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Chronic obstructive pulmonary disease (COPD) is a progressive lung disease comprising of respiratory-related and systemic effects, including impairments in balance. Balance impairments are especially problematic as they increase the risk of falling, potentially leading to negative outcomes such as hospitalization, disability, and death. The main objectives of this thesis were to 1. determine underlying balance impairments that distinguish between individuals with COPD with and without a history of falls and 2. explore facilitators and barriers of a home-based fall prevention program for people with COPD. The first study of this thesis was a secondary analysis of cross-sectional data that showed that the stability limits/verticality and postural responses subcomponents of the Balance Evaluation Systems Test (BESTest) distinguished between those with and without a fall history among 72 patients with moderate to severe COPD. The stability limits/verticality subcomponent also showed acceptable accuracy in identifying individuals with COPD at high risk of falls (cut-off score of 73.8%). In the second study, a qualitative analysis of interviews with 15 patients who completed a home-based fall prevention program, participants indicated that programs that are personalized and focus on providing support for older adults with COPD may help to improve adherence and reduce participants’ risk of falling. The findings from the two studies included in this thesis provide new knowledge for informing fall risk assessment and prevention for people with COPD. / Thesis / Master of Science (MSc)

No / The heat balance integral method is a familiar technique for treating transport problems, particularly phase-change scenarios. Here a number of differences arising in the method's implementation are investigated that result in quantitatively distinct solutions. As a consequence some guidance is provided for selecting the appropriate implementation of the method.

The Virginia Tech crossbreeding program began in the fall of 2002 by mating Holstein and Jersey foundation females to Holstein and Jersey bulls to create HH, HJ, JH, and JJ breed groups (sire breed listed first). Collection of daily dry matter intakes (DMI) began in the fall of 2005 and continued through spring of 2008. DMI were measured for two weeks out of every six week period in first lactation on 44, 32, 29, and 13 HH, HJ, JH, and JJ cows. Daily milk and body weights and monthly milk components were collected. The National Research Council (NRC) DMI prediction equation was used across breed groups to investigate breed differences. DMI prediction equations were developed across breeds. Random regression model were used to predict energy consumed (TEC), energy needed for production, maintenance, and growth at every week of lactation (WOL). Energy balance (EB) was calculated at every WOL by subtracting energy for production, maintenance, growth, and pregnancy from TEC. Common health events were recorded if they occurred in the first 100 days of lactation. Logistic regression was used to analyze health disorder. The HJ and JH were not different from each other in any analyses. The NRC under-predicted DMI for HH and over-predicted DMI for HJ, JH, and JJ. There were significant breed differences in the prediction equations developed. Results indicated that breeds differ in DMI after accounting for production and body weights. The HH cows consumed more energy than HJ and JJ cows. The HH, HJ, and JJ were not different from each other for production but were different from JJ. The JH allocated less energy to maintenance than the HH. There were no breed differences for weeks required to reach positive EB, return to positive cumulative EB, or EB at week 21 of lactation. The HJ, JH, and JJ were more likely to have an incidence of mastitis than HH. The HJ and JH were less likely to have an incidence of metritis than HH. The results indicate breeds differ in DMI, and health diseases and evidence suggests differences in characterization of EB and warrants further investigation. / Ph. D.

As many as 1.9 million sports-related concussions occur annually in youth sports in the United States (U.S.). Often considered a transient injury, research has begun to relate sports-related concussions to long-term neurodegeneration. Youth athletes are considered to be more vulnerable to concussion than their adult counterparts. The research presented in this dissertation was aimed at promoting player safety in youth football as it relates to concussion. Balance dysfunction is often cited as one of the most common symptoms associated with a concussion. Several postural control assessments were assessed in order to develop a youth-specific testing protocol. A cognitive, dual-task assessment was presented for clinician use in the management of sports-related concussion. On-field data collected from youth football players wearing instrumented helmets allowed for characterization of the biomechanics of head impacts and concussions for this population. A youth concussion risk function was developed using head impact data collected from youth football players with medically diagnosed concussions. The proposed testing standard for youth football helmets was assessed in the laboratory and related to on-field head impact data to determine how representative the standard is of youth football head impacts. Helmet safety standards and certifications operate on a pass-fail threshold that does not allow consumers to weigh the relative performance of helmets. A modification of the Summation of Tests for the Analysis of Risk (STAR) evaluation system was developed for youth football helmets. Data presented in this dissertation have direct application to the development of future helmet safety standards and potentially other safety applications as well. / Doctor of Philosophy / As many as 1.9 million sports-related concussions occur annually in youth sports in the United States (U.S.). Often considered a short-term injury, research has begun to relate sports-related concussions to long-term breakdowns in neurological processes. Youth athletes are considered to be more vulnerable to concussion than their adult counterparts. The research presented in this dissertation was aimed at informing player safety in youth football as it relates to concussion. Abnormal balance is often cited as one of the most common symptoms associated with a concussion. Several balance assessments were assessed in order to develop a youth-specific testing protocol. An assessment involving quiet standing while being subjected to a cognitive task was presented for clinician use in the management of sports-related concussion. On-field data collected from youth football players wearing instrumented helmets allowed for characterization of the biomechanics of head impacts and concussions for this youth population. A youth concussion risk function was developed that related linear and rotational head acceleration to risk of concussion. The proposed testing standard for youth football helmets was assessed in the laboratory and observed to assess the most severe head impacts a youth player may experience during participation in football. A modification of the Summation of Tests for the Analysis of Risk (STAR) evaluation system was developed for youth football helmets in order to give consumers more information about helmet performance beyond the pass-fail criteria of the helmet standards. Data presented in this dissertation have direct application to the development of future helmet safety standards and potentially other safety applications as well.

The research presented in this thesis focuses on head impact exposure in youth football. The on-field portion of this research investigated high magnitude head impacts that youth football players experience in games and practices. With previously validated data collection methods, linear and rotational head accelerations from head impacts were collected. Over the course of two seasons, 79 total player-seasons resulted in over 13,000 impacts. A small subset of these, 979 impacts exceeding 40 g, represented the focus of this research as these impacts pose the greatest risk of injury to individuals. Some tackling drills in practice were found to have higher acceleration severities than those observed in games. How practice activities are conducted also contributes towards the overall high magnitude head impact exposure for practice, not just the practice drill itself. Within games, players who are running backs and linebackers played most frequently and experienced higher magnitude impacts more often than their teammates. Data were also collected from all players off the field. Each player completed balance assessments at the beginning and end of the season to allow for comparison, even in absence of a clinically-diagnosed concussion. Current balance assessments were observed to fall short for detecting postural control differences in this youth population. Modifications to these assessments were recommended that might allow for further insights. Research presented in this thesis will inform youth football organizations as they continue to develop strategies to enhance player safety and mitigate head impact exposure. / Master of Science

In America, a person has a 1 in 3 chance of falling each year once they reach the age of 65. When someone falls, they risk bodily injury. There are products available to help people when they fall, but they are only effective once a person reaches a point where they are at risk of falling. In order to reduce an individual's chance of falling as they age, preventive measures must be taken before the problems develop. With the use of digital technology, adults can be properly instructed on how to keep they bodies strong and balanced for there golden years. This thesis documents the research, conceptualization, and development of the Xcel Sleeve. / Master of Science

Obesity is a major and growing health concern associated with an increased risk of falls. The majority of falls are thought to result from some kind of postural perturbation, yet the biomechanical mechanisms as to why obese individuals fall more often is unclear. Therefore, the goal of this study was to investigate the effects of obesity on balance recovery in response to small forward postural perturbations. Twenty male participants, including 10 lean (mean BMI ± SD: 21.9 ± 1.4) and 10 obese (BMI: 33.2 ± 2.3), were exposed to two types of postural perturbations (force impulses applied with a pendulum and angular displacements administered with a release mechanism). Participants attempted to recover balance with only an ankle strategy such that neither a step nor hip flexion was utilized. Quiet standing trials were also conducted for comparison with the literature. Obese individuals exhibited less center of mass (COM) displacement and a slower COM velocity compared to lean individuals when exposed to identical force perturbations. When exposed to the force perturbations relative to body weight, and when released from identical lean angles, no differences in COM performance were found. During quiet standing, no differences in center of pressure (COP) velocity were observed between obese and lean groups. In all tasks, the obese generated higher ankle torque than the lean. Overall, the obese participants exhibited no differences in movement or less/slower movement than the lean participants when recovering from small forward postural perturbations as well as during quiet standing. These results imply that obesity in young adult males did not impair balance recovery for the tasks investigated. / Master of Science