Mesozoic fold structure of the Otago and Alpine Schist Belt and its implications on the tectonic evolution of South Island, New Zealand

Erneute Untersuchungen der mesozoischen Faltenstruktur des Otago Schiefergürtels, Südinsel, Neuseeland, zeigen, dass diese aus zwei aufeinander folgenden, ähnlichen, asymmetrischen, offenen bis mäßig engen Großfaltengenerationen im km- Größenbereich besteht anstatt aus den vorher angenommenen Decken- oder Halbfalten. Hauptproblem der Großfaltenstruktur sind Zonen von durchgreifender Boudinage, die in der Nähe der Großfaltenscharniere entstanden sind. Vorherige Bearbeiter deuteten diese Zonen als 'starke Verformungszonen' oder Überschiebungszonen. Diese Arbeit zeigt, dass in diesen Zonen nur durch die asymmetrische Faltung die unteren liegenden Schenkel der Großfalten boudiniert und somit häufig die ansonsten typischen Faltenstrukturen des liegenden Schenkels einer symmetrischen Faltung überprägt wurden. Ein weiteres Problem dieser mesozoischen Großfaltenstruktur ist die Überprägung einer Faltengeneration auf eine frühere. Weil die Verkürzungsrichtung der überprägenden Faltengeneration nicht subparallel zur älteren Faltenachse ist, sondern einen Winkel von rund 30 Grad einschließt, ist ein Wechsel von orthogonalen zu koaxialen Interferenzmustern der Kleinfalten beobachtbar. Folglich ist die Orientierung der Scheitellinie einer überprägenden und überprägten Kleinfalte nicht unbedingt subparallel zur Orientierung der Faltenachse der Großfalte trotz zylindrischer Faltung. Im letzten Teil dieser Arbeit wird die Überprägung der mesozoischen Großfaltenstruktur durch das känozoisch entstandene, transpressionale Alpine Störungssystem, das einen zweiseitigen Falten- und Überschiebungsgürtel im Otago und im Nordwesten anschließenden Alpinen Schiefergürtel bildet, beschrieben.

Effects of eccentric cycle ergometry in alpine skiers

Eccentric cycling, where the goal is to resist the pedals, which are driven by a motor, increases muscle strength and size in untrained subjects. We hypothesized that it could also be beneficial for athletes, particularly in alpine skiing, which involves predominantly eccentric contractions at longer muscle lengths. We investigated the effects of replacing part of regular weight training with eccentric cycling in junior male alpine skiers using a matched-pair design. Control subjects ( N=7) executed 1-h weight sessions 3 times per week, which included 4-5 sets of 4 leg exercises. The eccentric group ( N=8) performed only 3 sets, followed by continuous sessions on the eccentric ergometer for the remaining 20 min. After 6 weeks, lean thigh mass increased significantly only in the eccentric group. There was a groupxtime effect on squat-jump height favouring the eccentric group, which also experienced a 6.5% improvement in countermovement-jump height. The ability to finely modulate muscle force during variable eccentric cycling improved 50% (p=0.004) only in the eccentric group. Although eccentric cycling did not significantly enhance isometric leg strength, we believe it is beneficial for alpine skiers because it provides an efficient means for hypertrophy while closely mimicking the type of muscle actions encountered while skiing.

Block training periodization in alpine skiing: effects of 11-day HIT on VO2max and performance

Attempting to achieve the high diversity of training goals in modern competitive alpine skiing simultaneously can be difficult and may lead to compromised overall adaptation. Therefore, we investigated the effect of block training periodization on maximal oxygen consumption (VO2max) and parameters of exercise performance in elite junior alpine skiers. Six female and 15 male athletes were assigned to high-intensity interval (IT, N = 13) or control training groups (CT, N = 8). IT performed 15 high-intensity aerobic interval (HIT) sessions in 11 days. Sessions were 4 x 4 min at 90-95% of maximal heart rate separated by 3-min recovery periods. CT continued their conventionally mixed training, containing endurance and strength sessions. Before and 7 days after training, subjects performed a ramp incremental test followed by a high-intensity time-to-exhaustion (tlim) test both on a cycle ergometer, a 90-s high-box jump test as well as countermovement (CMJ) and squat jumps (SJ) on a force plate. IT significantly improved relative VO2max by 6.0% (P < 0.01; male +7.5%, female +2.1%), relative peak power output by 5.5% (P < 0.01) and power output at ventilatory threshold 2 by 9.6% (P < 0.01). No changes occurred for these measures in CT. tlim remained unchanged in both groups. High-box jump performance was significantly improved in males of IT only (4.9%, P < 0.05). Jump peak power (CMJ -4.8%, SJ -4.1%; P < 0.01), but not height decreased in IT only. For competitive alpine skiers, block periodization of HIT offers a promising way to efficiently improve VO2max and performance. Compromised explosive jump performance might be associated with persisting muscle fatigue.