• Aging and the Effects of Power Training and Neuromuscular Enhancement on Standing Balance

      Inacio, Mario Pedro; Rogers, Mark William (2017)
      Background. Aging brings about impairments in hip abductor-adductor (AB-AD) neuromuscular performance and medio-lateral balance control. Power training (PT) has been used as an alternative to strength training that leads to further neuromuscular performance improvements. Furthermore, transcranial direct current stimulation (tDCS) can acutely increase force output. Aim. This dissertation investigated how aging, hip AB-AD power training (PT) and transcranial direct current stimulation (tDCS) affect maximal hip AB-AD neuromuscular performance and medio-lateral balance control during the weight transfer of induced lateral steps and forward/lateral voluntary stepping. Methods. Participants performed a hip AB-AD isometric maximal voluntary contractions (IMVC) task, an induced lateral stepping task at different initial limb pre-loads and forward/lateral voluntary stepping. PT program consisted of 8 weeks of hip AB-AD exercises focusing on maximal speed of execution. Anodal and cathodal tDCS were used to elicit acute neuromuscular improvements in the hip AB-AD. Results. Aging reduces maximal isometric hip AB-AD neuromuscular performance (31-67%, p<0.05). During induced lateral stepping, aging decreased hip AB-AD rate of neuromuscular activation (RActv) (60-109%, p<0.05) and delayed the weight transfer phase (30-78ms, p<0.05). Consequently, older individuals increased their vertical RFD (70-177%, p<0.05) and hip muscular output (31-74%, p<0.05), but still had lower balance performance than younger adults. PT significantly improved maximal isometric hip AB-AD neuromuscular performance (14-81%%, p<0.05) and increased incidence of single lateral balance recovery steps (43%, p<0.05), through increases hip AB torque (49-61%, p<0.05), AB power (21-54%, p<0.05) and AB-AD RActv (17-62%, p<0.05) during the weight transfer of the lateral balance stepping task. PT also improved voluntary stepping onset latencies (13-28%, p<0.05). Lastly, tDCS modulated maximal hip AB peak torque (8-12%, p<0.05) and anodal tDCS enhanced hip AB maximal RTD (28-55%, p<0.05). Conclusions. Aging impairs hip maximal neuromuscular performance. Consequently, medio-lateral balance recovery becomes impaired as individuals operate closer to their maximum capabilities. Furthermore, PT is able to increase older adults' hip maximal neuromuscular performance, which allows them to increase their hip AB-AD neuromuscular output during medio-lateral balance recovery and improve balance recovery. Lastly, tDCS seems to be a viable alternative to acutely modulate hip AB performance having strong implications for medio-lateral balance recovery.
    • Effects of Limb Length Discrepancy on Functional and Health-Related Outcomes in Hip Fracture Patients

      Johnson, Rasheeda J.; Orwig, Denise L.; 0000-0002-8397-9909 (2016)
      Background: Limb length discrepancy (LLD), a common complication following hip fracture, is present when paired lower extremities are of unequal lengths. LLD consequences include chronic low-back pain, standing imbalance, nerve palsy and gait abnormalities. There is a paucity of LLD studies in older adults and no study to date has investigated LLD in hip fracture patients, a large population of older adults experiencing late life disability and decline in functional mobility. Objectives: Specific aims of this study were to: (1) Determine the reproducibility, validity and repeatability of Dual Energy X-ray Absorptiometry-Linear Pixel Count (DXA-LPC) method to measure limb length and assess for LLD in hip fracture patients, using mixed effects regression modeling; (2) Determine the prevalence and changes in LLD over the 12-months post fracture using general linear modeling; and (3) Determine the association between LLD severity and functional and health-related outcomes during 12-months post fracture using general linear modeling. Methods: Data come from the Baltimore Hip Studies 4th cohort (BHS-4; 1998-2004), a study of 180 community-dwelling women age 65+ with incident hip fractures enrolled in a RCT of an in-home exercise intervention. Three expert assessors and study PI measured limb lengths from whole-body DXA images electronically stored from BHS-4 at baseline and 2, 6, and 12 months post-fracture. Functional and health-related outcomes included the Lower Extremity Gain Scale (LEGS), Yale Physical Activity Scale (YPAS), mobility score, number of falls, and hip and general pain and assessed at each follow-up time-point. Results: Reproducibility of DXA-LPC was moderate, while validity and repeatability were both excellent. Majority (~75%) of participants experienced LLD; findings were consistent across all study time-points. Mean absolute LLD did not statistically change over time (mean=14.7mm). Adjusted results indicate a significant adverse relationship between LLD severity and number of falls (p=0.006) with nonsignificant adverse relationships with other functional outcomes. Conclusions: LLD severity contributes significantly to falls during the year following a hip fracture. Findings also indicate clinically meaningful differences in functional outcomes between LLD groups. Interventional studies should investigate shoe lift therapy efficacy and other post-operative mechanisms to minimize the impact of LLD on post-fracture functional recovery.
    • Unit-level staffing, workload, and adverse events in Army Acute Care Hospitals: 2003-2006

      Breckenridge-Sproat, Sara Todd; Johantgen, Mary E. (2009)
      Background: A sequence of reports from the Institute of Medicine revealed quality and patient safety issues in hospitals. The crucial role of nurses was recognized, although much of the research has addressed staffing and, more recently, the work environment. Moreover, most of this research has been at the hospital level where attribution of care processes to adverse events is difficult. The Army, Air Force and Navy's hospitals have faced the same economic and quality challenges. However, military medical institutions also have the increased demands of supporting a nation at war. Purpose: This study examined unit level impact of nursing staffing and workload on medication errors and patient falls in Army hospitals between 2003 and 2006. Methods: A descriptive correlational longitudinal design was used to conduct a secondary analysis of 23 Army inpatient units from the Military Nursing Outcomes Database (MilNOD). Relationships among staffing, workload, and quality of care were examined from 2003 to 2006. A cross sectional design using only 2006 data examined the influence of practice environment on outcomes. Generalized Linear modeling (GZLM) was used to accommodate nested data. Results: Large turbulence was expected in the Army inpatient units from 2003-2006. Although some years were significantly higher, turbulence was far less than expected. Staff complement (measure of percent mix of military, civilian and contractor staff) was a significant predictor of medication errors. Patient census was a significant predictor of falls. The professional nursing Practice Environment Scale (PES) was a partial mediator of medication errors in all types of units. Although tested as both, the practice environment did not significantly mediate or moderate falls. Conclusion: This study supports the growing literature on nurse staffing and the influence on patient outcomes. This study was unique in that data was collected at the unit/shift level, outcomes assessed are considered nurse-sensitive, and statistical techniques accounted for the nested data. Despite these advantages, limitations of the measurement of nursing-related acuity and patient turnover are acknowledged. Well-defined and consistent measures are necessary to enhance interpretability and application across nursing settings.