Maximal Height Research Articles

The Components of the Jumps in Expert and Intermediate Water Polo Players

The aim of this study is to show the different multifactorial structure of jump capacity in expert and intermediate water polo players, using the principal component analysis (PCA) and multiple regression. We adopted the Teknotrain3, an instrument that enabled us to measure maximal height out of the water and dynamic components such as force, velocity, and power. The experts showed high levels of power (t = 2.75, p < 0.04) and velocity (t = 4.4, p < 0.007) with a considerable maximal height (mh) (t = 2.73, p < 0.04), whereas the intermediate players showed only an average velocity and mh and an inverse relation between power, velocity, and temporal variability in jumps, r = -0.89 (p <0.01) and r = -0.94 (p < 0.01). The intermediate players need a physical preparation of resistance training aimed at developing rapid rate of force development (RFD) and the maximal dynamic force and power and reducing temporal variability.

Neuromuscular adaptations to 4 weeks of intensive drop jump training in well-trained athletes

This study examined the effects of 4 weeks of intensive drop jump training in well-trained athletes on jumping performance and underlying changes in biomechanics and neuromuscular adaptations. Nine well-trained athletes at high national competition level within sprinting and jumping disciplines participated in the study. The training was supervised and augmented feedback on performance was used to ensure maximal training intensity. The drop jumps were performed with minimal contact time and maximal jumping height. Assessment of performance during training showed effects of motor learning. Before and after the training intervention maximal isometric muscle strength, the biomechanics, muscle activity pattern of the lower extremities and the soleus H-reflex and V-wave during drop jumping were measured. Maximal jump height and performance index (PI) defined as jumping height divided by contact time improved significantly by 11.9% (P = 0.024) and 16.2% (P = 0.009), respectively. Combined ankle and knee joint peak power was significantly increased by 7% after training (P = 0.047). The preactivity in the soleus muscle decreased 16% (P = 0.015). The soleus H-reflex was unchanged after training, while the soleus V-wave increased significantly at 45 msec after touchdown. This may indicate an increased drive to the α-motor neuron pool following training. Muscle strength parameters were unaffected by the training. The results demonstrate that 4 weeks of intensive drop jump training can improve jumping performance also in well-trained athletes without concomitant changes in muscle strength. It is suggested that the behavioral improvement is primarily due to neural factors regulating the activation pattern controlling the drop jump movement.

Stabilization Time for a Type of Evolution on Binary Strings

We consider a type of evolution on {0,1}^n which occurs in discrete steps whereby at each step, we replace every occurrence of the substring "01" by "10". After at most n-1 steps we will reach a string of the form 11..1100..11, which we will call a "stabilized" string and we call the number of steps required the "stabilization time". If we choose each bit of the string independently to be a 1 with probability p and a 0 with probability 1-p, then the stabilization time of a string in {0,1}^n is a random variable with values in 0,1,...,n-1}. We study the asymptotic behavior of this random variable as n goes to infinity and we determine its limit distribution after suitable centering and scaling . When p is not 1/2, the limit distribution is Gaussian. When p = 1/2, the limit distribution is a \chi_3 distribution. We also explicitly compute the limit distribution in a threshold setting where p=p_n varies with n given by p_n = 1/2 + \lambda / 2 \sqrt{n} for \lambda > 0 a fixed parameter. This analysis gives rise to a one parameter family of distributions that fit between a \chi_3 and a Gaussian distribution. The tools used in our arguments are a natural interpretation of strings in {0,1}^n as Young diagrams, and a connection with the known distribution for the maximal height of a Brownian path on [0,1].

Ordering Partial Partitions for Image Segmentation and Filtering: Merging, Creating and Inflating Blocks

The refinement order on partitions corresponds to the operation of merging blocks in a partition, which is relevant to image segmentation and filtering methods. Its mathematical extension to partial partitions, that we call standard order, involves several operations, not only merging, but also creating new blocks or inflating existing ones, which are equally relevant to image segmentation and filtering techniques. These three operations correspond to three basic partial orders on partial partitions, the merging, inclusion and inflating orders. There are three possible combinations of these three basic orders, one of them is the standard order, the other two are the merging-inflating and inclusion-inflating orders. We study these orders in detail, giving in particular their minimal and maximal elements, covering relations and height functions. We interpret hierarchies of partitions and partial partitions in terms of an adjunction between (partial) partitions (possibly with connected blocks) and scalars. This gives a lattice-theoretical interpretation of edge saliency, hence a typology for the edges in partial partitions. The use of hierarchies in image filtering, in particular with component trees, is also discussed. Finally, we briefly mention further orders on partial partitions that can be useful for image segmentation.

Maximal step-up height as a simple and relevant health indicator: a study of leg muscle strength and the associations to age, anthropometric variables, aerobic fitness and physical function

BackgroundLow muscle strength is related to an increased risk for several chronic diseases. Increased muscle strength improves daily function and quality of life.ObjectiveTo measure maximal step-up height, an assessment of...

Differences in Lateral Drop Jumps From an Unknown Height Among Individuals With Functional Ankle Instability

Functional ankle instability (FAI) is a debilitating condition that has been reported to occur after 20% to 50% of all ankle sprains. Landing from a jump is one common mechanism of ankle injury, yet few researchers have explored the role of visual cues and anticipatory muscle contractions, which may influence ankle stability, in lateral jumping maneuvers. To examine muscle-activation strategies between FAI and stable ankles under a lateral load and to evaluate the differences in muscle activation in participants with FAI and participants with stable ankles when they were unable to anticipate the onset of lateral loads during eyes-open versus eyes-closed conditions. Case-control study. Controlled laboratory setting. A total of 40 people participated: 20 with FAI and 20 healthy, uninjured, sex- and age-matched persons (control group). Participants performed a 2-legged lateral jump off a platform onto a force plate set to heights of 35 cm or 50 cm and then immediately jumped for maximal height. They performed jumps in 2 conditions (eyes open, eyes closed) and were unaware of the jump height when their eyes were closed. Amplitude normalized electromyographic (EMG) area (%), peak (%), and time to peak in the tibialis anterior (TA), peroneus longus (PL), and lateral gastrocnemius (LG) muscles were measured. Regardless of the eyes-open or eyes-closed condition, participants with FAI had less preparatory TA (t158 = 2.22, P = .03) and PL (t158 = 2.09, P = .04) EMG area and TA (t158 = 2.45, P = .02) and PL (t158 = 2.17, P = .03) peak EMG than control-group participants. By removing visual cues, unanticipated lateral joint loads occurred simultaneously with decreased muscle activity, which may reduce dynamic restraint capabilities in persons with FAI. Regardless of visual impairment and jump height, participants with FAI exhibited PL and TA inhibition, which may limit talonavicular stability and intensify lateral joint surface compression and pain.

Geometry and Markoff’s spectrum for ℚ(𝕚), I

We develop a study of the relationship between geometry of geodesics and Markoff’s spectrum for Q ( i ) \mathbb {Q}(i) . There exists a particular immersed totally geodesic twice punctured torus in the Borromean rings complement, which is a double cover of the once punctured torus having Fricke coordinates ( 2 2 , 2 2 , 4 ) (2\sqrt {2}, 2\sqrt {2}, 4) . The set of the simple closed geodesics on this once punctured torus is decomposed into two subsets. The discrete part of Markoff’s spectrum for Q ( i ) \mathbb {Q}(i) (except for one) is given by the maximal Euclidean height of the lifts of the simple closed geodesics composing one of the subsets.

Biomechanics of the heel-raise test performed on an incline in two knee flexion positions

BackgroundAlthough single-legged heel-raise cycles are often performed on an incline in different knee flexion positions to discriminate the relative contribution of the triceps surae muscles, detailed kinematic and kinetic analyses of this procedure are not available. Our study characterizes and compares the biomechanics and clinical outcomes of single-legged heel-raise cycles performed to volitional exhaustion on an incline with the knee straight (0°) and bent (45°), considering the effect of sex and age. MethodsFifty-six male and female volunteers, with equal numbers of younger (20 to 40years of age) and older (40 to 60years of age) individuals, completed a maximal number of heel-raise cycles on an incline at both nominal knee angles. Kinematic and kinetic data were acquired during testing using a 3D motion capturing system and multi-axial force plate. The impact of fatigue on performance was quantified using changes in maximal voluntary isometric contraction force and biomechanical performance of cycles. FindingsOverall, participants completed three more cycles and maintained better biomechanical performance with 45° than 0° of knee flexion. More precisely, the decreases in maximal heel-raise heights, plantar-flexion angles at maximal height and ranges of ankle motion per cycle were all smaller with the knee bent. However, several outcomes indicated similar plantar-flexion fatigue at both knee angles. Males demonstrated a more rapid decline in peak ground reaction forces during testing; but otherwise, neither sex nor age significantly impacted outcomes. InterpretationIt is concluded that the differences discerned here in the biomechanics of single-legged heel-raise cycles performed at 0° and 45° of knee flexion to volitional exhaustion on an incline may be too small to identify in clinical settings or reflect substantial alterations in the relative contribution of the triceps surae muscles.

Reply to Kennedy et al.: Katrina storm records in tide gauges

We appreciate the opportunity to discuss our definition of events of Katrina magnitude. Kennedy et al. (1) argue that our definition of Katrina magnitude events (2) is too low because we do not use any tide gauge data in the immediate proximity of New Orleans and the region of absolute maximal surge height.

Liquid marble granulation using super-hydrophobic powders

This work analyses the forces involved in liquid marble formation, primarily the surface energy of the powder on the liquid surface and the powder gravitational force, which we have shown to oppose liquid marble formation. In order to investigate these phenomena, hydrophobic powders possessing both high density and high contact angle need to be employed. For this purpose, superhydrophobic (SH) particles based on a copper substrate were prepared by a silver deposition technique of particle sizes 9, 20, 320 and 400μm having a contact angle with water approaching 160°. Liquid marbles formed using the SH copper substrate were compared with polymer powder (e.g., PMMA) based liquid marbles. Initially, the effective surface tension of the liquid marbles was determined using the maximal height methodology, which indicated that effective surface tension was a function of powder particle size. It is probable that the phenomena of heavy particles give rise to lower effective surface tension, is caused by the weight of the particles reducing the puddle height. Moreover, it was found that in cases with large dense SH powder particles, liquid marble formation was not possible, as the additional weight of the larger particles, lowered the “puddle” to an extent that marble became unstable and collapsed. Therefore, an analysis of the energies associated with the powder particles was undertaken to quantify the physical characteristics of powders that form liquid marbles under: (i) static and (ii) dynamic conditions. In addition, we have correlated this data using a regime map analysis in which we have plotted a surface energy versus a gravitational energy to provide operating regions within the regime map of potential liquid marble formation.

Constrained optimization of metabolic cost in human hopping

Constrained optimization of metabolic cost/distance travelled largely predicts the gait parameters selected by humans during walking and running. This study evaluates whether this is also the case for human hopping. Hop frequency (f), height (h) and metabolic energy expenditure were measured in partly constrained (f, h or hop speed, s ≡ fh, specified), fully constrained (both f and h specified) and unconstrained conditions (neither f nor h specified) for 4 min trials. Hop frequency and height were also measured in frequency-constrained (f specified), fully constrained (maximal height and f specified) and unconstrained conditions for 15 s trials. Metabolic cost surfaces were constructed from experimental data from the 4 min trials, and the least costly behaviour for each constraint was calculated. Subjects selected the same height-frequency pattern for all three partly constrained conditions because the metabolic cost/height surface for hopping was a slope with no observed minimum. The heights selected for the 15 s frequency-constrained trials were only slightly lower than maximal, the optimal behaviour predicted by constrained optimization of metabolic cost/height. This supports the hypothesis that constrained optimization of metabolic cost largely predicts movement selection during hopping. However, subjects often chose noticeably lower than optimal heights and higher than optimal frequencies during partly constrained and unconstrained conditions for the 4 min trials. It appears that they selected heights and frequencies that incurred a slightly greater metabolic cost/height in order to reduce metabolic cost/time to a level they could comfortably sustain for 4 min.

Size Ratio: A Morphological Factor Predictive of the Rupture of Cerebral Aneurysm?

Determining factors predictive of the natural risk of rupture of cerebral aneurysms is difficult. We studied morphological factors associated with rupture in a study model of patients with mirror location intracranial aneurysms, one aneurysm that had ruptured and one that had not, each patient served as their own control attempting to eliminate confounding variables. We collected five one-dimensional measurements and four two-dimensional indices from three-dimensional rotational digital subtraction angiography images of patients in the proposed study model and explored their correlation with aneurysm rupture. Parameters were analyzed with a paired Student's t test for significance and significant parameters were further examined by multivariate conditional logistic regression analysis. Fifty-two patients with 52 pairs of intracranial aneurysms in a mirror location were studied. The maximum perpendicular height, neck diameter, maximum width, maximum height, aspect ratio, size ratio, and bottleneck factor were significantly associated with ruptured aneurysms on bivariate analysis. A logistic regression analysis showed that only size ratio, which was defined as the ratio of the maximal height to parent artery average diameter, is independently correlated with ruptured intracranial aneurysms. In a case-control study of patients with mirror location intracranial aneurysms, size ratio was identified as the unique morphological factor associate with the rupture of cerebral aneurysms.

Extensor Function After Medial Gastrocnemius Flap Reconstruction of the Proximal Tibia

Reconstruction of the extensor mechanism after resection of the proximal tibia is challenging, and several methods are available. A medial gastrocnemius flap commonly is used, although it may be associated with an extensor lag. This problem also is encountered, although perhaps to a lesser extent, with other techniques for reconstruction of the extensor apparatus. It is not known how such lag develops with time and how it correlates with functional outcome. We therefore (1) assessed patellar height with time, (2) correlated patellar height with function using the Musculoskeletal Tumor Society (MSTS) score, and (3) correlated patellar height with range of motion (ROM) after medial gastrocnemius flap reconstruction. Sixteen patients underwent tumor endoprosthesis implantation and extensor apparatus reconstruction between 1997 and 2009 using a medial gastrocnemius flap after sarcoma resection of the proximal tibia. These patients represented 100% of the population for whom we performed extensor mechanism reconstructions during that time. The minimum followup was 2 years (mean, 5 years; range, 2-11 years). Fourteen patients were alive at the time of this study. We used the Blackburne-Peel Index to follow patellar height radiographically with time. Functional outcomes were assessed retrospectively using the MSTS, and ROM was evaluated through active extensor lag and flexion. Eleven patients had patella alta develop, whereby the maximal patellar height was reached after a mean of 2 years and then stabilized. More normal patellar height was associated with better functional scores, a smaller extensor lag, but less flexion; the mean extensor lag (and flexion) of patients with patella alta was 17° (and 94°) compared with only 4° (and 77°) without. In our patients patella alta evolved during the first 2 postoperative years. Patella alta is associated with extensor lag, greater flexion, and worse MSTS scores. Surgical fixation of the patellar tendon more distally to its anatomic position or strict postoperative bracing may be advisable. Level IV, clinical cohort study. See the Guidelines for Authors for a complete description of levels of evidence.

Agonist–antagonist muscle activation during drop jumps

Pre-programmed and stretch-induced muscle activities of agonist muscles can play important roles during stretch-shortening cycle exercises. It is still not clear how the antagonist muscles function when the drop and rebound intensities are varied during drop jump (DJ) exercises. The purpose of the present study was to examine the regulation of agonist–antagonist muscle activation during DJ with different drop and rebound heights. The subjects performed DJs with two drop heights (0.2 and 0.4 m) and three different efforts (maximal rebound height, 50% effort of maximal rebound height and landing without rebound). Ankle and knee joint angles, and vertical ground reaction force together with an electromyogram of the lower leg muscles (medial gastrocnemius [MG], soleus [SOL] and tibialis anterior [TA]) were measured simultaneously during DJ. Our results clearly showed that the pre-activation of the antagonist TA was increased with increasing rebound height. Our results further showed that the coactivations of agonist and antagonist muscles during the post-impact 30-ms phase were increased with increasing rebound height. These results suggested that not only the pre-programmed agonist MG muscle activation, but also the pre-programmed antagonist TA activation and the coactivation of the post-impact 30-ms phase may play important roles in the control of rebound height.

ON A CLASS OF MONOMIAL IDEALS

AbstractLet $S$ be a polynomial ring over a field $K$ and let $I$ be a monomial ideal of $S$. We say that $I$ is MHC (that is, $I$ satisfies the maximal height condition for the associated primes of $I$) if there exists a prime ideal $\mathfrak{p}\in {\mathrm{Ass} }_{S} \hspace{0.167em} S/ I$ for which $\mathrm{ht} (\mathfrak{p})$ equals the number of indeterminates that appear in the minimal set of monomials generating $I$. Let $I= { \mathop{\bigcap }\nolimits}_{i= 1}^{k} {Q}_{i} $ be the irreducible decomposition of $I$ and let $m(I)= \max \{ \vert Q_{i}\vert - \mathrm{ht} ({Q}_{i} ): 1\leq i\leq k\} $, where $\vert {Q}_{i} \vert $ denotes the total degree of ${Q}_{i} $. Then it can be seen that when $I$ is primary, $\mathrm{reg} (S/ I)= m(I)$. In this paper we improve this result and show that whenever $I$ is MHC, then $\mathrm{reg} (S/ I)= m(I)$ provided $\vert {\mathrm{Ass} }_{S} \hspace{0.167em} S/ I\vert \leq 2$. We also prove that $m({I}^{n} )\leq n\max \{ \vert Q_{i}\vert : 1\leq i\leq ~k\} - \mathrm{ht} (I)$, for all $n\geq 1$. In addition we show that if $I$ is MHC and $w$ is an indeterminate which is not in the monomials generating $I$, then $\mathrm{reg} (S/ \mathop{(I+ {w}^{d} S)}\nolimits ^{n} )\leq \mathrm{reg} (S/ I)+ nd- 1$ for all $n\geq 1$ and $d$ large enough. Finally, we implement an algorithm for the computation of $m(I)$.

A new modality for improving the efficacy of intrathecal injection for cesarean section

BackgroundIntrauterine resuscitation (IUR) is to improve O2 delivery to the placenta and umbilical blood flow, for reversal of foetal hypoxia and acidosis. We evaluated whether maintaining a lateral position after an intrathecal injection of a relatively low dose of hyperbaric bupivacaine and high dose of fentanyl improving the efficacy of spinal anaesthesia, IUR and preventing hypotension during cesarean delivery.MethodsOne hundred and seventy two healthy women undergoing elective cesarean delivery were enrolled in a double blind prospective randomized study. Spinal anesthesia was conducted in the right lateral position which maintained for 6 min for all the patients participated in the study, and then the subjects were turned supine. Patients were randomly allocated to two groups: low-dose spinal bupivacaine (LD) group (n = 86) patients received 6 mg of hyperbaric bupivacaine 0.5% and 15 μg of fentanyl, high-dose spinal bupivacaine (HD) group (n = 86) patients received 10 mg of hyperbaric bupivacaine and 15 μg of fentanyl. The incidence of hypotension and nausea, ephedrine requirement, maximal block height, and Apgar score at 1 and 5 min.ResultsThe authors found significant decrease in MAP in the group that was given the high dose of bupivacaine the incidence of hypotension was 80% but the LD spinal bupivacaine group was hemodynamically stable. The lowest blood pressure, boluses of inj. ephedrine used, or nausea were more significant in the HD group than in LD group. Onset of hypotension was more rapid (8 ± 3 vs. 16 ± 6 min, P < 0.001), and the sensory block level was more cephalad in HD group than in LD group (T2 [C8–T5] vs. T4 [T1–T6], P = 0.001). Apgar scores did not differ between the groups.ConclusionMaintaining the lateral position for 6 min after an intrathecal injection of a relatively low dose of hyperbaric bupivacaine and high dose of fentanyl resulted in improving the efficacy of spinal anaesthesia, IUR by more gradual and higher cephalad sensory block, without an increase in the incidence of maternal hypotension.

Factors Affecting Growth and Final Adult Height After Pediatric Renal Transplantation

BackgroundGrowth retardation is a common problem for children with chronic kidney disease. Although renal transplantation (RTx) resolves endocrine metabolic and uremic disturbances, growth continues to be suboptimal. This study aims to describe changes in height from diagnosis to final adult height (FAH) in Korean renal allograft recipients and determine factors associated with posttransplantation growth. MethodsWe retrospectively reviewed 63 renal allograft recipients who underwent RTx at <15 years of age with regular follow-up for >3 years afterwards. Pre- and post-RTx growth was analyzed by height Z scores (Ht_Z) at RTx, 2 and 5 years follow-up, and at FAH. ResultsHt_Z decreased from diagnosis to dialysis by −0.8 (P = .009) and from dialysis to RTx by −0.46 (P < .001). The mean baseline Ht_Z at RTx was −1.62 ± 1.36. The change in Ht_Z at 2 and 5 years after transplantation was 0.68 ± 0.88 and 0.48 ± 0.86, respectively. Both variables were negatively correlated with baseline age at RTx. Mean FAH was −1.22 ± 1.11 and was positively correlated with baseline height at RTx. Height at start of dialysis and dialysis duration were significant determinants of baseline height at RTx (P < .001). ConclusionsAlthough there is significant posttransplant catch-up growth among younger recipients and among those with greater baseline height deficit, catch-up growth is not sustained and greater FAH is attained in those who are taller at RTx. Achieving greater height before dialysis and decreasing dialysis duration leads to maximal height at RTx as well as greater FAH.

Spinal anesthesia with hyperbaric bupivacaine: A comparison of hypertensive and normotensive patients

BackgroundHypotension is the most common problem with spinal anesthesia. This prospective study aimed to compare normotensive and hypertensive patients with respect to the hemodynamic effects of spinal anesthesia performed with hyperbaric bupivacaine.Material/MethodsSixty patients who were scheduled to undergo various elective operations under spinal anesthesia were included into the study. The patients were separated into 2 groups: hypertensive patients constituted Group H (n=30) and normotensive patients constituted Group N (n=30). After fluid loading, spinal anesthesia was performed with 3.5 ml 0.5% hyperbaric bupivacaine. Demographic characteristics and incidence of hypotension and bradycardia were compared. Systolic (SBP), diastolic (DBP), and mean blood pressures (MBP) and heart rate (HR) were also compared before and after spinal anesthesia.ResultsThere was no significant difference between the groups with respect to demographic characteristics, maximal height of sensory block, incidences of hypotension and bradycardia, and the amount of fluids infused (p>0.05). In the hypertensive patient group, the SBP, DBP, and MBP values were significantly higher than in the normotensive patient group at all measurement times (p<0.05). Comparison within the groups did not reveal any significant differences in either group compared to the basal values (p>0.05). There were no significant differences in HR between or within groups (p>0.05).ConclusionsThere was no significant difference between normotensive and hypertensive patients in the incidences of hypotension caused by spinal anesthesia with 0.5% hyperbaric bupivacaine.

The Analysis of Plyometric Training Program on University Handball Players

The purpose of this study was to find out the efficiency of composed plyometric training program on beginners Handball players force capabilities in their usual training period. The plyometric training program was applied during 16 week period where was attended twenty-one 12-19 years old beginners Handball players. Twelve of them were female and nine male handball players. There were three control tastings. All subjects participated in following tests: standing long jump, depth leap long jump, medicine ball throws up in 10 seconds; medicine ball overhead throws forward against the wall in 10 seconds, maximal vertical jumps to the maximal height in 10 seconds, maximal vertical jump height. Testing results statistical analysis has shown athletes legs and arms speed force reliable improvement. Standing long jump, depth leap long jump and maximal vertical jump height test results, what has shown legs explosive power, has not shown remarkable reliable difference (P>0.05) . Medicine ball throws and maximal vertical jumps to the maximal height in 10 seconds, what show speed force improvement, showed reliable difference (P<0.01).

Muscle–tendon interaction and EMG profiles of world class endurance runners during hopping

The present study examined the muscle-tendon interaction of ten international level Kenyan runners. Ultrasonography and kinematics were applied together with EMG recordings of lower limb muscles during repetitive hopping performed at maximal level. The ten Kenyans had longer gastro Achilles tendon at rest (p < 0.01) as compared with ten control subjects matched in height. Conversely, the stretching and shortening amplitudes of the tendinous tissues of the medial gastrocnemius (MG) muscle were significantly smaller in the Kenyans than in controls during the contact phase of hopping. This applied also to the fascicle length changes, which were smaller and more homogeneous among Kenyans. These limited musculo-tendinous changes resulted in higher maximal hopping height and in larger power despite their reduced body weight. The associated finding of a greater shortening to stretching ratio of the MG tendinous tissues during contact could imply that the Kenyan MG muscle-tendon unit is optimized to favor efficient storage and recoil of elastic energy, while operating at optimal muscle fascicle working range (plateau region).