scholarly journals Dependence of human squat jump performance on the series elastic compliance of the triceps surae: a simulation study

2001 ◽  
Vol 204 (3) ◽  
pp. 533-542 ◽  
Author(s):  
M. Bobbert
Keyword(s):  
Vertical Velocity ◽  
The Body ◽  
Triceps Surae ◽  
Jump Height ◽  
Jump Performance ◽  
Lower Velocity ◽  
Squat Jump ◽  
Moments Of Inertia ◽  
Angular Velocities ◽  
Series Elastic

The purposes of this study were to determine the dependence of human squat jump performance on the compliance of series elastic elements (SEEs) of the triceps surae (consisting of the soleus and gastrocnemius) and to explain this dependence. Vertical squat jumps were simulated using an optimal control model of the human musculo-skeletal system. Maximum jump height was found for several values of triceps surae SEE strain at maximum isometric force (ε (0)). When ε (0) was increased from 1 to 10 %, maximum jump height increased by 8 cm. This was partly due to a higher work output of contractile elements (CEs) of the muscles, primarily of the soleus, and also partly to an increased efficacy of converting muscle work to energy contributing to jump height. The soleus produced more work at ε (0)=10 % because, as a result of SEE recoil, the CE covered its shortening range at lower velocity and hence produced more force. Efficacy was higher at ε (0)=10 % because a higher vertical velocity at take-off was achieved with a lower rotational energy of the body segments. This apparent discrepancy was explained by increased angular velocities of the shanks and feet, which have small moments of inertia, and decreased angular velocities of the thighs and trunk, which have larger moments of inertia. This redistribution of segmental contributions to the vertical velocity of the centre of mass was possible because the increased compliance of the triceps surae SEE enhanced the energy-buffering capacity of this muscle group and, thereby, allowed for a higher power output at the ankles. It seems that long compliant tendons in the plantar flexors are an elegant solution to the problem of maximizing jumping performance.

scholarly journals Muscle fibre recruitment can respond to the mechanics of the muscle contraction

2006 ◽  
Vol 3 (9) ◽  
pp. 533-544 ◽  
Author(s):  
James M Wakeling ◽  
Katrin Uehli ◽  
Antra I Rozitis
Keyword(s):  
Motor Unit ◽  
Muscle Activity ◽  
The Body ◽  
Motor Unit Recruitment ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Muscle Fibres ◽  
Strain Rates ◽  
Lower Velocity ◽  
Muscle Fascicle

This study investigates the motor unit recruitment patterns between and within muscles of the triceps surae during cycling on a stationary ergometer at a range of pedal speeds and resistances. Muscle activity was measured from the soleus (SOL), medial gastrocnemius (MG) and lateral gastrocnemius (LG) using surface electromyography (EMG) and quantified using wavelet and principal component analysis. Muscle fascicle strain rates were quantified using ultrasonography, and the muscle–tendon unit lengths were calculated from the segmental kinematics. The EMG intensities showed that the body uses the SOL relatively more for the higher-force, lower-velocity contractions than the MG and LG. The EMG spectra showed a shift to higher frequencies at faster muscle fascicle strain rates for MG: these shifts were independent of the level of muscle activity, the locomotor load and the muscle fascicle strain. These results indicated that a selective recruitment of the faster motor units occurred within the MG muscle in response to the increasing muscle fascicle strain rates. This preferential recruitment of the faster fibres for the faster tasks indicates that in some circumstances motor unit recruitment during locomotion can match the contractile properties of the muscle fibres to the mechanical demands of the contraction.

scholarly journals Correction of the Koenig Formula for the Kinetic Energy of a Rotating Solid

2021 ◽  
Author(s):  
Yuriy Alyushin
Keyword(s):  
Kinetic Energy ◽  
Superposition Principle ◽  
The Body ◽  
Initial State ◽  
Moments Of Inertia ◽  
Lagrange Form ◽  
Joint Plane ◽  
Angular Velocities ◽  
The Difference ◽  
Cyclic Changes

An exact solution is obtained for the kinetic energy in the general case of the spatial motion of solids with arbitrary rotation, which differs from the Koenig formula by three additional terms with centrifugal moments of inertia. The description of motion in the Lagrange form and the superposition principle are used, which provides a geometric summation of the velocities and accelerations of the joint motions in the Lagrange form for any particle at any time. The integrand function in the equation for kinetic energy is represented by the sum of the identical velocity components of the joint plane-parallel motions. The moments of inertia in the Koenig formula do not change during movement and can be calculated from the current or initial state of the body. The centrifugal moments change and turn to 0 when rotating relative to the main central axes only for bodies with equal main moments of inertia, for example, for a ball. In other cases, the difference in the main moments of inertia leads to cyclic changes in the kinetic energy with the possible manifestation of precession and nutation, the amplitude of which depends on the angular velocities of rotation of the body. An example of using equations for a robot with one helical and two rotational kinematic pairs is given.

scholarly journals Caffeinated Gel Ingestion Enhances Jump Performance, Muscle Strength, and Power in Trained Men

Nutrients ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 937 ◽  
Author(s):  
Sandro Venier ◽  
Jozo Grgic ◽  
Pavle Mikulic
Keyword(s):  
Vertical Jump ◽  
Average Power ◽  
Peak Torque ◽  
Knee Extension ◽  
Peak Power Output ◽  
Knee Extensors ◽  
Jump Performance ◽  
Squat Jump ◽  
Rowing Ergometer ◽  
Angular Velocities

We aimed to explore the effects of caffeinated gel ingestion on neuromuscular performance in resistance-trained men. The participants (n = 17; mean ± standard deviation (SD): age 23 ± 2 years, height 183 ± 5 cm, body mass 83 ± 11 kg) completed two testing conditions that involved ingesting a caffeinated gel (300 mg of caffeine) or placebo. The testing outcomes included: (1) vertical jump height in the squat jump (SJ) and countermovement jump (CMJ); (2) knee extension and flexion peak torque and average power at angular velocities of 60°·s−1 and 180°·s−1; (3) barbell velocity in the bench press with loads corresponding to 50%, 75%, and 90% of one-repetition maximum (1RM); and (4) peak power output in a test on a rowing ergometer. Compared to the placebo, caffeine improved: (1) SJ (p = 0.039; Cohen’s d effect size (d) = 0.18; +2.9%) and CMJ height (p = 0.011; d = 0.18; +3.3%); (2) peak torque and average power in the knee extensors at both angular velocities (d ranged from 0.21 to 0.37; percent change from +3.5% to +6.9%), peak torque (p = 0.034; d = 0.24; +4.6%), and average power (p = 0.015; d = 0.32; +6.7%) at 60°·s−1 in the knee flexors; (3) barbell velocity at 50% 1RM (p = 0.021; d = 0.33; +3.5%), 75% 1RM (p < 0.001; d = 0.42; +5.4%), and 90% 1RM (p < 0.001; d = 0.59, +12.0%). We conclude that the ingestion of caffeinated gels may acutely improve vertical jump performance, strength, and power in resistance-trained men.

scholarly journals Relationship Between Maximum Strength and Vertical Jump Performance in Junior Speed Skaters

GYMNASIUM ◽  
2020 ◽  
Vol XXI (2) ◽  
pp. 140
Author(s):  
Raluca Doina Ștef ◽  
Emilia Florina Grosu
Keyword(s):  
Intervention Program ◽  
Isometric Force ◽  
Vertical Jump ◽  
Jump Height ◽  
Countermovement Jump ◽  
Post Intervention ◽  
Jump Performance ◽  
Squat Jump ◽  
Jump Test ◽  
Maximal Isometric Force

The aim of this study was to determine the relationships between back squat maximal strength, maximal isometric force, jump squat and countermovement jump and whether power training improves parameters mentioned above in well-trained speed skaters. Sixteen athletes devided in two groups, performed two maximal squat strength test and two vertical jump test before and after the intervention program. Absolute strength showed a strong correlation with squat jump height (r = 0.762, p < 0.001) and countermovement jump height (r = 0.760, p < 0.001) but also between maximal isometric force and squat jump (r = 0.418, p = 0.036). Percentage change within the experiment group were significantly different from pre to post intervention for each parameter tested in the order described, respectively: 14%; 16.8%; 14.9%; 9.1%. These results suggest that jump squat training can improve several athletic performances developing high levels of lower body strength to enhance jump performance.

scholarly journals Effect of an Arm Swing on Countermovement Vertical Jump Performance in Elite Volleyball Players

2016 ◽  
Vol 53 (1) ◽  
pp. 41-50 ◽  
Author(s):  
Frantisek Vaverka ◽  
Daniel Jandačka ◽  
David Zahradník ◽  
Jaroslav Uchytil ◽  
Roman Farana ◽  
...  
Keyword(s):  
Body Position ◽  
Vertical Jump ◽  
Reaction Force ◽  
The Body ◽  
Jump Height ◽  
Vertical Ground Reaction Force ◽  
Average Force ◽  
Jump Performance ◽  
Arm Swing ◽  
Volleyball Players

AbstractThe aim of this study was to determine how elite volleyball players employed the arm swing (AS) to enhance their jump performance. The study assessed how the AS influenced the duration and magnitude of the vertical ground reaction force (VGRF) during the main phases (preparatory, braking and accelerating) of the countermovement vertical jump (CMVJ), the starting position of the body at the beginning of the accelerating phase and the moment when the AS began contributing to increasing the jump height. Eighteen elite volleyball players performed three CMVJs with and without an AS. Kinetics and kinematics data were collected using two Kistler force plates and the C-motion system. The time and force variables were evaluated based on the VGRF, and the position of the body and the trajectory of the arm movement were determined using kinematic analysis. The AS improved the CMVJ by increasing the jump height by 38% relative to jumping without an AS. The AS significantly shortened the braking phase and prolonged the accelerating phase, however, it did not influence the preparatory phase or the overall jump duration. The AS also significantly increased the average force during the accelerating phase as well as the accelerating impulse. The AS upward began at 76% into the overall jump duration. The AS did not influence the body position at the beginning of the accelerating phase. These findings can be used to improve performance of the CMVJ with the AS and in teaching beginning volleyball players proper jumping technique.

scholarly journals Comparison of the effects of static stretching on range of motion and jump height between quadriceps, hamstrings and triceps surae in collegiate basketball players

2019 ◽  
Vol 5 (1) ◽  
pp. e000631 ◽  
Author(s):  
Kosuke Takeuchi ◽  
Fumiko Tsukuda
Keyword(s):  
Range Of Motion ◽  
Vertical Jump ◽  
Random Order ◽  
Triceps Surae ◽  
Jump Height ◽  
Static Stretching ◽  
Basketball Players ◽  
Jump Performance ◽  
Vertical Jump Height ◽  
Collegiate Basketball

ObjectivesThe purpose of the present study was to compare the effects of static stretching (SS) on the range of motion and vertical jump height between the quadriceps, hamstrings and triceps surae in collegiate basketball players.MethodsFourteen male collegiate basketball players (20.2±0.7 years, 179.0±5.0 cm, 71.9±8.3 kg) underwent 5 min of SS for the quadriceps, hamstrings and triceps surae, in random order. Before and after each stretch, the range of motion (ROM) and vertical jump height were measured.ResultsROM of the quadriceps, hamstrings and triceps surae were increased without any difference of relative change in the range. The vertical jump height showed no change after SS of the quadriceps and hamstrings, while it decreased after SS of the triceps surae (p<0.05).ConclusionThese results suggested that SS for the triceps surae may have a large impact on jump performance.

scholarly journals Efectos agudos de la aplicación del Dynamic Tape® sobre el rendimiento de salto vertical: un estudio de caso

2021 ◽  
Author(s):  
Mateo Baena Marín ◽  
Alejandro Gómez Rodas ◽  
Diego A. Bonilla ◽  
Luis Enrique Isaza Velásquez ◽  
Anthony Baculima López
Keyword(s):  
Muscle Power ◽  
Vertical Jump ◽  
Flight Time ◽  
Muscle Performance ◽  
Jump Height ◽  
Jump Performance ◽  
Physically Active ◽  
Squat Jump ◽  
Before And After

Different types of neuromuscular tapes have led to no consensus about its benefits on muscle performance. Unlike kinesiology and rigid tapes, Dynamic Tape® has different composition and properties with unknown effects on performance. The aim of this exploratory-type case study was to report the acute effects of dynamic tape® application on vertical jump performance. Material and methods: Using a test-retest methodology, a case study was carried out in two 21-year-old, healthy and physically active women. Flight time, jump height and muscle power were evaluated by squat jump and countermovement jump tests using a contact mat, before and after the application of dynamic tape® on quadriceps and gastrocnemius muscles. Single and double taping were also used in different combinations. Results: Improvements of up to 10.8% on flight time, 22.6% on jump height and 8.9% on muscle power were observed for squat jump after the application of dynamic tape®. Conclusions: This preliminary and explo ...

Some Special Aspects of Hypersonic Flow Fields

1959 ◽  
Vol 63 (585) ◽  
pp. 508-512 ◽  
Author(s):  
K. W. Mangler
Keyword(s):  
Hypersonic Flow ◽  
High Speed ◽  
Flow Fields ◽  
The Body ◽  
Lower Velocity ◽  
Bow Wave ◽  
Total Head ◽  
Bow Shocks ◽  
Lower Entropy ◽  
Subsonic Region

When a body moves through air at very high speed at such a height that the air can be considered as a continuum, the distinction between sharp and blunt noses with their attached or detached bow shocks loses its significance, since, in practical cases, the bow wave is always detached and fairly strong. In practice, all bodies behave as blunt shapes with a smaller or larger subsonic region near the nose where the entropy and the corresponding loss of total head change from streamline to streamline due to the curvature of the bow shock. These entropy gradients determine the behaviour of the hypersonic flow fields to a large extent. Even in regions where viscosity effects are small they give rise to gradients of the velocity and shear layers with a lower velocity and a higher entropy near the surface than would occur in their absence. Thus one can expect to gain some relief in the heating problems arising on the surface of the body. On the other hand, one would lose farther downstream on long slender shapes as more and more air of lower entropy is entrained into the boundary layer so that the heat transfer to the surface goes up again. Both these flow regions will be discussed here for the simple case of a body of axial symmetry at zero incidence. Finally, some remarks on the flow field past a lifting body will be made. Recently, a great deal of information on these subjects has appeared in a number of reviewing papers so that little can be added. The numerical results on the subsonic flow regions in Section 2 have not been published before.

Acute consumption of p-synephrine does not enhance performance in sprint athletes

2016 ◽  
Vol 41 (1) ◽  
pp. 63-69 ◽  
Author(s):  
Jorge Gutiérrez-Hellín ◽  
Juan José Salinero ◽  
Javier Abían-Vicen ◽  
Francisco Areces ◽  
Beatriz Lara ◽  
...  
Keyword(s):  
Scientific Information ◽  
Monitoring Program ◽  
Well Being ◽  
Placebo Control Trial ◽  
Placebo Control ◽  
Jump Height ◽  
Countermovement Jump ◽  
Squat Jump ◽  
Jump Test ◽  
The Hours

P-Synephrine is a protoalkaloid widely used as an ergogenic aid in sports. This substance has been included in the World Anti-Doping Agency monitoring program, although scientific information about its effects on performance and athletes’ well-being is scarce. The purpose of this investigation was to determine the effectiveness of p-synephrine to increase performance in sprint athletes. In a randomized and counterbalanced order, 13 experienced sprinters performed 2 acute experimental trials after the ingestion of p-synephrine (3 mg·kg−1) or after the ingestion of a placebo (control trial). Forty-five minutes after the ingestion of the substances, the sprinters performed a squat jump, a countermovement jump, a 15-s repeated jump test, and subsequently performed 60-m and 100-m simulated sprint competitions. Self-reported questionnaires were used to assess side-effect prevalence. In comparison with the control trial, the ingestion of p-synephrine did not change countermovement jump height (37.4 ± 4.2 vs 36.7 ± 3.3 cm, respectively; P = 0.52), squat jump height (34.4 ± 3.6 vs 33.9 ± 3.7 cm; P = 0.34), or average 15-s repeated jumps height (31.8 ± 4.1 vs 32.2 ± 3.6 cm; P = 0.18). P-Synephrine did not modify maximal running speed during the 60-m (9.0 ± 0.5 vs 9.0 ± 0.4 m·s−1, respectively; P = 0.55) and 100-m sprint competitions (8.8 ± 0.5 vs 8.8 ± 0.5 m·s−1, respectively; P = 0.92). The ingestion of p-synephrine did not alter the prevalence of headache, gastrointestinal discomforts, muscle pain, or insomnia during the hours following the tests. Acute consumption of 3 mg·kg−1 of p-synephrine was ineffective to increase performance in competitive sprint athletes. Moreover, p-synephrine did not increase the occurrence of side effects after the competition.

Lower-Extremity Biomechanics and Maintenance of Vertical-Jump Height During Prolonged Intermittent Exercise

2014 ◽  
Vol 23 (4) ◽  
pp. 319-329
Author(s):  
Randy J. Schmitz ◽  
John C. Cone ◽  
Timothy J. Copple ◽  
Robert A. Henson ◽  
Sandra J. Shultz
Keyword(s):  
Lower Extremity ◽  
Outcome Measures ◽  
Principal Components ◽  
Intermittent Exercise ◽  
Vertical Jump ◽  
The Body ◽  
Rating Of Perceived Exertion ◽  
Jump Height ◽  
Lower Extremity Biomechanics ◽  
Biomechanical Factors

Context:Potential biomechanical compensations allowing for maintenance of maximal explosive performance during prolonged intermittent exercise, with respect to the corresponding rise in injury rates during the later stages of exercise or competition, are relatively unknown.Objective:To identify lower-extremity countermovement-jump (CMJ) biomechanical factors using a principal-components approach and then examine how these factors changed during a 90-min intermittent-exercise protocol (IEP) while maintaining maximal jump height.Design:Mixed-model design.Setting:Laboratory.Participants:Fifty-nine intermittent-sport athletes (30 male, 29 female) participated in experimental and control conditions.Interventions:Before and after a dynamic warm-up and every 15 min during the 1st and 2nd halves of an individually prescribed 90-min IEP, participants were assessed on rating of perceived exertion, sprint/cut speed, and 3-dimensional CMJ biomechanics (experimental). On a separate day, the same measures were obtained every 15 min during 90 min of quiet rest (control).Main Outcome Measures:Univariate piecewise growth models analyzed progressive changes in CMJ performance and biomechanical factors extracted from a principal-components analysis of the individual biomechanical dependent variables.Results:While CMJ height was maintained during the 1st and 2nd halves, the body descended less and knee kinetic and energetic magnitudes decreased as the IEP progressed.Conclusions:The results indicate that vertical-jump performance is maintained along with progressive biomechanical changes commonly associated with decreased performance. A better understanding of lower-extremity biomechanics during explosive actions in response to IEP allows us to further develop and individualize performance training programs.

Sign in / Sign up

Export Citation Format

Share Document