects were breathing at a lower lung volume, which, according to Sharp and associates (16), would result in the VT occurring at a less compliant portion of the pressure–volume curve, requiring more muscular work during respiration. However, this finding is not consistent with the other results of this study, as external pressure on the chest was actually greater during the sports brassiere trial for these subjects, which could be a mechanism causing changes in ERV measures. Visual analog scale recordings were also not significantly different between the two brassiere styles for the smaller breasted subjects, although nine of the eleven smaller breasted subjects preferred to exercise in the sports brassiere. These findings suggest that the subjects may have been more relaxed during the sports brassiere condition compared with the fashion brassiere condition, allowing them to breathe more freely.

Sports brassieres are typically categorized into two design types: encapsulation brassieres (containing molded cups that separate and support the breasts individually) and compression brassieres (designed to restrict breast movement by flattening the breasts against the body). No literature could be found assessing the effects of wearing a sports brassiere on respiratory function, regardless of the sports brassiere structure (encapsulation or compression). However, the limited scientific literature pertaining to sports brassiere design does suggest that encapsulation brassieres are more effective in limiting breast motion and related breast pain compared with compression brassieres (11), especially when worn by larger breasted women (sizes C+: 17). Although the sports brassiere used in this study did not contain underwire in the A cup size, the brassiere was still an encapsulation brassiere as it had separate molded cups. Whether encapsulation brassieres affect maximal oxygen consumption differently from compression brassiere types was not within the scope of the present study and warrants further investigation.

It is acknowledged that the results of the present study pertain to subjects who were professionally fitted for their brassiere before testing. Brassiere manufacturers have speculated that up to two thirds of Australian women wear the incorrect brassiere size (Deans, T., personal communication, 1999), with published literature suggesting that up to 80% of females wear the incorrect brassiere size (18). Not only can a poorly fitted sports brassiere fail to reduce breast motion and resultant breast pain, Stamford (17) suggested that the sports brassiere must fit properly to ensure that the brassiere does not impede breathing by being too tight.

In summary, the results of this study suggest that wearing a correctly fitted sports brassiere does not significantly affect maximal exercise performance, nor does a correctly fitted sports brassiere appear to affect respiratory function during submaximal exercise, when compared with wearing either a fashion brassiere or no brassiere. Although the sports brassiere did appear to impart more maximal pressure on some subjects compared with the fashion brassiere, no significant difference was found between the comfort ratings for each brassiere.

In conclusion, brassiere size did affect some temporal measures of respiration during rest as well as maximal exercise ability, although breast motion did not affect respiratory mechanics during submaximal exercise. Therefore, as no significant restriction of exercise performance or respiratory mechanics was found when subjects wore sports brassieres, it is recommended that active females use the additional breast support provided by a correctly fitted sports brassieres during physical activity. However, further research is recommended to investigate the effects of sports brassieres on other measures of performance, such as cardiovascular function during exercise, and to expand the subject base to include postpartum women. Such research is warranted to ensure that sports brassieres provide appropriate breast support for all women, irrespective of breast size, so that these women can exercise in comfort, without their brassieres impeding performance.

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Keywords:

RESPIRATORY MECHANICS; BREAST MOTION; BREAST HYPERTROPHY

©2005The American College of Sports Medicine