Search

Background: Muscle disuse from bed rest or spaceflight results in losses in muscle mass, strength and oxidative capacity. Capillary rarefaction may contribute to muscle atrophy and the reduction in oxidative capacity during bed rest. Artificial gravity may attenuate the negative effects of long-term space missions or bed rest. The aim of the present study was to assess (1) the effects of bed rest on muscle fibre size, fibre type composition, capillarization and oxidative capacity in the vastus lateralis and soleus muscles after 6 and 55 days of bed rest and (2) the effectiveness of artificial gravity in mitigating bed-rest-induced detriments to these parameters. Methods: Nineteen participants were assigned to a control group (control, n = 6) or an intervention group undergoing 30 min of centrifugation (n = 13). All underwent 55 days of head-down tilt bed rest. Vastus lateralis and soleus biopsies were taken at baseline and after 6 and 55 days of bed rest. Fibre type composition, fibre cross-sectional area, capillarization indices and oxidative capacity were determined. Results: After just 6 days of bed rest, fibre atrophy (−23.2 ± 12.4%, P RSD) was increased after 55 days by 12.7% (P = 0.004), tissue oxygenation at maximal oxygen consumption of the fibres was improved after 55 days bed rest. Daily centrifugation failed to blunt the bed-rest-induced reductions in fibre size and oxidative capacity and capillary rarefaction. Conclusions: The relationship between fibre size and oxidative capacity with the capillary supply of a fibre is uncoupled during prolonged bed rest as reflected by a rapid loss of muscle mass and capillaries, followed at later stages by a more than proportional loss of mitochondria without further capillary loss. The resulting excessive capillary supply of the muscle after prolonged bed rest is advantageous for the delivery of substrates needed for subsequent muscle recovery.

Background An exaggerated exercise blood pressure (BP) is associated with a reduced exercise capacity. However, its connection to physical performance during competition is unknown. Aim To examine BP responses to ischaemic handgrip exercise in Master athletes (MA) with and without underlying morbidities and to assess their association with athletic performance during the World Master Track Cycling Championships 2019. Methods Forty-eight Master cyclists [age 59 ± 13yrs; weekly training volume 10.4 ± 4.1 h/week; handgrip maximum voluntary contraction (MVC) 46.3 ± 11.5 kg] divided into 2 matched groups (24 healthy MA and 24 MA with morbidity) and 10 healthy middle-aged non-athlete controls (age 48.3 ± 8.3 years; MVC 40.4 ± 14.8 kg) performed 5 min of forearm occlusion including 1 min handgrip isometric contraction (40%MVC) followed by 5 min recovery. Continuous beat-by-beat BP was recorded using finger plethysmography. Age-graded performance (AGP) was calculated to compare race performances among MA. Healthy Master cyclists were further grouped into middle-age (age 46.2 ± 6.4 years; N:12) and old-age (age 65.0 ± 7.7 years; N:12) for comparison with middle-aged non-athlete controls. Results Healthy and morbidity MA groups showed similar BP responses during forearm occlusion and AGP (90.1 ± 4.3% and 91.0 ± 5.3%, p > 0.05, respectively). Healthy and morbidity MA showed modest correlation between the BP rising slope for 40%MVC ischaemic exercise and AGP (r = 0.5, p Conclusion Our findings associate long-term athletic training with improved BP recovery following ischaemic exercise regardless of age or reported morbidity. Exaggerated BP in Master cyclists during ischaemic exercise was associated with lower AGP during the World Master Cycling Championships.

Nonunion is a complication of long bone fractures that leads to disability, morbidity and high costs. Early detection is difficult and treatment through external stimulation and revision surgery is often a lengthy process. Therefore, alternative diagnostic and therapeutic options are currently being explored, including the use of external and internal sensors. Apart from monitoring fracture stiffness and displacement directly at the fracture site, it would be desirable if an implant could also vary its stiffness and apply an intervention to promote healing, if needed. This could be achieved either by a predetermined protocol, by remote control, or even by processing data and triggering the intervention itself (self-regulated 'intelligent' or 'smart' implant). So-called active or smart materials like shape memory alloys (SMA) have opened up opportunities to build active implants. For example, implants could stimulate fracture healing by active shortening and lengthening via SMA actuator wires; by emitting pulses, waves, or electromagnetic fields. However, it remains undefined which modes of application, forces, frequencies, force directions, time durations and periods, or other stimuli such implants should ideally deliver for the best result. The present paper reviews the literature on active implants and interventions for nonunion, discusses possible mechanisms of active implants and points out where further research and development are needed to build an active implant that applies the most ideal intervention. STATEMENT OF SIGNIFICANCE: Early detection of delays during fracture healing and timely intervention are difficult due to limitations of the current diagnostic strategies. New diagnostic options are under evaluation, including the use of external and internal sensors. In addition, it would be desirable if an implant could actively facilitate healing ('Intelligent' or 'smart' implant). Implants could stimulate fracture healing via active shortening and lengthening; by emitting pulses, waves, or electromagnetic fields. No such implants exist to date, but new composite materials and alloys have opened up opportunities to build such active implants, and several groups across the globe are currently working on their development. The present paper is the first review on this topic to date.

To assess which pre-operative parameters correlate with wound revisions after an extended lateral approach to the calcaneus. Pre-operative laser-Doppler spectrophotometry was applied in patients undergoing open reduction and internal fixation. The number of wound revisions was recorded during pos-toperative follow-up. Spearman rho analysis was used to identify factors associated with wound revision and receiver operator characteristics curves were calculated for the identified factors. Thirty-four patients (29 men, 5 women; 37 calcanei) with a mean patient age of 43 ± 14 years were analyzed. The minimal oxygen saturation value at the five measurement locations as well as the minimal value for flow correlated negatively with wound revisions (p value = 0.025 and 0.038, respectively). The area under the curve for the pre-operative minimal value of oxygen saturation was 0.841 (95%CI 0.64–1.00, p = 0.028), indicating a good accuracy as a test to predict wound revision. A pre-operative oxygen saturation of at least 20.5% across five measurement points along the anticipated incision identified all patients not needing a wound revision (negative predictive value 100%). On the other hand, patients with at least one measurement below 20.5% were at risk for wound revision surgery (sensitivity 100%, specificity 48.5%). ClinicalTrials.gov NCT01264146

Background: Parkinson’s disease (PD) is the most frequent movement disorder. Patients access YouTube, one of the largest video databases in the world, to retrieve health-related information increasingly often. Objective: We aimed to identify high-quality publishers, so-called “channels” that can be recommended to patients. We hypothesized that the number of views and the number of uploaded videos were indicators for the quality of the information given by a video on PD. Methods: YouTube was searched for 8 combinations of search terms that included “Parkinson” in German. For each term, the first 100 search results were analyzed for source, date of upload, number of views, numbers of likes and dislikes, and comments. The view ratio (views / day) and the likes ratio (likes * 100 / [likes + dislikes]) were determined to calculate the video popularity index (VPI). The global quality score (GQS) and title - content consistency index (TCCI) were assessed in a subset of videos. Results: Of 800 search results, 251 videos met the inclusion criteria. The number of views or the publisher category were not indicative of higher quality video content. The number of videos uploaded by a channel was the best indicator for the quality of video content. Conclusion: The quality of YouTube videos relevant for PD patients is increased in channels with a high number of videos on the topic. We identified three German channels that can be recommended to PD patients who prefer video over written content.

Purpose The objective of this study was to assess whether artificial gravity attenuates any long-duration head-down 60 bed rest (HDBR)-induced alterations in motor unit (MU) properties. Methods Twenty-four healthy participants (16 men; 8 women; 26–54 years) underwent 60-day HDBR with (n = 16) or without (n = 8) 30 min artificial gravity daily induced by whole-body centrifugation. Compound muscle action potential (CMAP), MU number (MUNIX) and MU size (MUSIX) were estimated using the method of Motor Unit Number Index in the Abductor digiti minimi and tibialis anterior muscles 5 days before (BDC-5), and during day 4 (HDT4) and 59 (HDT59) of HDBR. Results The CMAP, MUNIX, and MUSIX at baseline did not change significantly in either muscle, irrespective of the intervention (p > 0.05). Across groups, there were no significant differences in any variable during HDBR, compared to BDC-5. Conclusion Sixty days of HDBR with or without artificial gravity does not induce alterations in motor unit number and size in the ADM or TA muscles in healthy individuals.

GeroScience: dedicated to the biomedical investigation of geroscience and the basic mechanisms of aging 43(5), 2547-2559 (2021). doi:10.1007/s11357-021-00411-4, Published by Springer International Publishing, [Cham]

Medicina : monthly medical journal of Lithuanian Medical Association, Kaunas University of Medicine and Vilnius University 57(9), 884 (2021). doi:10.3390/medicina57090884 special issue: "Special issue "Hip and fragility fracture management" / special issue editor: Matthias Knobe, guest editor", Published by Kaunas Univ. of Medicine, Kaunas

The higher performance level of master athletes compared to non-athletes is often associated with better health throughout life. However, even the physical performance of master athletes declines with age, and this decline accelerates from about the age of 70 years onwards. A progressive loss of muscle mass, declines in force- and power-generating capacity, decreased flexibility, and the concomitant decline in specific tension characterize the muscular changes underlying performance declines. In the cardiovascular system, declines in stroke volume and cardiac output, and cardiac and vascular stiffness contribute to decreasing performance. Recent studies have shown that long-term endurance exercise in master athletes does not only have positive effects, but is associated with an increased incidence of atrial fibrillation, atherosclerotic plaques, and aortic dilation, and even more so in men than in women. Recently, larger longitudinal datasets were analysed and showed that the age-related decline in performance was similar in longitudinal and cross-sectional data. In conclusion, regular physical activity enhances the exercise capacity, and hence quality of life in old age, but it is not without risks.

Purpose Respiratory and musculoskeletal function decline with age, irrespective of physical activity levels. Previous work has suggested that the age-related rate of decline in function of these two systems might be similar, but it is not known to what extent each system contributes to decreasing performance in ageing master cyclists. Therefore, the purposes of this study are (1) whether the age-related rate of decline in respiratory function, respiratory muscle strength, muscle architecture, muscle function, haemoglobin concentration, haematocrit and performance in master cyclists is uniform and (2) which parameters contribute most to the reduction in performance with age. Methods Master cyclists were recruited during the Track Cycling Masters World Championship 2019 in Manchester. Respiratory function and respiratory muscle strength were determined using spirometry and a mouth pressure device, respectively. Muscle architecture was determined using ultrasonography, and muscle function by countermovement jump. Results Forced expiratory volume in the first second, forced vital capacity, fascicle length, muscle thickness, take-off velocity, jump power, jump power per body mass, handgrip strength, haemoglobin concentration and performance correlated negatively with age (p ≤ 0.043). The age-related rate of decline did not differ significantly between parameters (p = 0.124), but it was slower for haemoglobin concentration (p = 0.041). Take-off velocity was the major determinant of performance in 200, 500 and 2000 m track cycling disciplines (R2adj = 0.675, 0.786 and 0.769, respectively; p Conclusion Age-related decline in respiratory and muscle system is accompanied by a similar rate of decline in performance. The major contribution to the age-related decline of performance is reduced muscle function, specifically take-off velocity.

Sensors 21(4), 1495 (2021). doi:10.3390/s21041495 special issue: "Special Issue "Sensors and Methods for the Measurement of Cardiovascular and Respiratory Systems" / Special Issue Editors: Dr. Antti Vehkaoja, Guest Editor; Dr. Jari Viik, Guest Editor", Published by MDPI, Basel

Injury : international journal of the care of the injured 52(7), 1861-1867 (2021). doi:10.1016/j.injury.2021.04.058, Published by Elsevier Science, Amsterdam [u.a.]

Artificial gravity is a potential countermeasure to attenuate effects of weightlessness during long-term spaceflight, including losses of muscle mass and function, possibly to some extent attributable to disturbed neuromuscular interaction. The 60-day AGBRESA bed-rest study was conducted with 24 participants (16 men, 8 women; 33 ± 9 years; 175 ± 9 cm; 74 ± 10 kg; 8 control group, 8 continuous (cAG) and 8 intermittent (iAG) centrifugation) to assess the impact of bed rest with or without daily 30-min continuous/intermittent centrifugation with 1G at the centre of mass. Fasting blood samples were collected before and on day 6, 20, 40 and 57 during 6° head-down tilt bed rest. Concentrations of circulating markers of muscle wasting (GDF-8/myostatin; slow skeletal muscle troponin T; prostaglandin E2), neurotrophic factors (BDNF; GDNF) and C-terminal Agrin Fragment (CAF) were determined by ELISAs. Creatine kinase activity was assessed by colorimetric enzyme assay. Repeated-measures ANOVAs were conducted with TIME as within-subject, and INTERVENTION and SEX as between-subject factors. The analyses revealed no significant effect of bed rest or sex on any of the parameters. Continuous or intermittent artificial gravity is a safe intervention that does not have a negative impact of the neuromuscular secretome.

In master athletics research, cross-sectional data are easier to obtain than longitudinal data. While cross-sectional data give the age-related performance decline for a population, longitudinal data show individual trajectories. It is not known whether athletes who repeatedly compete have (a) a better performance and (b) a slower age-related decline in performance than that obtained from cross-sectional data from athletes competing only once. To investigate this, we analyzed 33 254 results of 14 118 male athletes from 8 disciplines in the database of “Swedish Veteran Athletics.” For each discipline and for the pooled data of all disciplines, quadratic models of the evolution of performance over time were analyzed by ANCOVA/ANOCOVA using MATLAB. The performance was higher in athletes with 2 or more data points compared to those with only n = 1 (p < .001), with further increases in performance with an increasing number of data points per athlete. The estimated performance decline was lower in people with 2 or more results (sprint, 10 km, jumps; p < .001). In conclusion, we showed that longitudinal data are associated with higher performance and lower performance decline rates.

GeroScience : dedicated to the biomedical investigation of geroscience and the basic mechanisms of aging (2020). doi:10.1007/s11357-020-00275-0, Published by Springer International Publishing, [Cham]

Physical performance declines with age, even in exercising, healthy individuals without major illnesses or orthopaedic issues. The rate of performance decline is often reported to accelerate after the age of 70 years, but almost no data are available on performance in the fittest oldest-old. To assess their rate of decline in performance, the biggest dataset of track and field athletes ≥80 years (1567 results) ever published was generated for different disciplines from German athletics Federations including 1997-2019. Performance at age 80 of athletes still participating at age 85 was compared to those who discontinued. Only one out of every 22 athletes competing at age 80 still competed at age 90. The performance decline was more than three times as steep in athletes ≥80 (on average 1.62%/year, men: 100m R=0.31, p

Objectives: The aim of this study was to assess ageing-related changes in middle-distance running kinematics and performance in master athletes. Methods: Male athletes (n=157; 57±13.3 years) competing in the 800- and 1500-m runs at the German Master Athletics Outdoor Championships 2018 were filmed and the bending-over angle, brake angle, leg-stiffness angle, propulsion angle and hip-flexion angle measured. Results: Leg-stiffness and propulsion angle decreased with age (all p

PurposeSpace flight and bed rest (BR) lead to a rapid decline in exercise capacity. Whey protein plus potassium bicarbonate diet-supplementation (NUTR) could attenuate this effect by improving oxidative metabolism. We evaluated the impact of 21-day BR and NUTR on fatigue resistance of plantar flexor muscles (PF) during repeated shortening contractions, and whether any change was related to altered energy metabolism and muscle oxygenation.MethodsTen healthy men received a standardized isocaloric diet with (n = 5) or without (n = 5) NUTR. Eight bouts of 24 concentric plantar flexions (30 s each bout) with 20 s rest between bouts were employed. PF muscle size was assessed by means of peripheral quantitative computed tomography. PF muscle volume was assessed with magnetic resonance imaging. PF muscle force, contraction velocity, power and surface electromyogram signals were recorded during each contraction, as well as energy metabolism (31P nuclear magnetic resonance spectroscopy) and oxygenation (near-infrared spectroscopy). Cardiopulmonary parameters were measured during an incremental cycle exercise test.ResultsBR caused 10–15% loss of PF volume that was partly recovered 3 days after re-ambulation, as a consequence of fluid redistribution. Unexpectedly, PF fatigue resistance was not affected by BR or NUTR. BR induced a shift in muscle metabolism toward glycolysis and some signs of impaired muscle oxygen extraction. NUTR did not attenuate the BR-induced-shift in energy metabolism.ConclusionsTwenty-one days’ BR did not impair PF fatigue resistance, but the shift to glycolytic metabolism and indications of impaired oxygen extraction may be early signs of developing reduced muscle fatigue resistance.

Objectives: Spaceflight back pain and intervertebral disc (IVD) herniations cause problems in astronauts. Purpose of this study was to assess changes in T2-relaxation-time through MRI measurements before and after head-down tilt bed-rest, a spaceflight analog. Methods: 8 men participated in the bed-rest study. Subjects remained in 6° head down tilt bed-rest in two campaigns of 21 days, and received a nutritional intervention (potassium bicarbonate 90 mmol/d) in a cross-over design. MRI measurements were performed 2 days before bed-rest, as well as one and five days after getting up. Image segmentation and data analysis were conducted for the IVDs Th12/L1 to L5/S1. Results: 7 subjects, average age of 27.6 (SD 3.3) years, completed the study. Results showed a significant increase in T2-time in all IVDs (p < 0.001), more pronounced in the nucleus pulposus than in the annulus fibrosus (p

Purpose Wound healing complications are a major concern after open reduction and internal fixation (ORIF) in patients with calcaneal fractures. Microcirculation is known to play a key role in bone and soft tissue healing. The present study aimed to characterize and contrast the dynamics of changes in microcirculation comparing two different surgical procedures: A) ORIF and B) a minimally invasive approach (MIA). Methods Blood flow (BF[AU]), oxygen saturation (sO2[%]) and relative amount of haemoglobin (rHb[AU]) were measured at two depths (2mm and 8mm) non-invasively by spectrophotometry (Micro-Lightguide O2C®, LEA Medizintechnik, Giessen, Germany) before surgery and every 24h after surgery for a duration of six days. A linear mixed model (LMM) was used to analyse longitudinal data and repeated measurements. Results Nineteen patients (44 years, range 21.9–71.0 years) were enrolled in the study. Surgical treatment consisted of ORIF (n=15) and MIA (n=9). The postoperative BF and sO2 at the 2mm and 8mm depths were higher in the ORIF group (BF: p Conclusions The spectrophotometry results were in line with the generally accepted phases of soft tissue wound healing. Postsurgical changes in microcirculation are predominantly independent of surgical techniques and may be primarily determined by wound and fracture healing. Future studies should focus on the potential of spectrophotometry to monitor wound healing after surgery. Moreover, studies with longer observation periods are needed in order to examine the changes in microcirculation during all wound-healing phases.

Lower physical activity levels in old age are thought to contribute to the age-related decline in peak aerobic and anaerobic power. Master athletes maintain high levels of physical activity with advancing age and endurance or power training may influence the extent to which these physical functions decline with advancing age. To investigate, 37-90-year-old power (n=20, 45% female) and endurance (n=19, 58% female) master athletes were recruited. Maximal aerobic power was assessed when cycling two-legged (VO2 Peak2-leg ) and cycling one-legged (VO2 Peak1-leg ), while peak jumping (anaerobic) power was assessed by a countermovement jump. Men and women had a similar VO2 Peak2-leg (mL·kg-1 ·min-1 , p=0.138) and similar ratio of VO2 Peak1-leg to VO2 Peak2-leg (p=0.959) and similar ratio of peak aerobic to anaerobic power (p=0.261). The VO2 Peak2-leg (mL·kg-1 ·min-1 ) was 17% (p=0.022) and the peak rate of fat oxidation (FATmax) during steady-state cycling was 45% higher in endurance than power athletes (p=0.001). The anaerobic power was 33% higher in power than endurance athletes (p=0.022). The VO2 Peak1-leg :VO2 Peak2-leg ratio did not differ significantly between disciplines, but the aerobic to anaerobic power ratio was 40% higher in endurance than power athletes (p=0.002). Anaerobic power, VO2 Peak2-leg , VO2 Peak1-leg and power at FATmax decreased by around 7-14% per decade in male and female power and endurance athletes. The cross-sectional data from 37-90-year-old master athletes in the present study indicates that peak anaerobic and aerobic power decline by around 7-14% per decade and this does not differ between athletic disciplines or sexes. This article is protected by copyright. All rights reserved.

Background The aim of this study was to assess the impact of two teaching interventions (ultrasound and arthroscopy) in a peer teaching (PT) environment on anatomy examination scores and also to examine the influence of gender and learning style on these scores. Methods We randomly assigned 484 second year medical students to one of three groups: musculoskeletal ultrasound (MSUS), arthroscopy (ASC) and control (CON). The MSUS- and the ASC-group attended two additional training sessions in ultrasound or arthroscopy; the CON-group received no additional lessons. Students were asked to complete Kolb's Learning Style Inventory test. We assessed differences in anatomical knowledge (multiple choice (MC) exam) and subjective evaluation with respect to gender and learning style. Results There were no relevant differences between the three groups regarding the MC exam. Acceptance of the peer teaching concept was good. All students preferred ultrasound to arthroscopy and thought that they learned more from ultrasound despite the fact that they rated the instructors as less competent and needed more time to gain in-depth knowledge. There was no significant effect of gender on evaluation results. Arthroscopy was best enjoyed by accommodators according to Kolb's Inventory and least by divergers, who found that they had learned a lot through ultrasound. The improvement in spatial conceptualization was greatest for accommodators and worst for assimilators. Conclusion Gender and learning style had no impact on quantitative parameters. Qualitative analysis, however, revealed differences for learning style and further evaluation is warranted to assess the impact on medical education.

Low-intensity pulsed ultrasound (LIPUS) has been shown to accelerate bone healing and is considered to increase blood flow. The aim of this study was to assess changes in micro-circulation of the foots’ soft tissue in response to LIPUS intervention. We hypothesised improved micro-circulation in response to LIPUS. Micro-circulation was assessed in 2 mm and 8 mm-deep skin of 50 healthy volunteers using non-invasive laser-doppler spectrophotometry (O2C-device). Measurements were performed before LIPUS-intervention (pre), directly after intervention (post) and 20, 40 and 60 minutes after LIPUS. All parameter of micro-circulation increased directly after LIPUS intervention at 8 mm depth. Participants with a low pre-intervention flow showed the largest changes (p

The effectiveness of whey protein plus potassium bicarbonate-enriched diet (WP+KHCO3) in mitigating disuse-induced changes in muscle fiber oxidative capacity and capillarization was investigated in a 21-day crossover design bed rest study. Ten healthy men (31 ± 6 yr) once received WP+KHCO3 and once received a standardized isocaloric diet. Muscle biopsies were taken 2 days before and during the 19th day of bed rest (BR) from the soleus (SOL) and vastus lateralis (VL) muscle. Whole-body aerobic power (V̇o2 max), muscle fatigue, and isometric strength of knee extensor and plantar flexor muscles were monitored. Muscle fiber types and capillaries were identified by immunohistochemistry. Fiber oxidative capacity was determined as the optical density (OD) at 660 nm of succinate dehydrogenase (SDH)-stained sections. The product of fiber cross-sectional area and SDH-OD (integrated SDH) indicated the maximal oxygen consumption of that fiber. The maximal oxygen consumption supported by a capillary was calculated as the integrated SDH in its supply area. BR reduced isometric strength of knee extensor muscles ( P < 0.05), and the fiber oxidative capacity ( P < 0.001) and V̇o2 max ( P = 0.042), but had no significant impact on muscle capillarization or fatigue resistance of thigh muscles. The maximal oxygen consumption supported by a capillary was reduced by 24% in SOL and 16% in VL ( P < 0.001). WP+KHCO3 attenuated the disuse-induced reduction in fiber oxidative capacity in both muscles ( P < 0.01). In conclusion, following 19 days of bed rest, the decrement in fiber oxidative capacity is proportionally larger than the loss of capillaries. WP+KHCO3 appears to attenuate disuse-induced reductions in fiber oxidative capacity.

Bone losses are common as a consequence of unloading and also in patients with chronic obstructive pulmonary disease (COPD). Although hypoxia has been implicated as an important factor to drive bone loss, its interaction with unloading remains unresolved. The objective therefore was to assess whether human bone loss caused by unloading could be aggravated by chronic hypoxia. In a cross-over designed study, 14 healthy young men underwent 21-day interventions of bed rest in normoxia (NBR), bed rest in hypoxia (HBR), and hypoxic ambulatory confinement (HAmb). Hypoxic conditions were equivalent to 4000 m altitude. Bone metabolism (NTX, P1NP, sclerostin, DKK1) and phospho-calcic homeostasis (calcium and phosphate serum levels and urinary excretion, PTH) were assessed from regular blood samples and 24-hour urine collections, and tibia and femur bone mineral content was assessed by peripheral quantitative computed tomography (pQCT). Urinary NTX excretion increased (P < 0.001) to a similar extent in NBR and HBR (P = 0.69) and P1NP serum levels decreased (P = 0.0035) with likewise no difference between NBR and HBR (P = 0.88). Serum total calcium was increased during bed rest by 0.059 (day D05, SE 0.05 mM) to 0.091 mM (day D21, P < 0.001), with no additional effect by hypoxia during bed rest (P = 0.199). HAmb led, at least temporally, to increased total serum calcium, to reduced serum phosphate, and to reduced phosphate and calcium excretion. In conclusion, hypoxia did not aggravate bed rest-induced bone resorption, but led to changes in phospho-calcic homeostasis likely caused by hyperventilation. Whether hyperventilation could have mitigated the effects of hypoxia in this study remains to be established.

Objectives: To investigate the effect of whey protein plus potassium bicarbonate supplement on disused skeletal muscle structure and proteolysis after bed rest (BR). Methods: Soleus (SOL) and vastus lateralis (VL) biopsies were sampled from ten (n=10) healthy male subjects (aged 31±6 years) who did BR once with and once without protein supplement as a dietary countermeasure (cross-over study design). The structural changes (myofibre size and type distribution) were analysed by histological sections, and muscle protein breakdown indirectly via the proteolysis markers, calpain 1 and 3, calpastatin, MuRF1 and 2, both in muscle homogenates and by immunohistochemistry. Results: BR caused size-changes in myofiber cross-sectional area (FCSA, SOL, p=0,004; VL, p=0.03), and myofiber slow-to-fast type transition with increased hybrids (SOL, p=0.043; VL, p=0.037) however with campaign differences in SOL (p

Partial weight bearing is part of treatment schemes in orthopedic surgery and traumatology. The aim of the present study was to explore to what degree ground reaction forces during partial weight bearing of the lower leg are related to given instructions and to tibia deformation.Tibia deformation (torsion, medio-lateral and anterio-posterior bending) was measured for rear foot and forefoot loading, 10kg, 20kg and half body weight instructions compared to full loading in five healthy male subjects using the "Optical Segment Tracking" approach, a motion-capturing based method that uses monocortically fixed bone screws.1. Ground reaction force was a good indicator of tibia deformation. 2. Participants significantly under-loaded during half-body weight instructions (P0.001) while they overloaded when loading the forefoot only. 3. Partial-loading instructions led to a highly significant and systematic reduction in peak ground reaction force (GRFpk) in all three types of tibia deformation with substantial variation between measurements. 4. Forefoot usage was associated with significant, albeit moderate increases in GRFpk (P=0.0031), in AP-bending (P=0.0027) and in torsion (P0.001), compared to rear foot loading.These findings result in the following clinical "lessons learned": 1. GRF is a good reflection of loading-induced deformation of the tibia. 2. GRFs are hard to control by subjects/patients. 3. The expectation that forefoot-loading results in larger tibia deformation could not be confirmed in our study. 4. When aiming at a reduction in tibia deformation, rear-foot loading is more preferable than forefoot loading.

It is thought that the prime determinant of global muscle capillary density is the mean 40 oxidative capacity. However, feedback control during maturational growth or adaptive 41 remodelling of local muscle capillarisation is likely more complex than simply matching O2 42 supply and demand in response to integrated tissue function. We tested the hypothesis that 43 the maximal oxygen consumption (MO2max) supported by a capillary is relatively constant, 44 and independent of the volume of tissue supplied (capillary domain). We demonstrate that 45 local MO2max assessed by succinate dehydrogenase histochemistry 1) varied more than 100- 46 fold between individual capillaries and 2) was positively correlated to capillary domain area 47 in both human vastus lateralis (R=0.750, P

Open reduction in displaced intra-articular calcaneal fractures entails a high rate of wound healing deficits and infections as well as an uncertain outcome, which leads to remaining ambiguity in treatment preferences. Between January and July 2011, we emailed 575 German chairpersons of trauma and/or orthopaedic departments, asking them to complete a 31–question web-based survey regarding three broad domains: fracture classification, surgical treatment algorithms and risk factors for wound healing deficits. The response rate was 47 %. With an incidence of 77 %, open reduction via an extended lateral approach and plate fixation was the main treatment option for displaced intra-articular fractures of the joint-depression-type (Sanders II or III). Percutaneous techniques were only preferred in individual cases, with mainly precarious wound situations (59 %) as well as in patients with a reduced general health condition (ASA 3 and 4; 41 %). The re-operation rate due to infections and wound healing deficits after an extended lateral approach was reported with a percentage of 0-5 % by 88 % of the respondents. Participants stated that especially a poor microcirculation of the foot, disregard of soft tissue conserving techniques, overall condition of the patient, smoking, long time-to-surgery and operation time are the main reasons for wound healing deficits. Given the extended lateral approach as the preferred treatment option, we found minimally invasive techniques and primary arthrodesis of the lower ankle joint play a minor role in treating intra-articular calcaneal fractures in Germany. Ninety percent of our respondents stated less than 5 % of patients required re-operations due to infections and wound healing deficits. Level of Evidence Level V, expert opinion.

The mechanical relationship between bone and muscle has been long recognized. However, it still remains unclear how muscles exactly load on bone. In this study, utilizing an optical segment tracking technique, the in vivo tibia loading regimes in terms of tibia segment deformation in humans were investigated during walking, forefoot and rear foot stair ascent and running and isometric plantar flexion. Results suggested that the proximal tibia primarily bends to the posterior aspect and twists to the external aspect with respect to the distal tibia. During walking, peak posterior bending and peak torsion occurred in the first half (22%) and second half (76%) of the stance phase, respectively. During stair ascent, two noticeable peaks of torsion were found with forefoot strike (38% and 82% of stance phase), but only one peak of torsion was found with rear foot strike (78% of stance phase). The torsional deformation angle during both stair ascent and running was larger with forefoot strike than rear foot strike. During isometric plantar flexion, the tibia deformation regimes were characterized more by torsion (maximum 1.35°) than bending (maximum 0.52°). To conclude, bending and torsion predominated the tibia loading regimes during the investigated activities. Tibia torsional deformation is closely related to calf muscle contractions, which further confirm the notion of the muscle-bone mechanical link and shift the focus from loading magnitude to loading regimes in bone mechanobiology. It thus is speculated that torsion is another, yet under-rated factor, besides the compression and tension, to drive long bone mechano-adaptation.

OBJECTIVE: The aim of this study was to measure the number of motor units and muscle mass in power-trained and endurance-trained master athletes compared with community-dwelling older adults. METHODS: Seventy-five master athletes (52 power- and 23 endurance-trained athletes) were recruited at the 2012 European Veteran Athletics Championships in Zittau (Germany). One hundred and forty-nine community-dwelling older adults served as controls. In all participants, the motor unit number index (MUNIX) in the hypothenar muscle and whole body muscle mass was determined by bioelectrical impedance analysis (BIA). RESULTS: In both male and female master athletes, there were significant negative correlations between age and muscle mass (female: r = -0·510, P = 0·002; male: r = -0·714, P

PLoS one 9(11), e112104 (2014). doi:10.1371/journal.pone.0112104, Published by PLoS [u.a.], Lawrence, Kan.

This paper demonstrates an optical segment tracking (OST) approach for assessing the in vivo bone loading regimes in humans. The relative movement between retro-reflective marker clusters affixed to the tibia cortex by bone screws was tracked and expressed as tibia loading regimes in terms of segment deformation. Stable in vivo fixation of bone screws was tested by assessing the resonance frequency of the screw-marker structure and the relative marker position changes after hopping and jumping. Tibia deformation was recorded during squatting exercises to demonstrate the reliability of the OST approach. Results indicated that the resonance frequencies remain unchanged prior to and after all exercises. The changes of Cardan angle between marker clusters induced by the exercises were rather minor, maximally 0.06°. The reproducibility of the deformation angles during squatting remained small (0.04°/m–0.65°/m). Most importantly, all surgical and testing procedures were well tolerated. The OST method promises to bring more insights of the mechanical loading acting on bone than in the past.

This paper introduces a case of local pigmented villonodular synovits (PVNS) of the upper ankle joint in a 37-year old patient. PVNS is a neoplasia of the synovial membrane. Two different entities of PVNS are known: generalized diffuse and local nodular. They differ in their degree of destruction and growth configuration, which is crucial for prognosis and operative treatment. The most common location of the local nodular form is the knee joint, followed by the finger joints. Occurrence in the ankle joint is not common but should be considered if clinical findings are present. MRI is the method of choice for diagnosis and assessment of the bone situation. Treatment consists of radical excision of the neoplasia. Radiosynoviorthesis is recommended as a post-operative treatment to increase the probability of a total removal of persisting PVNS cells. The rate of recurrence seems to be between 8 and 46%.

NEW FINDINGS: What is the central question of this study? While muscle fibre atrophy in response to immobilisation has been extensively examined, intramuscular connective tissue, particularly endomysium, have been largely neglected. We investigated whether endomysium content of the soleus muscle increases during bed rest. What is the main finding and its importance? Analysing muscle biopsy data from a 60-day bed rest study, we found that absolute endomysium content did not change, and previous studies reporting an increase are explicable by muscle fibre atrophy. It must be expected that even a relative connective tissue accumulation will lead to an increase in muscle stiffness. ABSTRACT: Muscle fibres atrophy during conditions of disuse. Whilst animal data suggest an increase in endomysium content with disuse, that information is not available in humans. We hypothesised that endomysium content increases during immobilisation. To test this hypothesis, biopsy samples of the soleus muscle obtained from 21 volunteers who underwent 60-days of bed rest were analysed using immunofluorescence-labelled laminin γ-1 to delineate individual muscles fibres as well as the endomysium space. The endomysium-to-fibre-area ratio (EFAr, in %) was assessed as a measure related to stiffness, and the endomysium-to-fibre-number ratio (EFNr) was calculated to determine whether any increase in EFAr was absolute, or could be attributed to muscle fibre shrinkage. As expected, we found muscle fibre atrophy (p = 0.0031) that amounted to shrinkage by 16.6% (SD 28.2%) on day 55 of bed rest. ENAr increased on day 55 of bed rest (p < 0.001). However, when analysing EFNr, no effect of bed rest was found (p = 0.62). These results demonstrate that an increase in EFAr is likely a direct effect of muscle fibre atrophy. Based on the assumption that the total number of muscle fibres remains unchanged during 55 days of bed rest, this implies that the absolute amount of connective tissue in the soleus muscle remained unchanged. The increased relative endomysium content, however, could be functionally related to an increase in muscle stiffness. This article is protected by copyright. All rights reserved.