Methodical approaches to determine the rate of radial muscle displacement using tensiomyography: A scoping review and new reporting guideline.

Tensiomyography is a non-invasive method to assess skeletal muscle contractile properties from the stimulated radial displacement. Many studies have used the rate of displacement (Vc) as an indirect measure of muscle contraction velocity. However, no standardised methodical approach exists to measure displacement and determine Vc. This review aimed to provide an overview of concepts to determine Vc and measurement protocols to foster the development of a standardised methodical approach. This review followed the Preferred Reporting Items for Systematic Reviews and meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guideline. Systematic searches were performed within five electronic databases and additional sources. The included 62 studies reported 10 different concepts to determine Vc, which we summarised in three groups. The determination concepts differed mainly regarding time intervals during the contraction phase considered and criteria used to define these intervals. Essential information on the equipment and raters, measurement setup, electrical stimulation procedure, and data analysis were frequently not reported. In conclusion, no consensus on how to determine Vc existed. Incomplete reporting of measurement protocols hindered study comparison, which obstructs developing a standardised approach. Therefore, we propose a new guideline for reporting measurement protocols, which covers the 1) equipment and rater, 2) measurement setup, including positioning of the subject, sensor and electrodes, 3) electrical stimulation, including initial stimulation amplitude, increment, and endpoint, and 4) data analysis, including selection criteria and number of analysed signals and a definition of derived parameters.

The relationship between external and internal load parameters in 3 × 3 basketball tournaments.

PURPOSE: 3 × 3 basketball games are characterized by high-intensity accelerations and decelerations, and a high number of changes of direction and jumps. It is played in tournament form with multiple games per day. Therefore, optimal regeneration is crucial for maintaining a high performance level over the course of the tournament. To elucidate how load of a match affects the athletes' bodies (i.e., internal load), muscular responses to the load of 3 × 3 games were analyzed. We aimed to investigate changes in contractility of the m. rectus femoris (RF) and m. gastrocnemius medialis (GC) in response to the load of single 3 × 3 games and a 3 × 3 tournament. METHODS: Inertial movement analysis was conducted to capture game load in 3 × 3. Changes in contractility were measured using tensiomyography (TMG). During a two-day tournament, TMG measurements were conducted in the morning and after each game. Additionally, off-game performance analysis consisting of jump and change-of-direction (COD) tests was conducted the day before the tournament. RESULTS: Significant changes of the muscle contractility were found for GC with TMG values being higher in the baseline than in the post-game measurements. In contrast to athletes of the GC group, athletes of the RF group responded with either decreased or increased muscle contractility after a single 3 × 3 game. A significant correlation between external and internal load parameters could not be shown. Concerning off-game performance, significant correlations can be reported for COD test duration, CMJ height and ∆Vc as well as COD test duration and ∆Dm. No systematic changes in muscle contractility were found over the course of the tournament in RF and GC. CONCLUSION: The athletes' external 3 × 3 game load and their performance level did not seem to affect muscular contractility after a single 3 × 3 game or a complete 3 × 3 tournament within this investigation. This might indicate that elite athletes can resist external load without relevant local muscular fatigue. With respect to the course of the tournament, it can therefore be concluded that the breaks between games seem to be sufficient to return to the initial level of muscle contractility.

Lean mass sparing in resistance-trained athletes during caloric restriction: the role of resistance training volume.

Many sports employ caloric restriction (CR) to reduce athletes' body mass. During these phases, resistance training (RT) volume is often reduced to accommodate recovery demands. Since RT volume is a well-known anabolic stimulus, this review investigates whether a higher training volume helps to spare lean mass during CR. A total of 15 studies met inclusion criteria. The extracted data allowed calculation of total tonnage lifted (repetitions × sets × intensity load) or weekly sets per muscle group for only 4 of the 15 studies, with RT volume being highly dependent on the examined muscle group as well as weekly training frequency per muscle group. Studies involving high RT volume programs (≥ 10 weekly sets per muscle group) revealed low-to-no (mostly female) lean mass loss. Additionally, studies increasing RT volume during CR over time appeared to demonstrate no-to-low lean mass loss when compared to studies reducing RT volume. Since data regarding RT variables applied were incomplete in most of the included studies, evidence is insufficient to conclude that a higher RT volume is better suited to spare lean mass during CR, although data seem to favor higher volumes in female athletes during CR. Moreover, the data appear to suggest that increasing RT volume during CR over time might be more effective in ameliorating CR-induced atrophy in both male and female resistance-trained athletes when compared to studies reducing RT volume. The effects of CR on lean mass sparing seem to be mediated by training experience, pre-diet volume, and energy deficit, with, on average, women tending to spare more lean mass than men. Potential explanatory mechanisms for enhanced lean mass sparing include a preserved endocrine milieu as well as heightened anabolic signaling.

[Training methods and trainability]. / Trainingsmethoden und Trainierbarkeit.

BACKGROUND: The need for effective training methods for positive adaptations in muscle strength and bone mineralization, suitable for all groups of patients, arises in both rehabilitation and pre-habilitation. In addition to mechanical stress, an increased metabolic stress, by means of reduced blood supply of the muscle, seems to induce positive adaptations as well. OBJECTIVES: Description of the effects of resistance training and opportunities of blood-flow restriction training in a clinical setting. METHODS: Key and specialized literature RESULTS: Regularly applied high mechanical loads are suitable to induce increases in muscle strength and mass as well as bone mineralization. In principle, the trainability of these tissues is given over the entire life span, although the adaptation of the muscle mass is reduced in the prepubertal and later stages of life. Classic strength training is particularly suitable as a training method to apply this stimulus quality (mechanical stress). For some years now, however, there has been increasing evidence that even low-intensity resistance training associated with metabolic stress is capable of producing hypertrophic effects and increasing muscle strength. This observation is particularly interesting for target groups whose mechanical capacity of the musculoskeletal system is reduced. Blood-flow-restriction training is particularly suitable as a training method for the application of this stimulus quality (metabolic stress). The data available on the effectiveness of low-intensity stress protocols on bone structure is still insufficient. Further research is needed to make evidence-based recommendations.

Plasma concentration of high-mobility group box 1 (HMGB1) after 100 drop to vertical jumps and after a 1200-km bicycle race.

High-mobility group box 1 (HMGB1) has recently been reported to be involved in proinflammation and tissue repair. Therefore, we hypothesized that HMGB1 is released into the bloodstream after eccentric exercises or prolonged endurance activities. Blood samples from 11 participants that performed 100 drop to vertical jumps (DVJ) and from 10 participants that took part in the 1200-km 'Paris-Brest-Paris' bicycle race (PBP) were tested for HMGB1 and creatine kinase (CK) levels. CK increased after both DVJ (pre: 150.6 ± 81.5 U/L; post: 188.8 ± 95.5 U/L 8 h: 790.5 ± 346.4 U/L) and PBP (pre: 81.3 ± 36.4 U/L; post: 725.2 ± 229.5 U/L; 12 h: 535.8 ± 188.6 U/L), indicating membrane damage. However, HMGB1 plasma levels remained below the detection limit (78 pg/mL) of the applied enzyme-linked immunosorbent assay kit for all blood samples analysed. That is, neither high intensity eccentric exercises (DVJ) nor prolonged endurance events (PBP) seemed to affect HMGB1 levels in blood at selected time points.

Electrically induced muscle cramps induce hypertrophy of calf muscles in healthy adults.

OBJECTIVES: Skeletal muscles usually cramp at short lengths, where the tension that can be exerted by muscle fibers is low. Since high tension is an important anabolic stimulus, it is questionable if cramps can induce hypertrophy and strength gains. In the present study we investigated if electrically induced cramps (EIMCs) can elicit these adaptations. METHODS: 15 healthy male adults were randomly assigned to an intervention (IG; n=10) and a control group (CG; n=5). The cramp protocol (CP) applied twice a week to one leg of the IG, consisted of 3x6 EIMCs, of 5 s each. Calf muscles of the opposite leg were stimulated equally, but were hindered from cramping by fixating the ankle at 0° plantar flexion (nCP). RESULTS: After six weeks, the cross sectional area of the triceps surae was similarly increased in both the CP (+9.0±3.4%) and the nCP (+6.8±3.7%). By contrast, force of maximal voluntary contractions, measured at 0° and 30° plantar flexion, increased significantly only in nCP (0°: +8.5±8.8%; 30°: 11.7±13.7%). CONCLUSION: The present data indicate that muscle cramps can induce hypertrophy in calf muscles, though lacking high tension as an important anabolic stimulus.

The repeated bout effect: is the blunted creatine kinase response an effect of an altered enzyme inactivation kinetic?

AIM: If unaccustomed lengthening contractions are repeated within a certain period of time, muscle damage symptoms are blunted. This observation, often referred to as the repeated bout effect (RBE), also holds true for the response of muscle damage markers like creatine kinase (CK). However, measuring plasma enzyme activity rather than the concentration of enzyme protein might conceal the actual amount of damaged tissue. Therefore, the primary aim of the study was to investigate if the RBE of CK can partially be explained by enzyme inactivation. METHODS: Ten healthy male subjects performed two bouts of 100 drop-to-vertical jumps (DVJs) from a 70-cm high platform at an interval of three weeks. CK activity, CK concentration, and neutrophils were measured prior to, and on four consecutive days after the interventions. RESULTS: Besides significant main effects, there was a significant group by time interaction for the specific CK activity (CK activity in blood [U/L] divided by the enzyme concentration [ng/mL]). Higher values following the first bout (133.1±99.4 U/µg) than the second bout (94.7±63.0 U/µg) indicate that the ratio of inactive to active CK molecules increased. Neutrophil levels were similar following both bouts and differed only at 8 hours (7.0±2.5 bout 1, 5.1±1.6 bout 2). CONCLUSION: The findings of the present study support the hypothesis that the blunted response of CK activity after a repeated bout of eccentric exercise is not solely the result of tissue protection, but can be at least partially attributed to enzyme inactivation.

Motor point map of upper body muscles.

PURPOSE: The purpose of the present study was to systematically investigate the upper body motor point (MP) positions of selected muscles and to create an atlas of the identified MPs. METHODS: MPs were searched bilaterally in 15 male and 15 female subjects by scanning the skin with a special pen electrode at low stimulation frequency (3 Hz) and current amplitude (<10 mA). The following muscles were investigated: biceps brachii, triceps brachii, deltoideus, trapezius, latissimus dorsi, erector spinae (lumbar part), pectoralis minor and major, and rectus abdominis. RESULTS: A total of 1,563 MPs were identified. The MPs could be clustered into 31 distinct positions on each side of the body. However, the number of MPs per muscle varied between subjects: 2 MPs were found for the biceps brachii, 2-3 for the triceps brachii, 4-5 for the deltoideus, 2-3 for the pectoralis major, 1 MP for the pectoralis minor, 4-5 for the trapezius, 3-4 for the latissimus dorsi, 4-5 for the rectus abdominis, and 2-3 for the erector spinae in its lumbar part. Referring to the applied grid, upper limb and lower back muscles presented a low inter-individual variation, whereas MPs of the deltoideus, the pectoralis major, and the rectus abdominis were characterized by a poor homogeneity. All MPs were found to be highly symmetrical between both sides of the body (r = 0.96; p < 0.001). CONCLUSION: The presented data and the corresponding map will help physiotherapists, and conditioning specialists improve their neuromuscular electrical stimulation therapy or training, respectively.

DNA identification and characterization of Campylobacter jejuni and Campylobacter coli isolated from caecal samples of chickens in Grenada.

AIMS: To speciate Campylobacter strains from the caeca of chickens in Grenada using PCR and to evaluate DNA-based typing methods for the characterization of these isolates. METHODS AND RESULTS: Isolates were speciated with two multiplex PCR assays and were typed with flaA-RFLP, pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Results confirmed that Campylobacter coli strains were more predominant than Campylobacter jejuni strains. From 56 isolates, 18 were misidentified using biochemical tests. PFGE typing gave the highest discriminatory power among the methods used (Simpson's index of diversity, D=0.9061). However, the combination of flaA-RFLP, PFGE and MLST results gave the highest discrimination for subtyping of these isolates (D=0.9857). A band position tolerance of 4% in BioNumerics was the most appropriate for the analysis of this database. MLST profiles were generally concordant with PFGE and/or flaA-RFLP types. Several isolates exhibited new MLST sequence types (STs), and 43 of the 49 Camp. coli strains belonged to the ST-828 clonal complex. CONCLUSIONS: Campylobacter coli was the most prevalent species isolated from broilers and layers in Grenada, and a combination of restriction and sequence methods was most appropriate for the typing of Camp. coli isolates. Campylobacter coli STs clustered with described poultry-associated Camp. coli STs by phylogenetic analysis. SIGNIFICANCE AND IMPACT OF THE STUDY: Further studies to understand the predominance of Camp. coli within Campylobacter spp. from chickens in Grenada may help elucidate the epidemiology of these pathogens in chickens.

Towards a medically approved technology for alginate-based microcapsules allowing long-term immunoisolated transplantation.

The concept of encapsulated-cell therapy is very appealing, but in practice a great deal of technology and know-how is needed for the production of long-term functional transplants. Alginate is one of the most promising biomaterials for immunoisolation of allogeneic and xenogeneic cells and tissues (such as Langerhans islets). Although great advances in alginate-based cell encapsulation have been reported, several improvements need to be made before routine clinical applications can be considered. Among these is the production of purified alginates with consistently high transplantation-grade quality. This depends to a great extent on the purity of the input algal source as well as on the development of alginate extraction and purification processes that can be validated. A key engineering challenge in designing immunoisolating alginate-based microcapsules is that of maintaining unimpeded exchange of nutrients, oxygen and therapeutic factors (released by the encapsulated cells), while simultaneously avoiding swelling and subsequent rupture of the microcapsules. This requires the development of efficient, validated and well-documented technology for cross-linking alginates with divalent cations. Clinical applications also require validated technology for long-term cryopreservation of encapsulated cells to maintaining a product inventory in order to meet end-user demands. As shown here these demands could be met by the development of novel, validated technologies for production of transplantation-grade alginate and microcapsule engineering and storage. The advances in alginate-based therapy are demonstrated by transplantation of encapsulated rat and human islet grafts that functioned properly for about 1 year in diabetic mice.

Real-time 3-D dark-field microscopy for the validation of the cross-linking process of alginate microcapsules.

Alginate-based microencapsulation is a promising method for long-term maintenance of cellular and membrane function of the cells and tissue fragments required for in vitro and in vivo biosensors, for tissue engineering and particularly for immunoisolation of non-autologous transplants. Microcapsules of high mechanical strength and optimum permeability can be produced by injection of BaCl2 crystals into alginate droplets before they come into contact with external Ba2+. A key requirement is that the system parameters (number of crystals, speed of the crystal stream etc.) are properly adjusted according to the mannuronic and guluronic acid ratio and the average molecular mass of the alginate as well as to the diameter of the microcapsules. Robust, reliable, rapid and low-cost validation tools are, therefore, needed for assurance of the microcapsule quality. Here, we describe a novel three-dimensional (3-D) dark-field microscopy that allows the real-time measurement of the number and spatial distribution of the injected Ba2+ ions throughout the microcapsules after treatment with sulphate. This novel method requires only a conventional microscope equipped with three polarising filters and a double aperture stop. In contrast to confocal laser scanning microscopy images, peripherally attached BaSO4 precipitates can clearly be distinguished from internal ones. The data also demonstrate that several steps of the alginate gelling process must be improved before such immunoisolation can be used in patients.

Human retinal pigment epithelium in vitro: influence of low oxygen tension, glucose and insulin.

Retinal pigment epithelium (RPE) cells migrating through the damaged retina into the vitreous body seem to play an important role for the pathogenesis of proliferative vitreoretinopathy (PVR) and other proliferative retina diseases. It is so far not known how the RPE cells are able to survive in the vitreous body without contact to the blood vessels of the choroid supplying them with oxygen and nutritive substances. To answer this question, we studied growth characteristics and sensitivity to glucose and insulin of human RPE cells, incubated with reduced oxygen partial pressure. In the first study, RPE cultures of 58 postmortem human eyes were grown with 5% O2/5% CO2 and with standard conditions (20% O2/5% CO2). The growth was assessed in five graded stages. Our data show that human RPE grows better under 5% oxygen than under 20% O2 (p < 0.0001). In consideration of this effect, we cultivated, in a further study, pigment epithelium of 49 postmortem human eyes with 5% oxygen and with 4 different glucose concentrations with and without addition of insulin. We found that glucose in higher concentrations was a potent stimulator of growth, whereas insulin was a modest stimulator when used alone. The combination of glucose and insulin was significantly more effective (p = 0.01) in the period of the first 7 days. These results suggest that proliferation of human RPE cells can be increased by oxygen reduction, glucose and insulin. These interactions may help in understanding the pathophysiology of retina damage and proliferative retina diseases like PVR.