Comparison of two methods in the estimation of vertical jump height

Vertical jumps are vital aspects in many sports. Many technologies are available to determine and calculate jump height. One such portable and easy-to-use technology is an Inertial Measurement Unit (IMU) that uses accelerometers, gyroscopes and magnetometers. The purpose of this study was to compare vertical jump heights calculated from the data captured with an IMU versus true jump height calculated using a gold standard 3-Dimensional Motion Capture system. Ten subjects completed five jumps for six different conditions including vertical counter-movement jumps and jumps involving rotations on the ground and using a trampoline. An average Pearson correlation coefficient of 0.87 was found between the IMU and motion capture for all conditions. Condition correlations ranged from 0.76 to 0.94. Bland-Altman analyses showed that the IMU underestimated the vertical jump height compared to the motion capture by 5.0 to 9.2 cm across all conditions. Results suggest an IMU can be used to measure jump height in a laboratory setting with a reasonable accuracy, even during vertical jumps that include rotations

Impact of Bilateral Training on Overhand Throwing Performance: Speed, Accuracy, Technique, and Upper-body Kinematics

Manuscript 1: The Sport Technology Research Lab developed an overhand throwing, eight task-component rubric designed to be used in multiple populations. This study assessed its inter-rater and intra-rater reliability. Three groups of raters, two individuals and one panel of three (consensus panel), assessed 480 video recorded overhand throws conducted by healthy adults. Individual raters assessed all videos twice with two weeks between the sessions. The consensus panel assessed all throws once. An ICC 2,k from aggregated data, independent t-tests, KR-20 and percentage agreements were conducted to assess reliability. Independent t-tests showed a significant difference between individual raters and the consensus panel, where the consensus panel scored performance significantly lower. KR-20 and percentage agreements demonstrated high reliability total scores, and moderate-high reliability for the eight task components. ICC 2,k showed high total reliability, suggesting the rubric is a reliable scale when evaluating the overhand throw in adults. However, inconsistencies in individual task components need to be addressed before the scale is used. Manuscript 2: The overhand throw is a complex whole-body motor skill that is fundamental to many sports and activities. The primary outcomes of the overhand throw are ball speed and accuracy. The momentum generated to complete the movement begins in the lower body and transfers through the trunk to the throwing arm. This study’s primary purpose was to evaluate the impact of the non-throwing arm on the ball speed during an overhand throw with both the dominant and non-dominant arms. Eighteen participants (age: 20.20±2.90 yrs., nine females) were divided into two intervention groups: a pulling group taught to engage the non-throwing arm through a pull towards the body, and a non-pulling group taught the overhand throw using a component-based physical education curriculum. Each participant completed 24 total throws, twelve for each side (dominant and non-dominant arm). Ball speed and kinematic data were collected using an eight-camera motion analysis system and were assessed using a pre-post study design. Throwing with both the dominant and non-dominant arms resulted in improvement in both training groups, but there was a much higher Cohen’s D effect size for increased ball velocity when the non-throwing arm was engaged

Hyperinsulinemic response to oral glucose challenge in individuals with posttraumatic stress disorder

BACKGROUND: Posttraumatic stress disorder (PTSD) is associated with a 2–4 fold increased risk of developing Type 2 diabetes mellitus. However, detailed assessments of glucose metabolism and insulin secretion in a study designed to minimize confounders are lacking. Furthermore, few studies examine potential mechanisms involved. We analyzed data from a case-control study of medically healthy, medication-free adults to determine whether individuals with PTSD had abnormal glucose or insulin response to oral glucose tolerance test (OGTT) compared to controls. Secondarily, we assessed potential mediators such as sleep, cortisol and adiponectin. METHODS: Data was analyzed from 92 age and gender-matched subjects (44 PTSD, 48 controls). Chronic PTSD was diagnosed using the Structured Clinical Interview for DSM-IV and Clinician Administered PTSD Scale. Subjects underwent 75-gram OGTT, actigraphy and sleep diary (to quantify sleep duration), polysomnography (to assess slow wave sleep [SWS] and delta power), and overnight blood sampling (for cortisol and adiponectin). RESULTS: At baseline, individuals with PTSD had mildly increased insulin levels (by 19%, compared to controls, p=0.048) that was mediated primarily by weight. In response to OGTT, the PTSD group had higher levels of insulin at 120 min (by 44%, p=0.03) and insulin AUC (by 43%, p=0.015) compared to controls, after adjusting for confounders. Glucose levels were similar in the two groups. Although self-reported sleep duration, SWS, and delta power differed between PTSD subjects and controls, they did not mediate the effects of PTSD status on insulin response. CONCLUSION: In this case-control study, individuals with PTSD had a hyperinsulinemic response to oral glucose challenge compared to controls, suggestive of insulin resistance