Kinesiology Theses

Whole-body vibration (WBV) has emerged as an exercise modality that is safe for most adults with and without clinical conditions. The aims of this research study were to investigate the effects of WBV on vertical acceleration transmission during WBV and counter-movement jump height after WBV in typically developing children ages 6-11 years old. Seventeen subjects were recruited (10M/7F) for our study. We used a side-alternating Galileo WBV and presented a total of six conditions with the combination of three vibration frequencies (20, 25, and 30 Hz) and two vibration amplitudes (1 and 2 mm). Subjects stood for one minute on the platform under each condition. We used reflective markers to register the body motion and calculate the transmission of vertical acceleration during WBV. We used a force plate to collect ground reaction force during vertical jump after WBV and calculated jump height. Results showed that vertical acceleration significantly decreased from the ankle to the head. While vertical acceleration and its transmission ratio (with respect to the platform acceleration) increased with frequency and amplitude at the ankle, body segments superior to the ankle and knee were less affected by the vibration conditions. Counter-movement jump height maintained its value after all vibration conditions. It was concluded that WBV is a safe intervention paradigm for children as little acceleration is transmitted to the head, and a single bout of WBV may not be adequate to improve jumping performance in children.

Hopping is considered a mass-spring model movement in which the leg supports the center of mass. There is a preferred hopping frequency and hopping outside of that frequency is more difficult and requires more energy. Leg stiffness has been shown to be an important factor when hopping at different frequencies in young adult populations. The purpose of this study was to observe how a still-developing preadolescent population would modify leg stiffness while hopping at different frequencies and if they have similar motor control strategies compared to young adults. The subjects hopped on their dominant leg to the beat of a metronome at one of four frequency conditions based on their calculated preferred frequency, MP (preferred frequency), MM (20% increase), MF (40% increase), and MS (20% decrease). It was found that this population could change their hopping frequency and they achieved this by manipulating their leg stiffness. At the higher frequency conditions there was less movement of the toe and the center of mass in both the vertical and horizontal directions, including decreased hopping height, decreased COM displacement and COM range of motion. Preadolescents demonstrated an adult-like ability to increase leg stiffness and modulate movement of the toe and the COM while adapting to a range of hopping frequencies. This ability could translate into other mass-spring model movements such as running and jumping.

tLess than half of all adults meet the federal exercise recommendations (CDC, 2010) and college-aged adults may be more vulnerable to the consequences of physical inactivity with about two-thirds of college students leading sedentary lifestyles (Harvey-Berino, Pope, Gold, et al., 2012; Tully & Cupples, 2011). Mobile apps provide an efficient way to track physical activity and electronic prompts can enhance mobile apps by reminding individuals to participate. Therefore, the purpose of this study was to examine the effectiveness of a mobile app and electronic prompts sent via Twitter for promoting exercise motivation and adherence in sedentary university students. The hypotheses tested were: (a) a significantly greater percentage of participants in the treatment group would progress through the stages-of-change (SOC) from pre- to post-program compared to the control group, and (b) the treatment group would demonstrate significantly greater exercise adherence than the control group. Thirteen participants followed an 8-week running program on a mobile app. The control group (n = 8) followed the running program while the treatment group (n = 5) also received electronic prompts sent via Twitter to remind participants to exercise. The SOC modified four stage algorithm was used pre- and post-program to assess exercise motivation. Exercise adherence was measured by total number of completed workouts out of the 24 prescribed. A significantly greater number of participants in the control group progressed at least one stage from pre- to post-program compared to participants in the treatment group, χ² = 6.9, p = 0.008. Additionally, participants in the control group reported a greater number of completed workouts (M = 12.5, SD = 7.6) compared to the participants in the treatment group (M = 3.6, SD = 4.0). These findings suggest that while the mobile app may be beneficial for promoting exercise motivation and adherence, the electronic prompts sent via Twitter appeared to have no effect. Further studies are needed to determine the most effective way to use Twitter to increase exercise motivation and adherence of sedentary university students.

Previous studies have tackled the effect of sole thickness on falls and suggested a significant relationship between the sole thickness and fall risk. However, the prior studies were based on qualitative survey. No quantitative studies have been conducted to closely examine the causal effect of the sole thickness on the risk of falls. The purpose of this cross-sectional study was to explore the effect of the sole thickness on fall risk and the body’s reactions in response to an unexpected slip during stance among young adults. Our overall hypothesis was that thick soles would impair dynamic stability, delay the body’s reactions to the external slip perturbation, and show effective reactional muscle activation. Specifically, I hypothesized that 1) individuals in the groups with thin soles would display greater dynamic stability than the thick groups at recovery step onset and touchdown; 2) the step latency in the thin sole groups would be shorter than the thick groups, contributing to the observed higher stability; and 3) the leg muscles would be activated faster along with a lesser EMG burst in the thin-soled groups than thick-soled groups. Nine young adults aged between 18 and 45 years were recruited and evenly randomized into three groups in terms of the thickness of the sole: barefoot (0 mm), thin (5 mm), and thick (10 mm). After warmup exercise and the familiarization process with the assigned sole, all groups experienced an identical unexpected stance-slip perturbation induced by quickly moving the treadmill belt. Full-body kinematics were collected by a motion capture system and used to calculate the kinematics of the body’s center of mass (COM). Then dynamic gait stability, as the primary outcome measure, was determined based on the COM’s position and velocity relative to the base of support. Other spatiotemporal parameters and electromyography of leg muscles after the slip were the secondary outcome measures, including the recovery step latency, duration, length, slip distance, muscle latency, and the EMG burst. Both the primary and secondary outcomes were compared among groups by using one-way ANOVA followed by appropriate post-hoc tests to test three hypotheses. The results showed instable balance status at the initiation of the recovery step with the thicker soles, changes in spatiotemporal parameters such as a prolonged step latency and duration and larger step length, and a shorter EMG latency and lower EMG burst in TA and GA. This study will advance our understanding of the influence of sole thickness on the risk of falls.

The sport industry is a popular and competitive career field with employees drawn to work in a dynamic, yet often untraditional work environment. The challenge of achieving work-life balance has received considerable study in sport, as employees often find a conflict in balancing their job and other life responsibilities, such as family (work-family conflict) and outside activities. This study introduces a new area of potential conflict (work-extracurricular conflict), the outside activities that may be neglected due to a job, which may impact employees. This area may be especially pertinent to a younger segment of the industry which has not been studied, graduate assistants who work in athletic departments while continuing their education. The purpose of this exploratory study was to assess work-life balance in graduate assistants (GAs) and their supervisors by comparing their levels of work-family conflict, work-extracurricular conflict, job satisfaction, and life satisfaction. Secondly, the study introduced the work-extracurricular conflict construct. Data were collected from GAs and supervisors (N = 47) working in five Division I university athletic departments. Descriptive statistics and ANOVA revealed significant differences between GAs’ and supervisors’ job satisfaction, while determining they did not differ on work-family conflict, work-extracurricular conflict and life satisfaction levels. They reported moderate levels of family and extracurricular conflict. Sport managers can utilize this information to better understand the work-life balance of GAs and establish dialogue on ways to improve GAs experience in hopes of keeping these sport professionals in the industry long-term.

The purpose of this study was to analyze kinetic and kinematic data of individuals with unilateral transtibial limb loss and the effect different alignments have on the individual’s gait while they walk over uneven terrain. Individuals with lower limb loss are currently having their prostheses dynamically aligned to ensure a satisfactory walking gait on level ground with smooth surfaces, usually in the clinician's office or hallway. This study was looking to determine whether or not current prosthesis alignment procedures are adequate for determining a satisfactory walking gait on non-level and non-smooth terrains as well level smooth surfaces. An effective and efficient walking pattern is necessary to prevent degenerative conditions within the bones, muscles or other tissues of the body, due to compensations of the gait pattern. Sometimes, individuals are able to mask any compensations if their safety is unaffected by their surroundings and they are able to maintain a gait that appears normal or optimal. However, if terrains used on a daily basis present a sense of insecurity, gait compensations could be more problematic to the individual and they need to be addressed and corrected as best they can. This study determined that while there were some changes in gait on the uneven surface, due to the number of subjects it is unclear whether the changes are significant. The individuals showed a decrease in walking speed and step length and an increase in step width. There were also changes in the peak axial force.

Introduction

Many chiropractic articles and textbooks discuss gait, but there actually has been little research into the effects of chiropractic adjustment on gait. This pilot study used a quantitative method of gait evaluation before and after a series of chiropractic visits. Hypotheses: (1) adults with chronic low back pain (CLBP) would show increased variability in vertical ground reaction forces (VGRF) while walking, as compared to healthy control subjects, and (2) that, following chiropractic care, will show decreased variability.

Methods

VGRF data were collected for 6 controls and compared to 9 CLBP participants, who were also evaluated before and after the first visit of care and over 7 visits. Data were analyzed by Mean Standard Deviation (MSD), Mean Coefficient of Variation (MCV), and the Coefficient of Variation of loading rate. Chiropractic care consisted of “high velocity low amplitude” thrust type procedures, flexion-distraction, pelvic wedges, light mobilization, and stretching.

Results

CLBP participants had somewhat greater variability and became slightly less variable post-care; differences were not significant. Limitations: Some participants had no impairment of walking at baseline; MSD is an uncommon measure, and more research is needed; these results (small group seen by a single doctor) may not be generalizable.

Conclusions

Participants with CLBP had slightly more variability and had slight decreases in variability following chiropractic care. Differences were not statistically significant. With this small pilot study as a guide, more research should be done with larger groups and improved participant selection.

Motorized treadmills have been widely used to examine the reactive balance control of the human body after an external perturbation, like slips or trips, and develop perturbation-based interventions for preventing falls. The treadmill-induced perturbation profile depends on the belt’s duration, velocity, acceleration, and displacement. The intensity of the perturbation is affected by these interrelated factors. There is a lack of consensus regarding how to choose the perturbation intensity. One prerequisite condition to bridge this knowledge gap is to examine how the perturbation intensity affects its outcome. The purpose of this study was to quantify how the slip intensity, characterized by the belt’s peak velocity (low intensity: 0.9 m/s; medium intensity: 1.2 m/s, or high intensity: 1.8 m/s), affects the slip outcome (fall or recovery) in young adults while the slip distance is controlled. Specifically, it was hypothesized that, in comparison with a low intensity, a high slip intensity would lead to 1) a greater risk of a slip-fall and 2) a shorter recovery step latency, longer slip distance, and larger hip descent after the slip onset. Thirty-one healthy young adults aged 18 to 45 years were enrolled and randomly assigned into three groups with different peak slip speeds: low (0.9 m/s), medium (1.2 m/s), and high (1.8 m/s). After the warmup, participants stepped on the ActiveStep treadmill. Following five standing trials without slips, all subjects experienced an unexpected slip perturbation induced by the treadmill with the assigned peak slip velocity. The slip displacement was the same for all groups at 0.36 m. A motion capture system collected participants’ full-body kinematics. The slip outcome (a binary variable: fall or recovery) was determined by the hip descent after the slip onset. The faller rate was the primary outcome variable. The secondary outcome measures included the continuous measurements of the hip descent, dynamic stability, and slip distance at the instant of recovery foot liftoff, and the latency of the recovery step. The outcome measures were compared among groups using χ² or one-way analysis of variance followed by appropriate post-hoc tests to test the hypotheses. The results overall support the hypotheses. Specifically, individuals in the high-intensity group fell significantly more than the other two groups. Additionally, they were less stable with a longer slip distance at liftoff than their peers in the lower intensity groups. This study could guide the selection of slip profiles for future studies that use perturbation as a test platform or interventional paradigm.

In the summer of 2020, after a series of incidents of police brutality, deaths of Black Americans, and protests throughout the world, people flooded social media with their opinions. As people and organizations began to raise their voices on social media about the country’s injustices, sport organizations and athletes also utilized social media to speak out, including college athletics departments.

Framed by critical race theory, researchers have examined how fans (e.g., Frederick et al., 2017) and athletes (e.g., Agyemang et al., 2010; Intosh et al., 2020) feel about athlete activism. However, research on sport organizations’ activism is limited. At the collegiate level, athletic directors may be concerned with student-athletes’ perceptions of athletic departments’ efforts in the racial justice movement, as 18% of NCAA student-athletes are African American, and representation drastically increases in the highest revenue producing sports (Kluch & Wilson, 2020). Researchers have noted that Black student-athletes frequently perceive their institutions as unsupportive (Cooper, 2017). Meanwhile, activism efforts through social media can build community and promote civic engagement (Skoric et al., 2015). The purpose of this study is to explore perceptions of student-athletes based on factors identified by Sappington et al. (2019)—namely, student-athletes’ emotional response to posts (affective response), the impact on the team (perceived conflict), and the role or perceived qualification of the athletics department to post about race relations.

To assess student-athlete perception of college athletics departments involvement in the BLM movement, an online survey was distributed to NCAA student-athletes. A modified version of the Attitudes Toward Athlete Activism Questionnaire (7-point Likert scale; Sappington et al., 2019) measured the student-athlete’s response to athletic department’s social media activism. In addition, original open-ended questions were asked to gauge specific response and feedback for future practices.

The findings suggest that overall student-athletes welcome their athletics departments’ activism efforts, especially in terms of low perceived conflict and affective reaction. Student-athletes were less likely to believe it was their athletics departments’ role or that they had the proper qualification. The answers to the open-ended questions suggest that athletics departments should work on authenticity, education, and being proactive.

Historically, many sports entities have generated revenue through media rights, which has now become a billion-dollar business with its convergence with technology. As technology advances, cord-cutters have criticized cable television providers based on the high costs of content and the lack of consumer choices. Over-the-top (OTT) platforms have since converted conventional television viewers to OTT platforms serving as a viable force that has altered the existing market. This disruption has created new opportunities for sports properties to exclude traditional media powerhouses and provide their own live and on-demand services to consumers, an opportunity that organizations across all levels of sport are exploring as a means of expanding their revenues and strengthening their reach. As online sports consumption is relevant to OTT, current research does not address the reasons why fans consume sports via digital platforms and their gratification with the product. Despite trends reflecting changes in consumption patterns and the expansion of the profits accumulated from digital sport media rights, there has been limited research exploring the OTT consumer, which would be practical in developing effective marketing strategies. The overarching purpose of this study was to determine the composition of an OTT sports consumer and examine what effect their motives have on their gratification and constant utilization of the platform. An online survey was administered to OTT users (N = 151). Descriptive statistics, cluster analyses, t-test, and MANOVAs revealed characteristics about the users.

This study examined the effectiveness of social media marketing on college students attending a recreation special event. Facebook and Twitter were assessed via an experimental design. To measure the effectiveness of these applications (through updating statuses) on a college student’s awareness, interest, and intent of attending a special event, three groups were employed (Facebook, Twitter, and Control). A total of 134 participants were recruited via six undergraduate courses and were assigned into three groups based on their social media consumption. Subjects responded to a pre-survey, joined their respective treatment group, and completed a post-survey. Descriptive statistics revealed that awareness increased for those who received Facebook status updates and tweets. The interest level of the treatment groups decreased from the pre to the post-test and the intention of participants to participate increased slightly for the Facebook treatment group, but the intent level of participants in the Twitter and Control groups decreased.

This study examined the effects of lyrical music compared to non-lyrical music on 5 km running performance. Thirteen subjects with an average age of 33.5 ± 8.3 years of age ran three separate 5 km time trials. The first trial acted as a familiarization trial where no music was present, followed by either a lyrical or non-lyrical music trial in a random counterbalanced order. Trial times, RPE, HR, and questionnaire information was analyzed using paired samples t-tests, ANOVA, and multivariate regression analyses. Lyrical music showed a significant improvement over non-lyrical music improving performance time compared to non-lyrical music, on average by 36 ± 41s (p=.000). While not statistically significant, a trend showing lyrical music was faster than no music, followed by the slowest trial of non-lyrical music. No change was detected in HR, or RPE at the 3.05 km mark suggesting that at the end although subjects were working harder (indicated by the faster completion times) they do not perceive themselves to be working harder. A correlation between increased mileage and the decreased effects of music as an ergogenic aid was seen (p=.044 r=.638) which supports previous research. This study suggests that lyrical music may improve 5 km running performance compared to no lyrical music.

Long-range correlation has been observed in the time series of the human neuromuscular system and indicative of a healthy system. However, this analysis has not been used for an scenario of asymmetrical loading during walking. This study aimed to understand the effect of unilateral ankle loading on long-range correlation of spatiotemporal gait parameters in healthy young adults during treadmill walking. We used four unilateral ankle loads (A0, A25, A50, and A75, representing the increase of the moment of inertia of the leg about the knee joint by 0%, 25%, 50% and 75%, respectively) and attached it on the non-dominant leg. We used a modified lower-extremity marker set to collect kinematic data. Subjects walked on a treadmill at their self-selected speed for five minutes under each load condition. For data analysis, we used the toe and heel markers to identify the gait events of heel strike and toe off. We divided each five minute trial into three 100-second segments to investigate potential time effect. We calculated the mean and standard deviation of step length and step time, and conducted a detrended fluctuation analysis (DFA) and calculated the scaling exponent for every 100 seconds. For statistical analysis, we conducted three-way (2 side x 3 time x 4 load) ANOVA with repeated measures on step length and time. Our results demonstrate that mean step time and step length showed three-way interaction, in which step length increased with the load for both sides whereas step time increased on the loaded side but decreased on the unloaded side. Asymmetry between two legs decreased in step length while asymmetry in step time remained over time and across load conditions. DFA results revealed long-range correlation in step length and step time; however, step length showed only a time effect whereas step time showed neither a time nor a load effect. Our results suggest that there might be different control mechanisms on regulating spatiotemporal variables and its long-range correlation while walking with unilateral ankle load.

In the sport industry, many stakeholders, including sport organizations, players, coaches, sports reporters, and fans, utilize Twitter. Twitter has become a practical marketing tool, in part, although Twitter users have not been studied in terms of sociodemographics, team identification, media consumption, team related Twitter consumption, or game consumption of their favorite team. Exploring the demographics and consumptive behavior of Twitter users can be valuable for sport organizations to create marketing plans and make managerial decisions. The purpose of this study was to determine the makeup of sport consumers on Twitter for market segmentation purposes and examine their sport media consumption levels, sport-related Twitter usage, team identification level, and team consumption. Differences between Generation X and Y consumers were also determined. An online survey was administered to Twitter users (N = 219). Descriptive statistics, chi-square analyses and MANOVAs revealed characteristics about the users.