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The article reports on research which was conducted to compare the force frequency characteristics of eccentric and concentric exercises in individuals with and without Achilles tendinopathy. Researchers evaluated the kinematics and ground reaction force of 11 male adults with unilateral midportion Achilles tendinopathy and nine control male adults without tendinopathy who performed a common eccentric rehabilitation exercise. They found that compared with healthy tendons, Achilles tendinopathy was characterized by lower frequency vibrations during eccentric rehabilitation exercises.

Previous research employing indirect measures of arch structure, such as those derived from footprints, have indicated that obesity results in a 'flatter' foot type. In the absence of radiographic measures, however, definitive conclusions regarding the osseous alignment of the foot cannot be made. We determined the effect of body mass index (BMI) on radiographic and footprint-based measures of arch structure. The research was a cross-sectional study in which radiographic and footprint-based measures of foot structure were made in 30 subjects (10 males, 20 female) in addition to standard anthropometric measures of height, weight, and BMI. Multiple (univariate) regression analysis demonstrated that both BMI ( β = 0.39, t26 = 2.12, p = 0.04) and radiographic arch alignment ( β = 0.51, t26 = 3.32, p < 0.01) were significant predictors of footprint-based measures of arch height after controlling for all variables in the model ( R2 = 0.59, F3,26 = 12.3, p < 0.01). In contrast, radiographic arch alignment was not significantly associated with BMI ( β = −0.03, t26 = −0.13, p = 0.89) when Arch Index and age were held constant ( R2 = 0.52, F3,26 = 9.3, p < 0.01). Adult obesity does not influence osseous alignment of the medial longitudinal arch, but selectively distorts footprint-based measures of arch structure. Footprint-based measures of arch structure should be interpreted with caution when comparing groups of varying body composition. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1351-1354, 2012 [ABSTRACT FROM AUTHOR]

The article presents a comparative analysis of the structural properties of the collateral ligaments of the human knee. According to the authors, the passive stability of the knee is primarily provided by a complex system of intra- and extra-articular ligaments that are resistant to anterior and posterior translation, abnormal tibial rotation, and varus and valgus rotation.

The article reports on research conducted to evaluate the sonographic characteristics and acute anteroposterior (AP) strain response of control (healthy), asymptomatic, and symptomatic Achilles tendons to eccentric exercise. Researchers evaluated 11 male adults with unilateral midportion Achilles tendinopathy and nine control male adults without tendinopathy. They found that Achilles tendinopathy is a bilateral or systemic process and that structural changes associated with symptomatic tendinopathy alter fluid movement within the tendon matrix. They concluded that altered fluid movement may disrupt remodeling and homeostatic processes and represents a plausible mechanism underlying the progression of tendinopathy.

With this research, we sought to establish the accuracy of stride velocity data collected by the s3 Stride Sensor. Participants walked along a GAITRite mat at self-selected slow, preferred, and fast velocities, with two s3 Stride Sensors attached to their right foot. The start position was systematically varied such that the GAITRite system would record the second through sixth strides at each walking velocity. Both slow and preferred walking velocities were underestimated by 14% relative to the GAITRite (p < .05), while independent of walking velocity, Strides 2 and 3 were underestimated by 26% and 9% (p < .05), respectively. Researchers should use caution when interpreting data collected at slow and preferred walking velocities and during the first three strides. [ABSTRACT FROM AUTHOR]

Abstract: Background: Altered mechanical properties of the heel pad have been implicated in the development of plantar heel pain. However, the in vivo properties of the heel pad during gait remain largely unexplored in this cohort. The aim of the current study was to characterise the bulk compressive properties of the heel pad in individuals with and without plantar heel pain while walking. Methods: The sagittal thickness and axial compressive strain of the heel pad were estimated in vivo from dynamic lateral foot radiographs acquired from nine subjects with unilateral plantar heel pain and an equivalent number of matched controls, while walking at their preferred speed. Compressive stress was derived from simultaneously acquired plantar pressure data. Principal viscoelastic parameters of the heel pad, including peak strain, secant modulus and energy dissipation (hysteresis), were estimated from subsequent stress–strain curves. Findings: There was no significant difference in loaded and unloaded heel pad thickness, peak stress, peak strain, or secant and tangent modulus in subjects with and without heel pain. However, the fat pad of symptomatic feet had a significantly lower energy dissipation ratio (0.55±0.17 vs. 0.69±0.08) when compared to asymptomatic feet (P <.05). Interpretation: Plantar heel pain is characterised by reduced energy dissipation ratio of the heel pad when measured in vivo and under physiologically relevant strain rates. [Copyright &y& Elsevier]

Abstract: This study evaluated the transport practices of school children and perceived factors that influenced parental decisions regarding their child’s use of active transport to commute to school. A self-administered parental questionnaire (n =324) was used to determine the transport practices of school children and factors that influence parental decisions regarding their child’s use of active transport to school. The relationship between transportation modes (active vs. passive), distance and descriptive variables were evaluated. Despite a median commuting distance of 2.5km (0.1–28.0km), only one-third of school trips involved active transport. Children using active transport commuted shorter distances (1.5 vs. 3.6km), were older (10 vs. 8 years) and more likely to be male than those using motorised transport (P <0.05). While logistic regression revealed only commuting distance was significantly associated with an increased odds of active transport (OR 0.29, 95% CI 0.17–0.48), the most frequently reported factors influencing parental decisions regarding their child’s use of active transport were: (1) the age of child; (2) provision of safe walking paths; (3) adult supervision; (4) commuting distance, and (5) child’s fitness level. While the majority of these factors have been identified within the literature, their validity has yet to be established. [Copyright &y& Elsevier]

Background and Purpose Although plantar fascial thickening is a sonographic criterion for the diagnosis of plantar fasciitis, the effect of local loading and structural factors on fascial morphology are unknown. The purposes of this study were to compare sonographic measures of fascial thickness and radiographic measures of arch shape and regional loading of the foot during gait in individuals with and without unilateral plantar fasciitis and to investigate potential relationships between these loading and structural factors and the morphology of the plantar fascia in individuals with and without heel pain. Subjects The participants were 10 subjects with unilateral plantar fasciitis and 10 matched asymptomatic controls. Methods Heel pain on weight bearing was measured by a visual analog scale. Fascial thickness and static arch angle were determined from bilateral sagittal sonograms and weight-bearing lateral foot roentgenograms. Regional plantar loading was estimated from a pressure plate. Results On average, the plantar fascia of the symptomatic limb was thicker than the plantar fascia of the asymptomatic limb (6.1±1.4 mm versus 4.2±0.5 mm), which, in turn, was thicker than the fascia of the matched control limbs (3.4±0.5 mm and 3.5±0.6 mm). Pain was correlated with fascial thickness, arch angle, and midfoot loading in the symptomatic foot. Fascial thickness, in turn, was positively correlated with arch angle in symptomatic and asymptomatic feet and with peak regional loading of the midfoot in the symptomatic limb. Discussion and Conclusion The findings indicate that fascial thickness and pain in plantar fasciitis are associated with the regional loading and static shape of the arch. [ABSTRACT FROM AUTHOR]

Plantar fasciitis is a musculoskeletal disorder primarily affecting the fascial enthesis. Although poorly understood, the development of plantar fasciitis is thought to have a mechanical origin. In particular, pes planus foot types and lower-limb biomechanics that result in a lowered medial longitudinal arch are thought to create excessive tensile strain within the fascia, producing microscopic tears and chronic inflammation. However, contrary to clinical doctrine, histological evidence does not support this concept, with inflammation rarely observed in chronic plantar fasciitis. Similarly, scientific support for the role of arch mechanics in the development of plantar fasciitis is equivocal, despite an abundance of anecdotal evidence indicating a causal link between arch function and heel pain. This may, in part, reflect the difficulty in measuring arch mechanics in vivo. However, it may also indicate that tensile failure is not a predominant feature in the pathomechanics of plantar fasciitis. Alternative mechanisms including ‘stress-shielding’, vascular and metabolic disturbances, the formation of free radicals, hyperthermia and genetic factors have also been linked to degenerative change in connective tissues. Further research is needed to ascertain the importance of such factors in the development of plantar fasciitis. [ABSTRACT FROM AUTHOR]

Only a small number of muscle activation patterns from lower limbs have been reported and simultaneous muscle activation from several lower limb muscles have not yet been investigated. The purpose of this study was to examine any gender differences in surface electromyography (EMG) activity from six recorded lower limb muscles of the dominant limb at baseline (i.e., with the foot placed flat on the floor and in the neutral position), and during concentric and eccentric phases when performing a heel raise task. In total, 10 females and 10 males performed a standing heel raise task comprising of three continuous phases: baseline, unloading (concentric muscle action), and loading (eccentric muscle action) phases. Muscle activation from six muscles (gastrocnemius medialis, gastrocnemius lateralis, soleus, tibialis anterior, peroneus longus, and peroneus brevis) were measured using the Myon 320 EMG System. Root mean squared values of each muscle were calculated for each phase. Descriptive and inferential statistics were incorporated into the study. Statistically significant p values were set at 0.05. The results showed no significant differences between baseline, concentric, and eccentric phases with respect to each of the muscles investigated. Except for the gastrocnemius medialis at baseline and concentric phases, no significant differences were observed between genders or contractions. The data suggests that gender does not significantly influence the eccentric phase during the standing heel raise task. [ABSTRACT FROM AUTHOR]

The original article contains an error during online publication. Table 2 was included during production round and now deleted. The Original article has been corrected. [ABSTRACT FROM AUTHOR]

Background: At a clinical level, the intensity of dynamic balance tasks incorporating cross-coordination movements (CCM) is typically progressed by changing the stability of the support surface on which the movement is undertaken. However, biomechanical changes in CCMs performed on stable and unstable surfaces have not yet been quantified.Research Question: Do movement patterns, muscle activity, coordination strategies, knee joint loading and center of mass (CoM) movement differ during a CCM performed on stable and unstable surfaces?Methods: Motion analysis was used to monitor limb kinematics and surface electromyography to analyze supporting leg muscle activity in sixteen healthy athletes during a single-limb support task involving a cyclic CCM on a stable and unstable surface. Angle-angle plots were used to explore coordination strategies in sagittal movement of the hip and shoulder, while differences in kinematics and muscle activity between stable and unstable conditions were evaluated using dependent t-tests (α-level = 0.05).Results: CCMs on an unstable surface were performed at a slower speed (p < .05), with a more flexed posture of the support knee (p < .05) and ankle (p < .05) and resulted in reduced hip and shoulder movement of the swing limbs (p < .05). Instability increased activation of selected muscles of the ankle and knee (p < .05), resulted in a two-fold increase in the peak knee adduction moment (p < .05), and was accompanied by greater CoM movement (p < .05). Three coordination patterns of the swing limbs observed when performing CCM on a stable surface, which were mostly preserved on the unstable surface.Significance: Despite adopting several stabilization strategies, CCM undertaken on an unstable surface still evoked greater excursion of the center of mass and, as such, presented a greater challenge to sensorimotor control. Adding instability in form of a swinging platform provides progression of dynamic balance CCM difficulty in an athletic population. [ABSTRACT FROM AUTHOR]

Due to conflicting data from previous studies a new methodological approach to evaluate heel pad stiffness and soft tissue deformation has been developed. The purpose of this study was to compare heel pad (HP) stiffness in both limbs between males and females during a dynamic unloading and loading activity. Ten males and 10 females volunteered to perform three dynamic trials to unload and load the HP. The dynamic protocol consisted of three continuous phases: foot flat (baseline phase), bilateral heel raise (unloading phase) and foot flat (loading phase) with each phase lasting two seconds. Six retroreflective markers (3 mm) were attached to the skin of the left and right heels using a customised marker set. Three‐dimensional motion analysis cameras synchronised with force plates collected the kinematic and kinetic data throughout the trials. Three‐way repeated measures ANOVA together with a Bonferroni post hoc test were applied to the stiffness and marker displacement datasets. On average, HP stiffness was higher in males than females during the loading and unloading phases. ANOVA results revealed no significant differences for the stiffness and displacement outputs with respect to sex, sidedness or phase interactions (p >.05) in the X, Y and Z directions. Irrespective of direction, there were significant differences in stiffness between the baseline and unloading conditions (p <.001) but no significant differences between the baseline and loaded conditions (p = 1.000). Post hoc analyses for the marker displacement showed significant differences between phases for the X and Z directions (p <.032) but no significant differences in the Y direction (p >.116). Finally, females portrayed lower levels of mean HP stiffness whereas males had stiffer heels particularly in the vertical direction (Z) when the HP was both unloaded and loaded. High HP stiffness values and very small marker displacements could be valuable indicators for the risk of pathological foot conditions. [ABSTRACT FROM AUTHOR]

Background: Instrumented treadmills that incorporate pressure platforms are increasingly used to characterize gait in children. Although footprint size is known to influence the measurement performance of pressure platforms, published evidence on the reliability of such systems for children's gait is lacking.Research Question: This study evaluated the test-retest reliability of temporospatial gait parameters and vertical ground reaction forces measured in healthy children during barefoot walking and running on a capacitance-based treadmill system.Methods: Temporospatial gait parameters, including cadence, stride length, stride duration, stance and swing phase durations and the magnitude and timing of conventional vertical ground reaction force peaks were determined on two occasions in 17 healthy children (mean age, 11 ± 2 years; height, 148.4 ± 9.3 cm; and mass, 43.3 ± 10 kg) during walking and running at preferred speed on an instrumented treadmill. Reliability was assessed using Intra Class Correlation Coefficients (ICC) and the standard error of measurement (SEM). The minimum detectable change (MDC95%) was also calculated.Results: ICC values ranged from 0.91-0.99 for all variables. When expressed as a percentage of the mean, the SEM was <5% for all gait parameters assessed during walking and running. The MDC95% values for gait parameters were typically higher during running than walking, and were ±4% of the gait cycle for temporal parameters, ±55 cm for stride length and ±0.1 bodyweights for peak vertical ground reaction force.Significance: Children's gait parameters varied by <5% between test occasions and were more consistent during walking than running. These findings provide clinicians and researchers with an index of the reliability and sensitivity of the treadmill to detect changes in common spatiotemporal gait parameters and vertical ground reaction forces in children. [ABSTRACT FROM AUTHOR]

Background: Heightened vertical load beneath the foot has been anecdotally implicated in the development of activity-related heel pain of the calcaneal apophysis in children but is supported by limited evidence.Research Question: This study investigated whether vertical loading patterns during walking and running differed in children with and without calcaneal apophysitis.Methods: Vertical ground reaction force, peak plantar pressure (forefoot, midfoot, heel) and temporospatial gait parameters (cadence, step length, stride, stance and swing phase durations) were determined in children with (n = 14) and without (n = 14) calcaneal apophysitis. Measures were acquired during barefoot walking and running at matched and self-selected speed using an instrumented treadmill, sampling at 120 Hz. Statistical comparisons between groups were made using repeated measure ANOVAs.Results: There were no significant between group differences in vertical ground reaction force peaks or regional peak plantar pressures. However, when normalised to stature, cadence was significantly higher (≈ 5%) and step length shorter (≈ 5%) in children with calcaneal apophysitis than those without, but only during running (P <.05). Maximum pressure beneath the rearfoot during running was significantly correlated with self-reported pain in children with calcaneal apophysitis.Significance: Peak vertical force and plantar pressures did not differ significantly in children with and without calcaneal apophysitis during walking or running. However, children with calcaneal apophysitis adopted a higher cadence than children without heel pain during running. While the findings suggest that children with calcaneal apophysitis may alter their cadence to lower pressure beneath the heel and, hence pain, they also highlight the benefit of evaluating running rather than walking gait in children with calcaneal apophysitis. [ABSTRACT FROM AUTHOR]

An abstract of the article "The Validity of Footprint-Based Measures of Arch Structure: Revisiting the Debate of Fat Versus Flat Feet in Adults," by Hin-Chung Lau, Scott C. Wearing, Nicole L. Grigg, and James E. Smeathers is presented.

Footwear may moderate the transiently heightened asymmetry in lower limb loading associated with peak growth in adolescence during running. This repeated-measures study compared the magnitude and symmetry of peak vertical ground reaction force and instantaneous loading rates (VILRs) in adolescents during barefoot and shod running. Ten adolescents (age, 10.6 ± 1.7 years) ran at self-selected speed (1.7 ± 0.3 m/s) on an instrumented treadmill under three counter-balanced conditions; barefoot and shod with partial-minimal and conventional running shoes. All participants were within one year of their estimated peak height velocity based on sex-specific regression equations. Foot-strike patterns, peak vertical ground reaction force and VILRs were recorded during 20 seconds of steady-state running. Symmetry of ground reaction forces was assessed using the symmetry index. Repeated-measures ANOVAs were used to compare conditions (α=.05). Adolescents used a rearfoot foot-strike pattern during barefoot and shod running. Use of conventional shoes resulted in a lower VILR (P <.05, dz = 0.9), but higher VILR asymmetry (P <.05) than running barefoot (dz = 1.5) or in partial-minimal shoes (dz = 1.6). Conventional running shoes result in a lower VILR than running unshod or in partial-minimal shoes but may have the unintended consequence of increasing VILR asymmetry. The findings may have implications for performance, musculoskeletal development and injury in adolescents. [ABSTRACT FROM AUTHOR]

An abstract of the article "The heel fat pad: mechanical properties and clinical applications," by Scott C. Wearing and James E. Smeathers, to be presented at the Australasian Podiatry Council Conference 2011 in Melbourne, Victoria on April 26-29, is presented.

Introduction: The frontal plane knee moment (KAM1 and KAM2) derived from non-invasive three-dimensional gait analysis is a surrogate measure for knee joint load and of great interest in clinical and research settings. Many aspects can influence this measure either unintentionally or purposely in order to reduce the knee joint load to relieve symptoms and pain. All these aspects must be known when conducting a study or interpreting gait data for clinical decision-making.Methods: This systematic review was registered with PROSPERO (CRD42020187038). Pubmed and Web of Science were searched for peer-reviewed, original research articles in which unshod three-dimensional gait analysis was undertaken and KAM1 and KAM2 were included as an outcome variable. Two reviewers independently screened articles for inclusion, extracted data and performed a methodological quality assessment using Downs and Black checklist.Results: In total, 42 studies were included. Based on the independent variable investigated, these studies were divided into three groups: 1) gait modifications, 2) individual characteristics and 3) idiopathic orthopedic deformities. Among others, fast walking speeds (1) were found to increase KAM1; There were no sex-related differences (2) and genu valgum (3) reduces KAM1 and KAM2.Conclusion: While consistent use of terminology and reporting of KAM is required for meta-analysis, this review indicates that gait modifications (speed, trunk lean, step width), individual characteristics (body weight, age) and idiopathic orthopedic deformities (femoral or tibial torsion, genu valgum/varum) influence KAM magnitudes during walking. These factors should be considered by researchers when designing studies (especially of longitudinal design) or by clinicians when interpreting data for surgical and therapeutic decision-making. [ABSTRACT FROM AUTHOR]

Abstract: The Achilles tendon has been seen to exhibit time-dependent conditioning when isometric muscle actions were of a prolonged duration, compared to those involved in dynamic activities, such as walking. Since, the effect of short duration muscle activation associated with dynamic activities is yet to be established, the present study aimed to investigate the effect of incidental walking activity on Achilles tendon diametral strain. Eleven healthy male participants refrained from physical activity in excess of the walking required to carry out necessary daily tasks and wore an activity monitor during the 24h study period. Achilles tendon diametral strain, 2cm proximal to the calcaneal insertion, was determined from sagittal sonograms. Baseline sonographic examinations were conducted at ∼08:00h followed by replicate examinations at 12 and 24h. Walking activity was measured as either present (1) or absent (0) and a linear weighting function was applied to account for the proximity of walking activity to tendon examination time. Over the course of the day the median (min, max) Achilles tendon diametral strain was −11.4 (4.5, −25.4)%. A statistically significant relationship was evident between walking activity and diametral strain (P <0.01) and this relationship improved when walking activity was temporally weighted (AIC 131 to 126). The results demonstrate that the short yet repetitive loads generated during activities of daily living, such as walking, are sufficient to induce appreciable time-dependant conditioning of the Achilles tendon. Implications arise for the in vivo measurement of Achilles tendon properties and the rehabilitation of tendinopathy. [Copyright &y& Elsevier]

Abstract: Background. : Despite evidence that ‘walking for pleasure’ represents the most common leisure-time physical activity, the exercise intensity associated with ‘walking for pleasure’ in the obese has not been established. Methods. : Heart rate (HR), perceived exertion (RPE) and walking speed were assessed for 30 obese and 20 non-obese adults as they completed two 2 km-walk tests on alternate days and were compared with a third 2 km walk with subjects walking ‘as fast as possible’. Results. : Despite both obese (O) and non-obese (NO) groups rating the intensity of ‘walking for pleasure’ as ‘light’, HR and RPE data for only the NO group complied with definitions of ‘light’ intensity effort. ‘Walking for pleasure’ was characterised by a higher absolute (15 bpm, P < 0.05) and relative (70% of predicted maximum, P < 0.01) HR in the O group, which was representative of the transition between ‘moderate’ and ‘hard’ intensity exercise. The findings in the third, maximal trial were comparable across groups for all variables. Conclusion. : Adiposity exerts a relative elevation-of-intensity effect on the cardiovascular system at walking speeds consistent with ‘walking for pleasure’. ‘Walking for pleasure’ is sufficient to improve cardiovascular fitness in obese, but not normal-weight, individuals. [Copyright &y& Elsevier]

Fibrotic diseases are still a serious concern for public health, due to their high prevalence, complex etiology and lack of successful treatments. Fibrosis consists of excessive accumulation of extracellular matrix components. As a result, the structure and function of tissues are impaired, thus potentially leading to organ failure and death in several chronic diseases. Myofibroblasts represent the principal cellular mediators of fibrosis, due to their extracellular matrix producing activity, and originate from different types of precursor cells, such as mesenchymal cells, epithelial cells and fibroblasts. Profibrotic activation of myofibroblasts can be triggered by a variety of mechanisms, including the transforming growth factor‐β signalling pathway, which is a major factor driving fibrosis. Interestingly, preclinical and clinical studies showed that fibrotic degeneration can stop and even reverse by using specific antifibrotic treatments. Increasing scientific evidence is being accumulated about the role of sirtuins in modulating the molecular pathways responsible for the onset and development of fibrotic diseases. Sirtuins are NAD+‐dependent protein deacetylases that play a crucial role in several molecular pathways within the cells, many of which at the crossroad between health and disease. In this context, we will report the current knowledge supporting the role of sirtuins in the balance between healthy and diseased myofibroblast activity. In particular, we will address the signalling pathways and the molecular targets that trigger the differentiation and profibrotic activation of myofibroblasts and can be modulated by sirtuins. [ABSTRACT FROM AUTHOR]

Malignant hyperthermia (MH) is a pharmacogenetic disorder of skeletal muscle metabolism characterized by generalized muscle rigidity, increased body temperature, rhabdomyolysis, hyperkalemia and severe metabolic acidosis. The underlying mechanism of MH involves excessive Ca2+ release from myotubes via the ryanodine receptor type 1 (RYR1) and the voltage-dependent L-type calcium channel (CACNA1S). As more than 300 variants of unknown significance have been detected to date, we examined whether freely available pathogenicity prediction tools are able to detect relevant MH causing variants. In this diagnostic accuracy study, blood samples from 235 individuals with a history of a clinical malignant hyperthermia or their close relatives were genetically screened for RYR1 variants of all 106 RYR1 exons and additionally for known variants of CACNA1S. In vitro contracture tests were conducted on muscle biopsies obtained from all individuals, independently of whether a pathogenic variant, a variant of unknown significance or no variant was detected. Comparisons were made to three established bioinformatic pathogenicity detection tools to identify the clinical impact of the variants of unknown significance. All detected genetic variants were tested for pathogenicity by three in silico approaches and compared to the in vitro contracture test. Sensitivity and specificity of exon screening of all individuals listed in our MH database was analyzed. Exon screening identified 97 (41%) of the 235 individuals as carriers of pathogenic variants. Variants of unknown significance were detected in 21 individuals. Variants of unknown significance were subdivided into 19 malignant-hyperthermia-susceptible individuals and 2 non-malignant-hyperthermia-susceptible individuals. All pathogenic variants as well as the malignant-hyperthermia-suspectible variants were correctly identified by the bioinformatic prediction tools. Sensitivity of in silico approaches ranged between 0.71 and 0.98 (Polyphen 0.94 [CI 95% 0.75; 0.99]; Sift 0.98 [CI 95% 0.81; 0.99]; MutationTaster 0.92 [CI 95% 0.75; 0.99]). Specificity differed depending on the used tool (Polphen 0.98 [CI 95% 0.32; 0.99]; Sift 0.98 [CI 95% 0.32; 0.99]; MutationTaster 0.00 [CI 95% 0.00; 0.60]). All pathogenic variants and variants of unknown significance were scored as probably damaging in individuals, demonstrating a high sensitivity. Specificity was very low in one of the three tested programs. However, due to potential genotype–phenotype discordance, bioinformatic prediction tools are currently of limited value in diagnosing pathogenicity of MH-susceptible variants. [ABSTRACT FROM AUTHOR]

In myotonia, reduced Cl− conductance of the mutated ClC-1 channels causes hindered muscle relaxation after forceful voluntary contraction due to muscle membrane hyperexcitability. Repetitive contraction temporarily decreases myotonia, a phenomena called "warm up." The underlying mechanism for the reduction of hyperexcitability in warm-up is currently unknown. Since potassium displacement is known to reduce excitability in, for example, muscle fatigue, we characterized the role of potassium in native myotonia congenita (MC) muscle. Muscle specimens of ADR mice (an animal model for low gCl− conductance myotonia) were exposed to increasing K+ concentrations. To characterize functional effects of potassium ion current, the muscle of ADR mice was exposed to agonists and antagonists of the big conductance Ca2+-activated K+ channel (BK) and the voltage-gated Kv7 channel. Effects were monitored by functional force and membrane potential measurements. By increasing [K+]0 to 5 mM, the warm-up phenomena started earlier and at [K+]0 7 mM only weak myotonia was detected. The increase of [K+]0 caused a sustained membrane depolarization accompanied with a reduction of myotonic bursts in ADR mice. Retigabine, a Kv7.2–Kv7.5 activator, dose-dependently reduced relaxation deficit of ADR myotonic muscle contraction and promoted the warm-up phenomena. In vitro results of this study suggest that increasing potassium conductivity via activation of voltage-gated potassium channels enhanced the warm-up phenomena, thereby offering a potential therapeutic treatment option for myotonia congenita. [ABSTRACT FROM AUTHOR]

Background Abnormalities in gait have been associated with high plantar pressures and diabetes-related plantar foot ulcers. Whether these are a transient response to the ulcer or are representative of long-term lower limb biomechanical abnormalities is currently unknown. Objective The aim of this study was to examine whether 12 gait parameters identified as being associated with nonhealing diabetes-related plantar foot ulcers at baseline remained associated during a 6-month follow-up period. Design This was a longitudinal observational case-control study. Methods Gait assessments were performed at entry and twice during follow-up over a 6-month period in 12 participants with nonhealing diabetes-related plantar foot ulcers (case participants) and 62 people with diabetes and no history of foot ulcers (control participants) using a standardized protocol. Linear mixed-effects random-intercept models were used to identify gait parameters that consistently differed between case participants and control participants at all assessments after adjustment for age, sex, body mass index, presence of peripheral neuropathy, and follow-up time. Standardized mean differences (SMD) were used to measure effect sizes. Results Five of the 12 gait parameters were significantly different between case participants and control participants at all 3 time points. Case participants had a more abducted foot progression angle (SMD = 0.37), a higher pelvic obliquity at toe-off (SMD = −0.46), a greater minimum pelvic obliquity (SMD = −0.52), a lower walking speed (SMD = −0.46), and a smaller step length (SMD = −0.46) than control participants. Limitations The limitations included a small sample size, the observational nature of the study, and the inability to evaluate the impact of gait on wound healing. Conclusions This study identified abnormal gait parameters consistently associated with nonhealing diabetes-related plantar foot ulcers. Further research is needed to test the clinical importance of these gait characteristics. [ABSTRACT FROM AUTHOR]