Knee osteoarthritis (OA) is a degenerative joint condition characterized by progressive joint pain, swelling, and loss of muscle and joint function for which there is no known cure. Current research indicates that the most important modifiable risk factor for the development and progression of knee OA is obesity, a condition that is increasingly common in older adults. Established treatment guidelines for knee OA recommend regular exercise for disease management. However, for obese patients weight-bearing exercise elicits large joint forces that can exacerbate symptoms and influence disease progression. Using a new anti-gravity treadmill capable of generating a lifting force called lower body positive pressure (LBPP), obese patients with knee OA can engage in regular physical activity while minimizing joint loading. The aim of this study was to assess the effect of a 12-week, anti-gravity treadmill walking (AGTW) program on knee pain and function in obese older adults with knee OA. The alternate hypothesis was that there would be a difference between Knee Injury and Osteoarthritis Outcome Score (KOOS) results before and after the anti-gravity treadmill walking program. A group of 25 participants with a mean (SD) age of 64.2 (6.1) years and BMI of 33.0 (6.8) kg/m2 completed AGTW twice per week for 12 weeks at a body weight percentage that minimized knee pain. Knee symptoms and function (KOOS), knee pain during full weight-bearing treadmill walking (FTW), isokinetic quadriceps and hamstring muscle strength, cardiovascular fitness (YMCA submaximal cycle ergometer test), general health status (SF-12), and activity level (average daily pedometer readings) were assessed at baseline and following the completion of the 12-week program using paired t-tests and Wilcoxon signed rank sum tests (α = 0.05). Improvements between baseline and outtake were found in all KOOS subscales, as well as hamstring and quadriceps thigh muscle strength. Knee pain during full FWB and AGTW decreased following the 12-week program. No significant differences were found in cardiovascular fitness, SF-12 scores, or average daily pedometer readings. The results of this study suggest that anti-gravity treadmill walking increases thigh muscle strength, reduces knee pain, and increases functional capacity during daily activities, including FTW in older, obese individuals with knee OA. Anti-gravity treadmill technology has the potential to improve the health and functional capacity of at-risk knee OA individuals, and advance current methods of rehabilitation and long-term management of chronic symptomatic knee OA.

The purpose of this study was to investigate the effect of various loads on the force-time characteristics associated with peak power during the hang high pull (HHP). Fourteen athletic men (age: 21.6 ± 1.3 years; height: 179.3 ± 5.6 cm; body mass: 81.5 ± 8.7 kg; 1 repetition maximum [1RM] hang power clean [HPC]: 104.9 ± 15.1 kg) performed sets of the HHP at 30, 45, 65, and 80% of their 1RM HPC. Peak force, peak velocity, peak power, force at peak power, and velocity at peak power were compared between loads. Statistical differences in peak force (p 0.001), peak velocity (p < 0.001), peak power (p 0.015), force at peak power (p < 0.001), and velocity at peak power (p < 0.001) existed, with the greatest values for each variable occurring at 80, 30, 45, 80, and 30% 1RM HPC, respectively. Effect sizes between loads indicated that larger differences in velocity at peak power existed as compared with those displayed by force at peak power. It seems that differences in velocity may contribute to a greater extent to differences in peak power production as compared with force during the HHP. Further investigation of both force and velocity at peak power during weightlifting variations is necessary to provide insight on the contributing factors of power production. Specific load ranges should be prescribed to optimally train the variables associated with power development during the HHP.

This study examined the impact of load on lower body performance variables during the hang power clean. Fourteen men performed the hang power clean at loads of 30%, 45%, 65%, and 80% 1RM. Peak force, velocity, power, force at peak power, velocity at peak power, and rate of force development were compared at each load. The greatest peak force occurred at 80% 1RM. Peak force at 30% 1RM was statistically lower than peak force at 45% (p = 0.022), 65% (p = 0.010), and 80% 1RM (p = 0.018). Force at peak power at 65% and 80% 1RM was statistically greater than force at peak power at 30% (p < 0.01) and 45% 1RM (p < 0.01). The greatest rate of force development occurred at 30% 1RM, but was not statistically different from the rate of force development at 45%, 65%, and 80% 1RM. The rate of force development at 65% 1RM was statistically greater than the rate of force development at 80% 1RM (p = 0.035). No other statistical differences existed in any variable existed. Changes in load affected the peak force, force at peak power, and rate of force development, but not the peak velocity, power, or velocity at peak power.

Cardiorespiratory responses to incremental dynamic exercise were assessed across four different levels of lower-body positive pressure (LBPP) and, as a separate study, during constant load (i.e constant work rate) exercise below and above each subject's ventilatory threshold (VT), both with and without 45 torr of LBPP.

Testosterone is a steroid and anabolic hormone found in all mammals. Previous research indicates that testosterone levels correlates with physical capacities related to physical performance. However, these studies refers only to men and boys. The aim of present study was therefore to investigate the potential relationship between body composition, strength, power and endurance capabilities in relation to blood levels of testosterone and DHEAS in young female football players. Seventeen female elite football (age: 15,4 ± 0,6, body mass: 57,2 ± 7,4kg, height 1,65 ±0,04m) players volunteered for the study. Morning levels of testosterone were plotted against results of Dual-energy X-ray absorptiometry, Biodex isokinetic dynamometer, maximal counter movement jump, drop jump, 10 and 20 meters sprints and aerobic fitness (Yo-Yo intermittent endurance test). Testosterone levels were significant correlated with DHEAS as well as bone density (BMD) in L1-L4 (p &lt;0,01) and whole body (WB) BMD (p &lt;0,05). DHEAS also correlated with BMD in L1-L4 and WB (p &lt;0,05). No correlations were found between testosterone, DHEAS and performance capacities. These results suggest that DHEAS predict the level of testosterone and BMD in young women. However, more research is needed to clarify the relationship between testosterone, DHEAS and physical capacities in a larger group of women.

Magnetic Resonance Imaging (MRI) was used to determine changes in the size of the Inferior Vena Cava (IVC) as a result of blood pooling induced by lower body negative pressure (LBNP). Images of the IVC of supine human subjects (10 males, 10 females) were obtained under four conditions: 1) steady-state 0 mmHg LBNP, 2) steady-state –35 mmHg LBNP, 3) ramping from 0 to –35 mmHg LBNP, 4) ramping from –35 to 0 mmHg LBNP. Volumes for a given IVC segment were obtained under the first two conditions during both end inspiration and end expiration breath-holds. Inferior Vena Cava widths were measured under all four conditions at the levels of portal entry and portal exit. The IVC volume for men and women combined decreased 41% due to LBNP (p andlt; 1.02 x 10-9). The IVC was 64.4% wider at portal exit than at portal entry in men (p andlt; 0.0003). Lower Body Negative Pressure induced a decrease in men's vena cava width up to 46% at portal exit and up to 62% at portal entry. Supported by NASA EPSCoR WKU 522611 and NIH GCRC MO1 RR262.

Orthostatic intolerance (OI), i.e., the inability to maintain stable arterial pressure during upright posture, is a major problem for astronauts after spaceflight. Therefore, one important goal of spaceflight-related research is the development of countermeasures to prevent post flight OI. Given the rarity and expense of spaceflight, countermeasure development requires ground-based simulations of partial gravity to induce appropriate orthostatic effects on the human body, and to test the efficacy of potential countermeasures. To test the efficacy of upright lower body positive pressure (LBPP) as a model for simulating cardiovascular responses to lunar and Martian gravities on Earth, cardiovascular responses to upright LBPP were compared with those of head-up tilt (HUT), a well-accepted simulation of partial gravity, in both ambulatory and cardiovascularly deconditioned subjects. Results indicate that upright LBPP and HUT induced similar changes in cardiovascular regulation, supporting the use of upright LBPP as a potential model for simulating cardiovascular responses to standing and moving in lunar and Martian gravities. To test the efficacy of a short exposure to artificial gravity (AG) as a countermeasure to spaceflight-induced OI, orthostatic tolerance limits (OTL) and cardiovascular responses to orthostatic stress were tested in cardiovascularly deconditioned subjects, using combined 70º head-up tilt and progressively increased lower body negative pressure, once following 90 minutes AG exposure and once following 90 minutes of -6º head-down bed rest (HDBR). Results indicate that a short AG exposure increased OTL of cardiovascularly deconditioned subjects, with increased baroreflex and sympathetic responsiveness, compared to those measured after HDBR exposure. To gain more insight into mechanisms of causal connectivity in cardiovascular and cardiorespiratory oscillations during orthostatic challenge in both ambulatory and cardiovascularly deconditioned subjects, couplings among R-R intervals (RRI), systolic blood pressure (SBP) and respiratory oscillations in response to graded HUT and dehydration were studied using a phase synchronization approach. Results indicate that increasing orthostatic stress disassociated interactions among RRI, SBP and respiration, and that dehydration exacerbated the disconnection. The loss of causality from SBP to RRI following dehydration suggests that dehydration also reduced involvement of baroreflex regulation, which may contribute to the increased occurrence of OI.

OBJECTIVES: To assess whether the Minimal Chair Height Standing (MCHS) test, could effectively identify “fallers” in a population of Canadian older adults, and to compare its effectiveness with the commonly used Sit-to-Stand (STS) test. DESIGN: Cross-sectional with counter-balanced assignment of testing order. SETTING: Community centers, independent-living and assisted-living facilities. PARTICIPANTS: 167 older adults (mean age=83.6yrs), able to walk independently. MEASUREMENTS: Participants were interviewed for medical conditions, physical activity, cognitive status (Mini Mental State Examination), mobility and independence (Independent Activities of Daily Living). Height, weight and shank length were measured. Fall history was self-reported and recorded retrospectively. The main outcome measures were MCHS and STS scores. RESULTS: MCHS performance was significantly worse for fallers (37.7cm, 95% CI: 35.5-40.0cm) than non-fallers (30.3cm, 95% CI: 28.1-32.5cm). Fallers showed significantly slower times in the STS. For participants with cardiac disease and/or stroke, MCHS scores discriminated between fallers and non-fallers (p=.001), but the STS did not (p=.233). For participants with knee replacements, MCHS discriminated between fallers and non-fallers (p=.044) but the STS did not (p=.076). CONCLUSIONS: The MCHS was found to be simple, practical and feasible for use with the elderly. The current study demonstrates its effectiveness as a fall-risk screening instrument for use with Canadian older adults. Further studies should be undertaken to determine its predictive validity. / Graduate

abstract: The purpose of this study was to investigate the Feasibility of Using a Non-Counter Movement Squat to Assess Lower Body Strength in Adults ages 20-70 years. Feasibility was tested by measuring five feasibility metrics described by Bowen et al. (Bowen et al., 2009): Acceptability, Demand, Implementation, Practicality, and Limited Efficacy. Seven male subjects and fifteen female subjects participated in the study. The subjects had their height, weight, body fat percentage by bioelectrical impedance analysis (BIA), and grip strength measured. Subjects performed a warm-up on a cycle ergometer, a Non-Counter Movement Squat Test (NCMST) 1-repetition maximal strength test using a Smith machine, and a cool down on a treadmill. Each subject then completed a post-participation questionnaire used to measure acceptability, Demand was measured by subjects who agreed to participate, implementation was measured by subjects who completed the protocol, practicality was measured by an administrator survey, and limited efficacy was measured by distribution of strength results by age and for all subjects by sex. Results showed acceptance of hypotheses of acceptability, demand, implementation and practicality for both males and females. Limited efficacy was inconclusive for both males and females resulting in rejection of hypothesis. The findings of this study show that further research is needed to compare the NCMST to other lower body muscular strength tests to determine the validity of the NCMST. / Dissertation/Thesis / Masters Thesis Healthcare Innovation 2019

Jumping ability in volleyball players is crucial to a team's success. There are both muscular and neural components in jumping. Coaches often test jumping ability and body composition prior to the start of the competitive season, but many fail to monitor these important variables during the course of the season. Jumping ability can decrease over the course of the season as the focus moves from strength training in the weight room to skill development on the court. It is imperative that players maintain their jumping ability and body composition over the course of the season. Seasonal changes in elite-male volleyball players were determined by testing the players body composition, spike jump, block jump and lower body power index at three distinct time points: prior to the first game, during their bye-week, and at the end of their regular season. It was found that these players were able to maintain their vertical jump and lower body power index. Also, those who were deemed players (those who played throughout the course of the season) had lower body fat percentages and higher jump scores. These results will aid coaches in understanding the changes that occur over the course of the season in elite-male collegiate volleyball players.