Effect of a submaximal half-squats warm-up program on vertical jumping ability

The purpose of the current research was to study the effect of a warm-up program including submaximal half-squats on vertical jumping ability. Twenty physically active men participated in the study. Each subject performed 5 sets of half-squats with 2 repetitions at each of the following intensities: 20, 40, 60, 80, and 90% of the 1 repetition maximum (1RM) load. Prior to the first set and immediately after the end of the last set, the subjects performed 2 countermovement jumps on a Kistler force platform; the primary goal was to jump as high as possible. The results showed that mean vertical jumping ability improved by 2.39% after the warm-up period. Subjects were then divided into 2 groups according to their 1RM values for the half-squat. Subjects with greater maximal strength ability improved their vertical jumping ability (4.01%) more than did subjects with lower maximal strength (0.42%). A warm-up protocol including half-squats with submaximal loads and explosive execution can be used for short-term improvements of vertical jumping performance, and this effect is greater in athletes with a relatively high strength ability.     

The effects of drop vertical jump technique on landing and jumping kinetics and jump performance

The drop vertical jump is a popular plyometric exercise. Two distinct techniques are commonly used to initiate the drop vertical jump. With the ‘step-off’ technique, athletes step off a raised platform with their dominant limb, while their non-dominant limb remains on the platform. In contrast, with the ‘drop-off’ technique, athletes lean forward and drop off the platform, with both feet leaving the platform more simultaneously. The purpose of this study was to compare landing and jumping kinetics, inter-limb kinetic symmetry, and jump performance when individuals used the step-off and drop-off techniques, and to examine whether potential differences between these techniques are affected by platform height. Sixteen subjects completed drop vertical jumps with the drop-off and step-off techniques, from relatively low and high platform heights. Ground reactions forces were recorded for the dominant and non-dominant limbs during the land-and-jump phase of the drop vertical jump. Subjects demonstrated greater inter-limb asymmetry in peak impact forces when using the step-off technique, vs. the drop-off technique. This difference between the techniques was consistent across platform heights. The step-off technique appears to result in greater asymmetry in limb loading, which could contribute to the development of neuromuscular asymmetries between the limbs and/or asymmetric landing patterns.     

Aerobic and anaerobic determinants of repeated sprint ability in team sports athletes

The aim of this study was to examine in team sports athletes the relationship between repeated sprint ability (RSA) indices and both aerobic and anaerobic fitness components. Sixteen team-sport players were included (age, 23.4 ± 2.3 years; weight, 71.2 ± 8.3 kg; height, 178 ± 7 cm; body mass index, 22.4 ± 2 kg · m⁻²; estimated VO₂max, 54.16 ± 3.5 mL · kg⁻¹ · min⁻¹). Subjects were licensed in various team sports: soccer (n = 8), basketball (n = 5), and handball (n = 3). They performed 4 tests: the 20 m multi-stage shuttle run test (MSRT), the 30-s Wingate test (WingT), the Maximal Anaerobic Shuttle Running Test (MASRT), and the RSA test (10 repetitions of 30 m shuttle sprints (15 + 15 m with 180° change of direction) with 30 s passive recovery in between). Pearson''s product moment of correlation among the different physical tests was performed. No significant correlations were found between any RSA test indices and WingT. However, negative correlations were found between MASRT and RSA total sprint time (TT) and fatigue index (FI) (r = -0.53, p < 0.05 and r = -0.65, p < 0.01, respectively). No significant relationship between VO₂max and RSA peak sprint time (PT) and total sprint time (TT) was found. Nevertheless, VO₂max was significantly correlated with the RSA FI (r = -0.57, p < 0.05). In conclusion, aerobic fitness is an important factor influencing the ability to resist fatigue during RSA exercise. Our results highlighted the usefulness of MASRT, in contrast to WingT, as a specific anaerobic testing procedure to identify the anaerobic energy system contribution during RSA.     

Comparative analysis of the regulation of vertical posture in athletes of different sports qualifications

The goal of study was to investigate the regulation of balance in athletes with different sports qualifications: masters of sport (MS, n=18) and candidates for master of sports (CMS, n=13). Balance examined by means of stabilographic complex ("Rhythm". Russia) in the static tests: in simple bipedal stance (BS) and squat positions (SQ), as well as in the dynamic tests: "Involute", evaluating the tracking movement and "Step input", assessing the reaction of the whole body on the visual-motor task. It was found that the MS with the same anthropometric data, PWC 170 and trunk power did not differ in linear and angular velocity of oscillations of the center of pressure (CP) in BS and SQ positions. MS had a relative dominance of low-frequency oscillations in the spectral analysis in the BS test with eyes open. In the test "Step input" MS had a lower latent period of reaction, a greater speed and an accuracy of the body motion forward and back in response to the step input signals, while they had a relative dominance of high frequency oscillations. Thus, the results showed that the masters of sport have improved postural regulation, which manifested itself mainly in the dynamic test on the speed and accuracy of the vertical body reaction to input visual signals.     

Comparing development with physical fitness, motor ability, and health of children among various living environment

This study had the purpose to compare with development of fitness, motor ability and health among various living environments of the sea-side, the urban, and the mountain districts, where were situated at Nadachi town on the suburbs of Niigata Prefecture. Five hundred thirty-five children (aged 4-15 yrs) were measured at the kindergarten, the fundamental school, and the junior high school. Measuring items of the physique were the height, the weight, the chest circumference, the sitting height, and the foot area. Physical fitness tests were the muscular grip-strength, the lung vital capacity, the closed-eye single-leg balance, the dipping time of the upper extremity, the vertical jump, the standing trunk flexibility, the endurance run, and pull-up. And, motor ability tests were the finger tapping, 5m shuttle run, 50m dash, and the ball throwing. As items of health inspection, the blood pressure (systolic and diasystolic) and the visual ability were adopted. As results of this study, following data were obtained; 1) At the sea-side environment, development of the muscle power, the respiratory function, and the physique were showed much faster rate of growth at the childhood than that of the other ones, significantly (P less than 0.01). 2) At the mountain environment, the arch-bend of the foot print only were appeared larger areas than that of the other ones, significantly (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparing host and parasite phylogenies: gyrodactylus flatworms jumping from goby to goby

The combination of exceptionally high species diversity, high host specificity, and a complex reproduction system raises many questions about the underlying mechanisms triggering speciation in the flatworm genus Gyrodactylus. The coevolutionary history with their goby hosts was investigated using both topology- and distance-based approaches; phylogenies were constructed of the V4 region of the 18S rRNA and the complete ITS rDNA region for the parasites, and 12S and 16S mtDNA fragments for the hosts. The overall fit between both trees was significant according to the topology-based programs (TreeMap 1.0, 2.0 beta and TreeFitter), but not according to the timed analysis in TreeMap 2.0 beta and the distance-based method (ParaFit). An absolute timing of speciation events in host and parasite ruled out the possibility of synchronous speciation for the gill parasites, favouring the distance-based result. Based on this information together with the biological background of host and parasite, the following TreeMap solution was selected. The group of gill parasites evolved from a host switch from G. arcuatus, parasitizing the three-spined stickleback onto the gobies, followed by several host-switching events among the respective goby hosts. The timing of these events is estimated to date back to the Late Pleistocene, suggesting a role for refugia-mediated mixing of parasite species. In contrast, it is suggested that co-speciation in the fin-parasites resulted in several host-associated species complexes. This illustrates that phylogenetically conserved host-switching mimics the phylogenetic signature of co-speciation, confounding topology-based programs.     

Differentiation of serum markers of homeostasis in highly qualified athletes engaged in various sports

Prognostic express diagnosis of metabolic dysregulation was tested in highly qualified athletes engaged in various Olympic sports. The method is based on laser correlation spectroscopy (LCS) of biological fluids, which has widely been approved for use in medicine and evaluation of risks for natural and anthropogenic anomalies. Evaluating the risk for metabolic dysregulations with the relevant criteria will help to objectively estimate the efficiency of preventive actions in athletes.     

Effectiveness of vertical posture recovery after external pushing impact in athletes specialized in different sports

The ability of athletes with different training specializations to recover vertical posture after an external pushing impact was studied. Athletes engaged in cyclic exercise sports (jogging, n = 7) and complex coordinate sports (wrestling, n = 10) and nonathletes (control, n = 10) were the subjects of this study. The recovery of vertical position after a small external pushing impact on the arms extended forward was assessed using stabilography. We determined the maximum amplitude (Amp-m) of deviation from the general center of pressure, the reaction time (RT) and the velocity of reaction (V-r), as well as the variance and mean velocity of vertical posture oscillations before and after an impact. It was found that, although no differences were observed in the vertical posture stability before pushing, the Amp-m was lower in the wrestlers than in the control group (by 17.5%, p = 0.018 under the eye-open conditions; by 27.3%, p = 0.002 under the eye-closed conditions). The deprivation of visual information about the pushing moment increases the Amp-m and V-r and had no effect on the RT in all groups. Under the eye-closed conditions, an increase in Amp-m as a result of pushing was significantly lower in the wrestlers (p = 0.033) than in the control group. Under the eye-closed conditions, the accuracy of the recovery of the initial vertical position after pushing was higher in the wrestlers than in the control group (p = 0.027). The indicators of postural stability, displacement of the center of pressure, and vertical posture sway and recovery after pushing did not differ between the runners and other groups. Therefore, compared to cyclic exercises, training in complex coordinating sports more effectively improves the ability to maintain vertical posture in response to its perturbation.     

The relative contributions of anthropometric variables to vertical jumping ability and leg power in Tunisian children

The purpose of this study was to examine the relative contributions of anthropometric variables to vertical jumping ability and leg power and to establish reference values of vertical jumping parameters in athletic Tunisian children aged 7-13 years in both sexes. Three hundred and ninety-one athletic Tunisian children (208 boys and 183 girls) aged 7-13 years were randomly selected to participate in our study. They were asked to perform squat jumps and countermovement jumps. Jump heights and leg power were simultaneously provided by the optojump device. Full and stepwise regression models were calculated to identify which anthropometric parameters significantly contributed to performance variables. The multiple regressions showed that age, weight, standing height and fat-free mass were the predictors of jumping performance. The results may help in verifying the effectiveness of a specific training program and detecting highly talented athletes.     

Plasma lecithin: cholesterol acyltransferase activity in elite athletes from selected sports

The activity of lecithin: cholesterol acyltransferase (LCAT) and the plasma lipoprotein concentrations of elite athletes from 8 selected sports (volleyball, judo, sprinting, wrestling, throwing, cycling, water polo and tennis) were determined and compared with those of a sedentary control group. Plasma LCAT activity levels in the athletes were significantly 2.2-7.0 times higher than in the controls in most sports (p less than 0.01). Judo, sprinting, wrestling and throwing had comparable LCAT values while tennis, volleyball and cycling were considerably higher. HDL-C concentration was significantly higher than controls in the water polo (p less than 0.05), cycling and volleyball (p less than 0.01) groups. Percentage lipoprotein distribution in the athletes in all sports except tennis, throwing and wrestling were similar to the controls. The differences among groups in LCAT activity may be related to the effect of physical exercise and training adaptations to lipid metabolism. This may be of importance when judging the benefit of exercise for atherosclerosis protection.     

Genetic basis of elite combat sports athletes: a systematic review

Each athlete’s innate talent is widely recognized as one of the important contributors to achievement in athletic performance, and genetic factors determine a significant portion of talent or traits. Advances in DNA sequencing technology allow us to discover specific genetic variants contributing to these traits in sports performance. The objective of this systematic review is to identify genes that may play a significant role in the performance of elite-level combat sports athletes. Through the review of 18 full-text articles, a total of 109 different polymorphisms were investigated in 14,313 participants (2,786 combat sports athletes, 8,969 non-athlete controls, 2,558 other sports athletes). Thirteen polymorphisms showed a significant difference between elite combat athletes and the control group, and consist of 8 (PPARA rs4253778, ACTN3 rs1815739, ACE rs4646994, CKM rs8111989, MCT1 rs1049434, FTO rs9939609, GABPβ1 rs7181866 and rs8031031) oriented to athletic performance and 5 (COMT rs4680, FEV rs860573, SLC6A2 rs2242446, HTR1B rs11568817, ADRA2A rs521674) focused on psychological traits including emotional and mental traits in combat sports athletes. In addition, a recent whole genome sequencing study identified 4 polymorphisms (KIF27 rs10125715, APC rs518013, TMEM229A rs7783359, LRRN3 rs80054135) associated with reaction time in wrestlers. However, it is not clearly identified which genes are linked explicitly with elite combat sports athletes and how they affect the elite athlete’s status or performance in combat sports. Hence, a greater number of candidate genes should be included in future studies to practically utilize the genetic information.     

Sensitivity of vertical jumping performance to changes in muscle stimulation onset times: a simulation study

The effect of muscle stimulation dynamics on the sensitivity of jumping achievement to variations in timing of muscle stimulation onsets was investigated. Vertical squat jumps were simulated using a forward dynamic model of the human musculoskeletal system. The model calculates the motion of body segments corresponding to STIM(t) of six major muscle groups of the lower extremity, where STIM is muscle stimulation level. For each muscle, STIM was allowed to switch “on” only once. The subsequent rise of STIM to its maximum was described using a sigmoidal curve, the dynamics of which was expressed as rise time (RT). For different values of stimulation RT, the optimal set of onset times was determined using dynamic optimization with height reached by the center of mass as performance criterion. Subsequently, 200 jumps were simulated in which the optimal muscle stimulation onset times were perturbed by adding to each a small number taken from a Gaussian-distributed set of pseudo-random numbers. The distribution of heights achieved in these perturbed jumps was used to quantify the sensitivity of jump height to variations in timing of muscle stimulation onsets. It was found that with increasing RT, the sensitivity of jump height to timing of stimulation onset times decreased. To try and understand this finding, a post-hoc analysis was performed on the perturbed jumps. Jump height was most sensitive to errors in the delay between stimulation onset times of proximal muscles and stimulation onset times of plantar flexors. It is explained how errors in this delay cause aberrations in the configuration of the system, which are regenerative and lead to relatively large jump height deficits. With increasing RT, the initial aberrations due to erroneous timing of muscle stimulation are smaller, and the regeneration is less pronounced. Finally, it is speculated that human subjects decrease or increase RT depending on the relative importance of different performance criteria. Received: 16 February 1998 / Accepted in revised form: 1 March 1999     

Comparing the content of lipids derived from the eye lenses of various species

The lipid content in the eye lens was analyzed and compared among various species in this study. The eye lens lipids of the following species were investigated: cow, horse, duck, and freshwater trout. Additionally, the lipids derived from cataractous bovine lens and from cataractous human eye lens lipoprotein complexes were analyzed. The following lipid classes were detected in clear lenses: cholesterol, sphingomyelin, phosphatidylcholine, phosphatidyletanolamine, and phosphatidylserine. In cataractous bovine lens and in lipoprotein complexes from human nuclear cataract, phosphatidyloinositol and phosphatidyloglycerol were detected. Cholesterol and sphingomyelin, essential for hypothetical formation of cholesterol-rich domains, were the most abundant lipids in the lenses of all investigated species. These two components of eye lens lipid fraction were analyzed quantitatively using thin layer chromatography and spectrophotometric assay; the other lipids were identified qualitatively using thin layer chromatography.     

Evolution of jumping capacity in Tropidurinae lizards: does habitat complexity influence obstacle‐crossing ability?

Jumping performance is relevant for lizards in many ecological contexts and might be favoured during the colonization of structurally complex habitats. Although ground-dwelling lizards use jumps to overcome small obstacles in their natural environments, jumping capacity has been mostly studied in arboreal species. Here, we analysed the evolution of jumping behaviour and performance in lizards from eight ground-dwelling species of Tropidurinae attempting to cross obstacles of different heights in a jumping track, both when undisturbed and under continuous stimulation. To establish ecological correlates with habitat complexity, individuals from two contrasting Brazilian habitats, the arid Caatingas (sand species) and the savannah-like Cerrados (rock species), were compared. Rock species jumped more often and crossed higher obstacles than sand ones in both tests, and performed more vertical than horizontal jumps. Although sand species performed less jumps, they were more successful at crossing the obstacles presented in comparison with rock species. Phylogenetic analyses confirmed these findings and demonstrated a large divergence in jumping capacity between sister-species from different habitats. Therefore, the differences in propensity and endurance for jumping activity appear to be independent of phylogenetic relationships in Tropidurinae and likely reflect an adaptation to the contrasting environments inhabited. The ecological implications of these findings are discussed.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 393–402.     

On classifying race in Brazil: Example from a study of the functional ability of older people (60+)

Abstract

How should race be categorized? This article investigates the usefulness of having three categories to describe a black‐white racial continuum, focusing on Brazil and the functional ability of elderly (60+) people there. Ironically, even as the U.S. census has started to acknowledge mixed race again, much social research in Brazil has begun not to. Using 1998 national household survey microdata (PNAD) for Brazil, we find it advantageous to use a three‐category scheme that separates a mixed black‐white (pardo) status from black or white when examining the functional ability of elders. We also find the tantalizing possibility of a crossover in which browns actually have more functional ability than white counterparts after controlling for many demographic, geographic, and socioeconomic factors.     

On classifying race in Brazil: example from a study of the functional ability of older people (60+)

How should race be categorized? This article investigates the usefulness of having three categories to describe a black-white racial continuum, focusing on Brazil and the functional ability of elderly (60+) people there. Ironically, even as the U.S. census has started to acknowledge mixed race again, much social research in Brazil has begun not to. Using 1998 national household survey microdata (PNAD) for Brazil, we find it advantageous to use a three-category scheme that separates a mixed black-white (pardo) status from black or white when examining the functional ability of elders. We also find the tantalizing possibility of a crossover in which browns actually have more functional ability than white counterparts after controlling for many demographic, geographic, and socioeconomic factors.     

Colorimetric detection of the hydroxyl radical: comparison of the hydroxyl-radical-generating ability of various iron complexes

An aromatic substrate for hydroxylation by OH radicals has been synthesized. Neither the substrate nor its hydroxylated product binds either iron(III) or iron(II). A spectrophotometric assay based on the hydroxylation of this substrate, N,N'-(5-nitro-1,3-phenylene)bisglutaramide, is described.     

Stress analysis of a complete maxillary denture under various drop impact conditions: a 3D finite element study

Complete maxillary dentures are one of the most economic and easy ways of treatment for edentulous patients and are still widely used. However, their survival rate is slightly above three years. It is presumed that the failure reasons are not only due to normal fatigue but also emerge from damage based on unavoidable improper usage. Failure types other than long-term fatigue, such as over-deforming, also influence the effective life span of dentures. A hypothesis is presumed, stating that the premature/unexpected failures may be initiated by impact on dentures, which can be related to dropping them on the ground or other effects such as biting crispy food. Thus, the behavior of a complete maxillary denture under impact loading due to drop on a rigid surface was investigated using the finite element method utilizing explicit time integration and a rate-sensitive elastoplastic material model of polymethylmethacrylate (PMMA). Local permanent deformations have been observed along with an emphasis on frenulum region of the denture, regardless of the point of impact. Contact stresses at the tooth–denture base were also investigated. The spread of energy within the structure via wave propagation is seen to play a critical role in this fact. Stress-wave propagation is also seen to be an important factor that decreases the denture's fatigue life.