The aim of this study was to compare the extent of central fatigue in the first dorsal interosseous (FDI) muscle of healthy adults in low, moderate and high-force submaximal contractions. Nine healthy adults completed four experimental sessions where index finger abduction force was recorded during voluntary contractions and in response to brief trains (five pulses at 100 Hz) of electrical stimulation. The ability to maximally activate FDI under volition, or voluntary activation, and its change with sustained activity (central fatigue) was assessed using the twitch interpolation technique. The fatigue tasks consisted of continuous isometric index finger abduction contractions held until exhaustion at four target force levels: 30%, 45%, 60% and 75% of the maximal voluntary contraction. The main finding was the presence of central fatigue for the 30% task, but not for the three other fatigue tasks. The extent of central fatigue was also associated with changes in a measure reflecting the status of peripheral structures/mechanisms. It appears that central fatigue contributed to task failure for the lowest force fatigue task (30%), but not for the other (higher) contraction intensities.

IntroductionIn 2015-2016, there were over 214,000 women competing in collegiate athletics in the United States and this number continues to rise (1). The exact sequelae of breast injury are unknown; however, a relationship between breast injury and fat necrosis, which can mimic breast carcinoma in manual exams and/or ultrasound and mammogram findings, has been documented outside of sports participation (2-6). Fat necrosis can occur following trauma to the breast, leading to persistent and sometimes painful masses in the breast (7). Breast injuries related to motor vehicle collisions and resultant blunt breast trauma with the seat belt (3)(4)(5)(8)(9)(10)(11) and breast blunt trauma as a result of a fall (11-12) have been reported; however, only one study has been found that explored female breast injury during competitive sports participation (13). For these reasons, it is important to investigate the prevalence, reporting, treatment and implications of female breast injuries in collegiate sports. The primary purpose of this study is to report the prevalence of self-reported breast injuries in female collegiate athletes. A secondary purpose is to explore the injury reporting, the severity and type of breast injury. The treatment of breast injuries including the impact of breast injury on sports participation in female collegiate athletes was also explored. S.). The National CollegiateAthletic Association (NCAA) collects injury data; however, breast-related injuries do not have a specific reporting category. The exact sequelae of breast injury are unknown; however, a relationship between breast injury and fat necrosis, which mimics breast carcinoma, is documented outside of sports participation. Breast injuries related to motor vehicle collisions, seatbelt trauma, and blunt trauma have been reported. For these reasons, it is important to investigate female breast injuries in collegiate sports. The objectives of this study are to report the prevalence of self-reported breast injuries in female collegiate athletes, explore injury types and treatments, and investigate breast injury reporting and impact on sports participation. Materials and Methods:A cross-sectional study of female collegiate athletes at four U.S. universities participating in basketball, soccer, softball, or volleyball. Main outcome measure was a questionnaire regarding breast injuries during sports participation.Results: Almost half of the 194 participants (47.9%) reported a breast injury during their collegiate career, less than 10% reported their injury to health personnel with 2.1% receiving treatment. Breast injuries reported by breast injuries reported by sport include softball (59.5%), basketball (48.8%), soccer (46.7%), and volleyball (34.6%). Conclusions:The long-term effects and sequelae of breast injuries reported by female collegiate athletes during sport play are unknown. Nearly 50% of participants had a breast injury during sports activities. Although 18.2% indicated that breast injury affected sports participation, only 9.6% of the ...

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