Ein einfaches System zum bewerten des gewichttrainings-die Anwendung bei der Bewertung von kraft Fähigkeiten

In order to monitor force and power produced during a weight exercise a simple computer based system has been designed. Utilizing Newton’s laws of mechanics the actual force while lifting the weight can be derived by multiplying mass and acceleration. The latter is being obtained as a derivation of velocity registered by means of a sensor mechanically coupled with a barbell. Multiplying the force and velocity provides the actual value of power. The system provides on-line graphical and digital data and calculates mean and maximal values separately for the eccentric and concentric phase. Monitoring the basic biomechanical parameter during repetitions with stepwise increasing weights up to LRM performed with maximal effort in the concentric phase provides data to draw individual force-velocity and power-velocity curves. These allow the estimation of strength and power at different velocities as a basis for a more sports specific assessment of strength abilities.Mit dem Ziel, die bei den Gewichtsübungen ausgeübte Kraft und Leistung zu messen, wurde ein einfaches Computersystem entwickelt. Aufgrund der Newtonschen Gesetze der Mechanik kann die eigentliche bei den Gewichtsübungen ausgeübte Kraft gerechnet werden, indem man Masse mit Akzeleration multipliziert. Die Akzeleration wird als Derivation der Geschwindigkeit bestimmt, die mittels eines mit der Hantel mechanisch verbundenen Sensors gemessen worden ist. Das Produkt der Kraft und Geschwindigkeit gibt den realen Wert der Leistung. Das System ermöglicht on-line graphische und digitale Darstellung der Daten und rechnet Mittel- und Gipfelwerte besonders für die exzentrische bzw. konzentrische Phase aus. Verzeichnet man die biomechanischen Grundparameter während Wiederholungen, wobei die Belastung stufenweise bis zam Maximum(1M) erhöht wird, das mit Höchstkraftaulwand in der konzentrischen Phase ausgeführt wird, werden die Daten für die Gestaltung der individuellen Kurven; Kraft- Geschwindigkeit und Schnellkralt-Geschwindigkeit erzielt. Diese Kurven ermöglichen die Bewertung des Kraftaufwands und der Leistung bei verschiedenen Geschwindigkeiten, womit die Basis für eine sportspezifische Bewertung der Kraftfähigkeiten gebildet wird

Long-term high-level exercise promotes muscle reinnervation with age.

The histologic features of aging muscle suggest that denervation contributes to atrophy, that immobility accelerates the process, and that routine exercise may protect against loss of motor units and muscle tissue. Here, we compared muscle biopsies from sedentary and physically active seniors and found that seniors with a long history of high-level recreational activity up to the time of muscle biopsy had 1) lower loss of muscle strength versus young men (32% loss in physically active vs 51% loss in sedentary seniors); 2) fewer small angulated (denervated) myofibers; 3) a higher percentage of fiber-type groups (reinnervated muscle fibers) that were almost exclusive of the slow type; and 4) sparse normal-size muscle fibers coexpressing fast and slow myosin heavy chains, which is not compatible with exercise-driven muscle-type transformation. The biopsies from the old physically active seniors varied from sparse fiber-type groupings to almost fully transformed muscle, suggesting that coexpressing fibers appear to fill gaps. Altogether, the data show that long-term physical activity promotes reinnervation of muscle fibers and suggest that decades of high-level exercise allow the body to adapt to age-related denervation by saving otherwise lost muscle fibers through selective recruitment to slow motor units. These effects on size and structure of myofibers may delay functional decline in late aging

FES Training in Aging: interim results show statistically significant improvements in mobility and muscle fiber size

Aging is a multifactorial process that is characterized by decline in muscle mass and performance. Several factors, including reduced exercise, poor nutrition and modified hormonal metabolism, are responsible for changes in the rates of protein synthesis and degradation that drive skeletal muscle mass reduction with a consequent decline of force generation and mobility functional performances. Seniors with normal life style were enrolled: two groups in Vienna (n=32) and two groups in Bratislava: (n=19). All subjects were healthy and declared not to have any specific physical/disease problems. The two Vienna groups of seniors exercised for 10 weeks with two different types of training (leg press at the hospital or home-based functional electrical stimulation, h-b FES). Demografic data (age, height and weight) were recorded before and after the training period and before and after the training period the patients were submitted to mobility functional analyses and muscle biopsies. The mobility functional analyses were: 1. gait speed (10m test fastest speed, in m/s); 2. time which the subject needed to rise from a chair for five times (5x Chair-Rise, in s); 3. Timed –Up-Go- Test, in s; 4. Stair-Test, in s; 5. isometric measurement of quadriceps force (Torque/kg, in Nm/kg); and 6. Dynamic Balance in mm. Preliminary analyses of muscle biopsies from quadriceps in some of the Vienna and Bratislava patients present morphometric results consistent with their functional behaviors. The statistically significant improvements in functional testings here reported demonstrates the effectiveness of h-b FES, and strongly support h-b FES, as a safe home-based method to improve contractility and performances of ageing muscles

Muscle Power during Standing and Seated Trunk Rotations with Different Weights

This study compares peak and mean power during standing and seated trunk rotations with different weights. Twenty seven fit men completed four trials of trunk rotations in both standing and seated positions with a bar weight of 5.5, 10.5, 15.5, and 20 kg placed on the shoulders. The FiTRO Torso Premium was used to monitor basic biomechanical parameters throughout the movement. Results showed significantly higher peak power during standing than seated trunk rotations at weights of 20 kg (274.4±63.5 vs. 206.4±54.6 W, p=0.004), 15.5 kg (371.2±93.9 vs. 313.5±72.3 W, p=0.007), and 10.5 kg (336.9±77.8 vs. 286.3±66.0 W, p=0.009) but not at 5.5 kg (191.6±46.2 vs. 166.0±37.0 W, p=0.061). Similarly, mean power in the acceleration phase of trunk rotations was significantly higher when performed in standing than seated position at weights of 20 kg (143.2±32.1 vs. 101.9±23.7 W, p=0.008), 15.5 kg (185.1±42.3 vs. 150.4±36.5 W, p=0.019), and 10.5 kg (169.8±40.7 vs. 139.7±31.6 W, p=0.024) but not at 5.5 kg (107.4±29.4 vs. 86.5±21.1 W, p=0.111). Furthermore, peak and mean power during standing trunk rotations significantly correlated with values achieved in the seated position at the weight of 5.5 kg (r=0.684, p=0.027; r=0.676, p=0.033) but not at 10.5 kg (r=0.589, p=0.089; r=0.552, p=0.143), 15.5 kg (r=0.493, p=0.243; r=0.436, p=0.298), and 20 kg (r=0.357, p=0.361; r=0.333, p=0.417). In conclusion, power production is greater during standing as compared to seated trunk rotations, with more pronounced differences at higher weights. This fact has to be taken into account when training and testing the trunk rotational power

Novel approach to imaging by cosmic-ray muons

Cosmic-ray muons can be used for imaging of large structures, or high-density objects with high atomic number. The first task can be performed by measurement of muon absorption within very thick material layers, while the second approach is based on muon multiple scattering. However, the muon imaging of small structures with low atomic number and density was not yet solved appropriately. Here we show the first results of cosmic-ray muon imaging of small objects made of elements of low atomic number. This novel approach includes detection of secondary particles produced by muons, which were not used at all in previous muon imaging methods. Thus, the list of elements, as well as the range of dimensions of objects which can be imaged are significantly expanded

Morphological, molecular and hormonal adaptations to early morning versus afternoon resistance training

It has been clearly established that maximal force and power is lower in the morning compared to noon or afternoon hours. This morning neuromuscular deficit can be diminished by regularly training in the morning hours. However, there is limited and contradictory information upon hypertrophic adaptations to time-of-day-specific resistance training. Moreover, no cellular or molecular mechanisms related to muscle hypertrophy adaptation have been studied with this respect. Therefore, the present study examined effects of the time-of-day-specific resistance training on muscle hypertrophy, phosphorylation of selected proteins, hormonal concentrations and neuromuscular performance. Twenty five previously untrained males were randomly divided into a morning group (n = 11, age 23 ± 2 yrs), afternoon group (n = 7, 24 ± 4 yrs) and control group (n = 7, 24 ± 3 yrs). Both the morning and afternoon group underwent hypertrophy-type of resistance training with 22 training sessions over an 11-week period performed between 07:30–08:30 h and 16:00–17:00 h, respectively. Isometric MVC was tested before and immediately after an acute loading exclusively during their training times before and after the training period. Before acute loadings, resting blood samples were drawn and analysed for plasma testosterone and cortisol. At each testing occasion, muscle biopsies from m. vastus lateralis were obtained before and 60 min after the acute loading. Muscle specimens were analysed for muscle fibre cross-sectional areas (CSA) and for phosphorylated p70S6K, rpS6, p38MAPK, Erk1/2, and eEF2. In addition, the right quadriceps femoris was scanned with MRI before and after the training period. The control group underwent the same testing, except for MRI, between 11:00 h and 13:00 h but did not train. Voluntary muscle strength increased significantly in both the morning and afternoon training group by 16.9% and 15.2 %, respectively. Also muscle hypertrophy occurred by 8.8% and 11.9% (MRI, p < 0.001) and at muscle fibre CSA level by 21% and 18% (p < 0.01) in the morning and afternoon group, respectively. No significant changes were found in controls within these parameters. Both pre- and post-training acute loadings induced a significant (p < 0.001) reduction in muscle strength in all groups, not affected by time of day or training. The post-loading phosphorylation of p70S6Thr421/Ser424 increased independent of the time of day in the pre-training condition, whereas it was significantly increased in the morning group only after the training period (p < 0.05). Phosphorylation of rpS6 and p38MAPK increased acutely both before and after training in a time-of-day independent manner (p < 0.05 at all occasions). Phosphorylation of p70S6Thr389, eEF2 and Erk1/2 did not change at any time point. No statistically significant correlations were found between changes in muscle fibre CSA, MRI and cell signalling data. Resting testosterone was not statistically different among groups at any time point. Resting cortisol declined significantly from pre- to post-training in all three groups (p < 0.05). In conclusion, similar levels of muscle strength and hypertrophy could be achieved regardless of time of the day in previously untrained men. However, at the level of skeletal muscle signalling, the extent of adaptation in some parameters may be time of day dependent.peerReviewe