OBJECTIVEWe sought to study and procure reference values for weight-related maximum isometric grip force (MIGF), maximum voluntary force in relation to body weight (Fmvrel) and peak whole body stiffness (pKwb) in multiple one-legged hopping (m1LH) in childhood.METHODSWe examined 868 children and adolescents (436 female) aged 3 to 19 yrs. Weight related results are reported as multiples of earth's gravity (g).RESULTSMIFG and Fmv(m1LH) are highly linearly correlated with body weight. After adjustment for weight, mean Fmvrel(m1LH) increases from the age of 3 to 6 yrs, then remains at 3.33 g (SD 0.31 g) between 6 and 19 yrs, independent of age and gender. The difference between legs decreases from 10% at 3 yrs to a constant 5.5% after the age of 7 yrs. Weight-adjusted MIGF also increases steeply from 3 to 6 yrs, then shows a further linear, less steep increase - in males through to age 19 yrs while females show a near-standstill after the age of 12 yrs. pKwb(m1LH) increases from the age of 7 yrs.CONCLUSIONThis data from normal children from a healthy Caucasian population provide a reference for tests of motor function.

Objectives: The aim of this cross-sectional study was to assess the vitamin D status and muscle function in children with NF1 compared with their unaffected siblings. Methods: NF1 children between 5 and 18 years of age and who had at least one unaffected sibling were identified. Serum concentrations of 25-hydroxyvitamin D (25(OH) D), calcium, inorganic phosphate, alkaline phosphate, parathyroid hormone and 1,25-dihydroxyvitamin D were measured. The Leonardo Mechanography Ground Reaction Force Platform (GRFP) was used to measure EFI, jump power, force and height. Results: There was no significant difference in 25(OH) D between NF1 subjects and unaffected siblings. Relative jump power and force were found to be significantly different. The adjusted means (95% confidence limits) of non-NF1 and NF1 children for relative jump power (W/kg), controlling for body mass and age, were 37.31 (34.14, 40.49) and 32.51 (29.34, 35.68), respectively (P=0.054); and force (N/kg), controlling for body mass, age and gender, were 25.79 (24.28, 27.30) and 21.12 (19.61, 22.63), respectively (P<0.0001). Jumping parameters were not related to serum 25(OH) D. Conclusions: There was no significant relationship between vitamin D status and NF1 status in children. NF1 children had significantly impaired jumping power and force, when compared to their unaffected siblings.

Maintaining neuromuscular function in older age is an important topic for aging societies, especially for older women with low bone density who may be at risk of falls and bone fracture. This randomized controlled trial investigated the effect of resistive exercise with either whole-body vibration training (VIB) or coordination/balance training (BAL) on neuromuscular function (countermovement jump, multiple 1-leg hopping, sit-to-stand test). 68 postmenopausal women with osteopenia or osteoporosis were recruited for the study. 57 subjects completed the 9-month, twice weekly, intervention period. All subjects conducted 30min of resistance exercise each training day. The VIB-group performed additional training on the Galileo vibration exercise device. The BAL-group performed balance training. An "intent-to-treat" analysis showed greater improvement in the VIB-group for peak countermovement power (p=0.004). The mean [95% confidence interval] effect size for this parameter was a +0.9[0.3 to 1.5] W/kg greater change in VIB than BAL after 9 months. In multiple 1-leg hopping, a significantly better performance in the VIB-group after the intervention period was seen on a "per-protocol" analysis only. Both groups improved in the sit-to-stand test. The current study provides evidence that short-duration whole-body vibration exercise can have a greater impact on some aspects of neuromuscular function in post-menopausal women with low bone density than proprioceptive training.

OBJECTIVE:We sought to procure age- and gender- related reference data and study the characteristics of body weight related peak force (pFrel), body mass related peak power (pPrel) for counter movement jumps (single two-legged jumps, s2LJ) and chair rising tests (CRT) in children.METHODS:We examined 868 healthy participants (436 female) aged 3 to 19 years. Weight-related results of the s2LJ and CRT Mechanography parameters were reported.RESULTS:pPrel during s2LJ (pPrel(s2LJ)) increased linearly with age for males age 5 to 19 and female age 5 to 11 at a rate of 4.6 W/kg per year. pPrel(s2LJ) for females age 12 to 19 increased only by 2.5 W/kg. CRT time per repetition was 1.065 s, independent of age and gender. pPrel per body mass during the rise phase (pPrel(CRT)) showed similar but smaller age and gender relations as peak power during s2LJ. pFrel was 2.5 g (multiples of earth's gravity) for s2LJ and 1.5 g for CRT.CONCLUSION:This data from normal children from a healthy Caucasian population provide reference values for tests that reflect everyday motor function.

Individuals who are involved in explosive sport types, such as 100-m sprints and long jump, have greater bone density, leg muscle size, jumping height and grip strength than individuals involved in long-distance running.

OBJECTIVESTo assess adaptations of the lower leg muscle-bone unit in 8- to 12-year-old children following a randomized controlled jumping exercise intervention for 9 months.METHODSTwelve boys and 10 girls (INT) performed a supervised jumping protocol during the first 10 min of their regularly scheduled physical education class twice a week, while 11 boys and 12 girls (CON) completed the regular curriculum. We assessed maximum voluntary ground reaction force during multiple one-legged hopping (F(m1LH)), and tibial bone strength/geometry by peripheral quantitative computed tomography (pQCT) at the 4-, 14-, 38- and 66%-site pre, intermediate, and post intervention.RESULTSWhether increases in F(m1LH) (+2.1% points, P= 0.752), nor changes in bone strength/geometry (+1 to +3% points, 0.169<P<0.861), were significantly different for INT relative to CON. The relationship between F(m1LH) and volumetric bone mineral content at the 14%-site (vBMC(14%)) was very strong for both groups, pre and post intervention (0.51≤R(2)≤0.88). However, changes in F(m1LH) and vBMC(14%) were not correlated.CONCLUSIONSIn children, growth and exercise did not increase maximum muscle force and bone strength in proportion to each other, meaning that the adaptive processes were not tightly coupled or follow different time courses.

Context: There has been a resurgence of vitamin D deficiency rickets throughout the developed world, with infants and adolescents being primarily affected. Adolescence is a crucial period for muscle and bone mineral accumulation. Objective: The aim was to determine the effect of vitamin D supplementation on the adolescent musculoskeletal system. Design and Setting: We conducted a community-based, double-blind, randomized controlled trial in a secondary school. Participants: Postmenarchal 12- to 14-yr-old females participated in the trial. Ninety-nine were screened, 73 were included in randomized controlled trial, and 69 completed the trial. There were no adverse events. Intervention: Four doses of 150,000 IU vitamin D2 (ergocalciferol) were given over 1 yr. Main Outcome Measures: Dual-energy x-ray absorptiometry, peripheral quantitative computed tomography, and jumping mechanography were used. Results: At follow-up, 25-hydroxyvitamin D [25(OH)D] status was 56.0 ± 8.9 nmol/liter in the intervention group and 15.8 ± 6.6 nmol/liter in controls. There were no effects of supplementation on bone; however, for muscle function, efficiency of movement improved in the vitamin D-treated group. There was an interaction between baseline 25(OH)D concentration and response to vitamin D supplementation for muscle jump velocity. Conclusions: Despite improvements in 25(OH)D status, treatment with vitamin D2 was not shown to increase mineral accretion, bone geometry or strength, muscle force, or power. There were greater increases in jump velocity in girls with the lowest baseline 25(OH)D concentrations. Lack of effect of intervention after the period of peak mineral and muscle mass accretion suggests that earlier action is required.

Article REALISIERUNG EINES LASER-VIBROMETERSYSTEMS ZUR BERÜHRUNGSLOSEN IN VIVO BESTIMMUNG DES INTRAOKULARDRUCKS was published on January 1, 2001 in the journal Biomedical Engineering / Biomedizinische Technik (volume 46, issue s1).

CONTEXT:There has been a resurgence of vitamin D deficiency among infants, toddlers, and adolescents in the United Kingdom. Myopathy is an important clinical symptom of vitamin D deficiency, yet it has not been widely studied.OBJECTIVE:Our objective was to investigate the relationship of baseline serum 25 hydroxyvitamin D [25(OH)D] concentration and PTH with muscle power and force.DESIGN:This was a cross-sectional study.SETTING:The study was community based in a secondary school.PARTICIPANTS:A total of 99 post-menarchal 12- to 14-yr-old females was included in the study.MAIN OUTCOME MEASURES:Jumping mechanography to measure muscle power, velocity, jump height, and Esslinger Fitness Index from a two-legged counter movement jump and force from multiple one-legged hops was performed. Body height, weight, and serum concentrations of 25(OH)D, PTH, and calcium were measured.RESULTS:Median serum 25(OH)D concentration was 21.3 nmol/liter (range 2.5-88.5) and PTH 3.7 pmol/liter (range 0.47-26.2). After correction for weight using a quadratic function, there was a positive relationship between 25(OH)D and jump velocity (P = 0.002), jump height (P = 0.005), power (P = 0.003), Esslinger Fitness Index (P = 0.003), and force (P = 0.05). There was a negative effect of PTH upon jump velocity (P = 0.04).CONCLUSION:From these data we conclude that vitamin D was significantly associated with muscle power and force in adolescent girls.

INTRODUCTION:In cystic fibrosis (CF), bone mass deficits as well as a lack of muscle mass and force have been described. The bone mass deficits are thought to be at least in part secondary to the reduced muscle mass. Whole body vibration has recently been suggested as an effective technique to increase muscle force and power. The aim of this pilot study was to evaluate the compliance and safety of a side-alternating, whole body vibration platform in patients with CF and to assess its effects on muscle force, muscle power, bone mass and lung function.PATIENTS AND METHODS:Eleven adult CF patients participated in a six-months home-based training programme on a whole body vibration platform. Muscle force and power were assessed with three standard manoeuvres on a ground reaction force plate at regular intervals. Bone densitometry was performed at the spine, the radius and the tibia using quantitative computerized tomography.RESULTS:Regular cardiovascular monitoring did not show any critical drop in oxygen saturation or blood pressure. Lung function remained relatively constant with a median FEV1 change [% of norm] of -3.1% (range -7-20). Trabecular density at the spine and parameters of bone density and geometry at the radius and tibia did not show consistent changes. A median decrease of -0.3% (-31.0-17.9) for muscle force and a median increase of 4.7% (-16.4-74.5) for muscle power and 6.6% (-0.9-48.3) for velocity was noted in the two-leg jump. In the one-leg jump, a median increase of 6.7% (-8.5-24.3) for muscle force was measured.CONCLUSIONS:Whole body vibration was well tolerated in the majority of the study participants. Most patients were able to increase peak force in the one-leg jump. In the two-leg jump, velocity and muscle power increased with equal or decreased muscle force. This may indicate an improvement in neuromuscular and intramuscular co-ordination (and therefore efficiency) with less muscle force necessary to generate the same power.

PURPOSE: To compare the imaging quality of several commercially available intraocular lenses (IOLs) using the modulation transfer function (MTF) method according to the requirements of the International Standard European Industrial Norm/International Organization for Standardization 11979.SETTING: Universitat fur Technik der Informationsverarbeitung, Universitat Karlsruhe, Karlsruhe and Universitats Augenklinik, Ulm, Ulm, Germany.METHODS: Two refractive powers (+ 13 diopter [D] and + 26 D) of each IOL type were tested. The imaging quality of all tested IOLs was measured before the injection test and in 5-minute intervals after the injection for 40 minutes. The measurement data were analyzed according to 2 quality criteria, Strehl ratio and the ISO condition. For analysis of the type of optical design, SEM images of the central cross section were taken of each IOL. Basic terms in optics such as MTF, resolution, and optical aberration are introduced, and their relevance for ophthalmology is discussed in detail. This paper represents an extensive study comparing the imaging quality of various IOLs including the comparison of measurements before and after injection through a cartridge as used for state-of-the-art implantation techniques. All measurements were performed using an MTF measurement system using a 546 nm optimized laser source and an effective aperture of 3.0 mm on the IOL according to ISO standard. An ISO standard eye model using an artificial cornea (spherical design) and a watery solution to simulate in vivo conditions was used.RESULTS: All IOLs apart from 1 + 26 D lens complied with ISO standard requirements. However, the imaging quality varied up to 49% depending on the optical design and the manufacturing quality.CONCLUSION: When the methods and materials recommended by the manufacturer for IOL injection through a cartridge were used, no long-term effect on the imaging quality of the IOLs was observed. However, the basic imaging quality of different designs and different manufacturers varied significantly (up to 50% at + 26 D) IOLs and should be considered when choosing an IOL. (c) 2005 ASCRS and ESCRS.

BACKGROUND:Foldable intraocular lenses (IOLs) are established in ophthalmic surgery and increasingly more complex geometries are available. This study investigates different designs of the optics of the IOL as well as the imaging quality of these optics utilizing electron microscopic photographs and mathematical approximations.METHOD:Included in this study were two different lens powers of common IOLs (+ 13 D and + 26 D). All studied IOLs were processed depending upon their water content: Aqueous IOLs with up to 25 % water content were fixed with 2.5 % glutaraldehyde in 0.1 M phosphate buffer (mPP), and then contrasted with 2 % OsO (4) and processed in an alcohol series of 30 - 100 % propanol. Subsequently, the IOLs were transferred into EPON (epoxy resin) and polymerization took place at 60 degrees C. After hardening, the samples were cut out with a leaves saw and divided into halves. Afterwards these were polished with glass and diamond knifes at the ultramicrotom (Ultracut, Rückert-Jung). After coal vaporization measurement took place in the scanning electron microscope (DSM 962, Zeiss). In the case of dry stored IOLs, the samples were sputtered with Au-Pd 20 nm and afterwards measurement was performed as described above. The measurement of the optical imaging quality was performed with correctly and inversely oriented IOLs according to the standard EN ISO 11979 -- 2 by means of a measuring system which works on the basis of the point spread function (PSF) and/or the modulation transfer function (MTF). From this the Strehl ratio was computed in each case.RESULTS:Utilizing a correlation of the electron microscopic investigation of the optics of different IOLs with their imaging quality (Strehl ratio), we were able to show that the optical design of the IOL has substantial influence on the imaging quality of an intraocular lens. In particular, with non-symmetrical designs of the optics (e. g., AR40 e; AMO) the orientation of an IOL in the eye is crucial; i. e., the Strehl ratio increased thereby from 0.68 to 0.87.CONCLUSIONS:The design of asymmetrical optics is crucial and much attention should be paid to the fact that the imaging quality can substantially be affected. A correct orientation of the lens within the eye is very important with these asymmetrical optics.

Zuletzt sind viel neue, von ihrem Konzept sehr unterschiedliche, intraokulare Multifokalinsen (MIOLs) auf den Markt gekommen. Ziel war es, an einem künstlichen Standardauge die Abbildungsqualität dieser neuen MIOLs zu untersuchen.

Hintergrund: Nachdem sich faltbare Intraokularlinsen in der Ophthalmochirurgie etabliert haben, werden immer komplexere Optikdesigns für Intraokularlinsen (IOL) angeboten. Diese Studie untersucht mithilfe von elektronenmikroskopischen Aufnahmen und Modellrechungen vergleichend die unterschiedlichen Designs der Optiken von IOL sowie der aus dem Optikdesign resultierenden Abbildungsqualität. Methode: Untersucht wurden von jedem IOL-Typ jeweils zwei unterschiedliche Linsenstärken (i. d. R. + 13 D und + 26 D). Alle untersuchten faltbaren IOL wurden je nach ihrem Wassergehalt (wasserhaltige IOL bis 25 % Wassergehalt) entweder mit 2,5 % Glutaraldehyd in 0,1-molarem Phosphatpuffer (mPP) fixiert, dann mit 2 % OsO4 kontrastiert und in einer Alkoholreihe 30 - 100 % Propanol entwässert. Anschließend erfolgte das Einlegen in EPON (Epoxidharz) und Polymerisation bei 60 °C. Nach Aushärten wurden die Proben mit einer Laubsäge ausgesägt und halbiert, danach mit Glasmesser und Diamantmesser am Ultramikrotom glatt geschnitten (Ultracut von Rückert-Jung). Nach der Kohlebedampfung erfolgte die Vermessung im Rasterelektronenmikroskop (DSM 962 Zeiss). Bei den trocken gelagerten IOL erfolgte Besputterung mit Au-Pd 20 nm und danach Messung wie oben beschrieben. Die Messung der optischen Abbildungseigenschaften erfolgte bei den jeweils richtig bzw. falsch herum orientierten IOLs nach der Norm EN ISO 11979 - 2 mittels eines Messsystems, das auf der Analyse der Punktbildfunktion (PSF) bzw. der Modulationstransferfunktion (MTF) beruht. Hieraus wurde jeweils die Strehl-Ratio berechnet. Ergebnisse: Mithilfe der Korrelation der elektronenmikroskopischen Untersuchung der Optiken unterschiedlicher IOL mit den Abbildungsqualitäten derselben (Strehl-Ratio) konnte gezeigt werden, dass das optische Design einer IOL wesentlichen Einfluss auf die Abbildungsqualität einer Intraokularlinse hat. Insbesondere ist bei nichtsymmetrischer Gestaltung der Optik (z. B. AR40 e; AMO) die Orientierung der IOL im Auge entscheidend; die Strehl-Ratio ändert sich hierdurch beispielsweise von 0,68 auf 0,87. Schlussfolgerungen: Beim Design von asymmetrischen Optiken sollte sorgfältig darauf geachtet werden, dass die Abbildungsqualität erheblich beeinflusst werden kann. Eine richtige Orientierung der Linse im Auge ist z. B. bei asymmetrischen Optiken sehr wichtig.

BACKGROUND:Diabetes mellitus is one of the most common diseases in industrialized countries as well as in emerging economies such as India or China. One of the key technologies for diabetes therapy is semi-continuous monitoring of the glucose level of diabetics.METHODS:Compared with skin-perforating techniques, optical measurement techniques promising good results bear the potential for high patient compliance with more frequent measurements. Due to its excellent optical properties, the anterior chamber and the aqueous humor (AH) contained therein offer promise for non-invasive in vivo glucose measurements. However, a number of strongly limiting factors, such as the precise optical properties of the eye, laser safety regulations and subconscious eye movements during the measurement period have to be considered for in vivo applications.RESULTS:This article presents a high-resolution polarimetric measurement system that utilizes the optical rotatory dispersion (optical activity) of the glucose molecule for measurements of the glucose concentration in AH.CONCLUSION:Based on this example of a suitable optical measurement system, the special limitations and conditions that have to be considered for in vivo glucose measurement at the human eye are presented and analyzed. This includes the optical properties of the cornea and the anterior chamber, the impact of typical eye movements during a measurement and laser safety regulations.

Article ANALYSIS OF SIGNAL PROCESSING SCHEME FOR POLARIMETRIC INVIVO GLUCOSE MEASUREMENT IN AQUEOUS HUMOR was published on January 1, 2003 in the journal Biomedical Engineering / Biomedizinische Technik (volume 48, issue s1).

Continuous monitoring of the glucose level is a key technology for improved diagnosis and therapy of Diabetes Mellitus patients. Non-invasive optical measurement techniques at the Anterior Chamber of the eye suffer from the lack of intensity of reflected light and the very small magnitudes of the optical effects. Hence using higher magnitude physical and/or chemical effects as primary effects and using non-contact optical readout increases feasibility for in-vivo measurement systems substantially. Hence this article proposes a miniaturized micro structured measurement cell covered by a semi permeable diaphragm to be implanted micro invasively into the anterior chamber of the eye. Osmotic pressure within this cell depends on the intraocular glucose concentration and is translated into deformation of the diaphragm which is measured using white light interferometry. A bio-compatible micro structured interference filter has to be added on parts of the diaphragm to ensure high reflection properties crucial for optical deformation measurement. The article also discusses the special requirements of in-vivo measurements for the optical measurement system.