The main purpose of the present study was to quantify and compare selected kinematic variables and their timing during the tennis forehand of different skill levels. An eight-camera 400 Hz, Vicon motion analysis system recorded kinematic data of six ATP- professionals (elite) and seven high performance (HP) players when shots were played cross court and down the line. Timing of the maximum angl...

A 3D gyroscope provides measurements of angular velocities around its three intrinsic orthogonal axes, enabling angular orientation estimation. Because the measured angular velocities represent simultaneous rotations, it is not appropriate to consider them sequentially. Rotations in general are not commutative, and each possible rotation sequence has a different resulting angular orientation. N...

There are not enough studies that describe the isokinetic strength of professional soccer players at high angular velocities. The purpose of this study was to evaluate the seasonal changes in isokinetic strength of Turkish professional soccer players (n=14) over the course of a 24-week soccer season. The isokinetic strength of players who underwent usual soccer training and weekly competition t...

The purpose of the study was to determine young male gymnasts’ and swimmers’ knee flexor:extensor (F:E) ratios during isokinetic testing at different velocities. Nine gymnasts (10.3 ± 0.5 years) and 14 swimmers (10.5 ± 0.5 years) participated. Concentric isokinetic peak torque was measured by a Cybex® Norm dynamometer at different angular velocities (60,120, and 180°/ s) during unilateral knee ...

Eleven sprinters with recent hamstring injuries were compared with nine uninjured runners. The flexibility of the hamstrings and the eccentric and concentric muscle torque were measured in the hamstrings and quadriceps muscles at different angular velocities. Sprinters with a previous hamstring injury had significantly tighter hamstrings than uninjured sprinters had. The uninjured sprinters had...

We carry out a molecular dynamics study of nanobearings based on double-walled carbon nanotubes with a short rotating outer tube. A (4, 4)/(9, 9) bearing configuration shows peculiar stabilization of rotational motion at certain values of angular velocities. The observed trend is found at those values of initial angular velocities (in the current context, 0.8-1.5 rad ps(-1)) which denote a tran...

Introduction The influence of spasticity may be represented as a dynamical constraint on functional performance. Spasticity has been defined as “a motor disorder characterized by a velocity dependent increase in stretch reflexes ...”. This pathologic reflex behavior is associated with increased resistance to motion at increased velocities thereby limiting the velocity and frequency of voluntary...

Distances in cosmology are usually inferred from observed redshifts—an estimate that is dependent on the local peculiar motion—giving a distorted view of the three-dimensional structure and affecting basic observables such as the correlation function and power spectrum. We calculate the full nonlinear redshiftspace power spectrum for Gaussian fields, giving results for both the standard flat-sk...

[Purpose] Fatigue alters lower extremity landing strategies and decreases the ability to attenuate impact during landing. The purpose of this study was to reveal the influence of fatigue on dynamic alignment and joint angular velocities in the lower extremities during a single leg landing. [Subjects and Methods] The 34 female college students were randomly assigned to either the fatigue or cont...