26 research outputs found

    A COMPARISON OF BASEBALL POSITIONAL DIFFERENCES WITH REACTIVE STRENGTH INDEX-MODIFIED

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    The purpose of this study was to examine positional differences amongst 29 baseball players using the Reactive Strength Index-modified (RSImod) values during unloaded and loaded countermovement jumps (CMJ). A secondary purpose was to determine the relationship between other jump performance characteristics and RSImod values. All athletes underwent CMJ testing and RSImod values were compared between pitchers and position players. The loaded condition CMJ produced statistically different RSImod values between the two groups. Scaled peak force was somewhat more strongly related to RSImod than rate of force development (RFD). The current study indicates that position players may possess higher reactive strength capabilities than pitchers and scaled peak force may be more important than RFD in determining reactive strength characteristics

    REACTIVE STRENGTH INDEX-MODIFIED: A COMPARISON BETWEEN SIX U.S. COLLEGIATE ATHLETIC TEAMS

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    The purpose of this study was to compare reactive strength index-modified (RSImod) between six U.S. collegiate sport teams. One hundred six athletes performed maximum effort countermovement jumps during unloaded and loaded conditions. RSImod measures for each team were compared using one-way ANOVAs, and Bonferroni post hoc tests where warranted. Statistically significant differences in RSImod values existed between teams during both unloaded (< 1kg) and loaded (20kg) conditions. The greatest RSImod values during both conditions were produced by men’s soccer and followed in order by baseball, women’s volleyball, men’s tennis, women’s soccer, and women’s tennis. The data indicate that athletes from different sports possess different reactive strength characteristics

    THE USE OF REACTIVE STRENGTH INDEX-MODIFIED AS AN EXPLOSIVE PERFORMANCE MEASUREMENT IN MALE AND FEMALE ATHLETES

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    This study examined the reliability of reactive strength index-modified (RSImod), relationships between RSImod and force-time variables, and difference in RSImod between male and female collegiate athletes. 106 Division I collegiate athletes performed unloaded and loaded countermovement jumps. Intraclass correlation coefficients and coefficients of variation were used to establish the reliability of RSImod. Correlations were calculated between RSImod and rate of force development, peak force, and peak power. RSImod appears to be a reliable performance measurement in male and female athletes. Furthermore, RSImod has moderate to very large relationships with rate of force development, peak force, and peak power. Statistically significant differences in RSImod existed between males and females during both unloaded and loaded CMJs

    THE RELATIONSHIP OF THE REACTIVE STRENGTH INDEX-MODIFIED AND MEASURES OF FORCE DEVELOPMENT IN THE ISOMETRIC MID-THIGH PULL

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    Reactive strength index-modified (RSImod) may be an important variable to measure in the performance testing and monitoring of athletes, and very little work has examined this particular variable. One hundred six Division-I collegiate athletes performed countermovement jumps and the isometric mid-thigh pull. The relationship between the RSImod and variables from the isometric mid-thigh pull representative of explosive performance were evaluated with Pearson’s r. Relationships between RSImod and variables related to explosiveness ranged from moderate to large. Maximum and relative maximum strength had the strongest correlations to RSImod. RSImod appears to be a measure of explosiveness. Furthermore, an athlete’s isometric strength may be an indicator of their reactive strength

    Orthostatic hypotension in young adults with and without posttraumatic stress disorder.

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    The purpose of this research is (1) to evaluate differences in orthostatic hypotension (OH) among young adults with and without posttraumatic stress disorder (PTSD) and (2) to examine whether group differences may be attributable to behavioral risk factors frequently associated with PTSD

    Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors

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    Background Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. Methods We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors. Results Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged. Conclusions Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.Peer reviewe

    Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

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    In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

    Using Reactive Strength Index-Modified as an Explosive Performance Measurement Tool in Division I Athletes

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    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 \u3c 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

    A Comparison of Reactive Strength Index-Modified Between Six U.S. Collegiate Athletic Teams

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    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 (\u3c1 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 \u3c 0.001), JH (p \u3c 0.001), and TTT (p 0.003) existed between teams during the unloaded jumping condition. Similarly, statistically significant differences in RSImod (p \u3c 0.001), JH (p \u3c 0.001), and TTT (p 0.028) existed between teams during the loaded jumping condition. Men\u27s soccer and baseball produced the greatest RSImod values during both the unloaded and loaded jumping conditions followed by women\u27s volleyball, men\u27s tennis, women\u27s soccer, and women\u27s tennis. The greatest JH during unloaded and loaded jumping conditions was produced by men\u27s baseball followed by men\u27s soccer, women\u27s volleyball, men\u27s tennis, women\u27s soccer, and women\u27s tennis. Men\u27s soccer produced shorter TTT compared with men\u27s baseball (12.7%) and women\u27s 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