Reproducibility of gastrocnemius medialis muscle architecture during treadmill running.

The purpose of this study was to assess the reproducibility of fascicle length (FL) and pennation angle (PA) of gastrocnemius medialis (GM) muscle during running in vivo. Twelve male recreational long distance runners (mean±SD; age: 24±3 years, mass: 76±7kg) ran on a treadmill at a speed of 3.0m/s, wearing their own running shoes, for two different 10min sessions that were at least 2 days apart. For each test day 10 acceptable trials were recorded. Ankle and knee joint angle data were recorded by a Vicon 624 system with three cameras operating at 120Hz. B-mode ultrasonography was used to examine fascicle length and pennation angle of gastrocnemius medialis muscle. The ultrasound probe was firmly secured on the muscle belly using a lightweight foam fixation. The results indicated that fascicle length and pennation angle demonstrated high reproducibility values during treadmill running both for within and between test days. The root mean square scores between the repeated waveforms of pennation angle and fascicle length were small (∼2° and ∼3.5mm, respectively). However, ∼14 trials for pennation angle and ∼9 trials for fascicle length may be required in order to record accurate data from muscle architecture parameters. In conclusion, ultrasound measurements may be highly reproducible during dynamic movements such as treadmill running, provided that a proper fixation is used in order to assure the constant location and orientation of the ultrasound probe throughout the movement.

Reproducibility of fascicle length and pennation angle of gastrocnemius medialis in human gait in vivo.

The purpose of the current study was to examine the reproducibility of fascicle length and pennation angle of gastrocnemius medialis while human walking. To the best of our knowledge, this is the first study of the reproducibility of fascicle length and pennation angle of gastrocnemius medialis in vivo during human gait. Twelve males performed 10 gait trials on a treadmill, in 2 separate days. B-mode ultrasonography, with the ultrasound probe firmly adjusted in the transverse and frontal planes using a special cast, was used to measure the fascicle length and the pennation angle of the gastrocnemius medialis (GM). A Vicon 624 system with three cameras operating at 120 Hz was also used to record the ankle and knee joint angles. The results showed that measurements of fascicle length and pennation angle showed high reproducibility during the gait cycle, both within the same day and between different days. Moreover, the root mean square differences between the repeated waveforms of both variables were very small, compared with their ranges (fascicle length: RMS= approximately 3mm, range: 38-63 mm; pennation angle: RMS= approximately 1.5 degrees, range: 22-32 degrees). However, their reproducibility was lower compared to the joint angles. It was found that representative data have to be derived by a wide number of gait trials (fascicle length approximately six trials, pennation angle more than 10 trials), to assure the reliability of the fascicle length and pennation angle in human gait.

Motor assessment of preschool aged children: A preliminary investigation of the validity of the Bruininks-Oseretsky test of motor proficiency - short form.

The aim of this study was to examine the validity of the Bruininks-Oseretsky test of motor proficiency - short form (BOTMP-SF) [Bruininks, R. (1978). Bruininks-Oseretsky test of motor proficiency: Examiners manual. Circle Pines, MN] for the assessment of preschool aged children. Three-hundred and eighteen children 48-71months old (M=58.97months, SD=6.73) participated in the study. For the data analysis both an ANOVA and a MANOVA were applied with the total battery score and the 14 item scores being the dependent variables, respectively. Age was found to have a significant effect on both children's total battery score (F(3, 314)=110.65, p<.001, eta(2)=.68) and 13 item scores (minimum F(3, 314)=8.75, p<.001, minimum eta(2)=.145). Although the aforementioned results represent an evidence for the validity of the BOTMP-SF, a closer study on the score of each item revealed a high percentage of zero scores on four items. Task difficulty has caused a floor effect, constituting a threat to the validity of the preschoolers' motor assessment with the above battery. A modification of the battery items is suggested, so that the BOTMP-SF will give valid results for children 4-6years old.

Use of the Bruininks-Oseretsky Test of Motor Proficiency for identifying children with motor impairment.

This study compared the consistency of the Short Form (SF) and the Long Form (LF) of the Bruininks-Oseretsky Test of Motor Proficiency (BOTMP) in identifying preschool children with motor impairment (MI). One hundred and forty-four Greek preschool children participated (74 males, 70 females; mean age 5 y 2 mo [SD 5 mo], range 4 y 6 mo-5 y 6 mo). Although total SF and LF scores were highly correlated (r=0.85), paired t-tests indicated significant differences (t=-27.466, p=0.001). SF total scores (mean 58.72 [SD 7.28]) were higher than LF total scores (mean 47.38 [SD 9.43]). SF had low sensitivity (13.6%) and negative predictive value (72.5%) for identifying MI. The BOTMP-SF does not appear to be a valid test for the identification of MI in 5-year-old children.

Underwater Stroke Kinematics During Breathing and Breath-holding Front Crawl Swimming.

The aim of the present study was to determine the effects of breathing on the three - dimensional underwater stroke kinematics of front crawl swimming. Ten female competitive freestyle swimmers participated in the study. Each subject swam a number of front crawl trials of 25 m at a constant speed under breathing and breath-holding conditions. The underwater motion of each subject's right arm was filmed using two S-VHS cameras, operating at 60 Hz, which were positioned behind two underwater viewing windows. The spatial coordinates of selected points were calculated using the DLT procedure with 30 control points and after the digital filtering of the raw data with a cut-off frequency of 6 Hz, the hand's linear displacements and velocities were calculated. The results revealed that breathing caused significantly increases in the stroke duration (t9 = 2.764; p < 0.05), the backward hand displacement relative to the water (t9 = 2.471; p<0.05) and the lateral displacement of the hand in the X - axis during the downsweep (t9 = 2.638; p < 0.05). On the contrary, the peak backward hand velocity during the insweep (t9 = 2.368; p < 0.05) and the displacement of the hand during the push phase (t9 = -2.297; p < 0.05) were greatly reduced when breathing was involved. From the above, it was concluded that breathing action in front crawl swimming caused significant modifications in both the basic stroke parameters and the overall motor pattern were, possibly due to body roll during breathing. Key pointsThe breathing action increases the duration of the total underwater pull.The breathing action increases the absolute backward displacement of the hand.The breathing action caused significant modifications in the overall motor pattern, possibly due to body roll during breathing.

Repeatability of electromyographic waveforms during the naeryo chagi in taekwondo.

The purpose of the research was to study the repeatability of electromyographic (EMG) waveforms of major lower limb muscles during the naeryo chagi (axe kick) in taekwondo. Six male and female athletes, aged between 20 and 24 years served as volunteers. All participants were black belt holders and performed the naeryo chagi with their right leg. The electromyographic activity of rectus femoris, biceps femoris, gastrocnemius lateralis and tibialis anterior was recorded during the kick through four preamplified surface electrodes. The participants preformed 10 successive kicks to a fixed target with 1 min inter-trial interval. The electromyograms were recorded during each kick at a sampling frequency of 1000Hz. After the processing of the raw EMG data, myoelectrical activity was normalized on the time and amplitude domain. The coefficient of variation (CV), intra-class correlation coefficient (ICC) and coefficient of multiple correlation (CMC) were computed to test the repeatability of the electromyographic waveforms in each participant. The electromyographic activity during the naeryo chagi demonstrated poor repeatability. More specifically, all CVs were greater than 80%, all CMCs were lower than 0.75 and the majority of the average measure ICCs as well as all single measure ICCs were lower than 0.55. It seemed that only ensemble averages of EMG waveforms obtained from more than ten kicks may be considered as representatives of the muscle function in naeryo chagi and conclusions that have been drawn from a single trial should be reconsidered. Key pointsThe paper is the only known paper focused on the EMG repeatability of a taekwondo kick (naeryo chagi).The paper is among the few papers of repeatability dealing with the whole EMG waveforms and not with discrete EMG parameters.Repeatability was tested using all the available statistical indices.The results suggested that conclusions drawn from a single trial in EMG studies of taekwondo kicks and probably in other sports should be treated carefully.

Construct validity of the Bruininks-Oseretsky Test of Motor Proficiency-short form for a sample of Greek preschool and primary school children.

The construct validity of the short form of the Bruininks-Oseretsky Test of Motor Proficiency for the assessment of gross and fine motor skills was assessed in 377 nondisabled Greek preschool and primary school children (age range 5 yr. to 8:3 mo.) from urban areas of northern Greece. Analysis showed the three factors accounted for 54.1% of the total score variance, agreeing with the earlier findings. Moreover, the item scores had statistically significant relationships with the total short-form score, except for that of copying a circle with the preferred hand. This latter item was also the only one with a small effect size. Age confirmed a statistically significant effect on the scores of the half items of the test battery, also an earlier finding. This test seemed to be a valid test of motor proficiency in normal Greek preschool and primary school children.

Effect of a submaximal half-squats warm-up program on vertical jumping ability.

The purpose of the current research was to study the effect of a warm-up program including submaximal half-squats on vertical jumping ability. Twenty physically active men participated in the study. Each subject performed 5 sets of half-squats with 2 repetitions at each of the following intensities: 20, 40, 60, 80, and 90% of the 1 repetition maximum (1RM) load. Prior to the first set and immediately after the end of the last set, the subjects performed 2 countermovement jumps on a Kistler force platform; the primary goal was to jump as high as possible. The results showed that mean vertical jumping ability improved by 2.39% after the warm-up period. Subjects were then divided into 2 groups according to their 1RM values for the half-squat. Subjects with greater maximal strength ability improved their vertical jumping ability (4.01%) more than did subjects with lower maximal strength (0.42%). A warm-up protocol including half-squats with submaximal loads and explosive execution can be used for short-term improvements of vertical jumping performance, and this effect is greater in athletes with a relatively high strength ability.

Comparative 3-dimensional kinematic analysis of the snatch technique in elite male and female greek weightlifters.

The purpose of the current research was the comparison of the snatch technique between elite male and female weightlifters. Two S-VHS cameras operating at 60 fields per second were used to record the snatch lifts of 6 male and 6 female Greek weightlifters under competitive conditions. The spatial coordinates of selected points on the body and the barbell were calculated using the direct linear transformation procedure, and the raw data were digitally filtered with a cutoff frequency of 4 Hz. Analyses of variance for dependent and independent samples were used to compare the selected variables in men with the corresponding variables in women. The results revealed that women flexed their knees significantly less and slower than men did during the transition phase (p < 0.05). Women also dropped under the barbell during the turnover and catch phases significantly less and slower than men did (p < 0.05). Moreover, the external mechanical work for the vertical displacement of the barbell in men was significantly greater in the first pull than in the second pull (p < 0.05). In contrast, women showed similar work outputs in the 2 phases. These differences between the 2 sexes might be because of the lower skill level of women in comparison with men, which is partly because of the recent participation of women in weightlifting.