scholarly journals In-Water and On-Land Swimmers’ Symmetry and Force Production

2019 ◽  
Vol 16 (24) ◽  
pp. 5018 ◽  
Author(s):  
Diogo D. Carvalho ◽  
Susana Soares ◽  
Rodrigo Zacca ◽  
Daniel A. Marinho ◽  
António J. Silva ◽  
...  
Keyword(s):  
Force Production ◽  
Peak Torque ◽  
Knee Extension ◽  
Peak Force ◽  
Propulsive Force ◽  
Testing Conditions ◽  
Symmetry Index ◽  
Elite Swimmers ◽  
Force Peak ◽  
Swimming Test

Although performance and biomechanical evaluations are becoming more swimming-specific, dryland testing permits monitoring of a larger number of performance-related variables. However, as the degree of comparability of measurements conducted in-water and on land conditions is unclear, we aimed to assess the differences between force production in these two different conditions. Twelve elite swimmers performed a 30 s tethered swimming test and four isokinetic tests (shoulder and knee extension at 90 and 300°/s) to assess peak force, peak and average torque, and power symmetry index. We observed contralateral symmetry in all the tests performed, e.g., for 30 s tethered swimming and peak torque shoulder extension at 90°/s: 178 ± 50 vs. 183 ± 56 N (p = 0.38) and 95 ± 37 vs. 94 ± 35 N × m (p = 0.52). Moderate to very large direct relationships were evident between dryland testing and swimming force production (r = 0.62 to 0.96; p < 0.05). Swimmers maintained similar symmetry index values independently of the testing conditions (r = −0.06 to −0.41 and 0.04 to 0.44; p = 0.18–0.88). Asymmetries in water seems to be more related to technical constraints than muscular imbalances, but swimmers that displayed higher propulsive forces were the ones with greater force values on land. Thus, tethered swimming and isokinetic evaluations are useful for assessing muscular imbalances regarding propulsive force production and technical asymmetries.

scholarly journals Neuromuscular Fatigue at Task Failure and During Immediate Recovery after Isometric Knee Extension Trials

Sports ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 156
Author(s):  
Christian Froyd ◽  
Fernando Beltrami ◽  
Timothy Noakes
Keyword(s):  
Femoral Nerve ◽  
Force Production ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Peak Force ◽  
Fatigue Threshold ◽  
Peripheral Fatigue ◽  
Neuromuscular Activation ◽  
Task Failure ◽  
Immediate Recovery

We asked whether the level of peripheral fatigue would differ when three consecutive exercise trials were completed to task failure, and whether there would be delayed recovery in maximal voluntary contraction (MVC) force, neuromuscular activation and peripheral fatigue following task failure. Ten trained sport students performed three consecutive knee extension isometric trials (T1, T2, T3) to task failure without breaks between trials. T1 and T2 consisted of repeated 5-s contractions followed by 5-s rests. In T1, contractions were performed at a target force at 60% pre-exercise MVC. In T2, all contractions were MVCs, and task failure occurred at 50% MVC. T3 was a sustained MVC performed until force fell below 15% MVC. Evoked force responses to supramaximal electrical femoral nerve stimulation were recorded to assess peripheral fatigue. Electromyography signals were normalized to an M-wave amplitude to assess neuromuscular activation. Lower levels of evoked peak forces were observed at T3 compared with T2 and T1. Within 5 s of task failure in T3, MVC force and neuromuscular activation recovered substantially without any recovery in evoked peak force. Neuromuscular activation 5–10 s after T3 was unchanged from pre-exercise values, however, evoked peak forces were substantially reduced. These results challenge the existence of a critical peripheral fatigue threshold that reduces neuromuscular activation. Since neuromuscular activation changed independently of any change in evoked peak force, immediate recovery in force production after exercise is due to increased central recruitment and not to peripheral mechanisms.

scholarly journals Neuromuscular Fatigue at Task Failure and During Immediate Recovery after Isometric Knee Extension Trials

2018 ◽  
Author(s):  
Christian Froyd ◽  
Fernando G. Beltrami ◽  
Timothy D. Noakes
Keyword(s):  
Femoral Nerve ◽  
Force Production ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Peak Force ◽  
Fatigue Threshold ◽  
Peripheral Fatigue ◽  
Neuromuscular Activation ◽  
Task Failure ◽  
Immediate Recovery

We asked whether the level of peripheral fatigue would differ when three consecutive exercise trials were completed to task failure, and whether there would be delayed recovery in maximal voluntary contraction (MVC) force, neuromuscular activation and peripheral fatigue following task failure. Ten trained sport students performed three consecutive knee extension isometric trials (T1, T2, T3) to task failure without breaks between trials. T1 and T2 consisted of repeated 5-s contractions followed by 5-s rest. In T1, contractions were performed at a target force at 60% pre-exercise MVC. In T2, all contractions were MVCs, and task failure occurred at 50% MVC. T3 was a sustained MVC performed until force fell below 15% MVC. Evoked force responses to supramaximal electrical femoral nerve stimulation were recorded to assess peripheral fatigue. Electromyography signals were normalized to M-wave amplitude to assess neuromuscular activation. Lower levels of evoked peak forces were observed at T3 compared to T2 and T1. Within 5 s of task failure in T3, MVC force and neuromuscular activation recovered substantially without any recovery in evoked peak force. Neuromuscular activation 5-10 s after T3 was unchanged from pre-exercise values, but evoked peak forces were substantially reduced. These results challenge the existence of a critical peripheral fatigue threshold that reduces neuromuscular activation. Since neuromuscular activation changed independently of any change in evoked peak force, immediate recovery in force production after exercise is due to increased central recruitment and not to peripheral mechanisms.

scholarly journals 602 THE EFFECT OF BILATERAL ISOKINETIC KNEE EXTENSION/FLEXION ON JOINT ANGLE AT PEAK TORQUE

1993 ◽  
Vol 25 (Supplement) ◽  
pp. S108 ◽  
Author(s):  
J. R. Bryant ◽  
L. E. Brown ◽  
M. Whitehurst
Keyword(s):  
Joint Angle ◽  
Peak Torque ◽  
Knee Extension

scholarly journals Reliability of a New Portable Dynamometer for Assessing Hip and Lower Limb Strength

2021 ◽  
Vol 11 (8) ◽  
pp. 3391
Author(s):  
Jan Marušič ◽  
Goran Marković ◽  
Nejc Šarabon
Keyword(s):  
Lower Limb ◽  
External Rotation ◽  
Peak Torque ◽  
Knee Extension ◽  
Lower Limb Muscles ◽  
Lower Limb Strength ◽  
Flexion Extension ◽  
Strength Tests ◽  
Hip Abduction ◽  
Maximal Peak

The purpose of this study was to evaluate intra- and inter-session reliability of the new, portable, and externally fixated dynamometer called MuscleBoard® for assessing the strength of hip and lower limb muscles. Hip abduction, adduction, flexion, extension, internal and external rotation, knee extension, ankle plantarflexion, and Nordic hamstring exercise strength were measured in three sessions (three sets of three repetitions for each test) on 24 healthy and recreationally active participants. Average and maximal value of normalized peak torque (Nm/kg) from three repetitions in each set and agonist:antagonist ratios (%) were statistically analyzed; the coefficient of variation and intra-class correlation coefficient (ICC2,k) were calculated to assess absolute and relative reliability, respectively. Overall, the results display high to excellent intra- and inter-session reliability with low to acceptable within-individual variation for average and maximal peak torques in all bilateral strength tests, while the reliability of unilateral strength tests was moderate to good. Our findings indicate that using the MuscleBoard® dynamometer can be a reliable device for assessing and monitoring bilateral and certain unilateral hip and lower limb muscle strength, while some unilateral strength tests require some refinement and more extensive familiarization.

scholarly journals Relationship between propulsive force of the arm, body composition and isokinetic muscle strength indicators in surfers

2018 ◽  
Vol 20 (3) ◽  
pp. 342-351
Author(s):  
Sidarta Oliveira Geber ◽  
Bruno Remígio Cavalcante ◽  
Antonio Henrique Germano-Soares ◽  
Raysa Catarina Cavalcante Figueiredo Montes ◽  
Arthur Henrique Oliveira Silva ◽  
...  
Keyword(s):  
Body Composition ◽  
Internal Rotation ◽  
Fat Mass ◽  
Muscle Function ◽  
External Rotation ◽  
Pearson Correlation ◽  
Peak Torque ◽  
Total Work ◽  
Propulsive Force ◽  
Teres Major

This study aimed to evaluate the potential relationship between body composition (percentage of fat mass (FM %), fat mass and lean mass), muscle function (e.g., muscles; deltoid side and front, pectoralis major and teres major) and the propulsive force of the arm (PFA). Sixteen competitive surfers (29.1 ± 7.3 years; 1.72 ± 0.06 m; 74.2 ± 1.4 kg) were assessed for height, body mass, body composition (dual-energy-DXA), muscle function and PFA. Pearson correlation analyses were used to verify the relationship between all variables. An inverse correlations were found between PFA and isokinetic parameters to 60o/s: external rotation (peak torque: r = -0.71; p = 0.014; total work: r = -0.75; p = 0.007; power: r = -0.72; p = 0.011) and internal rotation (peak torque: r = -0.61; p = 0.045; total work: r = -0.73; p = 0.010; power: r = -0.61; p = 0.045) and 300o/s: external rotation (peak torque: r = -0.79; p = 0.003; total work: r = -0.84; p<0,001; power: r = -0.81; p = 0.002) and internal rotation (peak torque: r = -0.69; p = 0.017; total work: r = -0.72; p = 0.011; power: r = -0.69; p = 0.017). There was no significant correlation between body composition components and PFA (p>0.05). Although correlations do not imply cause and effect, PFA is not correlated with body composition in surfers and these relationships are inversely related to the parameters of muscle function.

scholarly journals Muscle Strength Variations of Knee Joint Muscles in Elite Female Handball Players after Pre-Season Conditioning

2018 ◽  
Vol 63 (1) ◽  
pp. 105-115 ◽  
Author(s):  
Zuzana Gonosova ◽  
Petr Stastny ◽  
Jan Belka ◽  
Lucia Bizovska ◽  
Michal Lehnert
Keyword(s):  
Muscle Strength ◽  
Elite Athletes ◽  
Body Height ◽  
Peak Torque ◽  
Knee Extension ◽  
Training Process ◽  
Strength Performance ◽  
Risk Of Injury ◽  
Previous Season ◽  
Isokinetic Peak Torque

Abstract Monitoring seasonal variations in strength performance and the relative risk of injury indicators related to strength of hamstring (H) and quadriceps (Q) in female elite athletes is beneficial for the training process. The aim of this study was to examine and compare the level of muscle strength, the conventional ratio (HCONC/QCONC) as well as two functional and strength ratios reflecting the movement of knee extension (HECC/QCONC) and flexion (HCONC/QECC), and the bilateral percentage strength deficit (BSD) in elite female handball players. The concentric and eccentric isokinetic peak torque was measured at an angular velocity of 60°/s on three occasions (in-season cessation, 4 weeks of rest followed by 4 weeks of individual conditioning and 6 weeks of group conditioning) in eleven female handball players (age: 23.1 ± 3.5 years, body height: 1.73 ± 0.6 m). According to ANOVA results, the BSD of H muscles in the concentric mode decreased between the in-season cessation and the end of the pre-season, and HCONC/QCONC increased at the beginning of the pre-season and at the end of the pre-season in comparison with inseason cessation measurement. The effect size analyses showed that the off-season rest followed by 10 weeks of the conditioning programme increased Q and H strength in comparison with the previous season with a large effect. Coaches should include progressive conditioning in the pre-season phase to decrease the bilateral strength deficit and to support further conditioning development.

scholarly journals Musculoskeletal Outcomes from Chronic High-Speed, High-Impulse Resistance Exercise

2018 ◽  
Vol 39 (10) ◽  
pp. 791-801 ◽  
Author(s):  
John Caruso ◽  
Michael Voor ◽  
Jason Jaggers ◽  
T. Symons ◽  
Jeremy Stith ◽  
...  
Keyword(s):  
Mechanical Loading ◽  
High Speed ◽  
Type I Collagen ◽  
Training Session ◽  
Knee Extension ◽  
Type I ◽  
Before And After ◽  
Force Peak ◽  
Blood Marker ◽  
Hip Extension

AbstractWhile bones and muscles adapt to mechanical loading, it appears that very specific types of stimuli must be applied to achieve osteogenesis. Our study assessed musculoskeletal outcomes to 30 training sessions on an Inertial Exercise Trainer (Newnan, GA). Subjects (n=13) performed workouts with their left leg, while their right served as an untreated control. Workouts entailed three 60-s sets each of knee extension, hip extension and calf press exercises, separated by 90-s rests. Before and after the 30 training sessions, subjects underwent strength tests (knee and ankle extensors of both legs), DEXA scans (hip, knee and ankles of both legs), and blood draws. After 30 training sessions 2×2 ANOVAs showed left leg peak torques rose significantly. 2×2 ANCOVAs, with bone scan area as a covariate, showed significant left leg calcaneal bone mineral content (+29%) and density (+33%) increases after 30 training sessions. A significant decline in C-terminal telopeptides of type I collagen, a blood marker of bone resorption, also occurred after 30 training sessions. The Inertial Exercise Trainer’s large volume of training session repetitions elicited high peak force, peak acceleration and impulses that likely provided a mechanical loading stimulus that evoked calcaneal accretion.

Reliability and validity of a modified 3-minute all-out swimming test in elite swimmers

2017 ◽  
Vol 18 (3) ◽  
pp. 307-314 ◽  
Author(s):  
Lachlan J. G. Mitchell ◽  
David B. Pyne ◽  
Philo U. Saunders ◽  
Ben Rattray
Keyword(s):  
Reliability And Validity ◽  
Elite Swimmers ◽  
Swimming Test

scholarly journals Acute effect of tendon vibration applied during isometric contraction at two knee angles on maximal knee extension force production

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242324
Author(s):  
Jonathan Harnie ◽  
Thomas Cattagni ◽  
Christophe Cornu ◽  
Peter McNair ◽  
Marc Jubeau
Keyword(s):  
Isometric Contraction ◽  
Vastus Lateralis ◽  
Force Production ◽  
Knee Extensor ◽  
Acute Effect ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Tendon Vibration ◽  
Knee Angle

The aim of the current study was to investigate the effect of a single session of prolonged tendon vibration combined with low submaximal isometric contraction on maximal motor performance. Thirty-two young sedentary adults were assigned into two groups that differed based on the knee angle tested: 90° or 150° (180° = full knee extension). Participants performed two fatigue-inducing exercise protocols: one with three 10 min submaximal (10% of maximal voluntary contraction) knee extensor contractions and patellar tendon vibration (80 Hz) another with submaximal knee extensor contractions only. Before and after each fatigue protocol, maximal voluntary isometric contractions (MVC), voluntary activation level (assessed by the twitch interpolation technique), peak-to-peak amplitude of maximum compound action potentials of vastus medialis and vastus lateralis (assessed by electromyography with the use of electrical nerve stimulation), peak twitch amplitude and peak doublet force were measured. The knee extensor fatigue was significantly (P<0.05) greater in the 90° knee angle group (-20.6% MVC force, P<0.05) than the 150° knee angle group (-8.3% MVC force, P = 0.062). Both peripheral and central alterations could explain the reduction in MVC force at 90° knee angle. However, tendon vibration added to isometric contraction did not exacerbate the reduction in MVC force. These results clearly demonstrate that acute infrapatellar tendon vibration using a commercial apparatus operating at optimal conditions (i.e. contracted and stretched muscle) does not appear to induce knee extensor neuromuscular fatigue in young sedentary subjects.

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