Team sports frequently use inertial measurement units (IMU) fixed at the scapulae for the quantification of athlete performance. Similar IMU are used in clinical settings for gait analysis and jump testing but are located at the center of mass (COM). For clinical methods of jump and gait analysis to be translated to sports related IMU, an investigation of the validity of measure from the scapulae should be assessed. The objective of the current study was to translate clinical methods of gait analysis and jump assessment to commercially available trunk-mounted accelerometers. The current study created a gait program to analyze and compile the gait data. Following completion of the gait program, the IMU (STATSports APEX) was investigated for validity against ankle accelerometers. Once the validity was determined, an application study evaluated the relevance of collecting gait data during a NCAA D1 Women's Soccer season. Similarly, the trunk-mounted accelerometer was validated against force plates to assess countermovement jump height. The final study assessed how both jump height and gait variables changed due to game-related decline in performance. This study provides evidence that trunk-mounted accelerometers are a valid tool for assessing temporal gait variables (ICCRight = 0.95 and ICCLeft = 0.96), CMJ height (ICCJH = 0.90) and flight time (ICCFT = 0.88). A longitudinal analysis of gait showed that StepL, StrideL, kleg, and postural variables changed regularly in pre-post comparisons of performance. Postural variables had more changes towards the end of the season. Root mean squares (RMS) of accelerations and angular velocities had the highest correlations to High Speed Running (HSR). Fractal step and stride length (StepLα and StrideLα) had the strongest correlation to Total Distance (Rstep = -0.29 and Rstride = -0.29), or Tot Dist. When comparing gait and CMJ analyses to detect game-related changes in performance, CMJ was more descriptive of fatigue. In a proof-of-concept study, pre-post changes in CMJ immediately before and after a game had a moderate negative correlation (R = -0.57) to Tot Dist. When the protocol changed to assess the differences between the days before and after the game, the correlation weakened to R = -0.27. Spatiotemporal and spring mass variables did not change, whereas postural variables appeared to improve. The current study has provided evidence that running gait could be used as an athlete monitoring technique, however more data needs to be collected to understand how running gait variables change with team-sports related fatigue. / Doctor of Philosophy / Trunk-mounted accelerometers have become widely popular in team sports such as soccer. Prior to their use in team sports, accelerometers were used in clinical settings to assess gait, and in some cases jump performance. Different from the trunk-mounted accelerometers, the clinical accelerometers were fixed on the lower back to approximate the position of the center of mass. Consequently, the methods to assess gait and jump performance using an accelerometer assume that the accelerometer is fixed on the lower back. For these methods to be translated to trunk-mounted accelerometers, the validity of the methods needs to be established. This paper investigated the validity of trunk-mounted accelerometers in evaluating gait and countermovement jump height. A season-long assessment of gait provided insight into the utility of monitoring gait in team sports athletes. Lastly, a comparison of gait to countermovement jump analyses helped to elucidate what the changes in gait indicate, and how team staff may effectively utilize that information. The trunk-mounted accelerometer (STATSports APEX) was valid in estimating gait and jump variables. The seasonal analysis showed that gait variables changed frequently throughout the season. The main variables affected described the step and stride length of the individual, the stiffness of the leg, and variables representing the variability in trunk movements associated with running. The variability in trunk movements were more perturbed towards the end of the season when players may be beginning to tire from continuous training and competition. In the final study, the jump analysis proved to be more representative of the player's state of fatigue than gait. The gait variables appeared to improve after exhaustive exercise. The apparent improvement in gait variables could indicate that the players recovered quickly from the exhaustive exercise, or that gait variables respond in a more complex fashion than jump variables. More data needs to be collected on how gait changes due to game-related fatigue in soccer players to better understand its effect on neuromuscular performance.

This study begins to fill the gap in sociological literature on movements and countermovements by exploring the dynamic environment of two movement organizations. After documenting the climate of public opinion on abortion, it investigates the strategy and tactics employed by a movement to maintain that opinion and a countermovement to reverse that opinion. It relates social movements to their social environments, social change, opposition, and strategy and tactics. It illustrates the efficacy of single-issue groups in the American social and political environment. Finally, this thesis demonstrates the validity of exploratory studies by uncovering elements of social movements and countermovements that had not been previously investigated.

No description available.

This study examined the validity of various scaling methods, isometric mid-thigh pull (IMTP) peak force using various scaling methods, and the relationships between IMTP peak force and countermovement jump height. Fifty-one collegiate baseball and soccer athletes performed two maximal IMTPs. Absolute peak force was compared between teams and when data were scaled using ratio (RS), traditional allometric (ALLOTrad), and fitted allometric (ALLOFit) scaling. ALLOTrad and ALLOFit validity was violated because different derived exponents existed for baseball (b = 0.20) and soccer (b = 1.20). Soccer athletes produced greater RS peak force compared to baseball (p = 0.012), while no difference existed with absolute, ALLOTrad or ALLOFit (all p > 0.05) peak force. Moderate relationships existed between body mass and absolute (r = 0.402, p = 0.003) and RS (r = -0.328, p = 0.019) peak force, while trivial relationships existed with ALLOTrad and ALLOFit (both r < -0.10, p > 0.05). Trivial relationships existed between countermovement jump height and absolute, RS, ALLOTrad, and ALLOFit (all r < 0.20, p > 0.05) peak force. The current dataset violated allometric scaling assumptions, making it inappropriate to use ALLOTrad and ALLOFit scaling. Practitioners must understand the assumptions, limitations, and purpose of scaling methods.

Introduktion: Dynamic Strength Index är ett ratio som beskriver en individs förhållande mellan maximal och explosiv styrka. Post-activation potentiation (PAP) är ett fenomen där en förberedande aktivitet, exempelvis knäböj, används för att få en prestationsförbättring i en kommande aktivitet. Syftet med denna studie var att undersöka om (a) isometriska partiella knäböj (IPK) påverkar Dynamic Strength Index-ration (DSI), (b) IPK påverkar hopphöjd eller maximal kraft i CMJ, c) IPK påverkar maximal kraft i IMTP, (d) det finns någon signifikant korrelation mellan DSI-ratio och PAP-effekt. Metod: Fyra manliga och fyra kvinnliga beachvolleybollspelare (ålder 24.2 ± 3.8 år, vikt 72.7 ± 11.5 kg, längd 179.3 ± 9.2 cm) deltog i en counterbalanced measure design studie med två testtillfällen. Deltagarna utförde countermovement jump (CMJ) på kraftplattor och isometric mid-thigh-pull (IMTP) med en lastcell under båda testdagarna DSI och DSIPAP. Under DSIPAP utfördes även IPK som en förberedande aktivitet.                                                                                                                                Resultat: Resultaten visade ingen signifikant skillnad på DSI-ratio mellan testtillfällena DSI och DSIPAP (p=0.42). Resultaten för CMJ (cm) visade en lägre hopphöjd vid DSIPAP och en signifikant skillnad (p=0.042). Ingen signifikant skillnad för varken CMJ PF (p=0.96) eller IMTP PF (p=0.20) mellan DSI och DSIPAP hittades. Resultaten visade inte heller någon signifikant korrelation mellan DSI-ratio och PAP-effekt för CMJ peak power (r=-0.38) och CMJ hopphöjd (r=-0.21).                                                                                                                                                                       Konklusion: Maximala isometriska knäböj verkar varken påverka DSI-ratio, CMJ PF eller IMTP PF och hade en negativ påverkan på hopphöjd för beachvolleyspelare. Resultaten i den här studien stöder tidigare forskning att en möjlig negativ korrelation mellan styrka-effekt-ratio och PAP-effekt. Framtida studier behövs för att undersöka det närmare. / Introduction: Dynamic Strength Index (DSI) is a ratio which describes an individuals relationship between maximal and explosive strength. Post-activation potentiation (PAP) is a phenomenon where a conditioning activity, i.e. squats, is used to enhance a subsequent activity. The purpose of this study was to investigate if (a) isometric partial squats (IPS) could affect the DSI ratio, (b) IPS affects jump height or peak force in Countermovement jump (CMJ), (c) IPS will affect peak force in isometric mid thigh-pull (IMTP), (d) there is a significant correlation between DSI-ratio and PAP-effect. Methods: Four male and four female beach volleyball players (age 24.2 ± 3.8 years, weight 72.7 ± 11.5 kg, length 179.3 ± 9.2 cm) participated in a counterbalanced measure design study consisting of two experimental trials. The participants performed countermovement jump (CMJ) on force plates and isometric mid-thigh pull (IMTP) with a load cell during both trial days DSI and DSIPAP. During DSIPAP participants also performed IPS as a conditioning activity. Results: Results showed no significant difference on the DSI-ratio between the trials DSI and DSIPAP (p=0.42). Results for CMJ (cm) showed a decreased jump height at DSIPAP and a significant difference (p=0.042). No significant difference for neither CMJ PF (p=0.96) nor IMTP PF (p=0.20) between the trials were found. No significant correlation were found between DSI-ratio and PAP-effect neither for CMJ peak power (r=-0.38) nor CMJ jump height (r=-0.21). Conclusion: Maximal isometric squats does not seem to effect DSI-ratio, CMJ PF, CMJ PP nor IMTP PF but had a negative effect on jump height in CMJ for beach volleyball players. The findings in this study supports previous studies that a possible negative correlation exists between strength-power-ratio and PAP-effect. Future studies are required to investigate this further.

Abstract Aim The purpose of this study is to examine the correlation between commonly used jump tests and sprint performance over 10 m skate on-ice. The questions we will answer are; -       What correlations exist between a set of jumping tests and the sprint ability over 10 m skate on-ice? -       Which jumping test has the strongest correlation with the sprint ability over 10 m skate on-ice? -       Are there any differences between junior- and senior players, and in that case wich? Method In this study 34 subjects participated and they were between 16-25 years of age and had 9-20 years of icehockey playing experience. They performed five jumping tests; countermovement jump with arms (CMJa), one-legged vertical jump on the right leg, one-legged vertical jump on the left leg, squat jump (SJ) and a horizontal broad jump. On-ice skate test was performed to measure the acceleration ability over 10 m skate sprint in order to try to find correlations between vertical jumping height and the sprint ability, as well as horizontal jumping length and the sprint ability. The tests were performed 48 hours apart. At the first test occasion the jumping tests were performed and at the second the on-ice test was performed. Results The results of this study shows a significant correlation between SJ and the on-ice test result, as well as between CMJa and the on-ice test result. The correlation between SJ and the On-Ice test was r = -0.422 (p &lt; 0.05), and the correlation between CMJa and the on-ice test was r = -0.403 (p &lt; 0.05). When comparing the jump tests to the on-ice test for only juniors no significant correlations were found. However, the seniors (n=7) showed a stronger correlation between the SJ and the on-ice test (r = -0.761, p &lt; 0.05). Conclusions The study  confirmed that SJ is the jumping test that best correlates with  the acceleration/sprint ability skating on-ice. It was also shown that SJ is a more useful predictor for the acceleration/sprint ability for seniors than for juniors. More research will be needed for a deeper understanding of this area. / Sammanfattning Syfte Syftet med studien är att undersöka korrelationerna mellan vanligt förekommande hopptester och sprintförmåga i skridskoåkning över 10 m on-ice. De frågeställningar vi ämnar att besvara är; - Vilka eventuella korrelationer finns mellan de olika hopptesterna och sprintförmåga i skridskoåkning över 10 m on-ice? - Vilket hopptest har störst samband med sprintförmåga i skridskoåkning över 10 m onice? - Finns det några skillnader mellan junior- och seniorspelare, och i så fall vilka? Metod I denna studie deltog 34 försökspersoner (fp) de var mellan 16-25 år gamla och hade en idrottslig bakgrund på 9-20 år. De genomförde fem hopptester; countermovement jump med armdrag (CMJa), vertikalt enbenshopp på höger ben, vertikalt enbenshopp vänster ben, squat jump (SJ) och stående längdhopp. Ett on-ice test för att mäta accelerationsförmågan i skridskoåkning över 10 m genomfördes för att se samband mellan vertikal hopphöjd och accelerationsförmågan samt horisontell hopplängd och accelerationsförmåga. Testerna genomfördes med 48 timmars mellanrum. Vid första tillfället genomfördes hopptesterna och vid andra testtillfället genomfördes on-ice testet. Resultat Resultatet i denna studie visar på signifikanta korrelationer mellan SJ och on-ice testet samt mellan CMJa och on-ice testet. Mellan SJ och on-ice testet uppmättes värden där r = -0.422 (p &lt; 0.05). Mellan CMJa och on-ice testet uppmättes värden till r = -0.403 (p &lt; 0.05). I jämförelsen mellan hopptesterna och on-ice testet för enbart juniorer uppmättes inga signifikanta korrelationer. Däremot visade seniorspelarna (n=7) en signifikant korrelation mellan SJ och on-ice testet (r = -0.761, p &lt; 0.05). Slutsats Studien bekräftar att SJ är det hopptest som bäst förutser acceleration/sprintförmågan i skridskoåkning on-ice. Det visade sig även att SJ är ett mer användbart test för att förutse acceleration/sprintförmågan för seniorer än för juniorer. Vidare forskning kommer att behövas för att skapa djupare förståelse inom området.

Introduction: Running economy (RE) is known to be a strong indicator for performance on long distance running. RE is improved by plyometric training through an increase in stiffness in the musculotendinous system. Stretch shorten cycle (SSC) is a function in the muscle where a contraction is preceded by a stretch or an eccentric action. Orienteering is an endurance sport where RE is important for performance. Purpose: The purpose of the study was to examine whether or not there is a correlation between jumping performance and performance on long distance running in young elite orienteers 16-19 years old. Methods: 34 young elite orienteers did drop jumps (DJ) and countermovement jumps (CMJ) on an ErgoJump Bosco System contact mat. In conjunction with the jumps time on a 5 or 7 km (for girls and boys respectively) running test was collected. Pearson's correlation test was then used to determine the correlation between jumping height and running velocity. Results: The jumping height of the CMJ was on average 30,46 cm and 28,24 cm for the DJ. The running velocity was on average 14,19 km/h. Pearson's correlation test for the correlation between DJ and running velocity was 0,463 and for the correlation between CMJ and running velocity it was 0,461. In both cases the significance was 0,006. Conclusions: There is a significant, moderate to strong correlation between jump height in DJ and CMJ and performance on long distance running on a running test in young elite orienteers.

Suchomel, TJ, Bailey, CA, Sole, CJ, Grazer, JL, and Beckham, GK. Using reactive strength index-modified as an explosive performance measurement tool in Division I athletes. J Strength Cond Res 29(4): 899-904, 2015 - The purposes of this study included examining the reliability of reactive strength index-modified (RSImod), the relationships between RSImod and force-time variables, and the differences in RSImod between male and female collegiate athletes. One hundred six Division I collegiate athletes performed unloaded and loaded countermovement jumps (CMJs). Intraclass correlation coefficients and typical error expressed as a coefficient of variation were used to establish the relative and absolute reliability of RSImod, respectively. Pearson zero-order product-moment correlation coefficients were used to examine the relationships between RSImod and rate of force development, peak force (PF), and peak power (PP) during unloaded and loaded jumping conditions. Finally, independent samples t-tests were used to examine the sex differences in RSImod between male and female athletes. Intraclass correlation coefficient values for RSImod ranged from 0.96 to 0.98, and typical error values ranged from 7.5 to 9.3% during all jumping conditions. Statistically significant correlations existed between RSImod and all force-time variables examined for male and female athletes during both jumping conditions (p ≤ 0.05). Statistically significant differences in RSImod existed between male and female athletes during both unloaded and loaded CMJs (p < 0.001). Reactive strength index-modified seems to be a reliable performance measurement in male and female athletes. Reactive strength index-modified may be described and used as a measure of explosiveness. Stronger relationships between RSImod, PF, and PP existed in female athletes as compared with that in male athletes; however, further evidence investigating these relationships is needed before conclusive statements can be made. Male athletes produced greater RSImod values as compared with that produced by female athletes.

The purpose of this study was to examine the differences in reactive strength index-modified (RSImod), jump height (JH), and time to takeoff (TTT) between 6 U.S. collegiate sport teams. One hundred six male and female Division I collegiate athletes performed unloaded (<1 kg) and loaded (20 kg) countermovement jumps as part of an ongoing athlete monitoring program. Reactive strength index-modified, JH, and TTT values for each team were compared using 1-way analysis of variance. Statistically significant differences in RSImod (p < 0.001), JH (p < 0.001), and TTT (p 0.003) existed between teams during the unloaded jumping condition. Similarly, statistically significant differences in RSImod (p < 0.001), JH (p < 0.001), and TTT (p 0.028) existed between teams during the loaded jumping condition. Men's soccer and baseball produced the greatest RSImod values during both the unloaded and loaded jumping conditions followed by women's volleyball, men's tennis, women's soccer, and women's tennis. The greatest JH during unloaded and loaded jumping conditions was produced by men's baseball followed by men's soccer, women's volleyball, men's tennis, women's soccer, and women's tennis. Men's soccer produced shorter TTT compared with men's baseball (12.7%) and women's soccer (13.3%) during the unloaded and loaded jumping conditions, respectively. Collegiate sport teams exhibit varying reactive strength characteristics during unloaded and loaded jumping conditions. Understanding the differences in RSImod between sports may help direct the creation of training and monitoring programs more effectively for various sports.

Reactive strength index-modified (RSImod) is a measure of lower body explosiveness calculated by dividing jump height by time to takeoff. RSImod is different between stronger and weaker athletes and between males and females. The purpose of this study was to evaluate differences in RSImod between males and females while controlling for maximal strength and lower body explosiveness. Forty-three female and fifty-eight male Division-I athletes performed countermovement jumps on a force plate during unloaded (0kg) and loaded (20kg) conditions. We used an ANCOVA to test whether RSImod is different between sexes conditioning on relative maximum strength (PFa) and average RFD 0-200ms (RFD200) measured during the isometric midthigh pull (IMTP). Differences of 0.087 (95% CI: 0.040 - 0.134; p = 0.0005) and 0.075 (95% CI: 0.040 - 0.109, p < 0.0001) were observed for RSImod between sexes in unloaded and loaded conditions, respectively. A male with PFa of 186 (grand mean of the sample) and RFD200 of 6602 N/s (grand mean of the sample) is predicted to have 28% greater RSImod than a female of similar PFa and RFD200. Maximum strength development should be a primary aim of training in female athletes, in addition to other trainable factors, such as stiffness and RFD.