It was shown that countermovement and squat jump power were . Galileo vibration plate (Novotec, Pforzheim, Germany), oscillating at International Jumpstyle Meeting. Public. · Hosted by Benjamin Lebrasseur and Jelle Zangetsu. Interested. clock. Saturday, June 13, at PM UTC+ „Hell und Dunkel auch bedrohlich ziehen Wolken so dahin. Und die Sterne, die weit oben lassen diese Wolke ziehn.“ Gerhard Ledwina #pforzheim #pforzelona .
Elastic mechanisms play an important role in animals specialized for jumping tasks 3 — 5because the power returned from elastic elements is nearly independent of speed 46as opposed to the power developed by muscle fascicles 7.
Therefore, it is reasonable to suppose that artificial limb designs featuring greater quantities of highly elastic components would perform better than their biological counterparts would during the take-off step in the long jump 8. For the purposes of this article, it is assumed that athletes with BKA have a unilateral amputation and use a running-specific prosthesis below the site of amputation. It is also assumed that non-amputee athletes are not using any form of leg prosthesis or similar device.
The improved performances of athletes with BKA were observed after the introduction of carbon-fibre prostheses that are designed to mimic the spring-like behaviour of the biological lower extremities during running and sprinting 9.
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Today, the best long jumpers with BKA take off from their affected leg using a prosthesis. The improved performance of long jumpers with BKA has led to speculation about a potential performance advantage compared to non-amputee athletes.
Athletes with BKA elicit lower anterior ground reaction forces and have longer contact times during the push-off from the starting blocks and the first step of the acceleration phase compared to non-amputees 10 — This indicates a performance disadvantage during maximum acceleration tasks compared to non-amputees; potentially due to the missing muscles and reduced capacity for positive power generation and other constraints imposed by the use of RSPs 10 — Still, no published data of athletes with BKA for subsequent steps of the acceleration phase exist at the moment.
Furthermore, long jumpers do not accelerate maximally because the length of the run-up allows athletes to achieve maximum run-up speed over a longer period of time and distance.
Thus, theoretical limits on force and power needed to accelerate maximally are likely to have little effect on long jump performance. Correspondingly, the limits on maximum constant sprinting speed appear to be more important for long jump performance 2. Previous studies suggest that maximum constant sprinting speed is primarily limited by the ability to apply high vertical forces to the ground during progressively shorter periods of ground contact with increasing speed 14 Vertical impulse during the stance phase, the integral of force with respect to time, must be sufficiently high so that it yields aerial phases long enough for repositioning of the swing legs As running speed increases and consequently ground contact times decrease, higher average vertical support forces ASFs are required in order to create sufficient vertical impulse.
Therefore, maximizing ASFs during short contact times is crucial for attaining fast maximum sprinting speed. Athletes with BKA using RSPs have asymmetrical biomechanics between their affected and unaffected legs during constant speed running.
Nonetheless, between-leg asymmetries in force application of 4. Because of the considerable training effect, HIT is used in a variety of sports, encompassing a wide range from classical endurance sports to team sports. Accordingly, numerous HIT protocols have been established to meet the requirements associated with specific sport types.
Because of this, HIT protocols usually differ in regards to intensity e. With respect to cycling, it was shown that 4 min high-intensity intervals interspersed with 1. These authors also stated that from a practical point of view a 4x4 min HIT was easier to administer than HIT with shorter high-intensity intervals and shorter rest intervals [ 7 ]. Finally, irrespective of the interval lengths, HIT leads to a more oxidative metabolism [ 8 ] and to a reduction in proportion of myosin heavy chain MyHC -2X fibers [ 9 ].
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These adaptations might further increase fatigue resistance and thus benefiting endurance performance. Despite the proven benefits, there appear to be some pitfalls in using HIT. For example, the shift to a more oxidative metabolism and the alteration in MyHC fiber type distribution might reduce anaerobic performance and capacity.
Notably, a reduced share of MyHC-2 fibers is associated with a lower maximal muscular shortening velocity [ 12 ]. For a given physiological muscle CSA with given fiber type area distribution, the reduction in maximal shortening velocity will lead to a reduction in maximum muscle power.
However, the sole modification of cycling exercise intensity during the rest intervals may not attenuate the decrease in anaerobic performance without compromising the gain in aerobic performance. In addition, studies that investigated the effects of the rest intervals on training adaptations [ 13 — 14 ] were aimed primarily at increasing aerobic adaptations or at making training more bearable, while attaining an identical training effect.
To our knowledge, there have been no studies presented that investigated whether the modification of rest intervals might prevent the afore-mentioned decreases in anaerobic performance and capacity.
Whole-body vibration WBV is a training stimulus that might attenuate the aforementioned anaerobic loss. Despite the scientific controversy on the possible training effects of WBV, which is based on contradictory results, WBV training has been shown to increase several markers of anaerobic performance: In addition, improvements in knee extension power were paralleled by increased muscle mass [ 19 ]. An additional appealing aspect that might be relevant to HIT is the reduced pain sensation associated with WBV [ 20 ].
In fact, HIT is associated with high ratings of subjectively perceived exertion [ 21 ]. This factor presents special challenges involving attitudes surrounding HIT usage.
If WBV performed during the rest intervals significantly reduces leg pain sensation during the high-intensity cycling intervals, the implementation of these high-intensity intervals could be facilitated, by reducing negative perceptions that may lead to motivational deficits. As the rest intervals are as time-consuming as the high-intensity intervals, it would prove advantageous to increase effectiveness of these phases.
For a given vibration type side-alternating vertical sinusoidal vibration vs. Hence, frequencies above 20 Hz consist of stimuli that do not allow complete muscle relaxation to occur.
Furthermore, based on our experience, side-alternating WBV at 18 Hz is less demanding, and is associated with a lower rating of perceived exertion than WBV at 30 Hz. Provided that the similar acute and training effects with WBV at 18 and 30 Hz are achieved, the lower vibration frequency might thereby facilitate execution of HIT. Currently, however, little is known about the differences in training adaptations as well as acute physiological variables e.
In addition, we posed the question as to whether the side-alternating WBV intervals would decrease the rating of perceived exertion during the high-intensity cycling intervals. Methods Participants Thirty-six recreationally active males volunteered to participate in this study. The participants were recruited by placard. Prior to this study, the participants were instructed to maintain their individual training routines in terms of training frequency and training intensity, and were advised not to include new or additional high-intensity exercise during the study period.
Three participants withdrew from the study due to personal reasons not related to the trial. There were no statistically significant differences in physical and performance characteristics among the groups prior to the training period.
Participants were fully informed about the purposes, benefits and risks associated with the study, and completed a routine health questionnaire before giving written informed consent to participate in the study.
The study was approved by the ethics committee of the canton Zurich, and was conducted in accordance with the declaration of Helsinki. Training regimen The participants reported alternately two and three times per week to the laboratory for the supervised training sessions.
Each participant completed thereby twenty training sessions during the 8-week training phase. Hence, the time requirement to switch between the cycle ergometer and the vibration plate and vice versa was 30 s.