Oxygen uptake kinetics and biological age in relation to pulling force and 400-m front crawl performance in young swimmers.

Background: The study aimed to assess differences in the biological age (BA) of 13-year-old swimmers and show their ability, as biologically younger-late mature or older-early mature, to develop fast 60-s oxygen uptake (V˙O2) kinetics and tethered swimming strength. Furthermore, the interplay between swimming strength, V˙O2, and 400-m front crawl race performance was examined. Methods: The study involved 36 competitive young male swimmers (metrical age: 12.9 ± 0.56 years). Depending on BA examination, the group was divided into early-mature (BA: 15.8 ± 1.18 years, n = 13) and late-mature (BA: 12.9 ± 0.60 years, n = 23) participants, especially for the purpose of comparing tethered swimming indices, i.e., average values of force (F ave) and V˙O2 (breath-by-breath analysis) kinetic indices, measured simultaneously in 1-min tethered front crawl swimming. From the 400-m racing stroke rate, stroke length kinematics was retrieved. Results: In the 1-min tethered front crawl test, early-mature swimmers obtained higher results of absolute values of V˙O2 and F ave. Conversely, when V˙O2 was present relatively to body mass and pulling force (in ml∙min-1∙kg-1∙N-1), late-mature swimmers showed higher O2 relative usage. Late-mature swimmers generally exhibited a slower increase in V˙O2 during the first 30 s of 60 s. V˙O2, F ave, BA, and basic swimming kinematic stroke length were significantly interrelated and influenced 400-m swimming performance. Conclusion: The 1-min tethered swimming test revealed significant differences in the homogeneous calendar age/heterogeneous BA group of swimmers. These were distinguished by the higher level of V˙O2 kinetics and pulling force in early-mature individuals and lower efficiency per unit of body mass per unit of force aerobic system in late-mature peers. The higher V˙O2 kinetics and tethered swimming force were further translated into 400-m front crawl speed and stroke length kinematics.

Internal Mechanisms of Human Motor Behaviour: A System-Theoretical Perspective.

The authors present the conceptual and system-theoretical model of human motor behaviour. The main assumption is that movement is the only observable manifestation of all psychical processes, thus, it is the only phenomenon enabling the creation of hypotheses concerning the psychological conditioning of human behaviour. They pointed to the fact that in the field of biology, and all the more, in psychology, mathematical descriptions are hardly eligible. In this respect, a system-theoretical approach seems to be appropriate. The authors present two systems: information processing modalities in the human mind, based on Nikolai Bernstein's theory, and the series of processes from stimuli reception to motor response execution. Both these sub-systems make up a super-system. Its simplified graphical representation may be termed "Column Diagram." The authors analyse the functioning of this super-system in various intellectual-motor purposeful operations. The system-theoretical perspective enables clear categorisation of various human motor operations, their "driving" mechanisms, internal patterns, and their superficial physical and/or mathematical "appearance." The stream of consciousness in a human motor operation joins the various psychological constructs, which are reception, perception, attention, motivation, intellect, memory, etc., into one coherent, inseparable system.

Postural stability at different heights as well as in natural standing position and during tandem stance in female athletes who practice artistic gymnastics.

PURPOSE: The aim of this work was the assessment of postural stability at different heights as well as in natural standing position and during tandem stance in female athletes who practice artistic gymnastics. METHODS: The study comprised 34 athletes aged 8-12, practicing artistic gymnastics at a sports club "Korona Kraków". The research tool was CQ-Stab 2P two-platform posturograph. The elevation was achieved using the Light SPL platform. The data were analyzed based on Wilcoxon signed-rank test and Spearman's rank correlation. RESULTS: The height at which the posturograph was set differentiated the path length of the statokinesiogram, both in the natural stance ( p = 0.035) and tandem stance ( p = 0.012). When the posturograph was placed on the floor, statistically significantly higher sway area delimited by the COP point ( p < 0.001), statokinesiogram path length ( p < 0.001), mean amplitude of COP displacement ( p < 0.001) and mean frequency of COP displacement ( p = 0.048) values were recorded in the tandem stance position. On the other hand, when the posturograph was placed on a landing, statistically significantly higher sway area delimited by the COP point ( p < 0.001), statokinesiogram path length ( p < 0.001) and mean frequency of COP displacement ( p < 0.001) values were recorded in the tandem stance position. CONCLUSIONS: Increasing height was accompanied by deterioration of stability indices. Postural stability improves with training experience.

Gender effect on underwater undulatory swimming technique of young competitive swimmers.

PURPOSE: The study aim was determining gender-related differences of underwater undulatory swimming (UUS) kinematic indicators and their impact on UUS velocity. METHODS: The study included 18 girls (F: age 16.71 ± 0.64 years, FINA points 551 ± 68) and 23 boys (M: age 16.79 ± 0.57 years, FINA points 533 ± 66) training swimming. After marking characteristic anatomical points, subjects performed approximately 7 meters of UUS. A filming device placed behind the underwater window registered the trial. Recordings were analysed using the SkillSpector programme. RESULTS: Boys swam faster (F: 1.24 m/s, M: 1.35 m/s), overcame a greater distance during one cycle (F: 0.67 m, M: 0.74 m), performed movements with higher toes amplitude (F: 0.58 m, M: 0.63 m), obtained higher amplitude and frequency product (F: 1.05, M: 1.15) and smaller ankle joint range of motion (F: 64 °, M: 57 °). In both groups, relationships between velocity and: maximal ankle joint extension, distance covered during one cycle and backward toes shift during downward movement were found. The results were statistically significant ( p < 0.05). CONCLUSIONS: Girls and boys differed in kinematic indicator level, but UUS velocity depends on identical kinematic variables, meaning UUS technical training can be performed without gender-division.

Evaluation of relationship between the results of selected tests for muscle strength assessment of the hip abductors.

PURPOSE: The assessment of hip joint abductor muscle strength is most often carried out using a dynamometric test. However, both in clinical practice and literature, evaluation is performed by means of the single-leg half-squat or the amount of abduction movements performed in the hip joint. In this context, the question arises whether the results of individual tests are convergent. The aim of the study is to evaluate the relationship between strength of the hip abductor muscle measured by dynamometer, the single-leg-squat and the number of repetitions of the movements in time. METHODS: A group of 35 students (20 women and 15 men) between 20 and 24 years old participated in the study. Each student was subjected to three tests assessing the condition of the hip and associated abductor muscles. Those included: assessment of hip joint abduction muscle strength in a dynamometric study, assessment of the number of abdomen movements performed lying on the side and standing, during a 30-second interval, and the single-leg-squat test. RESULTS: Based on the tests conducted, a significant relationship was observed between the muscle strength measurement results for the left and right side in the dynamometric study and the number of hip abduction repetitions in 30 seconds and the single-leg-squat test. CONCLUSIONS: The obtained results indicate a significant relationship between the results of all the tests. In practice, this means that the tests can be used interchangeably.

Analysis of Tests Evaluating Sport Climbers' Strength and Isometric Endurance.

The present study was designed to determine which types of specific tests provide an effective evaluation of strength and endurance in highly trained competitive sport climbers. The research process consisted of three basic components: the measurement of selected somatic characteristics of the climbers, the assessment of their physical conditioning, and a search for correlations between the anthropometric and "conditioning" variables on the one hand, and climber's performance on the other. The sample of subjects consisted of 14 experienced volunteer climbers capable of handling 7a- 8a+/b on-sight rock climbing grades. The strongest correlations (Spearman's rank) were found between climber's competence and the relative results of the finger strength test (r = 0.7); much lower, but still statistically significant coefficients were found between the level of competence and the results of the muscle endurance tests (r = 0.53 - 0.57). Climbers aspiring to attain an elite level must have strong finger and forearm muscles, but most of all, they must be capable of releasing their potential during specific motor capability tests engaging these parts of the body. The forearm muscles of elite climbers must also be very resistant to fatigue. Since highly trained athletes vary only slightly in body mass, this variable does not have a major effect on their performance during strength and endurance tests.

Three-dimensional analysis of the pelvic and hip mobility during gait on a treadmill and on the ground.

Pelvic girdle combines two units: passenger and locomotor. That is why the importance of this part of the body is emphasized by all researchers in terms of gait economy. The purpose of our research was to determine the changes of pelvic girdle mobility and hip joint in men in three planes of movement (sagittal, frontal and horizontal) during gait at a speed of 5 km/h. The methodology used here aimed at assessing the impact of the surface (ground or treadmill) on the mobility in those planes. To register overground and treadmill locomotion we applied: Vicon 250, Cardionics Treadmill 3113. The sample of the study was the group of 30 men aged between 21 and 23. The analysis of the results revealed the biggest impact of the type of surface on both pelvis and hip joint in the transverse plane. When the subjects moved on the natural ground, the pelvic range of motion (ROM) in this plane was more than twice wider than that in treadmill walking. Whereas in the case of hip joint, significantly higher ROM values occurred in the transverse plane during walking on the treadmill.

Influence of surface on kinematic gait parameters and lower extremity joints mobility.

In biomechanical studies of human locomotion, treadmill is a widely used measuring device. The purpose of this paper was to determine the values of kinematic parameters describing gait with the velocity of 5 km/h, both on the ground and on a treadmill. Besides, the authors assessed the impact of the surface on the mobility of three main joints of lower extremities in the sagittal plane. The measurements were done on a sample of 48 men aged between 21 and 23. The most important element of a measuring set was the Vicon system. Based on kinematic parameters our data indicated that during walking on a treadmill step frequency was slightly higher than that on the ground. Probably, due to that fact there were found some differences in other variables (e.g., single support as well as step and stride time). Besides, the results revealed that the type of surface affects joint range of motion, in particular ankle plantar flexion, the instantaneous values of joint angles and change in dynamics of these values.

Changes of kinematic gait parameters due to pregnancy.

When a woman becomes pregnant her body undergoes tremendous changes hormonally and anatomically. Our survey revealed very little literature on biomechanics of gait in gravidas and lack of consensus among scientists in pregnancy-related mechanisms of body adaptation. That is why the authors felt encouraged to determine the effect of pregnancy on the biomechanical pattern of walking. To investigate alterations in natural locomotion, we used a 3D motion-analysis system Vicon. The inclusion criteria aimed at selecting only healthy subjects (n = 13). Each woman participated in 3 sessions: before pregnancy, during the last trimester of gestation and, finally, half year after delivery. For the purpose of this study, selected kinematic parameters for pregnant and non-pregnant conditions were compared. Gravid women performed lower velocity of their gait and lower frequency of steps. The length of their step decreased in comparison to pre pregnancy state. The results did not reveal any changes in the range of motion of the ankle, knee and hip in different physiological conditions. However, we observed increased base of support and double support phase in gravidas comparing to non pregnant states (by about 10%). This finding indicates that there is a tendency to maximize safety in gait during pregnancy.

An evaluation of symmetry in the lower limb joints during the able-bodied gait of women and men.

For many years, mainly to simplify data analysis, scientists assumed that during a gait, the lower limbs moved symmetrically. However, even a cursory survey of the more recent literature reveals that the human walk is symmetrical only in some aspects. That is why the presence of asymmetry should be considered in all studies of locomotion. The gait data were collected using the 3D motion analysis system Vicon. The inclusion criteria allowed the researchers to analyze a very homogenous group, which consisted of 54 subjects (27 women and 27 men). Every selected participant moved at a similar velocity: approximately 1,55 m/s. The analysis included kinematic parameters defining spatio-temporal structure of locomotion, as well as angular changes of the main joints of the lower extremities (ankle, knee and hip) in the sagittal plane. The values of those variables were calculated separately for the left and for the right leg in women and men. This approach allowed us to determine the size of the differences, and was the basis for assessing gait asymmetry using a relative asymmetry index, which was constructed by the authors. Analysis of the results demonstrates no differences in the temporal and phasic variables of movements of the right and left lower limb. However, different profiles of angular changes in the sagittal plane were observed, measured bilaterally for the ankle joint.

The impact of changes in gait speed and step frequency on the extent of the center of mass displacements.

Center of mass (COM) trajectory plays a crucial role in the analysis of human body movements. This research aimed at studying vertical and transverse COM displacements during gait on a treadmill at a given velocity and step frequency. Locomotion study was accomplished using: Vicon 250, Cardionics Treadmill 3113 and metronome Korg Ma-30. The data achieved for 12 women and 15 men aged 21-22 revealed similarity in vertical COM oscillations in both groups. Lateral COM displacements (L(COM)) were slightly higher in men than in women and they showed tendency to decrease as gait velocity increased. During natural locomotion there was an increasing trend as walking speed increased. At a given velocity of locomotion L(COM) were decreasing as step frequency increased. The only astonishing thing was that the biggest changes of vertical COM oscillations (V(COM)) were noticed at the fastest walking speed (6 km/h). It seems that so large decrease in V(COM) during walking with high velocity and increased step cadency is a consequence of considerable shortening of the movement cycles and performing time of one step.