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Journal ArticleDOI

A simple method for measurement of mechanical power in jumping.

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TLDR
The new jumping test seems suitable to evaluate the power output of leg extensor muscles during natural motion because of its high reproducibility and simplicity, and is suitable for laboratory and field conditions.
Abstract
A simple test for the measurement of mechanical power during a vertical rebound jump series has been devised. The test consists of measuring the flight time with a digital timer (+/- 0.001 s) and counting the number of jumps performed during a certain period of time (e.g., 15-60 s). Formulae for calculation of mechanical power from the measured parameters were derived. The relationship between this mechanical power and a modification of the Wingate test (r = 0.87, n = 12 males) and 60 m dash (r = 0.84, n = 12 males) were very close. The mechanical power in a 60 s jumping test demonstrated higher values (20 W X kgBW-1) than the power in a modified (60 s) Wingate test (7 W X kgBW-1) and a Margaria test (14 W X kgBW-1). The estimated powers demonstrated different values because both bicycle riding and the Margaria test reflect primarily chemo-mechanical conversion during muscle contraction, whereas in the jumping test elastic energy is also utilized. Therefore the new jumping test seems suitable to evaluate the power output of leg extensor muscles during natural motion. Because of its high reproducibility (r = 0.95) and simplicity, the test is suitable for laboratory and field conditions.

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Assessing the Magnitude and Direction of Asymmetry in Unilateral Jump and Change of Direction Speed Tasks in Youth Female Team-Sport Athletes.

Abstract: The direction of inter-limb asymmetries and the change of direction (COD) deficit are two aspects that have increased in recent years. The main objective of the present study was to assess the magnitude of neuromuscular asymmetries in an elite youth female team-sports sample and determine its directionality. Secondary objectives were to evaluate the relationship between COD deficit, linear speed and COD time performance. Elite female youth basketball and handball players (n = 33, age = 16 ± 1.17 y) performed the Single Leg Countermovement Jump in vertical (SLCJ-V), horizontal (SLCJ-H), and lateral (SLCJ-L) directions, the COD and the 10-m sprint. Results showed statistical differences between limbs in all the neuromuscular tests (p < 0.001). The Kappa coefficient showed poor to fair levels of agreement between tasks (K range = -0.087 to 0.233), indicating that asymmetries rarely favoured the same limb between skills. Additionally, small and non-significant correlations were found between the linear sprint capacity and the COD ability. The findings of the present study highlight the independent directionality of asymmetries across tests. The COD deficit does not appear to be much more advantageous than COD total time to measure asymmetry. Practitioners are encouraged to use a fitness testing battery to detect existing side differences and each ability should be specifically trained with functional tasks.
Journal ArticleDOI

Revisiting the Relative Age Effect From a Multidisciplinary Perspective in Youth Basketball: A Bayesian Analysis

TL;DR: In this article, a set of surveys with cross-sectional data collected from 2015 to 2019 in youth basketball was used to reveal the effects of the birth quarter on physical performances and psychological constructs in the age groups corresponding to the specialization years.
Journal ArticleDOI

High-density electromyographic assessment of stretch reflex activity during drop jumps from varying drop heights.

TL;DR: Results indicate that during drop jumps above OPT neuromuscular modifications result in VL no longer being maximally recruited, as well as novel insight into the associated motor unit recruitment via muscle fiber conduction velocity estimations.
References
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Journal Article

Utilization of stored elastic energy in leg extensor muscles by men and women

TL;DR: The results suggest that although the leg extensor muscles of the men subjects could sustain much higher stretch loads, the females may be able to utilize a greater portion of the stored elastic energy in jumping activities.
Journal ArticleDOI

Biomechanical analysis of knee flexion and extension

TL;DR: For the knee, mathematical analyses for the sagittal plane were performed on data obtained from roentgenograms and a load cell incorporated in a specially constructed force table to find the axis of rotation for the knee displaced 3·2 cm through a 90° range.
Journal ArticleDOI

Storage of Elastic Energy in Skeletal Muscles in Man

TL;DR: It is suggested that the elastic energy is stored in the active muscles, and it is demonstrated that the muscles of the legs are activated in the downward jumps before contact with the platform is established.
Journal ArticleDOI

Combined effect of elastic energy and myoelectrical potentiation during stretch-shortening cycle exercise

TL;DR: The observed results emphasize that both elastic energy and reflex potentiation may operate effectively during stretch-shortening cycle activity.
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