Hormones, Outcomes, and Pain Pathways in Exercise Study

Approximately 130 million individuals in the US (39% of the US population) are living with chronic musculoskeletal pain. Women experience more localizations of pain across their lifespan. Women report significantly more pain in the neck, shoulders, arms, back, and breasts due to altered musculoskeletal activity within in the neck and thoracic region due to the presence of breast tissue. Neck, shoulder, arm, and back (NSAB) pain has been strongly linked to bra cup size. Since 2000, there has been a significant increase in women's average bra cup size from B to E; women with cup sizes D and above are considered "full-busted". Most commercially available sport bras are designed for low- to medium-impact activities for women with cup size C or smaller, leaving women with cup sizes of D or larger without adequate breast support during physical activity. While the primary source of NSAB pain in these women is likely mechanical, evidence suggests non-mechanical pain pathways that may contribute to pain expression in women. Specifically, evidence of sex-hormone influences, systemic inflammation, and cortical remapping in female animal models with respect to chronic musculoskeletal pain is emerging; however, characterization of the influences of sex-hormone levels, inflammation, and concurrent cortical changes in the somatosensory and motor regions particularly in reference to chronic NSAB pain in women across the lifespan is a major gap in the evidence base. This critical gap in understanding physiological and neurological sex differences in chronic NSAB pain manifestation in full-busted women will be filled by our proposed project. In this project, the investigators will evaluate a non-pharmacological (mechanical) intervention to alleviate NSAB pain in full-busted women and investigate non-mechanical pathways associated with chronic NSAB pain in women. The investigators will measure both self-reported and objective measures of pain in conjunction with objective measures of behavior and blood-based measures to assess: (1) the impact of the mechanical intervention and (2) non-mechanical factors contributing to chronic musculoskeletal pain in women. The findings from this project will advance multifactorial understanding of pain in full-busted women, a population that lives with chronic musculoskeletal pain.

Inclusion criteria

• Able to provide informed consent
• Age of 18 to 60 years
• Assigned female sex at birth
• Right-handed by self-declaration
• Willing to participate in one online testing session and up to four in-person testing sessions
• Bra band size between 32-40"
• International Physical Activity Questionnaire - Short Form (IPAQ-SF) score of 2 or higher
• An answer of "NO" to any item of the general health questions of the PARQ+
• No history of surgery to the: back, neck, or shoulders or joint replacement
• No history of implanted pacemakers or other stimulation devices
• No history of spinal cord injury (SCI)

Exclusion criteria

• Inability to provide informed consent
• Age 17 years old or younger or 61 years or older
• Assigned male sex at birth
• Left-handed by self-declaration
• Not willing to participate in one online testing session and up to four in-person testing sessions
• Bra band size greater than 40" or less than 32"
• IPAQ-SF score of 1 or lower
• An answer of "YES" to any item of the general health questions of the PARQ+
• History of limb amputation (upper or lower extremity)
• Presence of open pressure sores on the upper or lower extremities
• Currently pregnant or lactating/breastfeeding
• History of surgery to the: back, neck, or shoulders or joint replacement
• History of breast cancer and/or mastectomy
• History of implanted pacemakers or other stimulation devices
• History of spinal cord injury (SCI)
• History of joint disease including osteoarthritis and/or Rheumatoid Arthritis
• History of the following neurological diseases: Cerebrovascular accident (CVA, stroke), Alzheimer's Disease (AD), Dementia (of any form), Huntington's Disease, Traumatic Brain Injury (TBI), Spinal cord injury (SCI), Multiple Sclerosis (MS), Parkinson's Disease (PD), Polio, Paraproteinaemic Demyelinating Neuropathy (PDN) and/or Monoclonal Gammopathy of Undetermined Significance (MGUS), Myasthenia Gravis, Muscular Dystrophy, Guillain-Barré Syndrome, Scoliosis, Charcot-Marie-Tooth Disorder or other hereditary neuropathies

Additional Inclusion Criteria for Intervention Group:

a. Self-declared breast size of D-I cup (US sizes: D, E, F, G, H)

Additional Inclusion Criteria for the Control Group:

a. Self-declared breast size of A-C cup (US sizes: AA, A, B, C)