Grants
AMSSM Foundation Grant: Impact of Chest Size and Sports Bra Satisfaction on Biomechanical Injury Risk in Adolescent Female Athletes, $25,000, Jan 2024-Jan 2025
Co-Investigators: Jane S. Chung, M.D., Sophia Ulman, Ph.D., Ashley L. Erdman, M.B.A, Jessi Garcia, C.S.C.S., Chanhee Jo, Ph.D.
Girls and women athletes are four to six times more likely to suffer an anterior cruciate ligament (ACL) injury in sport. Additionally, injury risk of adolescent female athletes may be further elevated by increased chest size as uncontrolled trunk motion and reduced trunk flexion during landing leads to increased knee abduction moments. In adult populations, larger chest size was associated with increased trunk range-of-motion and greater lower extremity injury risk. However, to our knowledge, no prior studies have investigated the potential impact of chest size on injury risk in an adolescent female athlete population.
The primary aims of the proposed study are to 1) investigate the differences in kinematic and kinetic risk factors based on chest size in adolescent female athletes, and 2) identify associations between kinematic and kinetic patterns and sports bra satisfaction.
Participants will complete questionnaires that capture chest size and sports bra satisfaction, as well as demographics, sports bra preferences, and physical activity level. Subsequently, motion capture technology will be used to model multi-segmented trunk (cervical, thoracic, lumbar), pelvis, and lower extremity mechanics during dynamic, sport-like movements. The pediatric sports medicine community lacks the knowledge to appropriately educate young female athletes on how to adapt to a larger chest size and remain physically active. The proposed study will help to gain a better understanding of the biomechanical differences exhibited by adolescent female athletes of various chest sizes, and ultimately encourage safe, lifelong physical activity and sports participation for all female athletes regardless of chest size.
Goldstein grant: Mechanical Properties of Sports Bras: Development of a Testing Protocol, $25,000, July 2024-June 2025
Co-Investigators: Mark Buckley PhD, Rebecca Grant PhD, Tasneem Sabir PhD, Sophia Ulman Phd, Courtney Jones
Sports bras have different fabric compositions and constructions, and there is no uniform formula for sports bra design. The design of each brand and model is distinct and can also vary by size. However, there are key components that are common in all bras, including the band strap, shoulder straps, and cup support. A common approach used to characterize the fatigue properties of a material is to apply cyclic levels of stress (force divided by area) and monitor (a) how the material’s intrinsic stiffness (i.e., Young’s modulus) evolves over time, and (b) when the material ultimately fails9,10. Performing these tests across several levels of cyclic stress can yield the endurance limit of a material, an important parameter indicative of a material’s ability to withstand load. Specifically, the endurance limit is defined as the threshold cyclic stress below which a material will not fail, even if an infinite number of loading cycles are applied. Assessing the endurance limit of different bra components could facilitate identification of the areas on a sports bra most vulnerable to fabric fatigue and is an important first step towards developing recommendations to women for when to replace their sports bras. Therefore, the objective of the current study is to establish fatigue parameters for different components of sports bras, and to characterize how washing influences these properties. Our central hypothesis is that fatigue properties vary across bra components, and that washing bras reduces their intrinsic stiffness and lifetime. To test this central hypothesis, the specific aims of this research project are:
Aim 1: Determine the endurance limit and time-dependent evolution of mechanical properties in different sports bra components subjected to cyclic loading. Because Young’s modulus will depend on the number of applied loading cycles, data acquired from these tests will be used to establish a relationship between Young’s modulus and number of remaining cycles prior to failure.
Aim 2: Determine the mechanical properties and estimated remaining lifetime of different sports bra components following washing. Diagnostic mechanical tests will be performed (as in Aim 1) to assess the Young’s modulus of different bra components before and after washing. The measured Young’s modulus will be related to an estimated “remaining lifetime” (i.e., number of remaining loading cycles prior to failure) using the relationship between these parameters determined in Aim 1.
The current study will provide key preliminary data for an external grant aimed at characterizing how bra mechanical properties and susceptibility to fatigue are influenced by key factors including bra size, bra brand, how long a bra is worn, how active the wearer of the bra is, and how well the bra fits. The findings of this study will pave the way towards our long-term objective of providing a framework for sports bra wearage recommendations and assessment of a bra’s lifetime.