This study investigated PAPE effects of two conditioning activities (CA) and recovery times on the peak jumping power (PP) of elite female volleyball athletes. Players performed CA separately: three sets of three repetitions of back squats with 85% of 1RM (BS) or one set of five depth drops (DD). PP was measured with countermovement (CMJ) and squat jumps (SJ) before (pre-test) and two minutes (post-test 1) and six hours (post-test 2) after each CA. BS significantly reduced PP at post-test 1 (CMJ and SJ: p < 0.04, d between −0.36 and −0.28). At post-test 2, following BS, PP for both jump forms was significantly greater than at post-test 1 (p < 0.001, d between 0.54 and 0.55) and at pre-test (p < 0.048, d between 0.21 and 0.30). DD increased PP significantly (CMJ and SJ p < 0.05, d between 0.40 and 0.41) relative to pre-test at post-test 2 (there was no significant difference between pre-test and post-test 1). Comparing BS with DD, there were no significant differences (p > 0.05). The greatest PAPE effects were observed six hours after BS. CA are recommended for female athletes to improve jumping performance, but individual responses should be determined prior to use.
Energy pumping is a way to gain kinetic energy based on an active vertical center of mass movement in rollers in sports like skateboarding, skicross, snowboard cross and BMX. While the principle of the energy transfer from the vertical movement to the horizontal movement is well understood, the question of how to achieve the optimal energy transfer is still unresolved. In this paper, we introduce an inverse pendulum model to describe the movement of the center of mass of an athlete performing energy pumping. On this basis, the problem of identifying the optimal movement pattern is formulated as an optimal control problem. We solve the discretized optimal control problem with the help of a SQP-algorithm. We uncover that the optimal movement pattern consists of a jumping, flying, and landing phase, which has to be timed precisely. We investigate how the maximal horizontal speed depends on parameters like rollers height and maximal normal force of the athlete. Additionally, we present a qualitative comparison of our results with measured results from BMX-racing. For athletes and coaches, we advice on the basis of our results that athlete’s performance is optimized by using maximal force and adopt an exact and proper timing of the movement pattern.
Two methods for challenging the musculoskeletal and nervous systems to better exploit the stretch-shortening cycle (SSC) mechanism during plyometric training are reactive strength exercises and accentuated eccentric loading (AEL). Combining repetitive, reactive jumping with AEL poses a novel approach, in which the effects of both methods may be combined to elicit a unique stimulus. This study compared kinematic, kinetic, and electromyographic variables between a control (CON1) and two AEL conditions (AEL2 and AEL3). Additionally, non-reactive and reactive jumps performed within these sets were compared. Participants performed two sets of six countermovement jumps (CMJ) under each loading condition. AEL3 had moderate to large positive effects (es) on peak and mean eccentric force (es = 1.1, 0.8, respectively; both; p; < 0.01), and eccentric loading rate (es = 0.8,; p; < 0.01), but no effect on concentric variables or muscle activation intensity. The effects of AEL2 were similar but smaller. With or without AEL, there were moderate to large positive effects associated with reactive CMJ (second jump in a set, compared to the first) on peak and mean eccentric velocity (es = 1.7, 0.8, respectively; both; p; < 0.01), peak and mean eccentric force (es = 1.3, 1.2,; p; < 0.01), eccentric loading rate (es = 1.3,; p; < 0.01) and muscle activity (es = 1.8-1.9,; p; < 0.01). Concentric variables did not differ. Thus, the flight phase and act of landing during reactive jumps elicited greater increases in eccentric forces, loading rates, and muscle activity than AEL. Nonetheless, kinetic variables were greatest when AEL was combined with reactive jumping. Considering the limitations or complexity associated with most AEL protocols, sets of repetitive (reactive) CMJ may be more pragmatic for augmenting eccentric kinetic variables and neuromuscular stimuli during training.
Performance on vault in artistic gymnastics depends on the difficulty and the execution quality of the performed vault. However, differences of kinetic energy between simple and difficult vaults remain elusive. Therefore, in this study, 48 Tsukahara and Yurchenko vaults, performed by 20 top-level gymnasts, were recorded with 3D-motion capture and the flux of translational (TKE), angular kinetic (AKE), potential (PE), and total energy were calculated and compared. Results revealed that upon initial springboard contact, almost all of the kinetic energy for Tsukahara vaults is comprised of TKE, whereas Yurchenko vaults were characterized by substantially less TKE, but far greater AKE (and similar PE). During springboard contact of Tsukahara vaults, AKE is increased (+70%) and thereafter mostly preserved during push off from the table (−6%). For Yurchenko vaults, AKE is preserved during springboard contact but reduced (−30%) in exchange for PE at push off. During the second flight phase of Yurchenko vaults, total energy was 10% higher than at initial springboard contact (Tsukahara: −1%). For vaults of increasing difficulty, 5.9% more AKE is needed for each additional 180° of longitudinal-axis rotation. This knowledge may help coaches evaluate athletes’ potential and focus training on appropriate physical and/or technical aspects of the vault performance.
max. 250 Wörter / 250 mots au max. Einleitung / Introduction: Ein Monitoring der Trainingsbelastung und der Leistungsanpassungen dient unter anderem der Optimierung des Trainings. Das Ziel dieser Untersuchung war deshalb, basierend auf den Erkenntnissen aus der Trainingsdatenanalyse der exzentrisch-isokinetischen Krafttrainingsintervention zur Verbesserung von Krafthalteelementen an den Ringen im Kunstturnen (Schärer et al. 2019; Studie 1), eine optimierte Trainingsintervention zu entwickeln sowie ihre Wirksamkeit zu überprüfen (Studie 2). Methode / Méthode: Die Analyse der vierwöchigen Trainingsintervention (acht Trainings) mit dem 1080 Quantum Syncro (Studie 1) ergab, dass sich die exzentrische Maximalkraft hauptsächlich in den Trainings 2 bis 4 verbessert hat. Die Trainingsübung (Rückenlage auf Heberbank, Hände greifen je einen Ring wie beim Kunstturnen, maximaler Gegendruck mit gestreckten Armen (Ausgangsposition: 70° über Hüfte; Endposition: -15° unter Hüfte) gegen das mit 0.1m/s computergesteuert nach unten synchron eingezogene Zugseil) sowie die "cluster-förmige" exzentrisch-isokinetische Belastungsmodalität dieser drei Trainings (Training 2: 2x2x4; Trainings 3 und 4: 3x3x4) wurden deshalb in der dreiwöchigen Intervention von Studie 2 von Training 1 bis 3 übernommen und als Reizwechsel von Training 4 bis 6 exzentrisch-isokinetisch + isoinertial mit zehn Nationalkaderathleten wiederholt. Eine Woche vor und nach Trainingsintervention wurde der maximale Widerstand (Körpergewicht plus Zusatzgewicht / minus Gegengewicht) bei den Krafthalteelementen Schwalbe und Stützwaage an den Ringen (Haltezeit: 5s) bestimmt. Resultate / Résultats: Die Maximalkraft der Krafthalteelemente verbesserte sich in Studie 2 um 7% (Stützwaage) respektive 8% (Schwalbe) (beide p < 0.01), in Studie 1 um 4% (Stützwaage; p < 0.01) respektive 3% (Schwalbe p > 0.05). Diskussion und Schlussfolgerung / Discussion et conclusion: Die Effizienz der Trainingsintervention in Studie 2 konnte dank dem Trainingsmonitoring von Studie 1 (mit zwei Trainings weniger) verdoppelt werden. Diese Studie zeigt, wie durch Monitoring "nicht-funktionale Trainingsreize" eliminiert und dadurch Krafttrainingsinterventionen effizienter gestaltet werden können. In Bezug auf die angewandte exzentrisch-isokinetische Trainingsform konnte festgestellt werden, dass diese bei Eliteathleten hochwirksam zu sein scheint, wenn erstens eine gewisse (minimale) Wiederholungsanzahl der Trainingsübung pro Training realisiert wird und zweitens ein Reizwechsel (exzentrsich-isokinetisch + isoinertial) nach nur wenigen Trainings stattfindet. Aufgrund der hohen Intensität sollte diese Trainingsform nicht als "Dauermethode", jedoch gezielt in Phasen mit geringer Belastung im sporttechnischen Training eingesetzt werden.
As hill jumps are very time-consuming, ski jumping athletes often perform various imitation jumps during training. The performed jumps should be similar to hill jumps, but a direct comparison of the kinetic and kinematic parameters has not been performed yet. Therefore, this study aimed to correlate 11 common parameters during hill jumps (Oberstdorf Germany), squat jumps (wearing indoor shoes), and various imitation jumps (rolling 4°, rolling flat, static; jumping equipment or indoor shoes) on a custom-built instrumented vehicle with a catch by the coach. During the performed jumps, force and video data of the take-off of 10 athletes were measured. The imitation and squat jumps were then ranked. The main difference between the hill jumps and the imitation and squat jumps is the higher maximal force loading rate during the hill jumps. Imitation jumps performed on a rolling platform, on flat ground were the most similar to hill jumps in terms of the force-time, and leg joint kinematic properties. Thus, non-hill jumps with a technical focus should be performed from a rolling platform with a flat inrun with normal indoor shoes or jumping equipment, and high normal force loading rates should be the main focus of imitation training.
In artistic gymnastics, the possibility of using 2D video analysis to measure the peak height (hpeak) and length of flight (L) during routine training in order to monitor the execution and development of difficult elements is intriguing. However, the validity and reliability of such measurements remain unclear. Therefore, in this study, the hpeak and L of 38 vaults, performed by top-level gymnasts, were assessed by 2D and 3D analysis in order to evaluate criterion validity and both intrarater and interrater reliability of the 2D method. Validity calculations showed higher accuracy for hpeak (±95% LoA: ±3.6% of average peak height) than for L (±95% LoA: ±7.6% of average length). Minor random errors, but no systematic errors, were observed in the examination of intrarater reliability (hpeak: CV% = 0.44%, p = 0.81; L: CV% = 0.87%, p = 0.14) and interrater reliability (hpeak: CV% = 0.51%, p = 0.55; L: CV% = 0.72%, p = 0.44). In conclusion, the validity and reliability of the 2D method are deemed sufficient (particularly for hpeak, but with some limitations for L) to justify its use in routine training of the vault. Due to its simplicity and low cost, this method could be an attractive monitoring tool for gymnastics coaches.
Abstract Alpine ski races can last up to 2.5 minutes and have very high metabolic demands. One limiting factor for performance is insufficient aerobic energy supply. We studied the effects of an 8-day interval training block on aerobic capacity (VO2max) and performance and physiology during the 90-second box jump test (BJ90), a maximal performance test employed to simulate the metabolic demands of alpine ski racing, in elite junior skiers. After 10 high-intensity interval training sessions, performed as cycling, running, or an obstacle course, VO2max increased in all subjects by 2.5 ± 1.9 ml · minute(-1) · kg(-1) (4.3 ± 3.2%), as did maximal blood lactate concentration in a graded cycling test (before: 11.7 ± 1.3 mmol · L(-1), after: 14.8 ± 1.8 mmol · L(-1), both parameters p ≤ 0.05). Performance (total jumps) and aerobic energy contribution (63.3 ± 2.8%) during the BJ90 did not increase as hypothesized; however, subjects altered their pacing strategy, which may have counteracted such an effect. Additionally, the present data support the practicality of the performance test used for mimicking the demands of alpine skiing.
We aimed to manipulate physiological determinants of severe exercise performance. We hypothesized that (1) beta-alanine supplementation would increase intramuscular carnosine and buffering capacity and dampen acidosis during severe cycling, (2) that high-intensity interval training (HIT) would enhance aerobic energy contribution during severe cycling, and (3) that HIT preceded by beta-alanine supplementation would have greater benefits.; Sixteen active men performed incremental cycling tests and 90-s severe (110 % peak power) cycling tests at three time points: before and after oral supplementation with either beta-alanine or placebo, and after an 11-days HIT block (9 sessions, 4 × 4 min), which followed supplementation. Carnosine was assessed via MR spectroscopy. Energy contribution during 90-s severe cycling was estimated from the O2 deficit. Biopsies from m. vastus lateralis were taken before and after the test.; Beta-alanine increased leg muscle carnosine (32 ± 13 %, d = 3.1). Buffering capacity and incremental cycling were unaffected, but during 90-s severe cycling, beta-alanine increased aerobic energy contribution (1.4 ± 1.3 %, d = 0.5), concurrent with reduced O2 deficit (-5.0 ± 5.0 %, d = 0.6) and muscle lactate accumulation (-23 ± 30 %, d = 0.9), while having no effect on pH. Beta-alanine also enhanced motivation and perceived state during the HIT block. There were no between-group differences in adaptations to the training block, namely increased buffering capacity (+7.9 ± 11.9 %, p = 0.04, d = 0.6, n = 14) and glycogen storage (+30 ± 47 %, p = 0.04, d = 0.5, n = 16).; Beta-alanine did not affect buffering considerably, but has beneficial effects on severe exercise metabolism as well as psychological parameters during intense training phases.
Supplementation with beta-alanine may have positive effects on severe-intensity, intermittent and isometric strength-endurance performance. These could be advantageous for competitive alpine skiers, whose races last 45 - 150 seconds, require metabolic power above the aerobic maximum and involve isometric muscle work. Further, beta-alanine supplementation affects the muscle force-frequency relationship, which could influence explosiveness. We explored the effects of beta-alanine on explosive jump performance, severe exercise energy metabolism, severe-intensity ski-like performance, and fatigue resistance during training camp in elite alpine skiers.; Nine male elite alpine skiers consumed 4.8 g/d beta-alanine or placebo for 5 weeks in a double-blind fashion. Before and after, they performed countermovement jumps (CMJ), a 90-s cycling bout at 110% VO2max (CLT), and a maximal 90-s box jump test (BJ90).; Beta-alanine improved maximal (+7±3%, d=0.9) and mean CMJ power (+7±2%, d=0.7), tended to reduce oxygen deficit (-3±8 %, p=0.06) and lactate accumulation (-12±31%) and enhance aerobic energy contribution (+1.3±2.9%, p=0.07) in the CLT, and improved performance in the last third of BJ90 (+7±4%, p=0.02). These effects were not observed with placebo.; Beta-alanine supplementation improved explosive and repeated jump performance in elite alpine skiers. Enhanced muscle contractility could possibly explain improved explosive and repeated jump performance. Increased aerobic energy production could possibly help explain repeated jump performance as well.
The goal of the 90-second box jump (BJ90) is to perform as many lateral jumps as possible onto and off of a bench within 90 seconds. We aimed to determine the physiologicaland biomechanical demands of the BJ90. Sixteen trained males (age range 23–45 y) performed a cycling test to determine maximal oxygen uptake (VO2 max), three countermovement jumps (CMJ) to determine explosive leg strength and the BJ90 on 1–3 occasions. Heart rate (HR), VO2, and ground reaction forces were recorded throughout the BJ90. Acceleration, work and powerwere derived from force measurements. Blood lactate and oxygen debt were measured after the test and aerobic energy contribution was estimated. Subjects performed (mean ± SD (range)) 75 ± 13 (52-94) jumps. Total work was 64.0 ± 6.3 (53–78) kJ, denoting a work rate of 711 ± 70 (590–868) W. Mean acceleration and impulse for the ground contact phase were 14.9 ± 4.3 (7.5–22.3) m/s2 and 521 ± 94 (410–783) N·s, respectively. Maximal concentric power remained higher than in CMJ for the first 60 s but dropped over the last 30 s to values similar to CMJ. Average concentric power was always lower than in CMJ, and dropped continuously throughout the BJ90. Maximal eccentric power was of lesser magnitude than in CMJ. Peak VO2 and HR were 93.1 ± 8.3% (77–110) and 95.6 ± 2.6% (89- 102) of maxima, respectively. Metabolic intensitycorresponded to 136 ± 12 (108–156)%VO2 max (80.1 ± 6.3 ml/min/kg) and aerobic contribution to total energy was 55.9 ± 4.2%. Metabolic efficiency was 34.5 ± 3.6%. Blood lactate reached 13.4 ± 1.6 (9.0-17.0) mM. Conclusions: Physiologically speaking, the BJ90 is similar to giant slalom skiing, whereas the movement frequency corresponds to slalom racing. The faster rate of force development in the BJ90 represents the main difference from ski racing.
Abstract Typically, free radicals are thought of as perpetrators of cell damage, ageing, even cancer, whereas antioxidants are seen as the defence against these threats. Accordingly, antioxidants are among the most common sports supplements used by amateur and professional athletes. However, the sensibility of this practice has recently been challenged in the scientific literature. This article briefly summarizes both positive and negative physiological effects of free radicals and antioxidants, culminating with emphasis on the signalling roles played by free radicals during training adaptations and the ability of superfluous antioxidants to weaken these desired signals, as revealed in several recent publications. The aim of this article is not to explicitly condemn antioxidant supplementation by athletes, but to underscore complexity of the situation and to champion efforts to achieve a deeper understanding of circumstances (e.g. dosage, timing, and setting) that might deem antioxidant supplementation as either largely beneficial or largely detrimental for endurance athletes in training.
