Balance Performance across the Lifespan Assessed by the Leonardo Mechanograph®: A Cross-Sectional Study

Reference values of sway parameters have not been published for the Leonardo mechanograph® so far. The aim of this cross-sectional study was to determine normative values on postural control measured by the force plate Leonardo Mechanograph® and to analyze the influence of age and sex on balance performance. A set of standardized standing positions with eyes opened (Romberg, semi-tandem, tandem, unipedal standing) was carried out. Analysis of covariance (ANCOVA) was used to detect age-and sex-related differences in center of pressure (COP) parameters (path length, velocity, elliptical area, anterior-posterior, and medio-lateral directions). Measurements were available for 570 subjects aged 20–86 years. Statistical analysis showed a high effect of age group on postural control (partial n² between 0.1 and 0.4) with a U-shaped dependency between postural control and age for all area- and path-related COP parameters, with the largest sway in the youngest (aged 20–40) and the oldest age group (aged 60–86). For velocity of COP, a linear deterioration with increasing age was found. Medio-lateral components of COP are likely to indicate the extent of postural control. Significant sex differences were not clearly supported by current findings. Age- and sex-related normative values are a useful resource for diagnostic, research, and training

Changes in lower extremity muscle function after 56 days of bed rest

Preservation of muscle function, known to decline in microgravity and simulation (bed rest), is important for successful spaceflight missions. Hence, there is great interest in developing interventions to prevent musclefunction loss. In this study, 20 males underwent 56 days of bed rest. Ten volunteers were randomized to do resistive vibration exercise (RVE). The other 10 served as controls. RVE consisted of muscle contractions against resistance and concurrent whole-body vibration. Main outcome parameters were maximal isometric plantar-flexion force (IPFF), electromyography (EMG)/force ratio, as well as jumping power and height. Measurements were obtained before and after bed rest, including a morning and evening assessment on the first day of recovery from bed rest. IPFF (-17.1%), jumping peak power (-24.1%), and height (-28.5%) declined (P < 0.05) in the control group. There was a trend to EMG/force ratio decrease (-20%; P < 0.051). RVE preserved IPFF and mitigated the decline of countermovement jump performance (peak power -12.2%; height -14.2%). In both groups, IPFF was reduced between the two measurements of the first day of reambulation. This study indicates that bed rest and countermeasure exercises differentially affect the various functions of skeletal muscle. Moreover, the time course during recovery needs to be considered more thoroughly in future studies, as IPFF declined not only with bed rest but also within the first day of reambulation. RVE was effective in maintaining IPFF but only mitigated the decline in jumping performance. More research is needed to develop countermeasures that maintain muscle strength as well as other muscle functions including power

Exercise and transversus abdominis muscle atrophy after 60-d bed rest

PURPOSE: This study aimed to investigate atrophy in the deep abdominal muscles, spinal extensors, and the effect of high-load resistive exercise with and without whole-body vibration after 60 d of strict bed rest. METHODS: Twenty-four subjects underwent 60 d of head-down tilt bed rest and performed either resistive vibration exercise (RVE), resistive exercise only (RE), or no exercise control (2nd Berlin BedRest Study). The thickness of the transversus abdominis, internal oblique, and erector spinae muscles and the area of the multifidus muscle were measured bilaterally via real-time ultrasound. Intention-to-treat analysis was implemented, and P values were adjusted by the false discovery rate method. RESULTS: At the end of the bed rest, transversus abdominis thickness was reduced by 18.3% in the inactive group (P = 0.00011) with no significant change in the RVE (-4.0%; P = 0.014 vs control) or RE (-5.0%; P = 0.10 vs control) groups. In the inactive subjects, internal oblique thickness reduced by 10.6% (P = 0.0025) and by 7% (P &gt; 0.05) in each of the training groups. The lengthening of the lumbar spine was greatest on day 1 (+7.4%, P = 0.004) and day 2 (+6.3%, P = 0.004; day 54: +4.1%, P = 0.023). A 4.7% reduction of multifidus area was observed on day 1 of bed rest (P = 0.0049) and a 4.2% reduction of erector spinae thickness was observed on day 2 (P = 0.0011). Extensor atrophy and spinal lengthening was not affected by exercise. No significant difference was seen between RVE and RE. CONCLUSION: Bed rest leads to atrophy of the transversus abdominis and internal oblique muscles. The exercise program, which implemented lower-limb and back extension exercises against shoulder restraints, was able to reduce atrophy seen in transversus abdominis in bed rest

Impact of the Gut Microbiota on Atorvastatin Mediated Effects on Blood Lipids

Background and aims: The mechanisms of interindividual variation of lipid regulation by statins, such as the low-density lipoprotein cholesterol (LDL) lowering effects, are not fully understood yet. Here, we used a gut microbiota depleted mouse model to investigate the relation between the gut microbiota and the regulatory property of atorvastatin on blood lipids. Methods: Mice (C57BL/6) with intact gut microbiota or antibiotic induced abiotic mice (ABS) were put on standard chow diet (SCD) or high fat diet (HFD) for six weeks. Atorvastatin (10 mg/kg body weight/day) or a control vehicle were applied per gavage for the last four weeks of dietary treatment. Blood lipids including total cholesterol, very low-density lipoprotein, low-density lipoprotein, high-density lipoprotein and sphingolipids were measured to probe microbiota-dependent effects of atorvastatin. The expression of genes involved in hepatic and intestinal cholesterol metabolism was analyzed with qRT-PCR. The alteration of the microbiota profile was examined using 16S rRNA qPCR in mice with intact gut microbiota. Results: HFD feeding significantly increased total blood cholesterol and LDL levels, as compared to SCD in both mice with intact and depleted gut microbiota. The cholesterol lowering effect of atorvastatin was significantly attenuated in mice with depleted gut microbiota. Moreover, we observed a global shift in the abundance of several sphingolipids upon atorvastatin treatment which was absent in gut microbiota depleted mice. The regulatory effect of atorvastatin on the expression of distinct hepatic and intestinal cholesterol-regulating genes, including Ldlr, Srebp2 and Npc1l1 was altered upon depletion of gut microbiota. In response to HFD feeding, the relative abundance of the bacterial phyla Bacteroidetes decreased, while the abundance of Firmicutes increased. The altered ratio between Firmicutes to Bacteroidetes was partly reversed in HFD fed mice treated with atorvastatin. Conclusions: Our findings support a regulatory impact of atorvastatin on the gut microbial profile and, in turn, demonstrate a crucial role of the gut microbiome for atorvastatin-related effects on blood lipids. These results provide novel insights into potential microbiota-dependent mechanisms of lipid regulation by statins, which may account for variable response to statin treatment

Progressive adaptation in physical activity and neuromuscular performance during 520d confinement

To understand whether prolonged confinement results in reductions in physical activity and adaptation in the musculoskeletal system, six subjects were measured during 520 d isolation in the Mars500 study. We tested the hypothesis that physical activity reduces in prolonged confinement and that this would be associated with decrements of neuromuscular performance. Physical activity, as measured by average acceleration of the body\u27s center of mass (&quot;activity temperature&quot;) using the actibelt&reg; device, decreased progressively over the course of isolation (p&lt;0.00001). Concurrently, countermovement jump power and single-leg hop force decreased during isolation (p&lt;0.001) whilst grip force did not change (p&ge;0.14). Similar to other models of inactivity, greater decrements of neuromuscular performance occurred in the lower-limb than in the upper-limb. Subject motivational state increased non-significantly (p = 0.20) during isolation, suggesting reductions in lower-limb neuromuscular performance were unrelated to motivation. Overall, we conclude that prolonged confinement is a form of physical inactivity and is associated with adaptation in the neuromuscular system

Effect of resistive exercise on musculoskeletal morphology and function during bed rest

Schwerelosigkeit und längere Bettruhe führen zu Muskelatrophien im posturalen System und vermindern dessen neuromuskuläre Leistungsfähigkeit und lokomotorische Kompetenz. Morphologische Anpassungen an die reduzierten muskulären Kräfte führen zudem zu Schmerzen, zumeist im Lumbalbereich. Muskel- und Knochenabbau sind erhebliche Limitationen geplanter Langzeitmissionen im All. Bisher auf der ISS eingesetzte Laufbänder und Fahrradergometer konnten diese Probleme nicht lösen. Die Untersuchung von Effekten eines neu entwickelten Krafttrainings auf Veränderungen der Skelettmuskulatur und alltagsrelevante Funktionen war Ziel der durchgeführten Bedrest-Studien. In die Berliner Bedrest-Studie 1 (BBR 1) wurden 20 männliche Probanden eingeschlossen. Während 56- tägiger Bettruhe trainierten 10 Probanden 2-mal täglich liegend mit einem Vibrationstrainingsgerät bei submaximaler Intensität. 10 Probanden der Kontrollgruppe trainierten nicht. Vor und nach der Liegephase wurden die isometrischen Kräfte der Plantarflexion (IPFF) sowie die maximale Leistung und Sprunghöhe beim counter-movement jump getestet. Gleichzeitig wurden Spannungszustände der eingesetzten Muskulatur mittels Elektromyographie (EMG) gemessen und ein EMG/Kraft- Quotient ermittelt. Die IPFF (-17,1%), die maximale Sprungleistung (-24,1%) und die Sprunghöhe (-28,5%) nahmen in der Kontrollgruppe ab (p<0,05). Für die Abnahme des EMG/Kraft Quotienten (-20%) gab es einen Trend (p=0,051). In der Interventionsgruppe konnte das Vibrationstraining die IPFF erhalten und Verluste der Sprungleistung (-12,2%) und Sprunghöhe (-14,2%) reduzieren. In der Berliner Bedrest-Studie 2 (BBR 2) lagen 24 Probanden 60 Tage in 6° Kopftieflage. Die Probanden der Interventionsgruppen führten ein hochintensives Widerstandstraining ohne (RE; n=8), beziehungsweise mit Ganzkörpervibration (RVE; n=7) durch. Zur Erhöhung von Compliance und Effizienz wurde im Gegensatz zur BBR 1 die Belastungszeit auf drei mal 6 Minuten pro Woche reduziert. Die Kontrollgruppe (CTR; n=9) trainierte nicht. Die intervertebrale Morphologie und die vertebralen Muskelquerschnittsflächen (CSA) wurden in 28-tägigen Intervallen mittels Magnetresonanztomographie gemessen. Ein neuromuskuläres Assessment auf einer Kraftmessplatte, Kurzsprints über 15m und 30m sowie ein Maximalkrafttest auf einer Beinpresse wurden vor und direkt nach der Immobilisation durchgeführt. Das Training verhinderte den Leistungsverlust bei Aufstehtests aus 30cm (p<0,001) und 45cm (p=0,034) Sitzhöhen, den Anstieg der Sprintzeiten über 15m (p=0,037) und 30m (p=0,005), sowie Verluste der Maximalkraft (p<0,001), maximalen Sprungleistung und Sprunghöhe (p<0,001). Die Interventionsgruppen zeigten eine geringere Abnahme der CSA in den Mm. multifidii, M. erector spinae und M. quadratus lumborum, sowie Zunahmen in den Mm. psoas major und minor (p≤0,004). Die Trainingsinterventionen zeigten keine Effekte auf Veränderungen der spinalen Morphologie (p≥0,22). Die in diesem Zusammenhang erstmals untersuchten Trainingsinterventionen konnten die muskulären Atrophien und Funktionsverluste während Immobilisation deutlich verringern. Die Integration der Trainingsregime in den klinischen Alltag und bemannte Weltraummissionen werden Ziele weiterer Forschung sein.Weightlessness and prolonged bed-rest result in postural muscle atrophy and decreases in neuromuscular performance. Adaptations to the reduced muscular forces during bed-rest can also lead in lower back pain. Muscle and bone loss are particular concerns for planned long term spaceflight missions. Presently on the International Space Station treadmills and bicycle ergometers are implemented, but cannot prevent all the detrimental effects of spaceflight. The aim of the bed-rest studies implemented by the Center of Muscle and Bone Research was investigation of effects of resistive exercise with and without whole-body vibration during prolonged immobilization (bed-rest). In the 1st Berlin BedRest Study (BBR1) 20 male subjects were included. During 56-day bed- rest 10 subjects conducted resistive vibration exercise two times daily in the supine position near maximal intensity. 10 subjects in the control group did not exercise. Isometric plantar flexion forces (IPFF), maximum power and jump height during countermovement jumping (CMJ) were tested before and after bed- rest. During CMJ, electromyography (EMG) of the lower-limb muscles and a EMG/Force quotient was calculated. IPFF (-17.1%), jump peak power (-24.1%) and jump height (-28.5%) decreased in the control group (p<0,05) and there was a trend (p=0,051) for decreased in EMG/Force-Quotient (-20%) in this group. In the RVE group IPFF was preserved and losses in peak jump power (-12.2 %) and jump height (-14.2%) were reduced. In the 2nd Berlin BedRest Study (BBR2) 24 subjects underwent in 60-day 6° head down tilt bed-rest. Subjects in intervention groups conducted a high load resistant training without (RE, n=8) or with whole body vibration (RVE, n=7). To assess efficiency, the training frequency was reduced to 3 times per week each with 6 minutes of actual loading. Control group (CTR, n=9) did not exercise. Intervertebral morphology and vertebral muscle- cross sectional area (CSA) was measured with magnetic resonance imaging before, at mid- and end-bed-rest. Neuromuscular assessments on a ground reaction force platform, 15m and 30 m sprints, and a one repetition maximum leg-press test were performed before and after immobilisation. Training (RE and RVE pooled) prevented losses in sit-to-stand tests from 30cm (p<0,001) and 45cm (p=0,034) sitting heights, increases in 15m (p=0,037) and 30m (p=0,005) sprint time, as well as loss in CMJ peak force (p<0,001), power (p<0,001) and height (p<0,001). The intervention groups shows less decreases in size of the multifidus, lumbar erector spinae and quadratus lumborum muscles, with greater increases in psoas major and minor muscles (p≤0,004). The exercise interventions had no effects to changing in spinal morphology (p≥0,22). The current studies represent the first implementations of resistive vibration exercise in bed-rest and these regimes were able to reduce muscle atrophy and losses in function due to immobilisation. Integration in clinical practice and manned spaceflight will be an aim of further research

Short-duration resistive exercise sustains neuromuscular function after bed rest

PURPOSE: The study\u27s purpose was to assess the effectiveness of a short-duration three-times-weekly high-load resistive exercise program on preventing deterioration in neuromuscular function after prolonged bed rest. METHODS: Twenty-four male subjects performed high-load resistive exercise (n = 8), high-load resistive exercise with whole-body vibration (n = 9), or no exercise (control, n = 9) during 60-d head-down tilt bed rest as part of the 2nd Berlin Bed Rest Study. Peak countermovement jump power and height, sit-to-stand performance, sprint time over 15 and 30 m, and leg press one-repetition maximum were measured before and after bed rest. RESULTS: The exercise interventions were capable of ameliorating losses of peak countermovement jump power (P &lt; 0.001) and height (P &lt; 0.001), deterioration of sit-to-stand time from 45-cm (P = 0.034) and 30-cm (P &lt; 0.001) sitting positions, increases of 15-m (P = 0.037) and 30-m (P = 0.005) sprint time, and losses of leg press one-repetition maximum (P &lt; 0.001). CONCLUSIONS: The short-duration (6-min time under tension per training session) exercise countermeasure program performed three times a week was capable of reducing the effect of prolonged bed rest on many neuromuscular function measures

The 2nd Berlin BedRest study: protocol and implementation

Long-term bed-rest is used to simulate the effect of spaceflight on the human body and test different kinds of countermeasures. The 2nd Berlin BedRest Study (BBR2-2) tested the efficacy of whole-body vibration in addition to high-load resisitance exercise in preventing bone loss during bed-rest. Here we present the protocol of the study and discuss its implementation. Twenty-four male subjects underwent 60-days of six-degree head down tilt bed-rest and were randomised to an inactive control group (CTR), a high-load resistive exercise group (RE) or a high-load resistive exercise with whole-body vibration group (RVE). Subsequent to events in the course of the study (e.g. subject withdrawal), 9 subjects participated in the CTR-group, 7 in the RVE-group and 8 (7 beyond bed-rest day-30) in the RE-group. Fluid intake, urine output and axiallary temperature increased during bed-rest (p<.0001), though similarly in all groups (pâÂÂ¥.17). Body weight changes differed between groups (p<.0001) with decreases in the CTR-group, marginal decreases in the RE-group and the RVEgroup displaying significant decreases in body-weight beyond bed-rest day-51 only. In light of events and experiences of the current study, recommendations on various aspects of bed-rest ethodology are also discussed

Decline of specific peak jumping power with age in master runners

Background: It is difficult to disentangle the effects of pure ageing from those of disuse. Master athletes, however, provide an opportunity to assess the effects of ageing per se, as these people maintain high activity levels during ageing. Methods: We examined 200 female and 295 male master runners over the age of 35 who participated at European and World master championships. Runners were grouped by short, middle and long distance disciplines. Besides a questionnaire about their sports activities, measurements of counter movement jumps on a ground reaction force plate were performed. Specific peak jump power was the main subject, i.e., maximum jump power per body mass. Results: All discipline groups showed an age-related decline in specific jump power when performing counter movement jumps (p<0.001). Except for female long distance runners, the amount of decline was the same for all discipline groups (p<0.001 to p<0.01) for each gender. The results for female long distance runners was highly spread caused by the small number of participants with older age. Conclusions: Our data indicate a decline in specific jump power that is similar to that reported in previous studies. The novelty from our results is the comparison of intra-gender decline. We observed the same amount of decline for all runners participating in different running disciplines