Checking bisimilarity for attributed graph transformation

Borrowed context graph transformation is a technique developed by Ehrig and Koenig to define bisimilarity congruences from reduction semantics defined by graph transformation. This means that, for instance, this technique can be used for defining bisimilarity congruences for process calculi whose operational semantics can be defined by graph transformation. Moreover, given a set of graph transformation rules, the technique can be used for checking bisimilarity of two given graphs. Unfortunately, we can not use this ideas to check if attributed graphs are bisimilar, i.e. graphs whose nodes or edges are labelled with values from some given data algebra and where graph transformation involves computation on that algebra. The problem is that, in the case of attributed graphs, borrowed context transformation may be infinitely branching. In this paper, based on borrowed context transformation of what we call symbolic graphs, we present a sound and relatively complete inference system for checking bisimilarity of attributed graphs. In particular, this means that, if using our inference system we are able to prove that two graphs are bisimilar then they are indeed bisimilar. Conversely, two graphs are not bisimilar if and only if we can find a proof saying so, provided that we are able to prove some formulas over the given data algebra. Moreover, since the proof system is complex to use, we also present a tableau method based on the inference system that is also sound and relatively complete.Postprint (published version

Hip abductors and thigh muscles strength ratios and their relation to electromyography amplitude during split squat and walking lunge exercises

Background: The hip abductors (HAB), quadriceps (Q) and hamstrings (H) reciprocal strength ratios are predictors of electromyography (EMG) amplitude during load carrying walking at moderate intensity. Therefore, these strength ratios might predict also the EMG during the exercises as walking lunge (WL) or split squat (SSq) at submaximal intensity. Objective: To determine whether the EMG amplitude of vastus mediali (VM), vastus laterali (VL), biceps femoris (BF) and gluteus medius (Gmed) is associated with muscle strength ratio during SSqs and WLs. To determine whether the EMG amplitude differs between individuals with HAB/H ratio above and below one and between individuals with H/Q or HAB/Q ratio above and below 0.5 during SSqs and WLs. Methods: 17 resistance-trained men (age 29.6 ± 4.6 years) with at least 3 years of strength training performed in cross-sectional design 5 s maximal voluntary isometric contractions (MVIC) on an isokinetic dynamometer for knee extension, knee flexion, and hip abduction. The MVIC was used to normalize the EMG signal and estimate the individual strength ratios. Than participants performed WL and SSq for a 5 repetition maximum, to find out muscle activity at submaximal intensity of exercise. Results: The H/Q ratio was associated by Kendall’s tau (τ) with VM (τ = .33) and BF (τ = -.71) amplitude, HAB/Q ratio was associated with BF (τ = -.43) and Gmed (τ = .38) amplitude, as well as HAB/H was associated with VM (τ = -.41) and Gmed (τ = .74) amplitude. ANOVA results showed significant differences between SSq and WL (F(4, 79) = 10, p \u3c .001, ηp2 = .34) in Gmed amplitude, where WL resulted in higher Gmed amplitude compared to SSq. Other significant differences were found between H/Q groups (F(4, 29) = 3, p = .04, ηp2 = .28) in VM and Gmed amplitude, where group with H/Q \u3e 0.5 showed higher VMO amplitude and lower Gmed amplitude. Furthermore, significant difference was found for HAB/H groups (F(4, 29) = 4, p = .02, ηp2 = .34) in VM amplitude, where group with HAB/H \u3c 1 showed higher VM amplitude. Conclusions: The ratios of HAB, H and Q are able to predict Gmed, VM and BF activity during WL and SSq. WL resulted in higher activity level of Gmed than SSq, because WL includes the impact forces as part of lunge movement. WL should be used in resistance-training programme, if the strengthening of Gmed or VM is the aim

Post activation potentiation (PAP) and its application in the development of speed and explosive strength in female soccer players: A review

The presented review presents the results of current research on the use of PAP during resistance training of soccer players. Researchers who have examined the mechanism behind PAP following complex strength training, have established a relationship between post-activation potentiation and improvements in speed and explosive strength of athletes. Most of the presented papers in this review have confirmed the effectiveness of PAP in eliciting performance in tasks requiring speed, jumping ability and agility in soccer players. These studies were discussed in detail in terms of research groups, methods, training means and study results. Many of these publications have also considered the aspect of rest intervals between the conditioning exercise and the subsequent explosive activity. Most authors indicate the necessity to individualize the time of the rest interval, depending on the athletes training status, strength level and most of all on the intensity and volume of the conditioning exercise. Some scientists have also attempted to incorporate PAP into warm-up protocols, especially prior to speed and power training sessions. A two-way analysis of the impact of PAP, separately on sprint speed and power of the players. The focus was on demonstrating the positive or negative impact of activating exercises on the two variables discussed. The last part of the paper presents the conclusions drawn based on the results of the studies and suggests the objectives of future research. Most publications have documented the results for male participants, whereas little data is available regarding the use of PAP in female soccer players

Complex analysis of movement in evaluation of flat bench press performance

The complex methodology of investigations was applied to study a movement structure on bench press. We have checked the usefulness of multimodular measuring system (SMART-E, BTS company, Italy) and a special device for tracking the position of barbell (pantograph). Software Smart Analyser was used to create a database allowing chosen parameters to be compared. The results from different measuring devices are very similar, therefore the replacement of many devices by one multimodular system is reasonable. In our study, the effect of increased barbell load on the values of muscles activity and bar kinematics during the flat bench press movement was clearly visible. The greater the weight of a barbell, the greater the myoactivity of shoulder muscles and vertical velocity of the bar. It was also confirmed the presence of the so-called sticking point (period) during the concentric phase of the bench press. In this study, the initial velocity of the barbell decreased (v min ) not only under submaximal and maximal loads (90 and 100% of the one repetition maximum; 1-RM), but also under slightly lighter weights (70 and 80% of 1-RM)

Fundamental motor skills of Czech children at the end of the preschool period

Background: Achievement of a sufficient fundamental motor skills (FMS) level by the end of the preschool period is an important premise for the later participation of children in many sports activities. However, only a few studies have focused on the assessment of motor proficiency before entrance to elementary school in the population of preschool children in the Czech Republic. Objective: The aim of this study was to assess the FMS of Czech boys and girls at the end of the preschool period. Methods: The Movement Assessment Battery for Children-second version (MABC-2) was used to assess the motor performance of the children in different domains, i.e., manual dexterity, aiming and catching, and balance. The research sample consisted of 121 children (age 6.5 ± 0.3 years, 61 boys and 60 girls). Results: According to the total test score performance on MABC-2, we found 2.5% of children with severe motor difficulties indicating the possible presence of Developmental Coordination Disorder and 10.7% of children with a risk of motor difficulties. In total, 64% of boys and 81.6% of girls had an MABC-2 score in the 50th percentile or lower. With respect to gender differences, boys outperformed girls in aiming and catching skills (p < .001; d = 1.10). Moreover, the girls' score in the 25th percentile indicated a low level of aiming and catching skills. Despite significantly better results for boys in one manual dexterity test item, and for girls in one manual dexterity and balance test item, there were no significant gender differences in overall manual dexterity and balance subtests. Conclusion: With the preschool years being a key developmental stage for the acquisition and development of FMS, the findings of low level of FMS in most of children and gender differences in aiming and catching skills highlight the need for improvements in motor competency. An effort should be made, especially for preschool girls, to stimulate the improvement of aiming and catching skills

Analysis of the adductors and abductors' maximum isometric strength on the level of speed and agility in basketball players

Introduction: his study investigated the relationship between hip abductor strength (Abd), adductor strength (Add), straight accelerations and decelerations, and during changes of direction (COD 90°) performance in basketball players. Material and Methods: Fourteen basketball players participated (age = 23.6 ± 4.4 years, body mass = 86.3 ± 5.9 kg, body height = 192.3 ± 6.2 cm, training experience = 6.7 ± 2.6 years). Straight running results and running with a change of direction (COD 90°) have been described as the time (s) obtained for a given length. Following tests were carried out: maximum isometric strength test, 20-m linear sprint and 20-m COD sprint with 90° direction change angles. Following the warm-up, all athletes performed two maximal 20-m linear sprints, interspersed with 5 min rest intervals. Following the 20-m linear sprint test, the participants were provided with a 5 min rest interval before completing the COD tests. Additionally, the balance in isometric strength of the dominant and non-dominant hip Abd-Add muscles were evaluated. Two maximum attempts interspersed with one-minute rest intervals were performed. Results: The t-test revealed statistically significant higher absolute and relative isometric strength of AddR (adductor right) in comparison to AddL (adductor left). Conclusion: The results of this study show that the maximum isometric force and the relative strength of the abductor muscle group have a significant effect on changing direction running. Moreover, hip Abd and Add are typical for strength bilateral strength imbalances. Therefore, the evaluation and development of these qualities are essential for coaches to monitor and prescribe adequate training regimens

The Effects of Eccentric Cadence on Power and Velocity of the Bar during the Concentric Phase of the Bench Press Movement

Training at a specific movement tempo is a relatively new concept in resistance training. It is based on manipulation of the duration of particular phases of a movement. General studies have demonstrated that faster movement tempo in resistance training leads to an increase in muscle power, whereas lower movement speed is beneficial in the development of muscle strength and hypertrophy. However, the studies in this area are inconclusive and do not relate precisely to various tempos and movement speeds. The aim of the study was to determine the effect of duration of the eccentric cadence ECCREG (2/0/X/0) and ECCSLO (6/0/X/0) on muscular power generated in the concentric phase of the movement expressed in maximal PMAX, VMAX and average values PAVE, VAVE. For the ECCSLO (6/0/X/0) cadence, a significantly lower value of P (401.95 ± 65.42 W) was observed compared to the ECCREG 2/0/X/0 tempo (467.65 ± 79.18 W), at p = 0.007. The same was true for power evaluated in maximal values (PMAX), as significantly higher values were recorded for the regular ECCREG (2/0/X/0) (671.55 ± 115.79 W) compared to the slow tempo ECCSLO (6/0/X/0) (565,70 ± 117,37 W), at the level of significance of p = 0.007. The velocity evaluated for ECCREG (2/0/X/0) tempo expressed in average values (VAVE) 0.60±0.09 m/s was significantly higher compared to the ECCSLO (6/0/X/0) tempo (0.52 ± 0.08 m/s), with p=0.004. When maximal velocity (VMAX), was considered higher values for ECCREG (2/0/X/0) tempo was registered (0.79 ± 0.10 m/s) compared to the ECCSLO (6/0/X/0) tempo (0.69 ± 0.13 m/s), at significance of p = 0.001. The main finding of the study indicates that the duration of the eccentric phase of the movement has a significant impact on muscular power and velocity during the concentric phase of the movement

Alkaline water improves exercise-induced metabolic acidosis and enhances anaerobic exercise performance in combat sport athletes.

Hydration is one of the most significant issues for combat sports as athletes often use water restriction for quick weight loss before competition. It appears that alkaline water can be an effective alternative to sodium bicarbonate in preventing the effects of exercise-induced metabolic acidosis. Therefore, the main aim of the present study was to investigate, in a double blind, placebo controlled randomized study, the impact of mineral-based highly alkaline water on acid-base balance, hydration status, and anaerobic capacity. Sixteen well trained combat sport athletes (n = 16), were randomly divided into two groups; the experimental group (EG; n = 8), which ingested highly alkaline water for three weeks, and the control group (CG; n = 8), which received regular table water. Anaerobic performance was evaluated by two double 30 s Wingate tests for lower and upper limbs, respectively, with a passive rest interval of 3 minutes between the bouts of exercise. Fingertip capillary blood samples for the assessment of lactate concentration were drawn at rest and during the 3rd min of recovery. In addition, acid-base equilibrium and electrolyte status were evaluated. Urine samples were evaluated for specific gravity and pH. The results indicate that drinking alkalized water enhances hydration, improves acid-base balance and anaerobic exercise performance

Chronic Ingestion of Sodium and Potassium Bicarbonate, with Potassium, Magnesium and Calcium Citrate Improves Anaerobic Performance in Elite Soccer Players

Anaerobic power and anaerobic capacity significantly influence performance in many sport disciplines. These include prolonged sprints in athletics, swimming, or cycling, and other high intensity intermittent sports, such as soccer or basketball. Considering the association of exercise-induced acidosis and fatigue, the ingestion of potential buffering agents such as sodium bicarbonate, has been suggested to attenuate metabolic acidosis and improve anaerobic performance. Since elite soccer players cover from 200 to 350 m while sprinting, performing 40⁻60 all out sprints during a game, it seems that repeated sprint ability in soccer players is among the key components of success. In our experiment, we evaluated the effectiveness of chronic supplementation with sodium and potassium bicarbonate, fortified with minerals, on speed and speed endurance in elite soccer players. Twenty-six soccer players participated in the study. The subjects were randomly divided into two groups. The experimental group was supplemented with sodium bi-carbonate and potassium di-carbonate fortified with minerals, while the control group received a placebo. The athletes were tested at baseline and after nine days of supplementation. Anaerobic performance was evaluated by the Repeated Anaerobic Sprint Test (RAST) protocol which involved 6 × 30 m max sprints, separated by 10 s of active recovery. Resting, post ingestion and post exercise concentrations of HCO3− and blood pH were measured as well as lactate concentration. The current investigation demonstrated a significant increase in RAST performance of elite soccer players supplemented with sodium and potassium bicarbonate along with calcium phosphate, potassium citrate, and magnesium citrate ingested twice a day over a nine-day training period. The improvements in anaerobic performance were caused by increased resting blood pH and bicarbonate levels