Time since injury influences eccentric hamstring force imbalance in collegiate American football players

Hamstring injuries (HSI) are among the most common non-contact injuries in American football. Understanding effects of duration since injury may inform how coaches, trainers, and athletes approach rehabilitation and return to play decisions. PURPOSE: To compare hamstring imbalance in athletes injured more than 12 months ago to hamstring imbalance in athletes with no HSI and compare hamstring imbalance in athletes injured within the last 12 months to imbalance in those with no HSI. METHODS: Sixty-one collegiate football players (age: 22.5 ± 1.8, height: 187.6 ± 6.2 cm, weight: 105 ± 21.6 kg) rostered in 2022 self-identified as having either (1) no HSI (n=45), or (2) having injured only one hamstring since grade 9. We separated those reporting previous injuries into two groups: those with injury longer ago than 12 months (historical HSI, n=12) and those injured with the last 12 months (recent HSI, n=4). All players performed eccentric hamstring curls on a Nordbord. For the group with no HSI, imbalance between legs was calculated as the stronger minus weaker leg. For both injured groups, imbalance was calculated as the difference between uninjured and injured legs. RESULTS: Analysis of the means was performed via Bayesian methods, assuming separate standard deviations for each group. Analysis of posterior chains indicated all parameters converged appropriately. The posterior mean of imbalance for players with no HSI was 34.7 ± 27.4 N. The posterior mean of imbalance in those with historical HSI was 10.8 ± 51.1 N. The posterior mean of imbalance in players with recent HSI was 48.9 ± 46.4 N. The posterior probability that the difference between imbalance of the no HSI group and the imbalance of the historical HSI group is greater than zero was 0.948, and the posterior probability that the imbalance of those with recent HSI and the imbalance of the no HSI group is greater than zero is 0.767. CONCLUSION: Collegiate football players with no HSI have greater hamstring imbalance than do those with historical HSI, implying healing process, rehabilitation efforts, and habitual movement patterns may reduce imbalance between hamstrings over a period of at least 12 months. As expected, players who have recent HSI demonstrate greater hamstring imbalance than players with no HSI

The Acute Effects of Whole-Body Corrective Exercise on Postural Alignment

International Journal of Exercise Science 8(3): 213-223, 2015. This study examined the acute effects of whole-body corrective exercise on postural alignment in a sample of 50 male participants (18-30 y) displaying asymmetrical postural deviations. All participants were randomly assigned to either a nonexercise control (n = 25) or corrective exercise treatment (n = 25) group. A three-dimensional motion analysis Vicon system was employed to quantify standing postural alignment at the beginning and end of a 6 d study. Postural misalignments were determined in degrees of symmetry (tilt) and rotation using horizontal and vertical virtual plumb lines for the following locations: hip (ASIS), leg (greater trochanter), shoulder (acromion process), and head (ear). The treatment group completed five corrective exercise sessions on separate days which included 11 exercises (requiring about 60 min per session to complete). The control group performed no intervention and maintained a normal lifestyle. At the commencement of the study there were no significant differences in the degree of postural misalignment between the control and treatment groups at any of the postural measurements. At the conclusion of the treatment period (following the five sessions of corrective exercise), there were no significant differences in any of the postural alignments of any of the postural measurements between the treatment and control groups. For example, all of the following postural measurements were not significantly different (critical F ≥ 4.24;df = 1,25) between groups: hip (ASIS) tilt (F = 0.05), hip (ASIS) rotation (F = 0.15), greater trochanter tilt (F = 1.58), greater trochanter rotation (F = 0.33), shoulder tilt (F = 2.63), shoulder rotation (F = 0.07), head tilt (F = 2.39), and head rotation (F = 2.79). The results of this study suggest that in this group of subjects, five sessions of corrective exercise were insufficient to significantly improve standing postural alignment. Although the results are non-significant, five sessions of corrective exercise were insufficient to measurably improve standing postural alignment. Although the results are non-significant, this study appears to be the first to use 3D video capture analysis to evaluate how corrective exercise might enhance standing whole-body postural alignment. Now, similar research methods can be employed to study a longer treatment period with the objective of identifying the minimal dose of corrective exercise necessary to improve postural alignment

Evaluating Acute Changes in Joint Range-of-motion using Self-myofascial Release, Postural Alignment Exercises, and Static Stretches

International Journal of Exercise Science 6(4) : 310-319, 2013. This study was designed to compare the acute effect of self-myofascial release (SMR), postural alignment exercises, and static stretching on joint range-of-motion. Our sample included 27 participants (n = 14 males and n = 13 females) who had below average joint range-of-motion (specifically a sit-and-reach score of 13.5 inches [34.3 cm] or less). All were university students 18–27 years randomly assigned to complete two 30–40-minute data collection sessions with each testing session consisting of three sit-and-reach measurements (which involved lumbar spinal flexion, hip flexion, knee extension, and ankle dorsiflexion) interspersed with two treatments. Each treatment included foam-rolling, postural alignment exercises, or static stretching. Participants were assigned to complete session 1 and session 2 on two separate days, 24 hours to 48 hours apart. The data were analyzed so carryover effects could be estimated and showed that no single acute treatment significantly increased posterior mean sit-and-reach scores. However, significant gains (95% posterior probability limits) were realized with both postural alignment exercises and static stretching when used in combination with foam-rolling. For example, the posterior means equaled 1.71 inches (4.34 cm) when postural alignment exercises were followed by foam-rolling; 1.76 inches (4.47 cm) when foam-rolling was followed by static stretching; 1.49 inches (3.78 cm) when static stretching was followed by foam-rolling; and 1.18 inches (2.99 cm) when foam-rolling was followed by postural alignment exercises. Our results demonstrate that an acute treatment of foam-rolling significantly increased joint range-of-motion in participants with below average joint range-of-motion when combined with either postural alignment exercises or static stretching

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Ergonomics problems and solutions in biotechnology laboratories

The multi-functional successful ergonomics program currently implemented at Lawrence Livermore National Laboratory (LLNL) will be presented with special emphasis on recent findings in the Biotechnology laboratory environment. In addition to a discussion of more traditional computer-related repetitive stress injuries and associated statistics, the presentation will cover identification of ergonomic problems in laboratory functions such as pipetting, radiation shielding, and microscope work. Techniques to alleviate symptoms and prevent future injuries will be presented

Skill Importance in Women's Volleyball

The purpose of this paper is to demonstrate two methods to quantify skill importance for teams in general, and women's volleyball in particular. A division I women's volleyball team rated each skill (serve, pass, set, etc.) and recorded rally outcomes during all home games in a competitive season. The skills were only rated when the ball was on the home team's side of the net. Events followed one of these three patterns: serve-outcome, pass-set-attack outcome, or block-dig-set-attack-outcome. These sequences of events were assumed to be first-order Markov chains, meaning the quality of the performance of the current skill only depended on the quality of the performance of the previous skill. We analyze the volleyball data using two different techniques: one uses a Markovian transition matrix, while the other is an implementation of logistic regression. To estimate the Markovian transition matrix, we assumed a multinomial likelihood with a Dirichlet prior on the transition probabilities. The logistic regression model also uses a Bayesian approach. The posterior distributions of parameters associated with skill performance are used to calculate importance scores. Importance scores produced by the two methods are reasonably consistent across skills. The importance scores indicate, among other things, that the team would have been well rewarded by improving transition offense. Importance scores can be used to assist coaches in allocating practice time, developing new strategies, and optimizing team performance relative to player selection.