Fit-climbing test: a field test for indoor rock climbing

Bertuzzi, R, Franchini, E, Tricoli, V, Lima-Silva, AE, Pires, FDO, Okuno, NM, and Kiss, MAPDM. Fit-climbing test: A field test for indoor rock climbing. J Strength Cond Res 26(6): 1558-1563, 2012-The aim of this study was to develop an indoor rock-climbing test on an artificial wall (Fit-climbing test). Thirteen climbers (elite group [EG] = 6; recreational group [RG] = 7) performed the following tests: (a) familiarization in the Fitclimbing test, (b) the Fit-climbing test, and (c) a retest to evaluate the Fit-climbing test's reliability. Gas exchange, blood lactate concentration, handgrip strength, and heart rate were measured during the test. Oxygen uptake during the Fit-climbing test was not different between groups (EG = 8.4 +/- 1.1 L; RG = 7.9 +/- 1.5 L, p > 0.05). The EG performance (120 +/- 7 movements) was statistically higher than the RG climbers' performance (78 +/- 13 movements) during the Fit-climbing test. Consequently, the oxygen cost per movement during the Fit-climbing test of the EG was significantly lower than that of the RG (p < 0.05). Handgrip strength was higher in the EG when compared with that in the RG in both pre-Fit- and post-Fit-climbing test (p < 0.05). There were no significant differences in any other variables analyzed during the Fit-climbing test (p > 0.05). Furthermore, the performance in the Fit-climbing test presented high reliability (intraclass correlation coefficient = 0.97). Therefore, the performance during the Fit-climbing test may be an alternative to evaluate rock climbers because of its specificity and relation to oxygen cost per movement during climbing.

Similar health benefits of endurance and high-intensity interval training in obese children

Purpose: To compare two modalities of exercise training (i.e., Endurance Training [ET] and High-Intensity Interval Training [HIT]) on health-related parameters in obese children aged between 8 and 12 years. Methods: Thirty obese children were randomly allocated into either the ET or HIT group. The ET group performed a 30 to 60-minute continuous exercise at 80% of the peak heart rate (HR). The HIT group training performed 3 to 6 sets of 60-s sprint at 100% of the peak velocity interspersed by a 3-min active recovery period at 50% of the exercise velocity. HIT sessions last similar to 70% less than ET sessions. At baseline and after 12 weeks of intervention, aerobic fitness, body composition and metabolic parameters were assessed. Results: Both the absolute (ET: 26.0%; HIT: 19.0%) and the relative VO2 peak (ET: 13.1%; HIT: 14.6%) were significantly increased in both groups after the intervention. Additionally, the total time of exercise (ET: 19.5%; HIT: 16.4%) and the peak velocity during the maximal graded cardiorespiratory test (ET: 16.9%; HIT: 13.4%) were significantly improved across interventions. Insulinemia (ET: 29.4%; HIT: 30.5%) and HOMA-index (ET: 42.8%; HIT: 37.0%) were significantly lower for both groups at POST when compared to PRE. Body mass was significantly reduced in the HIT (2.6%), but not in the ET group (1.2%). A significant reduction in BMI was observed for both groups after the intervention (ET: 3.0%; HIT: 5.0%). The responsiveness analysis revealed a very similar pattern of the most responsive variables among groups. Conclusion: HIT and ET were equally effective in improving important health related parameters in obese youth.

Evolution of form and function: morphophysiological relationships and locomotor performance in tropidurine lizards

Locomotor capacity is often considered an excellent measure of whole animal performance because it requires the integrated functioning of many morphological, physiological (and biochemical) traits. However, because studies tend to focus on either structural or functional suits of traits, we know little on whether and how morphological and physiological traits coevolve to produce adequate locomotor capacities. Hence, we investigate the evolutionary relationships between morphological and physiological parameters related to exercise physiology, using tropidurine lizards as a model. We employ a phylogenetic principal component analysis (PCA) to identify variable clusters (factors) related to morphology, energetic metabolism and muscle metabolism, and then analyze the relationships between these clusters and measures of locomotor performance, using two models (star and hierarchical phylogenies). Our data indicate that sprint performance is enhanced by simultaneous evolutionary tendencies affecting relative limb and tail size and physiological traits. Specifically, the high absolute sprint speeds exhibited by tropidurines from the sand dunes are explained by longer limbs, feet and tails and an increased proportion of glycolytic fibers in the leg muscle, contrasting with their lower capacity for overall oxidative metabolism [principal component (PC1)]. However, when sprint speeds are corrected for body size, performance correlates with a cluster (PC3) composed by moderate loads for activity metabolic rate and body size. The simultaneous measurement of morphological and physiological parameters is a powerful tool for exploring patterns of coadaptation and proposing morphophysiological associations that are not directly predictable from theory. This approach may trigger novel directions for investigating the evolution of form and function, particularly in the context of organismal performance.

Adiposity and age explain most of the association between physical activity and fitness in physically active men

[EN] BACKGROUND: To determine if there is an association between physical activity assessed by the short version of the International Physical Activity Questionnaire (IPAQ) and cardiorespiratory and muscular fitness. METHODOLOGY/PRINCIPAL FINDINGS: One hundred and eighty-two young males (age range: 20-55 years) completed the short form of the IPAQ to assess physical activity. Body composition (dual-energy X-Ray absorptiometry), muscular fitness (static and dynamic muscle force and power, vertical jump height, running speed [30 m sprint], anaerobic capacity [300 m running test]) and cardiorespiratory fitness (estimated VO(2)max: 20 m shuttle run test) were also determined in all subjects. Activity-related energy expenditure of moderate and vigorous intensity (EEPA(moderate) and EEPA(vigorous), respectively) was inversely associated with indices of adiposity (r = -0.21 to -0.37, P<0.05). Cardiorespiratory fitness (VO(2)max) was positively associated with LogEEPA(moderate) (r = 0.26, P<0.05) and LogEEPA(vigorous) (r = 0.27). However, no association between VO(2)max with LogEEPA(moderate), LogEPPA(vigorous) and LogEEPA(total) was observed after adjusting for the percentage of body fat. Multiple stepwise regression analysis to predict VO(2)max from LogEEPA(walking), LogEEPA(moderate), LogEEPA(vigorous), LogEEPA(total), age and percentage of body fat (%fat) showed that the %fat alone explained 62% of the variance in VO(2)max and that the age added another 10%, while the other variables did not add predictive value to the model [VO(2)max = 129.6-(25.1x Log %fat) - (34.0x Log age); SEE: 4.3 ml.kg(-1). min(-1); R(2) = 0.72 (P<0.05)]. No positive association between muscular fitness-related variables and physical activity was observed, even after adjusting for body fat or body fat and age. CONCLUSIONS/SIGNIFICANCE: Adiposity and age are the strongest predictors of VO(2)max in healthy men. The energy expended in moderate and vigorous physical activities is inversely associated with adiposity. Muscular fitness does not appear to be associated with physical activity as assessed by the IPAQ.

Anaerobic energy provision does not limit Wingate exercise performance in endurance-trained cyclists

[EN] The aim of this study was to evaluate the effects of severe acute hypoxia on exercise performance and metabolism during 30-s Wingate tests. Five endurance- (E) and five sprint- (S) trained track cyclists from the Spanish National Team performed 30-s Wingate tests in normoxia and hypoxia (inspired O(2) fraction = 0.10). Oxygen deficit was estimated from submaximal cycling economy tests by use of a nonlinear model. E cyclists showed higher maximal O(2) uptake than S (72 +/- 1 and 62 +/- 2 ml x kg(-1) x min(-1), P < 0.05). S cyclists achieved higher peak and mean power output, and 33% larger oxygen deficit than E (P < 0.05). During the Wingate test in normoxia, S relied more on anaerobic energy sources than E (P < 0.05); however, S showed a larger fatigue index in both conditions (P < 0.05). Compared with normoxia, hypoxia lowered O(2) uptake by 16% in E and S (P < 0.05). Peak power output, fatigue index, and exercise femoral vein blood lactate concentration were not altered by hypoxia in any group. Endurance cyclists, unlike S, maintained their mean power output in hypoxia by increasing their anaerobic energy production, as shown by 7% greater oxygen deficit and 11% higher postexercise lactate concentration. In conclusion, performance during 30-s Wingate tests in severe acute hypoxia is maintained or barely reduced owing to the enhancement of the anaerobic energy release. The effect of severe acute hypoxia on supramaximal exercise performance depends on training background.

Regulación de la actividad AMPK en músculo esquelético humano por radicales libres e hipoxia

Premio Extraordinario de Doctorado. Rama de Ciencias Sociales y Jurídicas

Azione antiossidante del sulforafane: analisi in cellule cardiache in coltura ed in un modello animale di esercizio fisico

Oxidative stress is considered to be of major relevance for a variety of pathological processes. Thus, it is valuable to identify compounds, which might act as antioxidants, i.e. compounds that antagonize the deleterious action of reactive oxygen species (ROS) on biomolecules. The mode of action of these compounds could be either to scavenge ROS directly or to trigger protective mechanisms inside the cell, thereby resulting in improved defense against ROS. Sulforaphane (SF) (1-isothiocyanato-(4R)-(methylsulfinyl)butane) is a naturally occurring cancer chemopreventive agent found as a precursor glucosinolate in Cruciferous vegetables like broccoli. Although SF is not a direct-acting antioxidant, there is substantial evidence that SF acts indirectly to increase the antioxidant capacity of animal cells and their abilities to cope with oxidative stress. Induction of phase 2 enzymes is one means by which SF enhances the cellular antioxidant capacity. Enzymes induced by SF include Glutathione S-transferases (GST) and NAD[P]H:quinone oxidoreductase (NQO1) which can function as protectors against oxidative stress. To protect themselves from oxidative stress, cells are equipped with reducing buffer systems including the GSH and thioredoxin (Trx) reductase. GSH is an important tripeptide thiol which in addition to being the substrate for GSTs maintains the cellular oxidation– reduction balance and protects cells against free radical species. Aim of the first part of this thesis was to investigate the ability of SF to induce the expression and the activity of different phase 2 and antioxidant enzymes (such as GST, GR, GPx, NQO1, TR, SOD, CAT) in an in vitro model of rat cardiomyocytes, and also to define if SF treatment supprts cells in counteracting oxidative stress induced by H2O2 It is well known that acute exhaustive exercise causes significant reactive oxygen species generation that results in oxidative stress, which can induce negative effects on health and well being. In fact, increased oxidative stress and biomarkers (e.g., protein carbonyls, MDA, and 8- hydroxyguanosine) as well as muscle damage biomarkers (e.g. plasmatic Creatine cinase and Lactate dehydrogenase) have been observed after supramaximal sprint exercises, exhaustive longdistance cycling or running as well as resistance-type exercises, both in trained and untrained humans. Markers of oxidative stress also increase in rodents following exhaustive exercise. Moreover, antioxidant enzyme activities and expressions of antioxidant enzymes are known to increase in response to exhaustive exercise in both animal and human tissues. Aim of this project was to evaluate the effect of SF supplementation in counteracting oxidative stress induced by physical activity through its ability to induce phase 2, and antioxidant enzymes in rat muscle. The results show that SF is a nutraceutical compound able to induce the activity of different phase 2 and antioxidant enzymes in both cardiac muscle and skeletal muscle. Thanks to its actions SF is becoming a promising molecule able to prevent cardiovascular damages induced by oxidative stress and muscle damages induced by acute exhaustive exercise.

Operating System Contribution to Composable Timing Behaviour in High-Integrity Real-Time Systems

The development of High-Integrity Real-Time Systems has a high footprint in terms of human, material and schedule costs. Factoring functional, reusable logic in the application favors incremental development and contains costs. Yet, achieving incrementality in the timing behavior is a much harder problem. Complex features at all levels of the execution stack, aimed to boost average-case performance, exhibit timing behavior highly dependent on execution history, which wrecks time composability and incrementaility with it. Our goal here is to restitute time composability to the execution stack, working bottom up across it. We first characterize time composability without making assumptions on the system architecture or the software deployment to it. Later, we focus on the role played by the real-time operating system in our pursuit. Initially we consider single-core processors and, becoming less permissive on the admissible hardware features, we devise solutions that restore a convincing degree of time composability. To show what can be done for real, we developed TiCOS, an ARINC-compliant kernel, and re-designed ORK+, a kernel for Ada Ravenscar runtimes. In that work, we added support for limited-preemption to ORK+, an absolute premiere in the landscape of real-word kernels. Our implementation allows resource sharing to co-exist with limited-preemptive scheduling, which extends state of the art. We then turn our attention to multicore architectures, first considering partitioned systems, for which we achieve results close to those obtained for single-core processors. Subsequently, we shy away from the over-provision of those systems and consider less restrictive uses of homogeneous multiprocessors, where the scheduling algorithm is key to high schedulable utilization. To that end we single out RUN, a promising baseline, and extend it to SPRINT, which supports sporadic task sets, hence matches real-world industrial needs better. To corroborate our results we present findings from real-world case studies from avionic industry.

The Scrum approach to software development

Agile methodologies have become the standard approach to software development. The most popular and used one is Scrum. Scrum is a very simple and flexible framework that respond to unpredictability in a really effective way. However, his implementation must be correct, and since Scrum tells you what to do but not how to do it, this is not trivial. In this thesis I will describe the Scrum Framework, how to implement it and a tool that can help to do this. The thesis is divided into three parts. The first part is called Scrum. Here I will introduce the framework itself, its key concepts and its components. In Scrum there are three components: roles, meetings and artifacts. Each of these is meant to accomplish a series of specific tasks. After describing the “what to do”, in the second part, Best Practices, I will focus on the “how to do it”. For example, how to decide which items should be included in the next sprint, how to estimate tasks, and how should the team workspace be. Finally, in the third part called Tools, I will introduce Visual Studio Online, a cloud service from Microsoft that offers Git and TFVC repositories and the opportunity to manage projects with Scrum. == Versione italiana: I metodi Agile sono diventati l’approccio standard per lo sviluppo di software. Il più famoso ed utilizzato è Scrum. Scrum è un framework molto semplice e flessibile che risponde ai cambiamenti in una maniera molto efficace. La sua implementazione deve però essere corretta, e visto che Scrum ci dice cosa fare ma non come farlo, questo non risulta essere immediato. In questa tesi descriverò Scrum, come implementarlo ed uno strumento che ci può aiutare a farlo. La tesi è divisa in tre parti. La prima parte è chiamata Scrum. Qui introdurrò il framework, i suoi concetti base e le sue componenti. In Scrum ci sono tre componenti: i ruoli, i meeting e gli artifact. Ognuno di questi è studiato per svolgere una serie di compiti specifici. Dopo aver descritto il “cosa fare”, nella seconda parte, Best Practices, mi concentrerò sul “come farlo”. Ad esempio, come decidere quali oggetti includere nella prossima sprint, come stimare ogni task e come dovrebbe essere il luogo di lavoro del team. Infine, nella terza parte chiamata Tools, introdurrò Visual Studio Online, un servizio cloud della Microsoft che offre repository Git e TFVC e l’opportunità di gestire un progetto con Scrum.

Basistests Suisse Sport Test Konzept: Validierung einer sportmotorischen Basistestbatterie für den Schul- und Nachwuchssport

Physical fitness can be evaluated in competitive and school sports with different field tests under different conditions and goals. To produce valid results, a field test must be practical and reach high standards of test criteria (objectivity, reliability, validity). The purpose of this study was to investigate the test criteria and the practicability of a group of field tests called «SUISSE Sport Test Konzept Basis Feldtestbatterie». For 20-m sprint, ventral trunk muscle test, standing long jump, 2-kg medicine ball shot, obstacle course and cooper-test, test quality and practicability were evaluated. 221 children and adolescents from competitive sports and different school levels took part in the study. According to school level, they were divided into 3 groups (P: 7–11.5 y, S1: 11.6–15.5 y, S2: 15.6–21.8 y). Objectivity was tested for time or distance measurement in all tests as well as for error rating in obstacle test. For reliability measurement, 162 subjects performed the field tests twice within a few weeks. For validity results of standing long jump were compared with counter movement jump performance on a force plate. Correlation analysis was performed and level of significance was set for p < 0.05. For accuracy standard error was calculated. All tests achieved sufficient to excellent objectiv - ity with correlation-coefficient (r) lying between 0.85 and 0.99. Reliability was very good (r = 0.84–0.97). In cooper- and trunk test, reliability was higher for athletes than for pupils (trunk test: r = 0.95 vs. r = 0.62, cooper-test: r = 0.90 vs. r = 0.78). In those tests the reliability decreases with increasing age (cooper-test: P: r = 0.84, S1: r = 0.69, S2: r = 0.52; trunk-test: P: r = 0.69, S1: r = 0.71; S2: r = 0.39). Validity for standing long jump was good (r = 0.75–0.86). The standard error of the mean was between 4–8%, with the exception for cooper-test (athletes: 6%, pupils: 11%) and trunk test (athletes: 14%, pupils: 46%). The results show that the evaluated group of field tests is a practicable, objective and reliable tool to determine physical skills in young athletes as well as in a scholar setting over a broad age range. Most of the tests achieved the test criteria with the grades good to excellent. The lower coefficient of reliability for cooper- and trunk test by the pupils could be explained by motivational problems in this setting. For up to 20 subjects, a tester can accomplish the tests within 3 h. Finally, age-dependent grades were elaborated

Back to the future in one week - implementing a Smalltalk VM in PyPy

We report on our experiences with the Spy project, including implementation details and benchmark results. Spy is a re-implementation of the Squeak (i.e., Smalltalk-80) VM using the PyPy toolchain. The PyPy project allows code written in RPython, a subset of Python, to be translated to a multitude of different backends and architectures. During the translation, many aspects of the implementation can be independently tuned, such as the garbage collection algorithm or threading implementation. In this way, a whole host of interpreters can be derived from one abstract interpreter definition. Spy aims to bring these benefits to Squeak, allowing for greater portability and, eventually, improved performance. The current Spy codebase is able to run a small set of benchmarks that demonstrate performance superior to many similar Smalltalk VMs, but which still run slower than in Squeak itself. Spy was built from scratch over the course of a week during a joint Squeak-PyPy Sprint in Bern last autumn.

Hybrid bodies in cyborg sports? The case of Oscar Pistorius

The capabilities of postmodern biotechnology inevitably lead to questioning if it is morally acceptable to use all possibilities offered by technology. In sport, this very complex issue is dealt with by drawing clear boundaries between naturalness and artificiality. Currently, new biotechnology is constantly being produced and with this, boundaries between naturalness and artificiality, between normal and abnormal, human and hybrid are constantly shifting . “Human enhancement” is a fascinating prism that reflects contemporary questions of participation, justice, equality and the autonomy of the subject in all social fields. The area of elite sports is particularly affected by “human enhancement”, according to the principle of exceeding what has come before, of aiming higher, faster and further. This paper analyses the postulated “naturalness” in the regulative and normalising function in the area of elite sports, in connection with Foucault’s theory of governmentality. The example of the South African sprinter Oscar Pistorius appears to be particularly suited to illustrate current definition difficulties in the area of disabled and non-disabled people in differentiated competitive sports. His is a vivid example of a multifaceted body-sociological analysis of current sport culture and the construction of reality or naturalness in the framework of the discourse of drafting and negotiating the accreditation for sprint competitions of non-disabled athletes, most recently in the London Olympics 2012. Using the case study of Oscar Pistorius, the negotiating processes in relation to the argumentation logic, dynamics and resistance in shifting distinctions are presented in detail using the fundamental documents of the IOC, IPC, CAS and IAAF. Represented through the inclusion and exclusion processes are hierarchies of the body that are (re)consolidated and transformed. The central question emerges as to how the worth of equal opportunity and fairness in regard to “naturalness” can be reconsolidated or transformed.

Selbstkontrolle und Handlungsinitiierung

Gemäß den Annahmen des Kraftspeichermodells der Selbstkontrolle basiert die Fähigkeit, eigene Impulse zu kontrollieren, auf einer limitierten Ressource, die vorübergehend erschöpfen kann. Während dieses Erschöpfungszustandes können anschließende Selbstkontrollhandlungen weniger erfolgreich ausgeführt werden. Die Regulation des Impulses, einen Sprint möglichst zeitnah zu einem akustischen Startsignal zu initiieren, erfordert Selbstkontrolle. Daher testeten wir an einer Stichprobe aus N = 37 Sportstudierenden die Annahme, dass die Initiierung von Sprints in Leichtathletik von der momentan verfügbaren Selbstkontrollkraft abhängt. Zur Untersuchung dieser Fragestellung führten die Versuchspersonen zunächst zu T1 drei Sprints über ca. 20 Meter aus einem Startblock aus und mittels Kontaktplatten wurde die Reaktionszeit (in Millisekunden) gemessen, die die Versuchspersonen benötigten, um den Sprint nach einem akustischen Signal zu initiieren. Im Anschluss daran wurde die temporär verfügbare Selbstkontrollkraft mittels einer Abschreibaufgabe experimentell manipuliert: Die Versuchspersonen wurden zufällig einer Ego Depletion Bedingung zugeordnet, in der die Selbstkontrollkraft temporär erschöpft wurde oder einer Kontrollgruppe, in der die Selbstkontrollkraft intakt gehalten wurde. Im Anschluss daran zu T2 wurden die Versuchspersonen erneut gebeten, drei Sprints über ca. 20 Meter auszuführen und die Reaktionszeiten wurden wieder mittels Kontaktplatten erfasst. Die Ergebnisse einer mixed between (Ego Depletion, kein Ego Depletion) within (T1, T2) Varianzanalyse unterstützen unsere Hypothese, so dass in der Ego Depletion Bedingung die Reaktionszeiten von T1 (M = 0.35, SD = 0.03) zu T2 signifikant zunahmen (M = 0.38, SD = 0.04), F(1, 35) = 6.77, p = .01, η2partial = .16, wohingegen sich in der Kontrollgruppe keine statistisch bedeutsamen Veränderungen der Reaktionszeiten zeigten (T1: M = 0.36, SD = 0.03; T2: M = 0.35, SD = 0.04), F(1, 35) = 0.47, p = .50, η2partial = .01. Eine Stärkung der Selbstkontrollkraft könnte Athleten dabei helfen, ihr Leistungsoptimum abzurufen.

Ego depletion and action initiation

Optimal sprint start performance requires the self-control of responses. Therefore, start performance should depend on self-control strength. It was expected that momentary depletion of self-control strength (ego depletion) would slow down the initiation of a sprint start, resulting in impaired reaction times. N = 37 participants performed three sprint starts at T1 and the average reaction times were measured with a foot-pressure release system attached under the starting block (in ms). Next, participants were randomly assigned to a depletion or a non-depletion condition and self-control strength was experimentally manipulated by applying the transcription task. Following the depletion manipulation, participants performed another series of three sprints (T2). The results of a mixed between (ego depletion: yes vs. no) within (T1 vs. T2) ANOVA supported the hypothesis as average reaction times in the depletion condition significantly increased from T1 (M = 0.35, SD = 0.03) to T2 (M = 0.38, SD = 0.04), F(1, 35) = 6.77, p = .01, η2p = .16. Average reaction times in the non-depletion condition did not differ significantly between T1 (M = 0.36, SD = 0.03) and T2 (M = 0.35, SD = 0.04), F(1, 35) = 0.47, p = .50, η2p = .01. In line with the hypothesis, higher levels of self-control strength were associated with quicker movement initiations. Therefore, improving self-control strength may serve as a buffer against the negative effects of ego depletion on performance.

Failure Rate and Conductor Externalization of the Biotronik Linox / Sorin Vigila Implantable Cardioverter Defibrillator Lead

BACKGROUND We observed a case of conductor externalization in a Biotronik Linox lead. OBJECTIVE To investigate lead performance of the Linox and identical Sorin Vigila lead and prevalence of conductor externalization. METHODS We compared lead performance of all Linox and Vigila leads implanted at our center (BL group; n=93) with all Boston Scientific Endotak Reliance leads (ER group; n=190) and Medtronic Sprint Quattro leads (SQ group; n=202) implanted during the same period. We screened all BL group patients for conductor externalization. RESULTS We identified 8 cases of lead failures in the BL group (index case of conductor externalization; 6 cases of non-physiological high rate sensing; one case of high voltage conductor fracture). Prospective, fluoroscopic screening of 98% of all active BL group cases revealed one additional case of conductor externalization. Median follow-up was 41, 27 and 29 months for the BL group, ER group and SQ group, respectively, lead survival 94.9%, 99.2% and 100% at 3 years, and 88%, 97.5% and 100% at 5 years (p=0.038 for BL group vs. ER group, and p=0.007 for BL group vs. SQ group by the log-rank test). Younger age at implant was an independent predictor for lead failure in the BL group (adjusted HR 0.85 [95% confidence interval 0.77-0.94]; p=0.001). CONCLUSION At our center, survival of the Linox lead is 88% at five years and significantly worse than its comparators. Conductor externalization is present in a minority of failed Linox leads. Younger age at implant is an independent predictor of Linox lead failure.