To determine the independent effect of soft tissues on bone mineral content (BMC) and density (BMD), and how physical activity (PA) could affect these relationships, body composition by DXA, and the physical fitness (PF) were assessed longitudinally (3-yr) in 26 active and 16 non-active prepubertal boys. Significant advantage in the development of PF, muscle mass and total and lumbar spine BMC and total, lumbar spine and lower-limb BMD were found in the active compared with non-active boys. Results imply that during puberty, lean mass development is the best predictor of bone mass accrual; and physical activity promotes bone acquisition by increasing lean mass but also by lean mass-independent mechanisms.

Key words: skeletal health, body composition, development, exercise.

The aim of this study was to examine the behaviour of several kinematical and physiological parameters throughout competitive matches in football referees. Match-analysis was carried out with a bidimensional photogrammetric video system in 12 games from the 2003 FIFA U-17 World Championship. Heart rate was recorded at 5 s intervals using Polar S610 heart rate monitors. An impairment of performance was detected at three different stages of the match: (i) after the most intense 5 min period of the game, in the following 5 min period the amount of high intensity activities were lowered (p<0.05) in relation to the 5 min average of the game; (ii) in the first 15 min of the second half distance covered (p<0.05), high-intensity activities (p<0.01) and mean heart rate (p<0.001) decreased in relation to the initial phase of the game; and (iii) during the second half of the game there was a global reduction of intensity. The results of this study suggest that specific fitness training plans for referees should be prescribed in order to avoid, or at least delay, the deterioration of the physical performance during a match.

Key words: procedural knowledge, experience, performance, volleyball.

This paper aims to identify the influence that the delay of the second foot in a vertical jump with run up approach, has on the total impulse, impulse absorption, impulse acceleration, and on the percentage participation of each foot during the takeoff phase. Twenty three physical education undergraduates students participated in the study recruited among university basketball and volleyball players (mean height: 179 ± 6.1 cm; mean mass: 70.96 ± 8.82 kg). Two force platforms were used, one for each foot support (Dinascan – IBV) at 250 Hz frequency and time-synchronized to one another and to a high speed video camera (Redlake Motion Space 1000 S). Results showed that the lower the time between the first and second contact foot, the lesser the takeoff time (p<0.001), although this reduction is only attributed to the negative period. The impulse of acceleration was not affected by the delay of the second foot, so that there would not be advantages regarding jump height. There is a bigger reduction of the horizontal velocity when the time between the first and the second contact foot is increased (p<0.01).

In this study, we analyzed the relation between maximum shot velocity with and without accuracy intention in soccer players (N= 108; 70 soccer players and 38 indoor soccer players), and how this accuracy can affect to maximum shot velocity. We found an moderate-high correlation between with and without accuracy intention shots (0,76; ρ<0,01), what suggests the existence of a tendency that soccer players that kicked faster without accuracy intention, did also kick faster with accuracy intention. On the other hand, we found significant differences in both velocities (28,355 ± 1,796 m/s and 27,001 ± 1,962 m/s with and without accuracy intention, respectively). In conclusion, we can say that accuracy intention means a significant reduction of maximum shot velocity.

Key words: soccer, indoor soccer, shot, accuracy.

The purpose of this study was to determine the effectiveness of four traditional motor games (“the tunnel”, “the chicken battle”, “the drunk” and “the wheelbarrow race”) for strengthening the abdominal muscles. Electromyography (EMG) was collected from rectus abdominis (RA), external oblique (EO), and internal oblique (IO) from twelve healthy volunteers during the performance of the games and the trunk curl-up exercise. The EMG amplitude was averaged and normalized using maximal voluntary isometric contractions. A two-way ANOVA (muscle / task) was used to compare the level of contraction activity and the way the abdominal muscles co-activated during the different tasks. For EO and IO, the EMG amplitudes during the games were equal or greater than the EMG amplitudes of the curl up. The wheelbarrow race produced the highest intensity of contraction for all muscles. The curl up principally activated RA and IO. On the other hand, the games activated the oblique muscles with higher intensity than RA. On the basis of these results, the motor games are effective for abdominal conditioning.

KEY WORDS: motor games, exercises, training, abdominal muscles, electromyography.

The flexion-relaxation-phenomenon is the specific response of the erector spinae muscles, in free-pain subjects, during forward bending from upright standing. The contraction intensity of the erector spinae has been studied during trunk exercises on the roman chair, which has brought about significant information in order to graduate lumbar training intensity. To our knowledge, no study determined the pattern of erector spinae activity in the course of movement at the roman-chair exercises. The EMG of the right erector spinae and the angular displacement of the dorso-lumbar spine were symultaneously recorded during the time-course of flexion-extension exercises at upright standing and roman chair (n=20, M: 21.4 years, 64.5Kg and 168.4cm), the muscles activation were compared between the two exercises and different patterns were observed. The flexion-relaxation–phenomenon was observed during flexion form upright standing but not during exercises at the roman chair, the maximum amplitude of flexion was significantly less (p ≤ 0.05) and progresive decrease in ES activity occurred when the trunk flexed by maximum. Avoiding maximum range of flexion during trunk exercises is recommended since, as a rule during lumbar training, it may prevent from spine injury.

KEY WORDS: Erector spinae, flexion-relaxation phenomenon, roman-chair exercises, lumbar-strengthening-exercises, lumbar motion.

The purpose of this study was to measure the acute effect of two explosive strength sessions on mechanical performance. In order to do that, 1 repetition maximum and maximum power load were obtained in 9 men. The experimental procedure begun five days after and it involved two training sessions. 7 bouts of 3 repetitions at maximum power load of bench press were developed in every session with a minimum rest period of three minutes. Power developed at 90% 1RM and at maximum power load were measured before and after every training day. Finally it was carried out a postest measuring. Although repeted-measures ANOVA showed significant differences between measurements at 90% 1RM , statistics analysis did not show significant differences regarding to before-after every sessions contrasts, and between measuring at maximum power load. Also, we did not find significant 1RM correlation with performance differences before-after session. Finally, it was found significant correlation between maximum strength and % 1RM associated to developed maximum power at postest.

Key words: strength, contrast load, bench press, power.

Considering basketball as an acyclic and discontinuous sport it has been designed and validated a field test (TIVRE‐Basket) for the evaluation of the specific resistance of the basketball player who allows to identify the anaerobic threshold and to analyze his capacity of recovery. 18 professional basketball players realized a treadmill test (PowerJog M30), with measurement of VO2máx and determination of the anaerobic ventilatory threshold (VT2). 48 h later realized the field test TIVREBasket with heart rate monitors (Polar Vantage NV). There were neither significant differences between the treadmill test and the TIVRE‐Basket neither in the maximum HR (189.2±1.3 vs 189.6±1bpm) nor the HR‐anaerobic threshold (175.2±8 vs 176.5±7bpm), but if in the máximum speed (17.58±0.1 vs 14.2±1.2 km/h) and in the anaerobic threshold speed (12.9±0.4 vs 10.34±0.1
km/h). Nevertheless there were obtained significant interrelations (p <0.01) between the VO2max and the maximum speeds in the treadmill and TIVRE‐Basket. Also significant differences were only below the intervallic anaerobic threshold in the cardiac maximum frequencies of every interval of effort and the minimum in every recovery. The TIVRE‐Basket is useful and specific in the evaluation of the aerobic resistance and capacity of recovery of the basketball players.
KEY WORDS: Basketball, Maximum Consumption of Oxygen, Anaerobic Threshold, Recovery, Field test.

The main aim of the current study was to determine the effectiveness of two strength training for climbing. 30 healthy men participated in the present study, and they were randomly divided into three groups: control group (GC) (n=10), maximal strength training group (GFM) and endurance-strength training group (GFR). The three groups trained three days per week, GC trained always in wall, but GFM and GFR changed one of them for a training session in the gym. The program lasted 10 weeks and we assesed different kinds of variables before and after the training: physical conditioning variables and hand-grip strength after climbing. We found significant differences in the three groups analysed. GFR obtained the best results according to climbing demands and GFM also obtained significant differences but not as specific as GFR. It could be said that endurance-strength training is the best for climbing.
Key words: Climbing, training, maximal strength, endurance-strength.

This study examined the influence of competition level on observed antisocial behaviours in soccer players. Data corresponding to different categories of a soccer club were obtained by an archival method, using sanctions from 285 referees´game summary sheets. No antisocial behaviours were punished in the 7 to 9 years-old categories, with a progression thereafter until a maximum of 2.4 sanctions per game in the 21 years-old category. Significant differences emerged among players in the different categories for behaviours such as fault to gain possession of the ball, discussing the referee´s decisions, holding and opponent, or delaying the restart of play. There were no sanctions for those behaviours in the lower categories, increasing their numbers from the 11-12 years-old category until the higher competitive levels. Other behaviours, such as making contact with the opponent before touching the ball, striking or threatening an opponent, and offensive or insulting language directed to the referee or to an opponent, first appeared in the 13-14 years-old players, but number of sanctions remained low and similar in the different competitive levels. Our data confirm that playing experience may be an important determinant of antisocial behaviours. However, the various types work differently, and are instrumental behaviours those that clearly increase as a function of competitive level.
Key Words: Antisocial behaviour, soccer, competition level, age

The aim of the study is of going more deeply into the knowledge of the behaviour of the HR of the professional football players into competition, identifying the most relevant criteria that define the context of the game situation where the professional players presents a marked increase in his values of HR in competition, elaborating a distinctive profile of the type of game situation associated with a high physiological load. To reach the mentioned aims it has resorted to a mixed methodology, in which the utilization of the methodology observational in complemented with a selective methodology. For the analysis of information there were retained a whole of 153 cases, correspondents to a whole of 6 professional players belonging to the first team of the R.C. Celta de Vigo, classified to dispute the Champions League in the season 2003/04. The results seem to indicate that they are three criteria that they allow arrange of a model with a high explanatory capacity of more than 80% of the variance of the behaviour of the HR, measured by the marked increases and the decreases in the values: centre of game, role and opposition, specially the first of them turns out to be key at the moment of being able to explain or predict it.

Key words: soccer, heart rate, game situation, centre of game.

Objectives. This study assessed the relationship between the presence of attitude and kyphosis kyphotic,
with a range of socio-demographic type variables (age, gender, location of source), anthropometric (obesity)
and functional (ability flexor).
Method. The final selection of the sample consisted of 2.956 participants with a mean age of 9,61 years and
belong to the province of Granada, sampling was performed in response to the natural composition of the
groups as a criterion for inclusion being enrolled in 2nd and 3rd cycle of primary education. We selected
several measuring instruments (questionnaire, methodology Adams, weight, height and depth of test trunk
flexion) for collecting the selected variables.
Results. The results indicated that 8,5% of participants had kyphosis or kyphotic attitude, not appearing or
gender differences or age. On the other hand, 26,3% of the target population showed obesity rates and
flexibility, was 19,34 cm. It also noted that areas disparate data were finally advisable to qualify the presence
of correlation between kyphosis, obesity, and flexibility.
Conclusions. Almost a tenth of the participants presented kyphosis, also a quarter of the population were
overweight or obese, where the capacity of trunk flexor 19.34 cm, so we highlighting the need for exercise
and health programs with a multidisciplinary approach tailored to the individual needs of each person and
encouraging the construction of new modern sports facilities in all rural areas of the province of Granada to
the people with this disorder may enjoy a greater range of sport and improve substantially their spine
pathologies (kyphosis).

This paper analyses the effects of combined electrostimulation and plyometric training on lower body strength training. The training programme was applied to three experimental groups and one control group. The experimental groups used both methods simultaneously but in different order. The participants were 78 sprinters (100m and 200m, and 100m and 110m hurdles), 38 male and 40 female. Their average age was 15,9 ± 1,4 years and their average weight was 58,53 ± 8,05kg. The training programme consisted in two days a week of plyometric training and two sessions with a Megasonic 313-P4 electrostimulation unit. After two months training, vertical jump height and lower body power were measured in Abalakov test and Drop Jump test with PSION ORGANISER II. The most significant pre- and post-test (p < 0.001) improvements in height and jump power were obtained in the programme combining electrostimulation with subsequent plyometric exercises. Simultaneous electrostimulation and plyometric exercises caused performance stagnancy.

Key words: muscle strength; explosive-elastic component; muscle power; Abalakov jump; drop jump.