Women with large breasts may sweat less than their smaller-breasted counterparts, British sports scientists have discovered.
Researchers found that sweat gland density decreases as breast size increases, which is likely why women with large breasts produce less fluid.
Meanwhile, less well-endowed women sweat more from the breast area, the study revealed.
The researchers said their findings will inform the design of sports bras for women of all sizes better addressed ‘wetness, stickiness, support and chafing’ to stay comfortable.
To put their theories to the test, scientists from the University of Southampton studied 22 healthy women aged 18 to 55 with different breast sizes.
They found that women with the smallest breasts had up to 71 sweat glands per square centimeter, while those with the largest had only 10 glands spread over the same area.
Researcher Hannah Blount said: ‘More than 85 percent of women consider a sports bra an essential part of their training, but it’s actually very difficult to find one that’s comfortable and supportive, so many women struggle with this.
‘Our thought process was to look at how sports bras provide support and comfort to women with different breast sizes, especially in hot conditions, when women are more likely to experience issues such as chafing and significant sweat build-up in the bra.
‘We were specifically interested in understanding how sweat gland density and local sweat rate change in women with different breast sizes, because that determines how much sweat ends up in the sports bra.
‘Here we got the most exciting finding, because our results indicated that women with larger breasts have fewer sweat glands, and therefore produce less sweat over their chest.
‘We can now use this fundamental knowledge to design sportswear, taking into account the needs of women with different breast sizes.’
New sweat delights no longer develop in a human body after two years of age. As a girl’s breasts develop during puberty, the sweat glands become less densely populated over the surface of her skin
She added: ‘We’re becoming increasingly sedentary as a society, so if we can do something to help women become more active while making sport more accessible then that’s really exciting.’
The body stops developing new glands around the age of two.
The researchers said that as a girl’s breasts develop during puberty, the sweat glands become less densely populated over the surface of her skin.
They also found that sweat glands do not produce more sweat when they are fewer in number, meaning larger breasts produce less sweat overall.
Each of the 22 women in the study was asked to jog for 45 minutes in a warm climate chamber at 32 degrees Celsius.
The amount of sweat they produced over their breasts was monitored in two places, above and below the nipple – and thermal cameras were used to monitor how much heat their bodies produced during the exercise.
Sweat production was also monitored among the arms.
3D scanning was used to calculate breast surface area, while sweat gland density was measured using iodine-infused paper that, when placed on the skin, reacts with the chemicals in sweat.
Women with larger breasts sweat less around the breasts, but the researchers found no clear difference in the amount of sweat produced under the arms, breasts or body temperature between women with larger and smaller breasts.
The experiments were carried out in ThermosenseLab’s state-of-the-art environmental chamber, at the NIHR (National Institute for Health and Care Research) at University Hospital Southampton.
Dr. Davide Filingeri, a leading expert in moisture sensing of human skin, said: ‘Women undergo unique anatomical, physiological and hormonal changes throughout their lives.
‘Consider the impact of the menstrual cycle, pregnancy and menopause, all of which influence a woman’s heat tolerance, thermal sensitivity and comfort.
‘As such, Hannah’s research into the unique and evolving ‘thermal needs’ of women’s bodies has the potential to drive person-centred innovation in sportswear, which will ultimately help women thrive in our warming climate.’
The study, published in the journal Experimental Physiology, shows that the number of women participating in sports has increased significantly over the past fifty years. Data shows that almost 50 percent of women worldwide are now interested in sports.
But a lack of suitable clothing can be a barrier for many women to participate in sports.
Although sports bras that expose more skin can cause the breasts to radiate more heat, this can reduce their effectiveness in providing the required support.