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The effects of cryotherapy on both muscles and joints have been studied using various techniques. The results on lower-extremity functional performance have been controversial. Replication of various aspects of previous studies, with appropriate modifications, will help to standardize cryotherapy interventions. The aims of this study were to examine the reliability of the single leg drop jump test and to evaluate the effects of 20 minutes knee joint cryotherapy application on the performance of this test in physical education students. Data were gathered using 52 subjects (age: 22.17 ± 1.53 year; body-mass: 74.83±11.90kg; Height: 1.78±0.08m). Twenty-two of them took part in reliability analysis of the single leg drop jump and all of the 52 participated in testing joint cooling effects. Reliability analyses were established by determining intraclass correlation coefficient and standard error of measurement. The sensitivity of agility tests was revealed by comparing standard error of measurement to the value of the smallest worthwhile change. The intraclass correlation coefficient that aims to assess relative reliability of the single leg drop jump was of 0.83. The standard error of measurement (7.65%) for absolute reliability was <10%. The single leg drop jump capacity to detect change is "good", its standard error of measurement (1.98) was smaller than the smallest worthwhile change (6.77). The 20 minutes knee joint cooling has not affected single leg drop jump height, immediately and 20 minutes after cryo-stimulation. The SLDJ is a reliable tool for the evaluation of vertical jump. A unilateral knee joint cooling does not produce any significant differences, between the pre- and the first post-cryo-stimulation single leg drop jump, as well as the pre- and the second 20 minutes post-cryo-stimulation single leg drop jump. [ABSTRACT FROM AUTHOR]

Knee functional disorders are one of the most common lower extremity non-traumatic injuries reported by cyclists. Incorrect bicycle configuration may predispose cyclist to injury but the evidence of an effect of saddle setback on knee pain remains inconclusive. The aim of this study was to determine the effect of saddle setback on knee joint forces during pedalling using a musculoskeletal modelling approach. Ten cyclists were assessed under three saddle setback conditions (range of changes in saddle position ~6 cm) while pedalling at a steady power output of 200 W and cadence of 90 rpm. A cycling musculoskeletal model was developed and knee joint forces were estimated using an inverse dynamics method associated with a static optimisation procedure. Our results indicate that moving the saddle forwards was not associated with an increase of patellofemoral joint forces. On the contrary, the tibiofemoral mean and peak compression force were 14 and 15% higher in the Backward than in the Forward condition, respectively. The peak compression force was related to neither pedal force nor quadriceps muscle force but coincided with the eccentric contraction of knee flexor muscles. These findings should benefit bike fitting practitioners and coaches in the design of specific training/rehabilitation protocols. [ABSTRACT FROM AUTHOR]

Tethered swimming is a method often used to measure or enhance the physical and technical resources of swimmers. Although it is highlighted that the technique used in tethered swimming is probably different from that used in free conditions, there are few comparative studies on this subject. The current study aims to compare fully tethered and free swimming based on kinematic hand parameters (orientation, velocity and acceleration of the hand, sweepback and angle of attack), which are known to act directly on the generation of propulsive forces. The results show that there are significant differences during the stretch and catch phases but less during the insweep and upsweep phases. Tethered swimming makes it possible to estimate the propelling forces generated by the hand in free swimming at distance and middle-distance paces, but overestimates it at sprint pace. However, in view of the modifications of the kinematic parameters, it should not be used under repeated conditions of use, such as for the development of swimmers' capacity. [ABSTRACT FROM AUTHOR]

A marker has to be seen by at least two cameras for its three-dimensional (3-D) reconstruction, and the accuracy can be improved with more cameras. However, a change in the set of cameras used in the reconstruction can alter the kinematics. The purpose of this study was to quantify the harmful effect of occlusions on two-dimensional (2-D) images and to make recommendations about the signal processing. A reference kinematics data set was collected for a three degree-of-freedom linkage with three cameras of a commercial motion analysis system without any occlusion on the 2-D images. In the 2-D images, some occlusions were artificially created based on trials of real cyclic motions. An interpolation of 2-D trajectories before the 3-D reconstruction and two filters (Savitsky—Golay and Butterworth filters) after reconstruction were successively applied to minimize the effect of the 2-D occlusions. The filter parameters were optimized by minimizing the root mean square error between the reference and the filtered data. The optimal parameters of the filters were marker dependent, whereas no filter was necessary after a 2-D interpolation. As the occlusions cause systematic error in the 3-D reconstruction, the interpolation of the 2-D trajectories is more appropriate than filtering the 3-D trajectories. [ABSTRACT FROM AUTHOR]

The aim of this study was to objectively predict individual improvements in a release-regrasp tkatchev skill. The prediction was based on a kinematic analysis of failed and successful trials. The modification of release conditions, and the correction of hip and shoulder joint motions during the aerial phase of failed trials, were determined by considering the successful trials as target executions. Computer simulations were used to confirm the effect of the corrected parameters on the flight trajectory and angular motion of the body over the bar. The results indicated that when time of release is initiated earlier, this presents a major problem the gymnast must overcome in order to grasp the bar. Moreover, the moment when the body's center of gravity is vertically above the bar represents a critical instant for the gymnast in initiating the hip and shoulder movements. The rotation motion analysis of the segments indicated that the stabilization motion of the upper limbs could be a good strategy for improving the failed tkatchev. This study showed that simple computer simulation using hypothetical data based upon real data could be an effective tool for improving acrobatic skills. [ABSTRACT FROM AUTHOR]