Load-velocity relationships may vary between people of different strength levels and across different loads. The purpose of this dissertation was to investigate how external loads influence the velocity characteristics of the back squat exercise, and the influence of strength on these variables. Healthy male students with a history of resistance training completed repetitions at specified intensities of their estimated one-repetition maximum (1RM) until they reached 1RM. Back squat 3D motion analysis was captured using four Vicon T010 cameras (Vicon Motion Systems Ltd.; Oxford, UK) and Vicon Nexus 1.8.5 software. Data were transported into R custom coding statistical analysis software (version 3.5.2; The R Foundation) to calculate velocity analyses which determined mean and peak concentric (MCV, PCV) and eccentric (MEV, PEV) values. Participants were grouped by their relative strength (body mass/1RM) in the back squat, as well as their ability to move often prescribed loads with greater speed (63-70%1RM, 83-87%1RM). Between-groups comparisons were made for MCV at all loading conditions, and correlational relationships between all velocity measures (MEV, PEV, MCV, PCV) were examined for each group. For all subjects, there was a significant effect for relative intensity (%1RM) on MCV, but only for the groups organized by MCV at 63-70%1RM and 83-87%1RM was there a between-subjects effect for group. Correlational analyses between velocity measurements during concentric and eccentric phase of the back squat showed a tendency for high relationships (r = 0.5-0.69) between all phases that weakened as the relative intensity increased. These differences were illustrated uniquely between subject grouping conditions. These results indicate that load-velocity characteristics of the back squat cannot necessarily be positively related to strength level in the movement, and that profiling athletes by their velocities at specific relative intensities could be an effective means of organization.

Introduction: Fall-related injuries are exceptionally prevalent in occupational settings. While endangering the workers’ health, falls cause poor productivity and increased economic burden in the workplace. Hence, identifying these threats and training workers to achieve proper postural control is crucial. Purpose: Study 1: To investigate the ankle joint kinematics in unexpected and expected trip responses during single-tasking (ST), dual-tasking (DT), and triple-tasking (TT), before and after a physically fatiguing exercise. Study 2: To investigate the impact of virtual heights, DT, and training on static postural stability and cognitive processing. Methods: Study 1: Twenty collegiate volunteers (10 males and females, one left leg dominant, age 20.35 plus-minus 1.04 years, height 174.83 plus-minus 9.03 cm, mass 73.88 plus-minus 15.55 kg) were recruited. Ankle joint kinematics were recorded while treadmill walking during normal gait (NG), unexpected trip (UT), and expected trip (ET) perturbations with DT and physical fatigue. Study 2: Twenty-eight collegiate volunteers (14 males and females; all right leg dominant; age 20.48 plus-minus 1.26 years; height 172.67 plus-minus 6.66 cm; mass 69.52 plus-minus 13.78 kg; body mass index 23.32 plus-minus 3.54 kg/m2) were recruited. They were exposed to different virtual environments (VEs) over three days with and without DT. Postural sway parameters, lower extremity muscle activity, heart rate, and subjective anxiety parameters were collected. Results: Study 1: Greater maximum ankle angles were observed during UT compared to NG, MDT compared to ST, and TT compared to ST, while greater minimum ankle angles were observed during ET compared to NG and during post-fatigue compared to pre-fatigue. Study 2: Greater postural decrements and poor cognitive processing were observed in high altitudes and DT. Discussion & conclusions: Study 1: Trip recovery responses are different between during DT, TT, and fatigue. Study 2: Static postural stability deteriorates at higher virtual altitudes and with DT, while it improves with a two-day training. Virtual height exposure reduces cognitive performance. Importance: The findings of these studies will provide insights into the biomechanics of falls in ergonomic settings and aid in designing functional and convenient fall prevention programs.

Introduction: Persons with Parkinson’s disease (PD) experience changes cortically, subcortically and behaviorally. This dissertation examines the asymmetry of motor behavior to explore the role of asymmetry in persons with PD and its connection to clinical symptoms. Purpose: Project 1: To assess the hand asymmetry difference in young adults versus older adults. Project 2: To investigate the difference in hand asymmetry in older adults and persons with PD. Project 3: To explore the correlation between function and clinical symptoms of persons with PD. Methods: 55 right-handed participants [Young Adults (YA) = 20, Female = 10; Older Adults (OA) = 20, Female = 10; Persons with PD = 15, Female = 5] were recruited and performed motor tasks: Purdue Pegboard test, grip strength test, response task, thumb opposition task, tapping task, three variations of timed-up-and-go test (TUG), single leg stance task (SLS), Weight Distribution test and Limits of Stability test. The two-way ANOVA was conducted to examine a variance between YA and OA. A separate two-way ANOVA was conducted comparing variance between OA and persons with PD. The purpose was to explore asymmetries, characterized by a significant difference between groups’ left and right sides. Pearson’s correlation was implemented to examine connection of clinical symptoms and motor behavior. Statistics: IBM SPSS 24 software was used. Two 2-way ANOVAs with the between group factor of group (Young vs. Older in Project 1; Older vs. PD in project 2), and within group factor of hand (Right vs. Left in Study 1 & Study 2) were used to examine if age (or PD) changes hand asymmetry. Pearson’s correlation coefficient was used to determine correlations between Unified Parkinson’s Disease Rating Scale (UPDRS) and motor tasks in PD patients (Study 3). Results: Project 1: Results indicate asymmetry reduces with age in fine motor tasks containing speed, dexterity and strength components. Project 2: The basal ganglia dysfunction does not overall further exacerbate the reduced asymmetry with age. Project 3: Clinical symptoms of PD measured by the UPDRS are generally not associated with fine motor tasks of this study.

In early 2020, many businesses (including gyms) were instructed to shut down for an unspecified period of time as a response to the SARS-CoV-2 virus (Casagrande et al., 2020, p.1; Erskine, M., 2020, para.1; O’Brien, 2020, Gyms and Health Centers section, para.1-16). As a result, many people experienced a change in how much they exercised and the quality and quantity of their sleep (Antunes et al., 2020, pp.3,5; Bigalke et al., 2020, p.7; Cellini et al., 2021, pp.113- 115, 117; Constandt et al., 2020, p.4; Pérez-Carbonell et al., 2020, pp.164, 166; Puccinelli et al., 2021, p.6). There was also an increase in the levels of negative mental states, such as anxiety and depression in various populations (Daly et al., 2020, pp.2-5). This study primarily explored changes in exercise and sleep (quality and quantity) as a result of the pandemic in a highly athletic adult population of rowers and triathletes. The data collected from the study also touched upon the changes in the mental states of the participants. A survey was sent across Canada to rowing and triathlon clubs from SurveyMonkey that had both qualitative and quantitative questions to examine these areas of contention. A majority of participants indicated that their sleep quality had worsened as a result the COVID-19 pandemic. However, there wasn’t enough evidence to indicate that the pandemic affected the length of their sleep. The athletic performance of the athletes, as measured by self-report, decreased during the pandemic in an overwhelming number of participants. Finally, although there were many indications of worsened mental health states (such as reports of increased anxiety), there wasn’t a validated questionnaire used to measure changes in mental health concerns in the population related to the COVID-19 pandemic. Some mental health concerns that were shared by the participants indicated other causes than only the pandemic. Future research should include more objective measures of sleep duration and anxiety and depression scores to better clarify those hypotheses. / Graduate

Exercise has been considered a cornerstone of diabetes prevention and treatment for decades, but the benefits of resistance training are less clear. Nineteen non-diabetic subjects (10 metabolic syndrome, 9 sedentary controls) underwent 8 weeks of supervised resistance training. After training, strength and V̇ O2max increased by 10% in both groups. Percent body fat decreased in subjects with the metabolic syndrome. Additionally, lean body mass increased in both groups (p<0.05). Expression of glucose transporter protein-4 (GLUT4), the principle insulin-responsive glucose transporter, increased significantly in both groups. 5-adenosine monophosphateactivated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) expression increased in both groups, indicating increased protein synthesis and mitochondrial biogenesis. Markers of insulin resistance measured by a euglycemic hyperinsulinemic clamp did not improve in subjects with the metabolic syndrome but increased significantly in control subjects (13%). Resistance training upregulates intracellular signaling pathways that may be beneficial for ameliorating the metabolic syndrome.

The current investigation was an examination of the kinetic and kinematic characteristics of the back squat using accentuated eccentric loading (AEL) and cluster set programming strategies. Trained male subjects (age = 26.1 ± 4.1 years, height = 183.5 ± 4.3 cm, body mass = 92.5 ± 10.5 kg, back squat to body mass ratio = 1.8 ± 0.3) volunteered to complete four different load condition sessions involving traditionally loaded straight sets (TL), traditionally loaded cluster sets (TLC), AEL cluster sets (AEC), and AEL straight sets where only the first repetition of each set used eccentric overload (AEL1). The use of AEL increased eccentric work (WECC) and eccentric rate of force development (RFDECC) but did not result in the expected potentiation of subsequent concentric output. Interrepetition rest, however, appears to have the largest influence on concentric peak power (PP), rate of force development (RFDCON), and average velocity (MV). Additionally, the current study was an investigation of the efficacy of novel methods of ultrasonography technique that can be applied to monitoring training response. Compared to lying measures of the vastus lateralis (VL), standing ultrasonography measures of muscle thickness (MT), pennation angle (PA), and cross-sectional area (CSA) were more strongly and abundantly correlated with dynamic and isometric strength performance. Finally, the present study was an exploration of the genetic underpinnings of performance outcomes and muscle phenotypic characteristics. The polymorphisms of two candidate genes (ACTN3, ACE) typical of strength-power athletes were used. ACTN3 RR tended to result in greater type II fiber CSA and alter maximal strength, while ACE DD tended to influence RFD through the presence of more favorable type II-to-type I CSA ratios. Overall, the current investigation provided valuable insight into the characteristics of advanced programming tactics. Furthermore, the ultrasonography measurement and genetic aspects of the current investigation may serve as a framework to inform monitoring practice and generate hypotheses related to the training process.

No description available.

Purpose: The Brigham Young University General Education Wellness Program has three options available to students to fulfill the programs requirement. The purpose of this study was to assess the impact of these three wellness options. Specifically we wanted to know; does the university wellness requirement affect student nutrition and physical activity behaviors and do the various options available differ in their abilities to impact student nutrition and physical activity behaviors? Methods: A three-group pretest/posttest design was used and a survey was administered, at both the beginning and end of the semester, to all students enrolled in HEPE 129, live and online, and all 100 level Physical Education activity classes. The final study design included 303 student responses from HEPE live, 551 responses from HEPE online and 270 responses from the activity classes. Data analysis of between and within group differences was conducted for each nutrition and physical activity behavior. Results: HEPE online students had small but significant improvements in estimated VO2 max, and in the percentage of students who ate bran or whole grain cereal once/day or more. The activity classes increased significantly for almost all of the physical activity behaviors including estimated VO2 max, days/week of moderate activity, and the percent of students getting 30 minutes/day of vigorous activity, but only one of the nutrition behaviors, whole wheat food intake. HEPE live students increased for every variable, some more significantly than others. Conclusion: These findings suggest that of the three wellness options offered at Brigham Young University, the HEPE live class had the largest impact on improving nutrition and physical activity behaviors across a one semester time period, the activity classes had the next largest impact, and HEPE online had the least impact.

In the sport of track and field, proper hurdling technique is a complicated combination of various running and jumping kinematics. With most research having been done on sprint hurdling, there is a growing need for research on hurdling events of different lengths. The intermediate hurdles (IH) and the steeplechase (SC) are two events where there are a number of differences in hurdling technique. This study compared the differences in hurdling technique between events (IH and SC) as well as the differences in technique between genders. Subjects for this study consisted of 20 elite intermediate hurdlers (10 male, 10 female) and 20 elite steeplechasers (10 male, 10 female). Subjects were filmed performing their respective events at the 2006 USA Outdoor Track and Field National Championships. A 2-D analysis was performed on each subject to determine differences between events and genders for the following variables: loss of horizontal velocity, peak center of mass relative to hurdle height, horizontal position at peak center of mass, deviation angle at takeoff, hurdle step length, penultimate, and recovery step lengths, takeoff and landing distance, minimum lead leg hip angle, trail leg knee height relative to the hip at peak height, trunk angle at peak height, landing angle, and finally, the ratio of the recovery step to the penultimate step. Significant differences (p < .05) were observed in 11 of the 13 variables analyzed. Steeplechasers showed significantly higher values than hurdlers in deviation angle, landing angle, minimum lead leg hip angle, peak height over the barrier, takeoff and landing distances, as well as penultimate, hurdle and recovery step lengths. Trail leg knee height was shown to be higher for hurdlers. Also, female steeplechasers were shown to have a greater trunk angle and loss of horizontal velocity than female hurdlers. Females showed higher values than males in deviation angle, landing angle, minimum lead leg hip angle, and peak height over the barrier. Landing distance, hurdle step length and trail leg knee height were higher for males. Also, female steeplechasers had a longer penultimate step length than males. Several differences in hurdling technique exist between events and gender. Hurdlers appear to place more emphasis on the kinematics which helps to promote a low center of mass hurdle clearance. Steeplechasers, on the other hand, are less pronounced with their hurdling kinematics. This is likely due to the greater economy required of the longer event. Gender differences appear to be, in large part, a function of differences in barrier height. As athletes and coaches go about evaluating and training hurdling technique, it is important to recognize the differences that exist between these different events.

The purpose of this study was to evaluate the use of nonexercise (N-EX) data, specifically, the Perceived Functional Ability (PFA) and Physical Activity Rating (PA-R) questionnaires, with the treadmill walk-jog-run protocol to estimate VO2max in 12 to 17 year old boys and girls. Ninety-one participants (49 males and 42 females) took part in this study. Data were collected via PFA and PA-R questionnaires, a walk-jog-run submaximal treadmill test, and a maximal graded exercise test (GXT). Data collected included gender, age, height, weight, PFA and PA-R scores, heart rate (HR), treadmill speed, maximal treadmill grade, respiratory exchange ratio (RER), rating of perceived exertion (RPE), and VO2max. Regression analysis resulted in the development of two valid and reliable models to predict VO2max. Nonexercise and submaximal exercise test data were used to build the following model: VO2max (mL∙kg-¹∙min-¹) = 11.201 + (6.877 x Gender; 0 = female; 1 = male) + (3.573 x treadmill speed; mph) – (0.174 x kg) + (0.405 x PFA score) + (0.653 x PA-R score) + (1.019 x age). The model resulted in an R2 = 0.69 and a SEE = 5.16 mL∙kg-¹∙min-¹. Maximal exercise test data were used to build the following model: VO2max (mL∙kg-¹∙min-¹) = -3.264 + (3.359 x Gender; 0 = female; 1 = male) – (0.082 x kg) + (7.351 x treadmill speed; mph) + (1.750 x maximal treadmill grade). The model resulted in an R2 = 0.88 and a SEE = 3.16 mL∙ kg-¹∙min-¹. The cross-validation PRESS statistics for both models demonstrated minimal shrinkage in the accuracy of the regression model. The results of this study demonstrate, for the first time, that N-EX data can be used to accurately predict VO2max in youth. The submaximal and maximal exercise tests validated in this study can be used to assess cardiorespiratory fitness of youth having a wide range on interests and fitness levels. In addition, the use of PFA and PA-R questionnaires enforces initiatives to increase physical activity among youth. Both exercise tests use a self-selected treadmill speed that elicits a steady-state HR of 70% of the participants age-predicted maximal HR. The use of a self-selected walking, jogging, or running speed accommodates youth with different levels of physical fitness, motivation, and interests. The exercise test protocol presented in this study is practical for use in schools, athletic facilities, and community fitness centers. The equipment required to administer the exercise test presented in this study is limited to a treadmill and a HR monitor. Together with the use of PFA and PA-R questionnaires, the submaximal and maximal exercise tests are efficacious to coaches, fitness professionals, and physical educators in a variety of settings.