Be as upright as possible when squatting: reply

Authors’ response to letter to the editor: integrated approach to correcting the high-bar back squat from “excessive forward leaning” by Bishop and Turner, (2017

Integrated approach to correcting the high-bar back squat from "excessive forward leaning"

The high bar back squat is often considered one of the cornerstones in an athlete’s physical training programme due to its capacity to enhance lower body strength development. However, movement compensations are common with many exhibiting an ‘excessive forward lean’ during their technique. This article aims to outline the potential reasons that may be contributing to this compensation. Furthermore, possible solutions that coaches could consider to remove the excessive forward lean and optimise high bar back squat technique have been offered

The importance of strength and power on key performance indicators in elite youth soccer

The purpose of this investigation was to examine the importance of strength and power in relation to key performance indicators (KPI’s) within competitive soccer match play. This was achieved through using an experimental approach where fifteen subjects were recruited from a professional soccer club’s scholarship squad during the 2013/14 season. Following anthropometric measures, power and strength were assessed across a range of tests which included the squat jump (SJ), countermovement jump (CMJ), 20 metre (m) sprint and arrowhead change of direction test. A predicted 1-repetition maximum (RM) was also obtained for strength by performing a 3RM test for both the back squat and bench press and a total score of athleticism (TSA) was provided by summing z-scores for all fitness tests together, providing one complete score for athleticism. Performance analysis data was collected during 16 matches for the following KPIs: passing, shooting, dribbling, tackling and heading. Alongside this, data concerning player ball involvements (touches) was recorded. Results showed that there was a significant correlation (p < 0.05) between CMJ (r = 0.80), SJ (r = 0.79) and TSA (r = 0.64) in relation to heading success. Similarly, a significant correlation (p < 0.05) between predicted 1RM squat strength and tackle success (r = 0.61). These data supports the notion that strength and power training are important to soccer performance, particularly when players are required to win duels of a physical nature. There were no other relationships found between the fitness data and the KPI’s recorded during match play which may indicate that other aspects of player’s development such as technical skill, cognitive function and sensory awareness are more important for soccer-specific performance

Collisionless heating in capacitive discharges enhanced by dual-frequency excitation

We discuss collisionless electron heating in capacitive discharges excited by a combination of two disparate frequencies. By developing an analytical model, we find, contrary to expectation, that the net heating in this case is much larger than the sum of the effects occurring when the two frequencies act separately. This prediction is substantiated by kinetic simulations, which are also in excellent general quantitative agreement with the model for discharge parameters that are typical of recent experiments

Scattering of elastic waves in heterogeneous media with local isotropy

The scattering of elastic waves in heterogeneous media is discussed. Explicit expressions are derived for the attenuation of longitudinal and transverse elastic waves in terms of the statistics of the density and Lame´ parameter fluctuations. The derivation is based upon diagrammatic methods with the problem posed in terms of the Dyson equation. The Dyson equation is solved for the mean field response. The results are given here in a straightforward manner, in which the attenuations reduce to simple integrals on the unit circle. The medium is assumed statistically homogeneous and statistically isotropic. This model, with assumed local isotropic properties, is expected to apply to many materials

The Extraordinary Infrared Spectrum of NGC 1222 (Mkn 603)

The infrared spectra of starburst galaxies are dominated by the low-excitation lines of [NeII] and [SIII], and the stellar populations deduced from these spectra appear to lack stars larger than about 35 Msun. The only exceptions to this result until now were low metallicity dwarf galaxies. We report our analysis of the mid-infrared spectra obtained with IRS on Spitzer of the starburst galaxy NGC 1222 (Mkn 603). NGC 1222 is a large spheroidal galaxy with a starburst nucleus that is a compact radio and infrared source, and its infrared emission is dominated by the [NeIII] line. This is the first starburst of solar or near-solar metallicity, known to us, which is dominated by the high-excitation lines and which is a likely host of high mass stars. We model the emission with several different assumptions as to the spatial distibution of the high- and low-excitation lines and find that the upper mass cutoff in this galaxy is 40-100 Msun.Comment: accepted, Astronomical Journal. 29 pp, 4 figures. In replacement version an acknowledgment to NRAO is adde