Gian Piero Grassi

Repeatability of mae-geri-keage in traditional karate: a three-dimensional analysis with black-belt karateka.

In karate, performance also depends on a correct body shape, and the repeatability of standardized movements conditions the effectiveness of techniques. The execution of mae-geri-keage (frontal snap kick) was studied in 13 karateka (1st–5th dan). The 3D trajectories of 13 body landmarks were analyzed by an optoelectronic instrument while each karateka performed 10 repetitions of the movement. For each karateka and repetition, the standard deviations of the spatial coordinates x, y, z for each landmark were computed. A total standard deviation of the single participant was also calculated. Two experienced karateka performed with the best repeatability (smaller standard deviation) while executing the studied kick. Generally, the best repeatability was observed in the horizontal plane. The lower variability was observed in hips and head. Ankle and knee of the dominant limb had the worse. The method could detect athletes particularly gifted for the discipline. Moreover, it could help in the identification of those parts of body that do not repeat the movement with the desired precision.

INFLUENCE OF TRAINING ON MAINTENANCE OF EQUILIBRIUM ON A TILTING PLATFORM

To assess the influence of training on the maintenance of equilibrium on a tilting platform, 13 young healthy male athletes aged 19 to 33 years were randomly divided into experimental (n = 7) and control (n = 6) groups. Two experimental sessions were performed before and after a specific 4-wk. training by the experimental group. Subjects stood upright on a tilting platform. The athletes were asked to maintain the platform as horizontal as possible during a 30-sec. test. The three-dimensional movements of the platform versus the ground were recorded by using a computerized optoelectronic digitiser. The platform plane was calculated and its directrix computed. The area of oscillation and instantaneous angular velocity of the directrix at standardized height were calculated. In both groups the area of oscillation and the angular velocity were reduced in Session 2, but the reduction was significant only in the experimental group. Specific training can significantly improve skill at maintaining equilibrium in young healthy sport performers.

Repeatability of Choku-Tsuki and Oi-Tsuki in Shotokan Karate: A 3-Dimensional Analysis with Thirteen Black-Belt Karateka

13 black-belt karateka performed two different standardized counter-offensive techniques. The trajectories of selected body landmarks were studied by using a computerized image analyzer that allows a 3-dimensional reconstruction of standardized movements. The repeatability of both karate techniques was quantified for each participant. Analysis confirmed that more experienced karateka obtained the best repeatability, as already demonstrated in a preliminary study conducted with a smaller sample of less experienced participants.

Transfer of training for two ball-throwing tasks.

The effects of training overhand ball throws to enhance underhand ball-throwing accuracy were studied with 921 Italian high school pupils (575 girls, M age = 16.5 yr., SD =1.3; 346 boys, M = 16.5 yr., SD = 1.2) ages 14 to 18 years. A standardized test (10 underhand tennis-ball throws into the floor area delimited by an 80-cm radius wooden hoop lying on the floor 9 m from the standing pupil) was performed and scored. An Experimental group (435 girls, M age = 16.5 yr., SD = 1.3; 204 boys, M age = 16.5 yr., SD =1.2) was randomly selected to participate in 10 weekly training periods. The set included 10 overhand throws of a rubber bouncing ball (14.5 cm diameter, weight 240 g) into a basketball hoop from 5 standardized positions (in front of the basketball hoop; at 45°, 90° on the right and on the left of the basketball hoop) at a distance of 4.40 m. The underhand test was repeated for both groups. On the average, boys obtained higher test scores than girls of the same age. Older adolescents had higher mean scores than younger adolescents. After 10 weeks, boys and girls of all ages improved. Mean differences between sessions were significant for the Experimental group (Student t test, p <.01). In Session 2, consistent differences between Experimental and Control groups were also found (Student t test, p < .05).

Growth in primary school-children: a longitudinal study in three age-groups

The growth of primary school-children was investigated in three different age-groups. On October 2007, weights and standing heights of 261 (116 girls; 145 boys), 277 (142; 135), and 289 (139; 150) respectively 6, 7, and 8yr-old primary school-children were measured in Voghera (Pavia, Italy). Body Mass Indices (BMI) were calculated. The measurements were repeated 1 and 2 years later. Within group of age, descriptive statistics of each parameter were computed within age, sex and session of measurements. Comparisons were performed by ANOVA (F1, factor 1, sex; F2, factor 2, age; F1×F2 interaction). Statistical significance was set at 5% for all comparisons. Frequencies and percentages of school-children relatively under- ( 97th percentile) were computed, while comparing BMI to reference data for Italian children (1, 2). On average, weight, height, and BMI were larger in boys than in girls. Differences between sexes were significant (F1, p<0.001) in 8yr-old group. Boys and girls significantly grew with age (F2, p<0.001 for all comparisons). In 6yr-old group, the effects of age on height increments were larger in boys than in girls (F1×F2 interaction, p=0.017). In boys of 6 and 8yr-old groups, BMI was too high in a larger percentage than in girls. In 6yr-old group, the percentage distribution of participants whose BMI was too law was larger in girls than in boys, and increased with age. In 7 and 8yr-old groups, this distribution decreased with age in both boys and girls. School-based anthropometric investigations represent a useful approach to address children and their families to correct life habits. The study allowed the monitoring of growth in school children during a 2yr life span. Further investigations on this matter should be extended to adolescents, and prolonged as much as possible. 1) Cacciari et al. Eur J Clin Nutr. 2002;56:171-180 2) Turci et al. IJAE. 2010;115 S1/2:170.

Growth in primary school children: a longitudinal study from 6 to 8 years of age

School-based anthropometric observations represent a potential approach to address children and their families to correct life habits. On October 2007, weights and standing heights of 261 6yr-old primary school children (116 girls; 145 boys) in Voghera (Pavia, Italy) were measured, and Body Mass Indices (BMI) calculated. Measurements were repeated 1 and 2 years later. Descriptive statistics of each parameter were computed within sex and session (Tab. 1). Comparisons were performed by ANOVA (F1, factor 1, sex; F2, factor 2, age; F1×F2 interaction). Statistical significance was set at 5% for all comparisons. Within age, the distributions and the percentages of boys and girls relatively under( 97th percentile) were computed (Tab. 1), while comparing BMI to reference data for Italian children (Cacciari et al., 2002).

Strength of knee flexor and extensor muscles in young male orienteers

In orienteering, a specially prepared map and a compass are used to navigate point to point in unfamiliar and uneven ground. Races test navigational skill, and running ability of the competitors. High levels of fitness and running speed are requested to cover long distances and climbs, and to compete successfully in international events. The strength of knee flexor and extensor muscles was investigated in young male orienteers. Eight junior Italian team orienteers (experimental group, EG, age, 19±1.6yr; weight, 62±7.0kg; height, 175±5.4cm; BMI, body mass index, 20±1.3kg/m2), and a control group (CG) of 8 cross country track and fields runners (20±4.5yr; 67±3.6kg; 179±3.5cm; 21±1.2kg/m2) volunteered. Right lower limb was dominant for all participants. Running capacities were tested on 3000m mean running speeds (EG, 17.8±1.0km/h; CG, 20.1±0.2km/h). Each athlete performed 5 repetitions of right and left knee flexion and extension at the angular speeds of 60-120-180-240-300deg/sec respectively. The peak torques of each movement at different angular speeds were measured by an isokinetic dynamometer. The obtained values were averaged within subject. Descriptive statistics were computed within group, movement, angular speed, and side. The differences between groups were compared by Mann-Whitney test; those within group, between sides were compared by Wilcoxon test. Statistical significance was set at 5% for all comparisons. Ages, weights, heights, and BMI of EG and CG did not differ (p>0.05, for all comparisons). CG runners were significantly faster than EG (p 0.05 for all comparisons). On average, EG performed peak torques larger than those obtained by CG, in both sides, and movements. The differences were significant in right knee flexor muscles at 60, 120, 300deg/sec (p<0.04; 0.03; 0.05 respectively), in left knee flexors at 60deg/sec (p<0.04), and in right knee extensor muscles at 60deg/sec (p<0.02). Further investigations into this matter should be extended to a larger group of participants and to other muscular districts. Data could be of interest for athletes, coaches, and physicians to allow a correct training planning, to prevent accidental injuries, and also to quantify the effects of rehabilitation.