KINETIC, SPATIAL, AND TEMPORAL ASSESSENT OF OVERSPEED TOWING WITH ELASTIC TUBING

Subjects (N = 15) performed sprints over force platforms in a normal condition and in three overspeed conditions of differing elastic tube stretch length. Kinetic and kinematic data were derived. A 3 x 4 RM ANOVA was used to analyze the results. The horizontal and vertical ground reaction force (GRF), and the ratio of horizontal to vertical GRF did not differ among conditions (p ˃ 0.05). However, ground contact time was 8.3% to 10.4% shorter, time between steps was 1.4% to 2.7% lower, distance between steps was up to 1.2% greater, and velocity was 3.7% higher in some overspeed towing conditions compared to the normal condition (p ≤ 0.05). Longer tube conditions were more optimal in most cases. Compared to normal running, overspeed towing results in increased sprinting velocity despite no differences in horizontal or vertical kinetics compared to normal running

BIOMECHANICAL ANALYSIS OF TIRE FLIPPING WITH TIRES OF DIFFERENT MASSES AND THEIR POTENTIAL SPECIFICITY TO SPRINTING

This study compared the kinetics of tire flipping with different mass tires and sprinting to evaluate the potential specificity of this training stimulus. Subjects (N=15) performed tire flips with a 54.3 kg tire, a 102.1 kg tire, and sprinted on two large force platforms. Dependent variables included peak horizontal ground reaction force (HGRF), peak vertical GRF (VGRF), horizontal to vertical GRF ratio (H:V), and rate of vertical GRF development (VRFD). A RM ANOVA was used to analyze the data. Significant main effects were found for all dependent variables (p ≤ 0.03). Post-hoc analysis showed that the tires were different (p ≤ 0.04) for all dependent variables except for VRFD (p = 0.99). Post-hoc analysis showed that the 54.3 kg tire was more similar to the kinetics of sprinting for HGRF, VGRF, and H:V. Only tire flipping with a lighter tire was similar to key kinetic parameters of sprinting

KINEMATIC AND KINETIC ANALYSIS OF THE HORIZONTAL HANG CLEAN PERFORMED WITH A VARIETY OF LOADS AND THEIR COMPARISON TO THE SPRINT START

This study evaluated kinetic and kinematic aspects of the horizontal hang clean (H-HC) at a variety of loads and also compares these results to the standing sprint start (SSS). Subjects were tested during the H-HC at 30%, 50% and 70% of their five-repetition maximum (5RM), and during the SSS, using two force platforms. Analysis revealed significant differences for the H-HC conditions for the propulsive phase vertical GRF (p ≤ 0.001), propulsive phase horizontal to vertical GRF ratio (H:V) (p = 0.001), subject/barbell displacement (p ≤ 0.001), and velocity (p ≤ 0.001). The propulsive H:V of the H-HC at 30% of the 5 RM was correlated to the propulsive H:V of the first step of the SSS (p = 0.04, r = 0.55). To maximize subject anterior displacement and velocity and propulsive H:V, practitioners should use the H-HC with loads of 30% of the 5 RM. Training in this manner offers specificity for sprinting starts

BIOMECHANICAL ANALYSIS OF LOADED PLYOMETRIC EXERCISES

Plyometric intensity and specificity are determined by the exercises performed. This study assessed ground reaction forces (GRF) in the frontal (F), horizontal-anterior (H), and vertical (V) planes, and the ratio of H to V GRF (H:V) of plyometric exercises and load conditions. Subjects (N=15) performed five plyometric variations with five handheld loads on two force platforms. A two-way RM ANOVA was used. Analysis of F GRF revealed main effects for plyometric exercise (p = 0.004). Analysis of H GRF revealed main effects for plyometric load (p = .042) and plyometric exercise (p ≤ 0.001). Analysis of V GRF revealed main effects for plyometric load (p ≤ 0.001) and plyometric exercise (p ≤ 0.001). Analysis of H:V revealed main effects for plyometric exercise (p ≤ 0.001). Practitioners should use the plyometric exercises and loads that optimize the kinetics and transfer of training

KINETIC ANALYSIS OF AGILITY LADDERS DRILLS AND THEIR COMPARISON TO SPORT-SPECIFIC MOVEMENTS SUCH AS SHUFFLING AND SPRINTING

This study assessed agility ladder drills for the purpose of comparing kinetic characteristics of these drills to one another, and to sprinting and shuffling. Subjects (N=30) performed six agility ladder drills as well as sprinted and shuffled to the left and right over two large force platforms. A repeated measure ANOVA was used to assess horizontal and vertical ground reaction force (GRF) and the ratio of horizontal to vertical GRF, averaged from three steps for each drill. Significant main effects were found for all variables (p ≤ 0.001). Post-hoc analysis identified differences (p ≤ 0.05) between the agility drills as well as between the agility drills and the sprinting and shuffling. Results can be used to guide the progression of agility ladder drills based on known intensity and allow practitioners to prioritize drills that are most similar to sport-specific movements such as sprinting and shuffling

BIOMECHANICAL ANALYSIS OF ACCELERATION LADDERS WITH VARYING STEP DISTANCES

This study assessed select kinetics and kinematics of each of the first three steps of the acceleration phase of sprinting using three different acceleration ladders. Subjects (N=15) performed sprints using acceleration ladders with short, medium, and long rung spacing, over two large force platforms. Multi-factorial repeated measure ANOVAs were used to assess horizontal and vertical ground reaction force (GRF), the ratio of horizontal to vertical GRF, the duration of vertical GRF, time between steps, distance between steps, and velocity between steps and across all steps. Main effects were significant (p ≤ 0.05) for all variables except time. Post-hoc analysis identified a variety of differences in the dependent variables in the analysis of steps, test condition and their interaction (p ≤ 0.05). Results show that greater velocity is attained with ladders that have longer step distances

KINETIC AND SEX-BASED ANALYSIS OF THE TRADITIONAL AND HORIZONTAL HANG CLEAN

The horizontal hang clean (H-HC) is a novel variation of the traditional hang clean (T-HC). This study evaluated the H-HC and T-HC and compared the horizontal and vertical ground reaction forces and the ratio of those forces (H:V), to the horizontal and vertical ground reaction forces and H:V of the countermovement jump (CMJ) and standing sprint start (SSS). Ten men and ten women NCAA Division III athletes performed the T-HC, H-HC, CMJ, and SSS on a force platform. Results revealed that the H-HC produced a significantly (p ≤ 0.001) greater H:V than the T-HC. There was no interaction between any of these variables and sex (p \u3e 0.05). The H-HC should be included in training programs of men and women to increase the likelihood of transfer of training to activities such as sprinting

Association of the infant gut microbiome with early childhood neurodevelopmental outcomes: An ancillary study to the VDAART randomized clinical trial

Importance: In animal models, the early life gut microbiome influences later neurodevelopment. Corresponding data in human populations are lacking. Objective: To study associations between the gut microbiome in infants and development at preschool age measured by the Ages and Stages Questionnaire, third edition (ASQ-3). Design, Setting, and Participants: This ancillary cohort study of the Vitamin D Antenatal Asthma Reduction Trial (VDAART) used data from 715 participants who had development assessed at 3 years of age by the ASQ-3, which included scores in 5 domains (gross motor skills, fine motor skills, problem solving, communication, and personal and social skills). A total of 309 stool samples were collected from infants aged 3 to 6 months for microbiome analysis using 16S rRNA gene sequencing. Exposures: Infant gut microbiome. Main Outcomes and Measures: Continuous ASQ-3 scores and typical vs potential delay in the 5 developmental domains. Factor scores for bacterial coabundance groups were used as predictors in regression models of continuous ASQ-3 scores. Logistic regression was used to examine bacterial coabundance scores and odds of scoring below the threshold for typical development. Multivariate analysis examined the abundance of individual taxa and ASQ-3 scores. Results: The 309 participants (170 [55.0%] male) with ASQ-3 scores and stool samples were ethnically diverse (136 [44.0%] black, 41 [13.3%] Hispanic, 86 [27.8%] white, and 46 [14.9%] other race/ethnicity); the mean (SD) age at ASQ-3 assessment was 3.0 (0.07) years. Coabundance scores dominated by Clostridiales (Lachnospiraceae genera and other, unclassified Clostridiales taxa) were associated with poorer ASQ-3 communication (β, -1.12; 95% CI, -2.23 to -0.01; P = .05) and personal and social (β, -1.44; 95% CI, -2.47 to -0.40; P = .01) scores and with increased odds of potential delay for communication (odds ratio [OR], 1.69; 95% CI, 1.06 to 2.68) and personal and social skills (OR, 1.96; 95% CI, 1.22 to 3.15) per unit increase in coabundance score. The Bacteroides-dominated coabundance grouping was associated with poorer fine motor scores (β, -2.42; 95% CI, -4.29 to -0.55; P = .01) and with increased odds of potential delay for fine motor skills (OR, 1.52; 95% CI, 1.07 to 2.16) per unit increase in coabundance score. Multivariate analysis detected similar family-level and order-level associations. Conclusions and Relevance: These findings suggest an association between infant gut microbiome composition and communication, personal and social, and fine motor skills at age 3 years. The majority of associations were driven by taxa within the order Clostridiales

What's in a message? Delivering sexual health promotion to young people in Australia via text messaging

<p>Abstract</p> <p>Background</p> <p>Advances in communication technologies have dramatically changed how individuals access information and communicate. Recent studies have found that mobile phone text messages (SMS) can be used successfully for short-term behaviour change. However there is no published information examining the acceptability, utility and efficacy of different characteristics of health promotion SMS. This paper presents the results of evaluation focus groups among participants who received twelve sexual health related SMS as part of a study examining the impact of text messaging for sexual health promotion to on young people in Victoria, Australia.</p> <p>Methods</p> <p>Eight gender-segregated focus groups were held with 21 males and 22 females in August 2008. Transcripts of audio recordings were analysed using thematic analysis. Data were coded under one or more themes.</p> <p>Results</p> <p>Text messages were viewed as an acceptable and 'personal' means of health promotion, with participants particularly valuing the informal language. There was a preference for messages that were positive, relevant and short and for messages to cover a variety of topics. Participants were more likely to remember and share messages that were funny, rhymed and/or tied into particular annual events. The message broadcasting, generally fortnightly on Friday afternoons, was viewed as appropriate. Participants said the messages provided new information, a reminder of existing information and reduced apprehension about testing for sexually transmitted infections.</p> <p>Conclusions</p> <p>Mobile phones, in particular SMS, offer health promoters an exciting opportunity to engage personally with a huge number of individuals for low cost. The key elements emerging from this evaluation, such as message style, language and broadcast schedule are directly relevant to future studies using SMS for health promotion, as well as for future health promotion interventions in other mediums that require short formats, such as social networking sites.</p

Human mucosal associated invariant T cells detect bacterially infected cells

Control of infection with Mycobacterium tuberculosis (Mtb) requires Th1-type immunity, of which CD8+ T cells play a unique role. High frequency Mtb-reactive CD8+ T cells are present in both Mtb-infected and uninfected humans. We show by limiting dilution analysis that nonclassically restricted CD8+ T cells are universally present, but predominate in Mtbuninfected individuals. Interestingly, these Mtb-reactive cells expressed the Va7.2 T-cell receptor (TCR), were restricted by the nonclassical MHC (HLA-Ib) molecule MR1, and were activated in a transporter associated with antigen processing and presentation (TAP) independent manner. These properties are all characteristics of mucosal associated invariant T cells (MAIT), an "innate" T-cell population of previously unknown function. These MAIT cells also detect cells infected with other bacteria. Direct ex vivo analysis demonstrates that Mtb-reactive MAIT cells are decreased in peripheral blood mononuclear cells (PBMCs) from individuals with active tuberculosis, are enriched in human lung, and respond to Mtb-infected MR1-expressing lung epithelial cells. Overall, these findings suggest a generalized role for MAIT cells in the detection of bacterially infected cells, and potentially in the control of bacterial infection. © 2010 Gold et al