Whole body vibration (WBV) is a training modality that involves an individual standing on a plate that provides vibrations at multiple frequencies and amplitudes. Improvements in muscular concentric force production such as power and strength have been extensively studied, however little work has been conducted looking at the effects of WBV on eccentric actions. The landing phase of a jump is an eccentric mechanism to decelerate the body as it prepares to stop or initiate another movement. This study sought to identify the effects of WBV on ground reaction forces, loading rates, valgus knee angles, frontal plane knee moment and jump height, as well as a higher order interaction between gender and time as a result of the vibration. An individualized frequency WBV protocol was utilized as 10 female and 9 male subjects completed drop jumps pre-vibration, post vibration and at 10 and 20 minutes post vibration. Baseline valgus knee angle increased 0.857 degrees post vibration, while remaining increased by 0.917 and 1.189 degrees at the 10 and 20 minute post vibration time intervals, respectively. Repeated measure ANOVA’s revealed that valgus knee angle significantly (p=0.011) increased post vibration. Gender comparisons revealed that females had a significantly greater knee moment (p=0.038) and males significantly jumped higher than females (p<0.001). As an end result following WBV, the subjects landed in significantly greater knee valgus, regardless of sex. Since it has been demonstrated that a knee in a valgus position increases the potential risk for anterior cruciate ligament injury, caution should be taken when combining WBV and jump training protocols. / School of Physical Education, Sport, and Exercise Science

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Fourteen college softball players were recruited to participate in this study to determine if a strength imbalance between the lower extremities, how significant this difference this may be and of any correlations existed among all the functional tests. Subjects took part in isokinetic flexion and extension at 60 and 240 deg/sec, parallel squats, 2-legged vertical jump, single leg vertical jump, and a five-hop test. Peak and average torque was recorded for isokinetic testing and revealed significant differences between the dominant and non-dominant limbs (13.00%- 16.00%). Peak and average force was analyzed for squats and all vertical jumps. Significance was found among all activities between dominant and non-dominant legs, other than average force for single leg vertical jump. A significant difference was also exhibited for the five-hop test between the lower extremities. Significant correlations were also found at the 0.05 and 0.01 levels amongst the various functional tests. Overall findings revealed a significant strength imbalance between the dominant and non-dominant limbs. Further research needs to be conducted in determining how detrimental these differences could be in daily performance for athletes. / School of Physical Education

The present study was undertaken to determine the relationship between perinatal complications and subsequent development of Attention Deficit Hyperactivity Disorder (ADHD) and other behavioral characteristics. The biological mothers of 74 children diagnosed with ADHD and 77 children displaying no characteristics of the disorder completed the Maternal Perinatal Scale (MPS), the Behavior Assessment System for Children-Parent Rating Scales (BASC-PRS), and a demographic survey. In addition, the biological mothers of 120 children with no characteristics of ADHD or any other behavior disorders completed only the MPS so that exploratory factor analysis of the MPS could be completed.Following factor analysis, stepwise discriminant analysis of the resulting five factors was utilized to explore the nature of the relationship between such perinatal factors and ADHD. Results of this analysis indicated that emotional factors, or the amount of stress encountered during pregnancy and the degree to Relationship Between Perinatal Complications 3 was planned, were the items that maximized the separation between the ADHD and Non-ADHD groups. Additional discrimination between the groups was attributed to the extent of insult or trauma to the developing fetus and the outcome of prior pregnancies. ADHD children were also found to have experienced twice as many behavioral, social, or medical problems, and were more likely to reach developmental milestones with delays.Stepwise discriminant analysis also revealed the Attention Problems and Hyperactivity scales of the BASC-PRS were most significant in differentiating between the ADHD and Non-ADHD subjects. Using the BASC-PRS resulted in approximately 90% of the total sample being correctly classified as ADHD or Non-ADHD. Canonical correlation analysis indicated that emotional factors and the general health of both the mother and the developing fetus were the best predictors of later behavioral patterns reported on the BASC-PRS. / Human Performance Laboratory

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Background: Rugby injuries are a common phenomenon. The aim of medical professionals is to treat these injuries to the best of their abilities, and if possible, to help prevent their occurrence. Bahr and Holme (2003) argue that sports participation carries with it a risk of injury, with the even more weighty issue that it might later even lead to physical disability. Junge, Cheung, Edwards and Dvorak (2004) recommends the development and implementation of preventative interventions to reduce the rate and severity of injuries in Rugby Union. The Medical and Risk Management Committee of USA Rugby (2003) also reports that the key to preventing injuries in any sport is identifying and addressing the risk factor associated with it. Various studies have identified weakness in plyometric strength, proprioception arid balance as - of lower leg and ankle injuries (Margison, Rowlands, Gleeson arid Eston, 2005; Stasiwpoulos, 2004; Verhagen, Van der Beck, Twisk, Bahr and Mechelen, 2004; Baltaci & Kohl, 2003; Mlophy, Conaoly and Beynnon, 2003; Moss, 2002; Anderson). Aims: ThE aim of this study was to investigate the influence of proprioception, balance and plyometric strength on the occurrence of lower leg injuries in schoolboy rugby players. A further aim was to develop a preventative training programme to address these variables, should they prove to have an influence on lower leg injuries. The possible inclusion of these tests in talent identification test batteries will also be examined. Design: A prospective cohort study. Subjects: A group of 240 schoolboys in U/14, U/15, U/16 and U/18 age groups in two schools (Hoër Volkskool Potchefstroom ("Volkskool") and Potchefstroom Boys High School ("Boys High")) in the North West Province of South Africa was used as the test cohort. Method: At the beginning of the 2006 rugby season all players were tested for proprioception, balance and plyometric strength. These tests were conducted using a computerised tilt board for proprioceptive testing; Star Excursion Balance Test for Balance and an electronic timing mat for plyometric strength. During the season, weekly injury clinics were held at both schools to document all injuries that occurred following the preceding weekend's matches. A statistical analysis was done on all the data collected from the test batteries and injury clinics. Descriptive statistics (means, standard deviation, minimum and maximum) were used as well as practical significant differences (d-values) (Cohen, 1988). The ratios for left and right leg plyometric strength to bilateral plyometric strength (L+R/Bil) and individual left and right leg plyometric strength to bilateral plyometric strength (L/Bil and R/Bil) were also calculated. Results: A profile of proprioception, balance and plyometric strength was compiled for schoolboy rugby players using the test data The U/18 players generally bad the best test results of all the age groups, outperforming U/14, U/15 and U/16 players with most tests. U/15 players outperformed both U/14 and U/16 players. Backline players performed better than loose forwards and forwards in plyometric tests in most age groups. Loose-forwards also outperformed tight-forwards with plyometrics at most age groups. At U/15 and U/16 level, tight-forwards slightly outperformed loose-forwards with Star Excursion Balance Tests. Generally, A-teams performed better than B-teams with all the tests except L+R/Bil; L/Bil and R/BiI. The difference between the teams, however, only had a small to medium effect and cannot be considered practically significant. At U/14 and U/15 levels, there were more practically significant differences between the A- and B-teams, with A-teams outperforming B-teams. The tests could have some value for talent identification at this age level. A rugby epidemiological study was done on the data collected in the weekly injury clinics. This study recorded 54 injuries at the two schools involved during the 2006 season from April to July. Two hundred and forty players were involved in 10890 hours of play. Eight thousand nine hundred and ten of these player hours were practices and 1980 were match hours. These injuries occurred at a prevalence rate of 4.96/1000 player hours. Match injuries accounted for 77.78% of all injuries with training sessions resulting in the remaining 22.22% of injuries, with a match injury rate of 1 injury per individual player every 3.14 matches. U/14 players showed an overall match injury rate of 11.11/1000 match hours. U/15 players showed a rate of 2.47/1000 match hours. The low rate may be attributed to underreporting of injuries by the U/15 players. U/16 players showed a late of 22.33/1000 hours, while U/18 players showed an exceptionally high rate of 45/1000 match hours. The tackle situation was responsible for the highest percentage of injuries (57.14%). Boys High presented with more injuries (57.4%) than Volkskool at a higher prevalence rate (5.60/1000 player hours). In a positional group comparison, backline players presented with 51.85% of injuries. Since backline players only present 46.7% of players in a team, this shows that backline players have a higher risk of injury. A-team players presented with 66.6% of injuries at a prevalence rate of 6.37/1000 player hours. B-team players had an injury rate of 3.43/1000 player hours. The test values for the players suffering lower leg injuries were compared to those for uninjured players. There were eight players with nine lower leg injuries: one player had injuries of both legs. Six of the injuries were intrinsic of nature and two players had extrinsic injuries. Test values for all five tested players with intrinsic injuries were weaker by a high practically significant margin for the L+R/Bil ratio. Conclusion: L+R/Bil proved to be the test result with the most influence on the occurrence of intrinsic lower leg injuries. When the individual test results for the players with intrinsic injuries are compared to the percentiles for all players, it becomes visible that the injured players fall in the 20th percentile for both L+R/Bil and Injured leg/Bil ratios. These 20th percentile values could thus be used as a standard for determining the possible occurrence of intrinsic lower leg injuries. These 20th percentile values are 1.012 for R+L/Bil ratios; 0.483 for L/Bil ratios and 0.492 for R/Bil ratios. This study shows that plyometric ratios for L+R/Bii, L/Bil and R/Bil have an influence on lower leg injuries in schoolboy rugby players. Proprioception and balance did not have any practically significant effects on the occurrence of these injuries. A preventative training programme was also designed following a study of the literature, combined with these results. The tests could also possibly be integrated in talent identification test batteries at U/14 and U/15 level. / Thesis (M.Ed.)--North-West University, Potchefstroom Campus, 2007

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.

Thesis (MAppSc in Physiotherapy) -- University of South Australia, 1992

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

Thesis (M. Phil.)--University of Sydney, 2009. / Title from title screen (viewed September 25, 2009) Submitted in fulfilment of the requirements for the degree of Master of Philosophy to the Faculty of Medicine. Includes bibliographical references. Also available in print form.