scholarly journals Effect of cadence selection on peak power and time of power production in elite BMX riders: A laboratory based study

2016 ◽  
Vol 35 (14) ◽  
pp. 1372-1376 ◽  
Author(s):  
Lee P Rylands ◽  
Simon J Roberts ◽  
Howard T Hurst ◽  
Ian Bentley
Keyword(s):  
Author(s):  
Bill I Campbell ◽  
Marcus Kilpatrick ◽  
Colin Wilborn ◽  
Paul La Bounty ◽  
Brittany Parker ◽  
...  

Author(s):  
Javier Raya-González ◽  
Daniel Castillo ◽  
Marta Domínguez-Díez ◽  
José Luis Hernández-Davó

This study aimed to evaluate the differences in power production between movement phases (i.e., concentric and eccentric) during the execution of resistance exercises with a flywheel device, differentiating between execution regimes (i.e., bilateral, unilateral dominant leg and unilateral non-dominant leg). Twenty young elite soccer players (U−17) performed two sets of six repetitions of the bilateral half-squat (inertia 0.025 kg·m−2) and the lateral-squat exercise (inertia 0.010 kg·m−2) on a flywheel device. During the testing sessions, mean and peak power in concentric (MPcon) and eccentric (MPecc) phases were recorded. The non-dominant leg showed higher values in all power variables measured, although substantial differences were only found in MPecc (ES = 0.40, likely) and PPcon (ES = 0.36, possibly). On the other hand, for both exercises, MPcon was higher than MPecc (ES = −0.57 to −0.31, possibly/likely greater), while only PPecc was higher than PPcon in the dominant lateral-squat (ES = 0.44, likely). These findings suggest that young soccer players have difficulty in reaching eccentric-overload during flywheel exercises, achieving it only with the dominant leg. Therefore, coaches should propose precise preventive programs based on flywheel devices, attending to the specific characteristics of each limb, as well as managing other variables to elicit eccentric-overload.


Author(s):  
G. Spazzafumo

Wind is a significant renewable energy source in Patagonia, which could generate a very large amount of electrical energy. However, it is not possible to put such a large amount of energy on to the grid due to instability issues. Electrolysis could facilitate the storage of such energy in the form of hydrogen, which could be used for peak power production or for vehicles. However, hydrogen storage and distribution are still very expensive. On the other hand, South Patagonia has reserves of coal which exploitation is not easy. One solution could be underground coal gasification. Unfortunately, using coal results in high emissions of carbon dioxide. Hydrogen from wind energy could be the solution to convert coal to methane and to eventually generate electrical power. In this way, a large amount of renewable energy could be introduced to the energy system with a reduction in the emissions of carbon dioxide.


2017 ◽  
Vol 12 (8) ◽  
pp. 1052-1058 ◽  
Author(s):  
Andrea Monte ◽  
Francesca Nardello ◽  
Paola Zamparo

Purpose:The effects of different loads on kinematic and kinetic variables during sled towing were investigated with the aim to identify the optimal overload for this specific sprint training.Methods:Thirteen male sprinters (100-m personal best: 10.91 ± 0.14 s) performed 5 maximal trials over a 20-m distance in the following conditions: unloaded and with loads from 15% to 40% of the athlete’s body mass (BM). In these calculations the sled mass and friction were taken into account. Contact and flight times, stride length, horizontal hip velocity (vh), and relative angles of hip, knee, and ankle (at touchdown and takeoff) were measured step by step. In addition, the horizontal force (Fh) and power (Ph) and maximal force (Fh0) and power (Ph0) were calculated.Results:vh, flight time, and step length decreased while contact time increased with increasing load (P < .001). These variables changed significantly also as a function of the step number (P < .01), except between the 2 last steps. No differences were observed in Fh among loads, but Fh was larger in sled towing than in unloaded. Ph was unaffected by load up to +20%BM but decreased with larger loads. Fh0 and Ph0 were achieved at 20%BM. Up to 20%BM, no significant effects on joint angles were observed at touchdown and takeoff, while at loads >30%BM joint angles tended to decrease.Conclusion:The 20%BM condition represents the optimal overload for peak power production—at this load sprinters reach their highest power without significant changes in their running technique (eg, joint angles).


1994 ◽  
Vol 4 (1) ◽  
pp. 14-24 ◽  
Author(s):  
Lucas H. V. van der Woude ◽  
D. Drexhage ◽  
H. E. J. Veeger

2020 ◽  
Vol Publish Ahead of Print ◽  
Author(s):  
Nicole M. Bordelon ◽  
Devin H. Jones ◽  
Kael M. Sweeney ◽  
Daniel J. Davis ◽  
Meghan L. Critchley ◽  
...  

Life ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 282
Author(s):  
Marco Duca ◽  
Athos Trecroci ◽  
Enrico Perri ◽  
Damiano Formenti ◽  
Giampietro Alberti

Background: Effective sprinting requires large acceleration capabilities. To accelerate, large amount of force must be produced and applied effectively. The use of different implements such as sleds and vests can increase the amount of force produced and alter sprinting effectiveness. We propose the use of increasing overload via the Bulgarian Bag (BB) as a means to modify athletes’ sprint and acutely increase force and power production. Methods: 24 young athletes performed three sprints over 20 m in three different conditions: unloaded (BW) and loaded with BB weighing 2.5% (BB2.5) and 5% (BB5) of the athlete’s body mass. Sprint times at 2.5, 5, 10, 15, and 20 m were acquired and used to compute the force–velocity relationship for the sprints. Maximal velocity (V0), peak force (F0), peak power (PP), and decrease in ratio of force (DRF) were computed. Results: the additional load caused a decrease in sprint times (p < 0.05) and V0 (p = 0.028), conversely no differences were found for F0 (p = 0.21), PP (p = 0.50), and DRF (p = 0.83). Conclusions: Based on those findings, BB can be an alternative method to effectively overload sprint training toward improving sprinting performance.


2018 ◽  
Vol 28 (83) ◽  
pp. 63-68
Author(s):  
Krzysztof Krawczyk ◽  
Maciej Słowak

Abstract Introduction: An overview of the literature on the subject of handball indicates that today’s top-level handball is dominated by sequences of short-duration (5 – 20 seconds) intensive anaerobic physical effort. Taking into account this data and the lack of scientific contribution describing the levels of the anaerobic capacity of top-level handball players, it seems essential to research this sphere of capacity in men’s Superleague teams. Aim: The objective of the study is to evaluate the relative mechanical work (J/kg), peak power (W/kg), peak power production time (s) and peak power sustainment time (s) in Wingate tests performed on players in various positions. Basic procedures: Research participants: 18 players in the Superleague handball team; average age of participants = 25.96±3.97 years old, average height = 192.76±7.21 cm, average body mass = 97.61±11.46 kg; average BMI = 25.84±1.92. The evaluation of anaerobic capacity was performed according to the 30-second Wingate test procedure, with the use of the Monark 824E cycle ergometer and the MCE v5.0 computer software. Results: The mean peak power of the research participants was 11.12±0.84 W/kg; mean work value – 254.56±16.92J/kg, mean peak power production time – 4.82±0.82s; peak power sustainment time – 2.98±1.04s; fatigue index – 25.82±3.64%. Conclusions: In the process of top-level handball training, it is necessary to pay more attention to the development of anaerobic endurance through the increased use of interval workload. Key words: anaerobic capacity, interval training, handball


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