Is muscle coordination affected by loading condition in ballistic movements?

This study aimed to investigate the effect of loading on lower limb muscle coordination involved during ballistic squat jumps. Twenty athletes performed ballistic squat jumps on a force platform. Vertical force, velocity, power and electromyographic (EMG) activity of lower limb muscles were recorded during the push-off phase and compared between seven loading conditions (0-60% of the concentric-only maximal repetition).

Validity of trunk extensor and flexor torque measurements using isokinetic dynamometry.

This study aimed to evaluate the validity and test-retest reliability of trunk muscle strength testing performed with a latest-generation isokinetic dynamometer. Eccentric, isometric, and concentric peak torque of the trunk flexor and extensor muscles was measured in 15 healthy subjects. Muscle cross sectional area (CSA) and surface electromyographic (EMG) activity were respectively correlated to peak torque and submaximal isometric torque for erector spinae and rectus abdominis muscles.

Effect of aerobic training on inter-arm coordination in highly trained swimmers.

The effect of three months of aerobic training on spatio-temporal and coordination parameters was examined during a swim trial at maximal aerobic speed. Nine male swimmers swam a 400-m front crawl at maximal speed twice: in trial 1, after summer break, and trial 2, after three months of aerobic training. Video analysis determined the stroke (swimming speed, stroke length, and stroke rate) and coordination (Index of Coordination and propulsive phase duration) parameters for every 50-m segment.

Mechanical and muscular coordination patterns during a high-level fencing assault.

Purpose: This study aimed to investigate the coordination of lower limb muscles during a specific fencing gesture in relation to its mechanical effectiveness.

Methods: Maximal isokinetic concentric and isometric plantarflexor, dorsiflexor, knee and hip extensor and flexor torques of 10 female elite saber fencers were assessed and compared between both legs. Sabers completed three trials of a specific fencing gesture (i.

Coordination profiles of the expert field hockey drive according to field roles.

The aim of this study was to determine coordination profiles for the field hockey drive. Nine elite female players performed five drives each. They were asked to primarily maximize ball placement accuracy, and secondly to drive with high velocity.

Influence of the scale function on wavelet transformation of the surface electromyographic signal.

The scale function in wavelet transformation (WT) determines wavelet dilation and optimises the processing of a given signal. Here, the objective was to determine the influence of the scale function on the WT of 160 surface electromyograms using second-degree polynomial (WT(poly)) and exponential (WT(exp)) scale functions. For each WT, a mean frequency (MNF) was calculated from the original wavelet spectrum and from the cubic spline interpolated wavelet spectrum, and these were compared with the MNF obtained from a fast Fourier transform (FFT).

Hip velocity and arm coordination in front crawl swimming.

The hip intracyclic velocity variability and the index of coordination in front crawl swimming were examined in relation to performance level. 22 swimmers were assigned to either an elite or a recreational swimming group and performed 4 swim trials at different paces relative to their individual maximum velocity. A velocity meter system was set to determine intracyclic velocity variability and video analysis allowed the determination of the index of coordination.

Apnea training effects on swimming coordination.

Triathletes and elite breath-hold divers show an adaptive response to hypoxia induced by repeated epochs of breath holding. We hypothesized that hypoxic training could also improve swimming coordination. Before and after a 3-month breath-hold training program, 4 male swimmers performed a maximal incremental test on bicycle and a 50-m front crawl race at maximal speed without breathing so that interarm coordination could be assessed.

Variability of coordination parameters at 400-m front crawl swimming pace.

This study examined the variability of physiological, perceptual, stroke and coordination parameters in both genders during several swim trials at the 400-m pace speed. Twelve national level competitors (6 men, 6 women) swam 400-m at maximal speed. They then swam three additional trials (100, 200 and 300-m) at the pace (speed) of the previous 400-m.

Modelling spatial-temporal and coordinative parameters in swimming.

This study modelled the changes in spatial-temporal and coordinative parameters through race paces in the four swimming strokes. The arm and leg phases in simultaneous strokes (butterfly and breaststroke) and the inter-arm phases in alternating strokes (crawl and backstroke) were identified by video analysis to calculate the time gaps between propulsive phases. The relationships among velocity, stroke rate, stroke length and coordination were modelled by polynomial regression.

Differences in spatial-temporal parameters and arm-leg coordination in butterfly stroke as a function of race pace, skill and gender.

Spatial-temporal parameters (velocity, stroke rate, stroke length) and arm-leg coordination in the butterfly stroke were studied as a function of race pace, skill (due to technical level, age, and experience) and gender. Forty swimmers (ten elite men, ten elite women, ten less-skilled men, and ten less-skilled women) performed the butterfly stroke at four velocities corresponding to the appropriate paces for the 400-m, 200-m, 100-m, and 50-m, respectively. Arm and leg stroke phases were identified by video analysis and used to calculate four time gaps (T1: the time difference between the start of the arms' catch phase and the start of the legs' downward phase of the first leg kick; T2: the time difference between the start of the arms' pull phase and the start of the legs' upward phase of the first leg kick; T3: the time difference between the start of the arms' push phase and the start of the legs' downward phase of the second leg kick; and T4: the time difference between the start of the arms' recovery and the start of the legs' upward phase of the second leg kick) and the total time gap (TTG), i.

Comparison of the decrease in strength between hamstrings and quadriceps during isokinetic fatigue testing in semiprofessional soccer players.

An imbalance in the agonist/antagonist ratio has been identified as a pathologic factor. Using an isokinetic dynamometer, several studies have investigated the loss of quadriceps strength due to fatigue, but few have explored this phenomenon in the hamstrings. This study assessed the decline in strength of the hamstring and quadriceps muscles with fatigue.

Comparison of spatio-temporal, metabolic, and psychometric responses in recreational and highly trained swimmers during and after a 400-m freestyle swim.

Spatio-temporal, metabolic and psychometric responses during and after a 400-m freestyle swim trial were investigated for gender and skill-level effects. Thirty-four men and women, 18 national and international competitors and 16 recreational swimmers, were compared. Mean speed, stroke rate (SR), and stroke length (SL) were obtained from video recordings.

Intra-cyclic distance per stroke phase, velocity fluctuations and acceleration time ratio of a breaststroker's hip: a comparison between elite and nonelite swimmers at different race paces.

The aim of this study was to compare the intra-cyclic velocity graphs of breaststroke swimmers at two skill levels in relation to their movement phases. Two groups of nine male swimmers were videotaped underwater at three swimming race paces corresponding to their actual competitive times for the 200-m, 100-m and 50-m breaststroke. Their forward intra-cyclic hip velocity was recorded with a velocity-meter.

Kinematic analysis of the golf swing in men and women experienced golfers.

Golf has become an increasingly popular sport, which is enjoyed by both men and women. This paper addresses the question what differences may exist between men and women golfers. The purpose of this study is to analyze the kinematic pattern of the golf swing in both men and women experienced golfers.

Arm to leg coordination in elite butterfly swimmers.

This study proposed the use of four time gaps to assess arm-to-leg coordination in the butterfly stroke at increasing race paces. Fourteen elite male swimmers swam at four velocities corresponding to the appropriate paces for, respectively, the 400-m, 200-m, 100-m, and 50-m events. The different stroke phases of the arm and leg were identified by video analysis and then used to calculate four time gaps (T1: time gap between entry of the hands in the water and the high break-even point of the first undulation; T2: time gap between the beginning of the hands' backward movement and the low break-even point of the first undulation; T3: time gap between the hands' arrival in a vertical plane to the shoulders and the high break-even point of the second undulation; T4: time gap between the hands' release from the water and the low break-even point of the second undulation), the values of which described the changing relationship of arm to leg movements over an entire stroke cycle.

Arm coordination symmetry and breathing effect in front crawl.

This study analysed the relationships among arm coordination symmetry, motor laterality and breathing laterality during a 100-m front crawl, as a function of expertise. Ten elite swimmers (G1), 10 mid-level swimmers (G2), and 8 non-expert swimmers (G3) composed three skill groups, which were distinguished by velocity, stroke rate, stroke length, breathing frequency (BF) and the mean number of strokes between two breaths - the stroke breath (SB) - over a 100-m front crawl. Four stroke phases were identified by video analysis (catch, pull, push and recovery) and the index of coordination (IdC) measured the lag time between the propulsive phases of the two arms.