Erfolge mittels Rudererergometer und anaerobe leistungsmöglichkeit bei den Ruderern-studenten

The aim of the study presented was to assess the relationships between the 6-minute "all-out" rowing ergometer test with physical performance indices in college rowers. Ten male rowers (21.60+4.20 yrs; 186,90+5.64 cm; 84.10+6.59 kg; %body fat: 9.62+2.81%) performed a 6-minute "all-out" rowing ergometer test on a rowing ergometer (Concept II, USA) at the first measurement session. In addition, a graded exercise test at the intensities of 150, 200 and 250 W (6-minutes each) and a maximal 5x1 minute interval test were performed at separate measurement sessions. The heart rate (HR) was recorded at the end of each load during a graded exercise test. The individual physical working capacity (PWC) of the rowers was calculated at the maximum of HR recorded during a 6-minute "all-out" test. Blood samples for lactate (LA) determination were obtained from the fingertip before and immediately after each bout of exercise. The anaerobic threshold (AT) indices were determined by interpolation from the relationships between the LA concentration and the respective variable at a LA concentration of 4.0 mmol/l. The LA concentration in the blood was also determined before, immediately after and after 3 minutes and 5 minutes of recovery of the maximal 5 x 1 minute interval test. Significant correlations (p<0.05) were observed between the AT (W) and power (r=0.56) and the covered distance (r=0.55) of a 6-minute "all-out" test. In addition, the power and distance covered of the 6-minute "all-out" test were significantly related to the covered distance and power of all five trials of the maximum interval test (r=0.64-0.77). The stepwise multiple interval test indicated that the power of a 6-minute "all-out" test was explained by the mean power of a maximal 5 x 1 minute interval test at 82.75% (R2). In conclusion, the results of our study suggest that our proposed interval test has a high diagnostic value in the assessment of the anaerobic work capacity of rowers.Das Ziel dieser Untersuchung war, die Zusammenhange zwischen 6-Minuten Leistungstest mittels eines Rudererergometers und Indexen der körperlichen Leistungsmöglichkeit von Ruderern-Studenten zu erstellen. Zehn männliche Ruderer (21.60+/-4.20 Jahre; 186,90+/-5,64cm; 84,10+/-6,59kg; 9,62+/-2,81% Fettgewebe) wurden dem 6-Minuten Leistungstest am Rudererergometer (Concept II, USA) in der ersten Messung unterzogen. Zusätzlich wurden der progressive Belastungstest mit den Werten 150, 200 und 250 W (je 6 Minuten) und der Intervall-Leistungstest in der Zeitspanne von 5x1 Minute in abgesonderten Messungen durchgeführt. Die Herzfrequenz (Heart Rate - HR) wurde in der Endphase jeder Belastung des Stufentestes gemessen. Persönliche körperliche Arbeitsleistung (PWC - engl. physical working capacity) der Ruderer wurde nach maximal gemessener Herzfrequenz in der Zeitspanne des 6-Minuten Leistungtestes errechnet. Aus der Fingerkuppe wurden vor und nach jeder Leistung die Blutproben zur Feststellung des Milchsäurespiegels (LA) entnommen. Die Indexe der anaeroben Schwelle (anaerobic threshold - AT) wurden nach der vorgenommenen Interpolation der Wechselbeziehung zwischen dem LA-Spiegel und der entsprechenden Variable mit der Konzentration von 4,0 mmol/ festgestellt. Der LA-Spiegel wurde im Blut vorher, anschließend, 3 wie auch 5 Minuten nach dem Intervall-Leistungstest 5x1 gemessen. Es wurde eine bedeutende Wechselbeziehung (p<0,05) zwischen der anaeroben Schwelle (W) und dem Kraftaufwand (r=0,56) einerseits und der zurückgelegten Entfernung (r=0,55) in den Zeitspannen des Leistungtestes festgestellt. Der Kraftaufwand und die zurückgelegten Entfernung im Laufe des Leistungtestes hingen auch bedeutend von der zurückgelegten Entfernung und dem Kraftaufwandin allen fünf Zeitspannen des Intervall- Leistungtestes (r=0,64-0,77) ab, Der wicderholende Intervall-Test mit progressiver Belastung ‘beweist, dass sich der 82,75% (R2) Kraftaufwand, gemessen in 6-Minuten Leistungtest, über arithmetisches Mittel vom Kraftaufwand, gemessen im Leistungtest mit Intervallen von 5x1 Minute erklären lasst. Wir schlussfolgern, dass die Ergebnisse unserer Untersuchung darauf hinweisen, wie hoch der diagnostische Wert des vorgeschlagenen Intervall-Leistungtests bei der Einschätzung von Arbeitsleistung der Ruderer ist

Predation on postlarvae and juveniles of the shore crab Carcinus maenas: importance of shelter, size and cannibalism

Settlement and early juvenile stages are considered a bottleneck in the Life history of many epibenthic organisms because of high predation mortality. Nursery habitats may play an important role in mitigating settlement and post-settlement mortality by providing refuge from predation. We examined these relationships in postlarvae and early juvenile stages of the shore crab Carcinus maenas L. in laboratory and field tethering experiments. We studied habitat and size related habitat mortality using postlarvae and young juvenile crabs as prey, and various predators, including juvenile conspecifics, in several habitats common in shallow (0 to 1 m) soft bottom nursery areas on the Swedish west coast. Settling mortality was high in open sand (80 to 90%), whereas a significant habitat refuge was obtained in mussel beds, eelgrass and filamentous green algae, the latter yielding the lowest mortality (13 to 14%). Small differences in structural complexity of ephemeral macroalgae dramatically affected predation mortality of first instar crabs, with a significant refuge obtained only in algae of medium complexity. Predation rate on tethered crabs in the field was high (52 to 67%) only on the smallest crabs (\u3c5 mm carapace width, CW), which obtained a significant refuge in the eelgrass habitat compared to open sand. Mortality for larger crabs (5 to 25 mm CW) was low (\u3c10%) and similar in sand and eelgrass habitats. Our results indicate that predation is an important process that can create a bottleneck for juvenile shore crab populations during settlement and early juvenile stages, mediated by the availability of nursery habitats. Postlarvae obtained refuge from predation in several different habitats, suggesting that the recruitment of juvenile shore crabs will be less affected by temporal and spatial variation of any single habitat type. The strong size refuge for crabs larger than 4 mm CW indicates that key predators are small. We suggest that cannibalistic juveniles, which caused predation rates similar to or higher than all other investigated predators, are dominant predators on settling postlarvae and young juvenile crabs in nursery areas. We further propose that habitat- and size-specific predation by small epibenthic predators are an important selective force in habitat selection by postlarvae and ontogenetic shifts in habitat use by juveniles

The Effects of Ceria Loading on Three-Way Catalysts for Passive SCR Operation

Passive SCR systems, which employ both a three-way catalyst and SCR catalyst, are effective for the reduction of nitrogen oxide (NOx) emissions from lean burn gasoline engines. However, questions remain regarding the effect of three-way catalyst formulations on their performance in these systems. Here, Pd/CeOx/Al2O3 catalysts with variable CeOx loading were synthesized, characterized, and evaluated to determine the effects of CeOx on catalyst performance. While a small amount of ceria was beneficial for promoting essential reactions, excess ceria was detrimental due to the increase in oxygen storage capacity. Additionally, insights into potential reaction pathways for NH3 production were determined

The Effects of Ceria Loading on Three-Way Catalysts for Passive SCR Operation

Passive SCR systems, which employ both a three-way catalyst and SCR catalyst, are effective for the reduction of nitrogen oxide (NOx) emissions from lean burn gasoline engines. However, questions remain regarding the effect of three-way catalyst formulations on their performance in these systems. Here, Pd/CeOx/Al2O3 catalysts with variable CeOx loading were synthesized, characterized, and evaluated to determine the effects of CeOx on catalyst performance. While a small amount of ceria was beneficial for promoting essential reactions, excess ceria was detrimental due to the increase in oxygen storage capacity. Additionally, insights into potential reaction pathways for NH3 production were determined