- Journal Details
- First Published
- 13 Jan 2009
- Publication timeframe
- 5 times per year
- Open Access
Morphometric Study for Estimation and Validation of Trunk Transverse Surface Area To Assess Human Drag Force on Water
Page range: 5 - 13
The aim of this study was to compute and validate estimation equations for the trunk transverse surface area (TTSA) to be used in assessing the swimmer's drag force in both genders. One group of 133 swimmers (56 females, 77 males) was used to compute the estimation equations and another group of 131 swimmers (56 females, 75 males) was used for its validations. Swimmers were photographed in the transverse plane from above, on land, in the upright and hydrodynamic position. The TTSA was measured from the swimmer's photo with specific software. Also measured was the height, body mass, biacromial diameter, chest sagital diameter (CSD) and the chest perimeter (CP). With the first group of swimmers, it was computed the TTSA estimation equations based on stepwise multiple regression models from the selected anthropometrical variables. For males TTSA=6.662*CP+17.019*CSD-210.708 (R2=0.32; Ra2=0.30; P<0.01) and for females TTSA=7.002*CP+15.382*CSD-255.70 (R2=0.34; Ra2=0.31; P<0.01). For both genders there were no significant differences between assessed and estimated mean TTSA. Coefficients of determination for the linear regression models between assessed and estimated TTSA were R2=0.39 for males and R2=0.55 for females. More than 80% of the plots were within the 95% interval confidence for the Bland-Altman analysis in both genders.
- frontal surface area
- Open Access
Test-Retest Reliability of Measurements of the Center of Pressure Displacement in Quiet Standing and During Maximal Voluntary Body Leaning Among Healthy Elderly Men
Page range: 15 - 23
The aim of the study was to evaluate intra- and intersession test-retest reliability for the measurements of centre of pressure displacement in quiet standing and during maximal voluntary body leaning (approximate area of stability limits).
27 elderly men participated in the study (71.4±4.9 of age). Intrasession (4 measurements with two-minute breaks) and intersession (4 measurements one week apart) reliability were examined. Parameters connected to the centre of pressure data (AMTI force platform) were measured during a quiet stance and voluntary body leaning in medio-lateral and anterior-posterior directions (approximate limits of stability). Intraclass correlation coefficients (ICC2,1 and ICC2, k) were calculated.
In case of quiet standing, only mean velocity of centre of pressure sway provides high reliability in intrasession - ICC2,1 of .84 and ICC2, k of .96, and in intersession - ICC2,1 of .76. Evaluation of limits of stability showed high values of all parameters (maximal and minimal displacement in sagittal and frontal planes, distance between maximal and minimal position of centre of pressure in sagittal and frontal planes and approximated area of stability limits) in intrasession - ICC2,1 between .82 to .96 and ICC2, k between .95 to .99. Similar tendency was observed in the intersession retest.
Average velocity of the centre of pressure is the only parameter that showed a high application value in case of measurements during quiet standing. Parameters related to the stability limits appeared very reliable what proves that this evaluation may have potential application in the clinical practice.
- center of pressure
- limits of stability
- Open Access
Page range: 25 - 31
Technical development of human civilisation brings about a decrease of adaptation potential of an individual, which is directly linked to deficient motor activity. Only precise identification of factors leading to hypokinesia would make prophylactic and therapeutic actions possible. In this article, authors would like to introduce a new, original tool aiming at diagnosing limitations of motor activity in adults. They propose a synthetic diagnosis of hypokinesia in two domains: biological and psycho-social, which is based on the contemporary model of health.
- low motor activity
- fear of movement
- Open Access
Page range: 33 - 44
The velocity of movement and applied load affect the production of mechanical power output and subsequently the extent of the adaptation stimulus in strength exercises. We do not know of any known function describing the relationship of power and velocity and load in the bench press exercise. The objective of the study is to find a function modeling of the relationship of relative velocity, relative load and mechanical power output for the bench press exercise and to determine the intensity zones of the exercise for specifically focused strength training of soccer players. Fifteen highly trained soccer players at the start of a competition period were studied. The subjects of study performed bench presses with the load of 0, 10, 30, 50, 70 and 90% of the predetermined one repetition maximum with maximum possible speed of movement. The mean measured power and velocity for each load (kg) were used to develop a multiple linear regression function which describes the quadratic relationship between the ratio of power (W) to maximum power (W) and the ratios of the load (kg) to one repetition maximum (kg) and the velocity (m•s-1) to maximal velocity (m•s-1). The quadratic function of two variables that modeled the searched relationship explained 74% of measured values in the acceleration phase and 75% of measured values from the entire extent of the positive power movement in the lift. The optimal load for reaching maximum power output suitable for the dynamics effort strength training was 40% of one repetition maximum, while the optimal mean velocity would be 75% of maximal velocity. Moreover, four zones: maximum power, maximum velocity, velocity-power and strength-power were determined on the basis of the regression function.
- bench press
- Open Access
Motor Development of Children and Adolescents Aged 8-16 Years in View of Their Somatic Build and Objective Quality of Life of Their Families
Page range: 45 - 53
The differences in human motor development are determined by predispositions and living conditions. The aim of the present study was to examine relationships between motor fitness of children and adolescents aged 8-16 years (277 boys and 247 girls), and their somatic build and quality of life of their families. Body height, body mass and skinfold thickness were measured. On the basis of these measurements body mass index (BMI), Rohrer's index and lean body mass (LBM) were calculated. The subjects' physical fitness was also assessed with motor tests: speed of arm movement (plate tapping), agility (10 × 5 m shuttle run), explosive strength of the legs (standing broad jump), trunk strength (situps), explosive strength of the trunk and shoulder girdle (1-kg medicine ball throw), and flexibility (sit and reach) regarded as a morpho-functional predisposition of motor abilities. The standing broad jump results were then used to calculate maximal anaerobic power (MPA). The examination was completed with a questionnaire survey of the children's parents concerning their families' quality of life. On the basis of the parents' answers to the questionnaire, two quality of life indices were constructed: objective quality of life index and subjective quality of life index. Due to the wide age bracket of subjects the sample was divided into two age groups: 8-12 and 13-16-year-olds. The relationships between subjects' motor development, somatic traits and their families' quality of life were examined with the use of multivariate comparative analysis. The level of motor development of studied children was more strongly determined by their somatic build than the quality of life of their families. The most important somatic determinants of the subjects' motor abilities were body height and subcutaneous adiposity. These determinants primarily affected speed and strength abilities of younger school children. Objective quality of life of children's families determined the development of some strength abilities in children aged 8-12 years. No correlations between the subjects' motor development and subjective quality of life of their families were found.
- motor development
- somatic traits
- quality of life
- Open Access
Page range: 55 - 61
Alpha-actinins are an ancient family of actin-binding proteins that play structural and regulatory roles in cytoskeletal organization. In skeletal muscle, α-actinin-3 protein is an important structural component of the Z disc, where it anchors actin thin filaments, helping to maintain the myofibrillar array. A common nonsense polymorphism in codon 577 of the ACTN3 gene (R577X) results in α-actinin-3 deficiency in XX homozygotes. Based on knowledge about the role of ACTN3 R557X polymorphism in skeletal muscle function, we postulated that the genetic polymorphism of ACTN3 could also improve sprint and power ability.
We compared genotypic and allelic frequencies of the ACTN3 R557X polymorphism in two groups of men of the same Caucasian descent: 158 power-orientated athletes and 254 volunteers not involved in competitive sport.
The genotype distribution in the group of power-oriented athletes showed significant differences (P=0.008) compared to controls. However, among the investigated subgroups of athletes, only the difference of ACTN3 R577X genotype between sprinters and controls reached statistical significance (P=0.041). The frequencies of the ACTN3 577X allele (30.69% vs. 40.35%; P=0.005) were significantly different in all athletes compared to controls. Our results support the hypothesis that the ACTN3 577XX allele may have some beneficial effect on sprintpower performance, because the ACTN3 XX genotype is significantly reduced in Polish power-oriented athletes compared to controls.
This finding seems to be in agreement with previously reported case-control studies. However, ACTN3 polymorphism as a genetic marker for sport talent identification should be interpreted with great caution.
- power-orientated athletes
- Open Access
Page range: 63 - 71
The main purpose of the present study is to investigate the relationship between anaerobic power achieved in repeated anaerobic exercise and aerobic power. The study group consisted of 40 soccer players (age 17.3 ± 1.36 years). All participants performed 3 tests: a running-based anaerobic sprint test (RAST), a graded treadmill test (GXT), and a multistage fitness test (20mPST). A statistically significant correlation was found among peak power in the GXT and the maximum (r = 0.365, p=0.02), minimum (r=0.334, p=0.035) and average (r=0.401, p=0.01) power in the RAST. No relationships were found between VO2max obtained from both aerobic tests and any performance indices in the RAST. A statistically significant correlation was found between the VO2max obtained from the spiroergometry examination (GXT) and the calculated VO2max of 20mPST (r=0.382, p=0.015). In conclusion, the level of VO2max does not influence the performance indices in the RAST in elite junior soccer players. It is possible that the modification of anaerobic test protocol or a more heterogeneous study group would influence the results. The estimation of the VO2max in the 20mPST is too inaccurate and should not replace the laboratory spiroergometry examination.
- intermittent activity
- maximal oxygen uptake
- treadmill test
- shuttle run
- physical efficiency
- Open Access
Page range: 73 - 78
The purpose of this study was to investigate changes in reaction time of elite volleyball players during a game. Fourteen volleyball players participated in the study. Reaction time was measured using the Optojump system. In addition, blood lactate concentration was assessed to monitor physiological load during the game. All measurements were performed during a pre-game test and during sets 1, 2, 3 and 4. Reaction time during set 1 decreased significantly by 13,3 % compared with pre-game values, from 600 ms during the pre-game test to 520 ms during set 1 (p<0,05). Blood lactate concentration increased significantly during set 1, 2, 3 and 4 compared with pre-game conditions (p<0,05). Reaction time stays in the first phase of its changes pattern and elite volleyball players do not reach psychomotor fatigue threshold throughout the game.
- psychomotor fatigue threshold
- reaction time
- Open Access
Page range: 79 - 89
This case study evaluated the response of objective and subjective markers of overreaching to a highly demanding conditioning training mesocycle in elite tennis players to determine 1) whether players would become functionally or non-functionally overreached, and 2) to explore how coherently overreaching markers would respond.
Performance, laboratory and cardiac autonomous activity markers were evaluated in three experienced male tennis professionals competing at top 30, top 100 and top 1000 level before and after their strength and conditioning training was increased by 120, 160 and 180%, respectively, for 30 days. Every week, subjective ratings of stress and recovery were evaluated by means of a questionnaire.
After 74, 76 and 55 h of training, increases in VO2max (+8, +5 and +18%) and speed strength indices (+9, +23 and +5%) were observed in all players. Changes of maximal heart rate (-5, -6, +4 beats per minute), laboratory markers (e.g. insulin-like growth factor -26, -17, -9%; free testosterone to cortisol ratio -63, +2, -12%) and cardiac autonomous activity markers (heart rate variability -49, -64, -13%) were variable among the players.
Improved performance provides evidence that overreaching was functional in all players. However, several overreaching markers were altered and these alterations were more pronounced in the two top 100 players. The response of overreaching indicators was not coherent.
- racket sports
- strength and conditioning mesocycle
- overreaching markers
- Open Access
Page range: 91 - 105
It is possible to plan an altitude training (AT) period in such a way that the enhanced physical endurance obtained as a result of adaptation to hypoxia will appear and can be used to improve performance in competition. Yet finding rationales for usage of AT in highly trained swimmers is problematic. In practice AT, in its various forms, is still controversial, and an objective review of research concentrating on the advantages and disadvantages of AT has been presented in several scientific publications, including in no small part the observations of swimmers. The aim of this article is to review the various methods and present both the advantageous and unfavourable physiological changes that occur in athletes as a result of AT. Moreover, AT results in the sport of swimming have been collected. They include an approach towards primary models of altitude/hypoxic training: live high + train high, live high + train low, live low + train high, as well as subsequent methods: Intermittent Hypoxic Exposure (IHE) and Intermittent Hypoxic Training (IHT). Apnoea training, which is descended from freediving, is also mentioned, and which can be used with, or as a substitute for, the well-known IHE or IHT methods. In conclusion, swimmers who train using hypoxia may be among the best-trained athletes, and that even a slight improvement in physical endurance might result in the shortening of a swimming time in a given competition, and the achievement of a personal best, which is hard to obtain by normal training methods, when the personal results of the swimmer have reached a plateau.
- Open Access
Influence of the Numbers of Players in the Heart Rate Responses of Youth Soccer Players Within 2 vs. 2, 3 vs. 3 and 4 vs. 4 Small-sided Games
Page range: 107 - 114
The purpose of this study was to compare heart rate (HR) responses within and between small-sided games (SSG) training methods in elite young soccer players. Twenty-seven youth soccer players (age: 16.5 ± 0.5 years, height: 174.5 ± 5.5 cm, weight: 62.9 ± 8.3, velocity at maximal aerobic speed (MAS): 15.9 ± 0.9 km.h-1) performed 3 different SSG (2 vs. 2, 3 vs. 3, 4 vs. 4 without goalkeeper). In each SSG, HR was continuously measured and expressed as a mean percentage of HR reserve (%HRreserve). The mean %HRreserve calculated during the SSG was significantly lower during 4 vs. 4 (70.6 ± 5.9 %) compared to 2 vs. 2 (80.1 ± 3.6 %, p<0.001) and 3 vs. 3 (81.5 ± 4.3 %, p<0.001) SSG. Regardless of the time spent above 60, 65, 70, 75, 80, 85 and 90 % of HRreserve, 4 vs. 4 solicited lower percentage of time than 3 vs. 3 and 2 vs. 2. Intersubject coefficients of variation were significantly higher during 4 vs. 4 compared to 2 vs.2 and 3 vs. 3. The %HRreserve after 30s of recovery was significantly higher for 3 vs. 3 (70.6 ± 5.3 %) compared to 2 vs. 2 (65.2 ± 4.8 %, p<0.05) and 4 vs. 4 (61.6 ± 9.3 %, p<0.05). In conclusion, this study demonstrates that the physiological demands is higher during 2 vs. 2 and 3 vs. 3 compared to 4 vs. 4 in youth soccer players. This difference could be due to that young soccer players do not have the same technical ability and experience as adult players and thus, their activity during the 2 vs. 2 and 3 vs. 3 induces a greater physical demand due to their lack of experience. The age of the players could be linked with the physical demands within small-sided games.
- youth soccer players
- physiological responses
- reserve heart rate
- fitness training
- aerobic training
- Open Access
Page range: 115 - 122
The coaching carousel or turnover is an extreme but frequently occurring phenomenon in soccer. Among the reasons for firing a coach, the most common is the existence of a shock-effect: a new coach would be able to motivate the players better and therefore to improve results. Using data from the Spanish Soccer League during the seasons from 1997-1998 to 2006-2007, this paper investigates the relationship between team performance and coach change over time. The empirical analysis shows that the shock effect of a turnover has a positive impact on team performance in the short term. Results reveal no impact of coach turnover in the long term. The favourable short-term impact on team performance of a coach turnover is followed by continued gradual worsening of results. The turnover effect is non-existent when the comparison between the new coach and the old coach is done over 10, 15 or 20 matches before and after termination.
- coach change
- team performance
- short term
- Open Access
Gender Differences in Physical Activity, Sedentary Behavior and BMI in the Liberec Region: the IPAQ Study in 2002-2009
Page range: 123 - 131
The occurrence of overweight, obesity and physical activity (PA) belongs to major factors influencing health. However, information on the longitudinal development of PA in Europe has been, up until now, insufficient. The aim of the study was to describe the changes in PA, sedentary behavior and BMI in the inhabitants of the Liberec region during the surveybetween 2002 - 2009. The data were obtained in 2002-2004 using the short version of the IPAQ questionnaire, in 2005-2009 using the long version of the IPAQ. The sample of participants comprised 957 males and 1066 females aged 25-60 years. A significant decrease in sitting accounting for minutes on working days has been recorded both in men and women. A significant increase of PA both in men and women was reported, however the interpretation of the increase needs to be done cautiously due to the application of the short and long version of the IPAQ. Regarding PA intensity, men show more PA in total than women, which can be explained mainly by the differences in vigorous PA. Women show significantly lower values of BMI in all years in which surveys were conducted than men (p<0.001). Based on self-reported data, we have recorded an increase in the number of overweight and obese people. Time spent sitting on working days has had a tendency to decrease, yet a negative trend in the decrease in self-reported total PA has not been confirmed. Despite the fact that there has been an increase in self-reported PA, no decrease in BMI was registered.
- physical activity
- Open Access
Page range: 133 - 139
A method of hyper-sphere cover in multidimensional space for human Mocap (Motion Capture) data retrieval is presented in this paper. After normalization and feature extraction, both the retrieval instance and the motion data are mapping into a multidimensional space. Several hyper-spheres are constructed according to the retrieval instance, and the domain covered by these hyper-spheres can be considered as the distribution range of a same kind of motions. By use of CMU free motion database, the retrieval algorithm has been implemented and examined and the experimental results are illustrated. At the same time, the main contributions and limitations are discussed.
- MoCap (Motion Capture) Data
- Multidimensional Space
- Hyper-sphere Cover
- Open Access
Page range: 141 - 154
The objective of the paper was to determine body composition and somatotype of male Greco-Roman wrestlers grouped by different weight categories and level of competition. Twenty three contestants (aged 24.9±5.5 years, training experience 13.7±5.8 years) were examined during their competitive period. They were divided into heavier (n=12) and lighter weight categories (n=11). Twelve of them took part in Olympic Qualification Tournaments, whereas six others participated in the Olympic Games in Athens. An experienced evaluator performed 10 measurements necessary to designate Heath-Carter somatotypes and additional skinfolds to estimate the percentage of body fat and body composition. Heavier wrestlers (weight=92.4 kg) exhibited more endomorphy and mesomorphy than lighter wrestlers (weight=70.1 kg). Heavier wrestlers were characterized by higher BMI, fat mass, fat percentage and fat free mass index than wrestlers in lighter weight categories. Sports level was evaluated with discriminant analysis which revealed significant results (p<0.01) with canonical correlation coefficient of 0.754, and Wilks' λ=0.431. Discriminant function=0.593774*Training Experience-0.300177*EN+0.627894*ME-0.242241*EC - 0.636081*Pelvis/Shoulder Ratio. Among the 23 observations used to fit the model, 19 (82.6%) were correctly classified. When compared with untrained subjects, wrestlers exhibited higher body mass (81.8 vs. 72.1 kg, t=3.15, p<0.01) and lower height-weight ratio (40.50 vs. 43.21, t=13.5, p<0.001). Wrestlers' somatotypes differed from those of untrained subjects (2.0-6.6-1.2 vs. 3.7-4.3-3.1). They were also characterized by lower adiposity (12.1 vs. 15.7%, t=7.84, p<0.001).
In conclusion, body build and composition in wrestlers depend on their weight category. In heavier categories, characteristic type is endomorph-mesomorph, whereas lighter weight categories are dominated by balanced mesomorph. A considerable difference in endomorphy and indices of body composition can also be observed. Higher sport experience with lower endomorphy (tendencies for lower fat content) and Pelvis/Shoulder Ratio are interrelated with higher competition level presented by wrestlers.
- sports level
- Open Access
Page range: 155 - 164
The aim of this paper is to present the morphological features of rowers. The objective is to establish the type of body build best suited to the present requirements of this sports discipline through the determination of the most important morphological features in rowing with regard to the type of racing boat. The subjects of this study included competitors who practise rowing and were members of the Junior National Team. The considered variables included a group of 32 anthropometric measurements of body composition determined using the BIA method among male and female athletes, while also including rowing boat categories. In order to determine the analysed structures of male and female rowers, an observation analysis was taken into consideration and performed by the k-means clustering method. In the group of male and female rowers using long paddles, higher mean values for the analysed features were observed, with the exception of fat-free mass, and water content in both genders, and trunk length and horizontal reach in women who achieved higher means in the short-paddle group. On the men's team, both groups differed significantly in body mass, longitudinal features, horizontal reach, hand width and body circumferences, while on the women's, they differed in body mass, width and length of the chest, body circumferences and fat content. The method of grouping used in this paper confirmed morphological differences in the competitors with regard to the type of racing boat.
- somatic variables
- anthropometric typology
- Open Access
Page range: 165 - 176
This research examines the use of Facebook and Twitter, two social networks, for sportive reasons in Turkey.
To this end, the literature was surveyed and a 5 Likert type data collection tool consisting of 21 questions was developed by the researcher based on the expert views. The sample of the research included 460 sport fans who are college students at Abant İzzet Baysal University and Sakarya University.
It was found in the research that 91.7% of the participants had a profile on Facebook and 13.3% had a profile on Twitter. The rate of opening an account on Twitter, which still has no version in Turkish language, was low. It was found that the fans mostly followed the official site of their favorite team on Facebook, got informed about the sports activities through Facebook and learned news, which they did not hear from other sources. It was also ascertained that male fans used social networks for sportive reasons more than female fans did (p<.05). It is possible to state that social networks such as Facebook and Twitter have become a rapidly-developing alternative medium in sports against traditional media such as newspaper and television.
- social networks