Jumping Mechanography: Reference Centiles in Childhood and Introduction of the Nerve-Muscle Index to Quantify Motor Efficiency

Jumping mechanography provides robust motor function indicators among children. The study aim was to develop centiles for the single 2-leg jump (S2LJ) in German children and adolescents and to identify differences in children with obesity. Data were collected in 2004-2021 through the German DOrtmund Nutritional and Anthropometric Longitudinally Designed (DONALD) study. All participants (6-18 years, mean age 11.4) performed annually an S2LJ aiming for maximum height on a Ground Reaction Force Platform. LMS (lambda-mu-sigma), including resampling, was used to develop centiles for velocity (vmax), jump height (hmax), relative force (Fmax/BW), relative power (Pmax/mass), impulse asymmetry and a new parameter to describe jump efficiency, the Nerve-Muscle Index (NMI), defined as vmax/(Fmax/BW). Data from 882 children and adolescents were analyzed (3062 measurements, median 3 per individual). In females, Fmax/BW values were higher in younger age but remained constant in adolescence. vmax, hmax and Pmax/mass increased in childhood, reaching a plateau in adolescence. In males, vmax, hmax and Pmax/mass showed a constant increase and the Fmax/BW remained lower. Children with obesity showed lower Fmax/BW, hmax, vmax and the NMI, hence, lower velocity per relative force unit and less efficient jump. The centiles should be used to monitor motor development in childhood. The NMI is a surrogate for motor efficiency.

Mechanographic analysis of the timed 4 stair climb test - methodology and reference data of healthy children and adolescents

OBJECTIVES

The timed 4 stair climb test (4SC) is an accepted and widely used tool to assess motor function of patients with neuromuscular diseases. We aimed to establish reference data for the 4SC, and for mechanographic analysis of ascent (4SC-Up) and descent (4SC-Dn) in healthy children and adolescents.

METHODS

We used a custom-made staircase measuring device to assess force, power and velocity during the ascent of 4 stairs in healthy subjects. Secondary outcome measures included mechanographic analyses such as the Chair-Rising-test and the myometric Grip Force-test.

RESULTS

Data of 288 participants aged 4 to 16 years (144 males, 144 females) were analyzed. A simple algorithm integrating the minimal applied force was used to compensate for different movement strategies. Percentiles for average power, force and horizontal velocity were calculated. While results of the 4SC-Up test showed no age or gender dependency, we found 4SC-Dn results to be age dependent. Mean device measured times were significantly shorter than manually measured times (mean difference -0.19 s; p<0.001).

CONCLUSIONS

Mechanographic analysis of the 4SC appears to be a promising tool for evaluation of muscle strength and function of the lower extremities as it enables physically exact measurements of a highly relevant activity of daily living.

Age-Related Declines in Lower Limb Muscle Function are Similar in Power and Endurance Athletes of Both Sexes: A Longitudinal Study of Master Athletes

The age-related decline in muscle function, particularly muscle power, is associated with increased risk of important clinical outcomes. Physical activity is an important determinant of muscle function, and different types of physical activity e.g. power-based versus endurance-based exercise appear to have differential effects on muscle power. Cross-sectional studies suggest that participation in power-based exercise is associated with greater muscle power across adulthood but this has not been investigated longitudinally. We recruited eighty-nine male and female power and endurance master athletes (sprint and distance runners respectively, baseline age 35-90y). Using jumping mechanography, we measured lower limb muscle function during a vertical jump including at least two testing sessions longitudinally over 4.5 ± 2.4y. We examined effects of time, discipline (power/endurance) and sex in addition to two- and three-way interactions using linear mixed-effects models. Peak relative power, relative force and jump height, but not Esslingen Fitness Index (indicating peak power relative to sex and age-matched reference data) declined with time. Peak power, force, height and EFI were greater in power than endurance athletes. There were no sex, discipline or sex*discipline interactions with time for any variable, suggesting that changes were similar over time for athletes of both sexes and disciplines. Advantages in lower limb muscle function in power athletes were maintained with time, in line with previous cross-sectional studies. These results suggest that improvements in lower limb function in less active older individuals following power-based training persist with continued adherence, although this requires further investigation in interventional studies.

Mechanography in children: pediatric references in postural control

OBJECTIVE

To establish pediatric age- and sex-specific references for measuring postural control with a mechanography plate in a single centre, prospective, normative data study.

METHODS

739 children and adolescents (396 male/343 female) aged 4 to 17 years were studied. Each participant completed the following test sequence three times: Romberg, semi-tandem, tandem, each with eyes open and closed, and a one-leg stand with eyes open, and a single two-legged jump. Normal ranges were determined based on percentile calculations using the LMS method. Results from the two-legged jump were compared to a reference population the single two-legged jump (s2LJ) assessment in 2013.

RESULTS

38 different equilibrium parameters calculated were analysed. Of all parameters Path Length, vCoFmean, Equilibrium Score and Sway Angle showed a low variation within the same age group but high dependency on age and were thus chosen for automated balance assessment.

CONCLUSION

Standard values of postural control in healthy children derived from automated balance testing using a mechanography plate were successfully acquired and a subset of parameters for automated balance assessment identified.

Determinants of muscle power and force as assessed by Jumping Mechanography in rural Indian children

OBJECTIVES

To: 1. Assess muscle function (MF) of rural Indian children (6-11y, n=232), using Jumping Mechanography (JM) and hand dynamometer, 2. Investigate gender differences, 3. Identify determinants of MF.

METHODS

Data on anthropometry, muscle mass%, diet, physical activity, sunlight exposure, MF (maximum relative power Pmax/mass, maximum relative force Fmax/BW by JM; relative grip strength (RGS) by hand dynamometer) were collected. Pearson's correlation and hierarchical linear regression was performed.

RESULTS

Pmax/mass, Fmax/BW and RGS of the group were 31.7±5.0W/kg, 3.0±0.3 and 0.4±0.1 (mean±SD), respectively. The Pmax/mass Z-score was -1.1±0.9 and Fmax/BW Z-score was -0.9±1 (mean±SD) which was significantly lower than the machine reference data (p<0.05). Positive association of muscle mass% and protein intake was observed with all MF parameters and moderate+vigorous physical activity with Fmax/BW (p<0.05). Determinants of MF identified through regression for Pmax/mass were age (β=1.83,95% CI=0.973 - 2.686), muscle mass% (β=0.244,95% CI=0.131-0.358) and protein intake (β=3.211,95% CI=1.597-4.825) and for Fmax/BW was protein intake (β=0.130,95% CI=0.023-0.237) (p<0.05). Male gender was a positive predictor of having higher Pmax/mass (β=1.707,95% CI=0.040-3.373) (p<0.05).

CONCLUSION

MF was lower than in western counterparts. To optimize MF of rural Indian children, focus should be on improving muscle mass, ensuring adequate dietary protein, and increasing physical activity, especially in girls.

Jumping Mechanography is a Suitable Complementary Method to Assess Motor Function in Ambulatory Boys with Duchenne Muscular Dystrophy

OBJECTIVE

The number of clinical trials for Duchenne muscular dystrophy (DMD) has increased substantially lately, therefore appropriate clinical instruments are needed to measure disease progression and drug efficacy. Jumping mechanography is a medical diagnostic method for motion analysis, which allows to quantify physical parameters. In this study, we compared mechanography with timed function tests (TFTs).

METHODS

41 ambulatory DMD patients performed a total of 95 chair rising tests (CRT) and a total of 76 single two-legged jumps (S2LJ) on a mechanography ground reaction force platform. The results were correlated with a 6-minute walk test (6MWT) and the time required to run 10 meters, stand up from a supine position, and climb four stairs, all performed in the same setting.

RESULTS

Our measurements show a high correlation between mechanography and the TFTs: S2LJ/10-m run, r = 0.62; CRT/10-m run, r = 0.61; S2LJ/standing up from supine, r = 0.48; CRT/standing up from supine, r = 0.58; S2LJ/climb four stairs, r = 0.55; CRT/climb four stairs, r = 0.51. The correlation between mechanography and the 6MWT was only moderate with r = 0.38 for S2LJ/6MWT and r = 0.39 for CRT/6MWT.

INTERPRETATION

Jumping mechanography is a reliable additional method, which can be used for physical endpoint measurements in clinical trials. We confirmed our assumption, that the method provides additional information concerning performance at movement with higher power output. We suggest using the S2LJ as a first-choice tandem tool combined with the 6MWT. In patients with higher disability, the CRT is an alternative measuring method, because with the progression of the disease this is longer feasible.

Potential Application of Whole Body Vibration Exercise For Improving The Clinical Conditions of COVID-19 Infected Individuals: A Narrative Review From the World Association of Vibration Exercise Experts (WAVex) Panel

COVID-19 is a highly infectious respiratory disease which leads to several clinical conditions related to the dysfunction of the respiratory system along with other physical and psychological complaints. Severely affected patients are referred to intensive care units (ICUs), limiting their possibilities for physical exercise. Whole body vibration (WBV) exercise is a non-invasive, physical therapy, that has been suggested as part of the procedures involved with pulmonary rehabilitation, even in ICU settings. Therefore, in the current review, the World Association of Vibration Exercise Experts (WAVEX) reviewed the potential of WBV exercise as a useful and safe intervention for the management of infected individuals with COVID-19 by mitigating the inactivity-related declines in physical condition and reducing the time in ICU. Recommendations regarding the reduction of fatigue and the risk of dyspnea, the improvement of the inflammatory and redox status favoring cellular homeostasis and the overall improvement in the quality of life are provided. Finally, practical applications for the use of this paradigm leading to a better prognosis in bed bound and ICU-bound subjects is proposed.

Jumping Mechanography as a Complementary Testing Tool for Motor Function in Children with Hereditary Motor and Sensory Neuropathy

Objective This study aims to compare mechanography, measuring force in jumping, and rising, with the 6-minute walk test (6MWT) and time function tests in pediatric patients with hereditary motor and sensory neuropathies.

Methods A cohort of 23 patients performed the 6MWT and time function tests (time to run 10 m, to rise from a supine position, and to climb four stairs), as well as the chair rising test (CRT) and the single two-legged jump (S2LJ) on a mechanography ground reaction force platform. Results were correlated calculating linear regression.

Results Correlation revealed high or moderate correlation between mechanography and the 6MWT and the time function tests: S2LJ/6MWT = 0.64; CRT/6MWT = 0.52; S2LJ/rising from floor = 0.63; CRT/rising from floor = 0.67; S2LJ/10 m run = 0.74; CRT/10 m run = 0.66; S2LJ/climb four stairs = 0.56; CRT/climb four stairs = 0.47.

Conclusion Jumping mechanography is a good additional tool for the assessment of pediatric patients with Charcot-Marie-Tooth disease and might be used for primary outcome measures. It was not feasible in more advanced stages of the disease. In less disabled children, the S2LJ, which quantifies force generated by proximal and distal muscles, might be superior to other tests.

Associations of muscle force, power, cross-sectional muscle area and bone geometry in older UK men

BACKGROUND

Ageing is associated with sarcopenia, osteoporosis, and increased fall risk, all of which contribute to increased fracture risk. Mechanically, bone strength adapts in response to forces created by muscle contractions. Adaptations can be through changes in bone size, geometry, and bending strength. Muscle mass is often used as a surrogate for muscle force; however, force can be increased without changes in muscle mass. Increased fall risk with ageing has been associated with a decline in muscle power-which is a measure of mobility. The aims of this study were as follows: (i) to investigate the relationship between muscle parameters in the upper and lower limbs with age in UK men and the influence of ethnicity on these relationships; (ii) to examine the relationships between jump force/grip strength/cross-sectional muscle area (CSMA) with bone outcomes at the radius and tibia.

METHODS

White European, Black Afro-Caribbean, and South Asian men aged 40-79 years were recruited from Manchester, UK. Cortical bone mineral content, cross-sectional area, cortical area, cross-sectional moment of inertia, and CSMA were measured at the diaphysis of the radius and tibia using peripheral quantitative computed tomography. Lower limb jump force and power were measured from a single two-legged jump performed on a ground-reaction force platform. Grip strength was measured using a dynamometer. Associations between muscle and bone outcomes was determined using linear regression with adjustments for age, height, weight, and ethnicity.

RESULTS

Three hundred and one men were recruited. Jump force was negatively associated with age; for every 10 year increase in age, there was a 4% reduction in jump force (P < 0.0001). There was a significant age-ethnicity interaction for jump power (P = 0.039); after adjustments, this was attenuated (P = 0.088). For every 10 year increase in age, grip strength decreased by 11%. Jump force was positively associated with tibial bone outcomes: a 1 standard deviation greater jump force was associated with significantly higher cortical bone mineral content 3.1%, cross-sectional area 4.2%, cortical area 3.4%, and cross-sectional moment of inertia 6.8% (all P < 0.001). Cross-sectional muscle area of the lower leg was not associated with tibial bone outcomes. Both grip strength and CSMA of the arm were positively associated, to a similar extent, with radius diaphyseal bone outcomes.

CONCLUSIONS

Jump force and power are negatively associated with age in UK men. In the lower limb, the measurement of jump force is more strongly related to bone outcomes than CSMA. It is important to consider jump force and power when understanding the aetiology of bone loss and mobility in ageing men.

A randomized exploratory phase 2 study in patients with chemotherapy-related peripheral neuropathy evaluating whole-body vibration training as adjunct to an integrated program including massage, passive mobilization and physical exercises

BACKGROUND

Chemotherapy-induced polyneuropathy (CIPN) is a common toxicity after chemotherapy, immunomodulatory drugs or proteasome inhibitors, which is difficult to treat and may also have impact on quality of life. The objective of the study was to evaluate whole-body vibration (WBV) on the background of an integrated program (IP) including massage, passive mobilization and physical exercises on CIPN.

PATIENTS AND METHODS

In an exploratory phase-2 study patients with CIPN (NCI CTC grade 2/3) were randomized for WBV plus IP (experimental) to IP alone (standard). 15 training sessions within 15 weeks were intended. As primary endpoint we used chair-rising test (CRT) to assess physical fitness and coordination. In addition, locomotor and neurological tests and self-assessment tools were performed.

RESULTS

A total 131 patients with CIPN were randomized (standard, n = 65; experimental, n = 66). The median age was 60 (range 24-71) years; 44 patients had haematological neoplasms and 87 solid tumors. At baseline, all patients presented with an abnormal CRT. Fifteen (standard) and 22 (experimental) patients left the program due to progression/relapse or concomitant disease. There was no significant difference in the proportion of patients with normal CRT (<10 s) at follow up between experimental (68%) and standard (56%) (p = 0.20). All patients experienced less symptoms and pain (p < 0.001) and had improved CRT (p < 0.001) over time. WBV was significantly associated with a higher reduction of time needed for CRT (p = 0.02) and significantly improved warm-detection-threshold comparing baseline to follow-up assessment (p = 0.02).

CONCLUSION

Whole-body vibration on the background of an IP may improve physical fitness and coordination in patients suffering from CIPN. Trial registration Retrospectively registered at http://www.iscrtn.com (ISRCTN 51361937) and http://www.clinicaltrials.gov (NCT02846844).

Greater association of peak neuromuscular performance with cortical bone geometry, bone mass and bone strength than bone density: A study in 417 older women

BACKGROUND

We evaluated which aspects of neuromuscular performance are associated with bone mass, density, strength and geometry.

METHODS

417 women aged 60-94years were examined. Countermovement jump, sit-to-stand test, grip strength, forearm and calf muscle cross-sectional area, areal bone mineral content and density (aBMC and aBMD) at the hip and lumbar spine via dual X-ray absorptiometry, and measures of volumetric vBMC and vBMD, bone geometry and section modulus at 4% and 66% of radius length and 4%, 38% and 66% of tibia length via peripheral quantitative computed tomography were performed. The first principal component of the neuromuscular variables was calculated to generate a summary neuromuscular variable. Percentage of total variance in bone parameters explained by the neuromuscular parameters was calculated. Step-wise regression was also performed.

RESULTS

At all pQCT bone sites (radius, ulna, tibia, fibula), a greater percentage of total variance in measures of bone mass, cortical geometry and/or bone strength was explained by peak neuromuscular performance than for vBMD. Sit-to-stand performance did not relate strongly to bone parameters. No obvious differential in the explanatory power of neuromuscular performance was seen for DXA aBMC versus aBMD. In step-wise regression, bone mass, cortical morphology, and/or strength remained significant in relation to the first principal component of the neuromuscular variables. In no case was vBMD positively related to neuromuscular performance in the final step-wise regression models.

CONCLUSION

Peak neuromuscular performance has a stronger relationship with leg and forearm bone mass and cortical geometry as well as proximal forearm section modulus than with vBMD.

Bone density and neuromuscular function in older competitive athletes depend on running distance

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.

INTRODUCTION

The purpose of this study is to examine the relationship between different types of physical activity with bone, lean mass and neuromuscular performance in older individuals.

METHODS

We examined short- (n = 50), middle- (n = 19) and long-distance (n = 109) athletes at the 15th European Masters Championships in Poznań, Poland. Dual X-ray absorptiometry was used to measure areal bone mineral density (aBMD) and lean tissue mass. Maximal countermovement jump, multiple one-leg hopping and maximal grip force tests were performed.

RESULTS

Short-distance athletes showed significantly higher aBMD at the legs, hip, lumbar spine and trunk compared to long-distance athletes (p ≤ 0.0012). Countermovement jump performance, hop force, grip force, leg lean mass and arm lean mass were greater in short-distance athletes (p ≤ 0.027). A similar pattern was seen in middle-distance athletes who typically showed higher aBMD and better neuromuscular performance than long-distance athletes, but lower in magnitude than short-distance athletes. In all athletes, aBMD was the same or higher than the expected age-adjusted population mean at the lumbar spine, hip and whole body. This effect was greater in the short- and middle-distance athletes.

CONCLUSIONS

The stepwise relation between short-, middle- and long-distance athletes on bone suggests that the higher-impact loading protocols in short-distance disciplines are more effective in promoting aBMD. The regional effect on bone, with the differences between the groups being most marked at load-bearing regions (legs, hip, spine and trunk) rather than non-load-bearing regions, is further evidence in support of the idea that bone adaptation to exercise is dependent upon the local loading environment, rather than as part of a systemic effect.

Whole-body vibration versus proprioceptive training on postural control in post-menopausal osteopenic women

BACKGROUND

To prevent falls in the elderly, especially those with low bone density, is it necessary to maintain muscle coordination and balance. The aim of this study was to examine the effect of classical balance training (BAL) and whole-body vibration training (VIB) on postural control in post-menopausal women with low bone density.

METHODS

Sixty-eight subjects began the study and 57 completed the nine-month intervention program. All subjects performed resistive exercise and were randomized to either the BAL- (N=31) or VIB-group (N=26). The BAL-group performed progressive balance and coordination training and the VIB-group underwent, in total, four minutes of vibration (depending on exercise; 24-26Hz and 4-8mm range) on the Galileo Fitness. Every month, the performance of a single leg stance task on a standard unstable surface (Posturomed) was tested. At baseline and end of the study only, single leg stance, Romberg-stance, semi-tandem-stance and tandem-stance were tested on a ground reaction force platform (Leonardo).

RESULTS

The velocity of movement on the Posturomed improved by 28.3 (36.1%) (p<0.001) in the VIB-group and 18.5 (31.5%) (p<0.001) in the BAL-group by the end of the nine-month intervention period, but no differences were seen between the two groups (p=0.45). Balance tests performed on the Leonardo device did not show any significantly different responses between the two groups after nine months (p≥0.09).

CONCLUSIONS

Strength training combined with either proprioceptive training or whole-body vibration was associated with improvements in some, but not all, measures of postural control in post-menopausal women with low bone density. The current study could not provide evidence for a significantly different impact of whole-body vibration or balance training on postural control.

Mechanography in childhood: references for force and power in counter movement jumps and chair rising tests

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.

Mechanography in childhood: references for grip force, multiple one-leg hopping force and whole body stiffness

OBJECTIVE

We 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.

METHODS

We examined 868 children and adolescents (436 female) aged 3 to 19 yrs. Weight related results are reported as multiples of earth's gravity (g).

RESULTS

MIFG 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.

CONCLUSION

This data from normal children from a healthy Caucasian population provide a reference for tests of motor function.

Vibration or balance training on neuromuscular performance in osteopenic women

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 30 min 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.

Vitamin D status and muscle function in children with neurofibromatosis type 1 (NF1)

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.

Effects of jumping exercise on maximum ground reaction force and bone in 8- to 12-year-old boys and girls: a 9-month randomized controlled trial

OBJECTIVES

To 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.

METHODS

Twelve 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.

RESULTS

Whether 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.

CONCLUSIONS

In 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.

A randomized, controlled trial of vitamin D supplementation upon musculoskeletal health in postmenarchal females

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 D(2) (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 D(2) 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.

Vitamin D status and muscle function in post-menarchal adolescent girls

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.

Whole body vibration in cystic fibrosis--a pilot study

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.

[Does the orientation of the IOL in the eye play a role? Imaging quality of foldable intraocular lenses measured utilizing point spread function (PSF-measurement) and scanning electron microscopy cross-sectional images]

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.

Imaging quality of intraocular lenses

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 für Technik der Informationsverarbeitung, Universität Karlsruhe, Karlsruhe and Universitäts 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.

Non-invasive polarimetric measurement of glucose concentration in the anterior chamber of the eye

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.

Polarimetric methods for measurement of intra ocular glucose concentration

Due to the increasing lifespan in the industrialized world the number of senior Diabetes patients is growing rapidly. Using non-invasive techniques, measurements of the blood sugar level could be done more frequently and hence diagnosis as well as therapy of type II Diabetes Mellitus can be improved especially for this group of senior patients. Especially polarimetric techniques measuring at the human eye offer promising properties for non-invasive and painless measurement. This article discusses different approaches for utilizing the polarizing properties of the Aqueous Humour (AH) for quantitative glucose measurements.