Does level of breast support differentially affect exertional symptoms and respiratory system responses in large- and small-breasted women during treadmill exercise?

We assessed how different levels of breast support affected exertional symptoms and respiratory responses in small- and large-breasted females during treadmill exercise. Twenty recreationally-active females (mean ± SD age: 22 ± 2 years) were divided into small (SBV: 322±77 mL) and large breast volume (LBV: 580±88 mL; p < 0.001, g = 2.98) groups. Participants completed three 5 min bouts of treadmill exercise at 30%, 60%, and 90% of individual peak power output (PPO)-corresponding to walking, low-intensity running, and high-intensity running-wearing either a high-support or low-support sports bra (randomized). Measurements included cardiorespiratory variables, operating lung volumes, inspiratory muscle electromyographic, respiratory muscle pressures, breast acceleration, and exertional symptoms (breathlessness, chest tightness due to bra). High- versus low-support sports bras reduced mean breast acceleration (p < 0.001, η p 2 =0.55), but evoked higher ratings of chest tightness (p = 0.040, η p 2 =0.16) in LBV participants at low- and high-intensity running (g = 1.09 and g = 0.99, respectively). Although breathlessness was not significantly different by bra or breast volume (all p > 0.05), LBV participants consistently reported breathlessness intensity and unpleasantness ≥ 1 Borg unit (BU) higher than SBV participants during low- and high-intensity running (breathlessness intensity: ∼5 vs. ∼3 BU at 60% PPO; ∼9 vs. ∼7 BU at 90% PPO; breathlessness unpleasantness: ∼4 vs. ∼2 BU at 60% PPO, ∼8 vs. ∼6 BU at 90% PPO). There were no differences in cardiorespiratory variables, inspiratory muscle activity, operating lung volumes between breast volume groups or sports bras (all p > 0.05). We emphasize the importance of addressing subjective discomfort, including chest tightness and breathlessness, when developing effective breast support for weight-bearing exercise, especially for larger-breasted individuals.