scholarly journals Isokinetic evaluation of knee muscles in soccer players: discriminant analysis

2015 ◽  
Vol 21 (5) ◽  
pp. 364-368 ◽  
Author(s):  
Bruno Fles Mazuquin ◽  
Ligia Maxwell Pereira ◽  
Josilainne Marcelino Dias ◽  
João Pedro Batista Junior ◽  
Mônica Angélica Cardoso Silva ◽  
...  
Keyword(s):  
Human Performance ◽  
Average Power ◽  
Peak Torque ◽  
Knee Extension ◽  
Soccer Players ◽  
Total Work ◽  
Wilks Lambda ◽  
Discriminant Analyses ◽  
Definition Of ◽  
Flexion And Extension

ABSTRACT Introduction: Muscle activity in soccer players can be measured by isokinetic dynamometer, which is a reliable tool for assessing human performance. Objectives: To perform isokinetic analyses and to determine which variables differentiate the under-17 (U17) soccer category from the professional (PRO). Methods: Thirty four players were assessed (n=17 for each category). The isokinetic variables used for the knee extension-flexion analysis were: peak torque (Nm), total work (J), average power (W), angle of peak torque (deg.), agonist/ antagonist ratio (%), measured for three velocities (60°/s, 120°/s and 300°/s), with each series containing five repetitions. Three Wilks' Lambda discriminant analyses were performed, to identify which variables were more significant for the definition of each of the categories. Results: The discriminative variables at 60°/s in the PRO category were: extension peak torque, flexion total work, extension average power and agonist/antagonist ratio; and for the U17s were: extension total work, flexion peak torque and flexion average power. At 120°/s for the PRO category the discriminant variables were: flexion peak torque and extension average power; for the U17s they were: extension total work and flexion average power. Finally at 300°/s, the variables found in the PRO and U17 categories respectively were: extension average power and extension total work. Conclusion: Isokinetic variables for flexion and extension knee muscles were able to significantly discriminate between PRO and U17 soccer players.

scholarly journals Impaired muscle capacity of the hip and knee in individuals with isolated patellofemoral osteoarthritis: a cross-sectional study

2021 ◽  
Vol 12 ◽  
pp. 204062232110287
Author(s):  
Cristiano Carvalho ◽  
Fábio Viadanna Serrão ◽  
Letícia Mancini ◽  
Paula Regina Mendes da Silva Serrão
Keyword(s):  
Physical Functioning ◽  
Average Power ◽  
Peak Torque ◽  
Knee Extension ◽  
Cross Sectional Study ◽  
Healthy Controls ◽  
Patellofemoral Osteoarthritis ◽  
Total Work ◽  
Sectional Study ◽  
Cross Sectional

Aims: The aims of this study were to compare the capacity of the knee and hip muscles between individuals with and without isolated patellofemoral osteoarthritis (PFOA) and to evaluate the impact of PFOA on pain, stiffness, and physical function. Methods: This cross-sectional study evaluated muscle capacity of the hip and knee using an isokinetic dynamometer. The isokinetic variables used in the statistical analysis were peak torque, total work, and average power. Pain, stiffness, and physical function were assessed using questionnaires. Results: A total of 26 individuals participated in the study (13 with PFOA and 13 controls). The PFOA group exhibited lower peak torque, total work, and average power for knee extension and flexion in the concentric mode ( p ⩽ 0.01) as well as lower peak torque and total work for knee extension ( p ⩽ 0.005) and lower total work for knee flexion ( p = 0.05) in the eccentric mode. The PFOA group exhibited lower peak torque of the extensor, abductor, adductor, and internal rotator muscles of the hip ( p ⩽ 0.05), less total work of the abductor and adductor muscles ( p ⩽ 0.04), and lower average power of eccentric adduction of the hip ( p = 0.01) compared with the healthy controls. Compared with the control group, the PFOA group had a higher level of pain, stiffness, and compromised physical functioning self-reported ( p ⩽ 0.005). Conclusion: Participants with PFOA exhibited impairments regarding muscle capacity of the hip and knee, higher level of pain and stiffness as well as compromised physical functioning in comparison with healthy controls.

Age- and sex-associated differences in isokinetic knee muscle endurance between young children and adults

2009 ◽  
Vol 34 (4) ◽  
pp. 725-731 ◽  
Author(s):  
Mark B.A. De Ste Croix ◽  
Martine A. Deighan ◽  
Sebastien Ratel ◽  
Neil Armstrong
Keyword(s):  
Young Children ◽  
Peak Torque ◽  
Knee Extension ◽  
Total Work ◽  
Adult Males ◽  
Significant Interaction Effect ◽  
Peak Knee ◽  
Knee Muscle ◽  
Main Effects ◽  
Age And Sex

The purpose of this study was to examine the age- and sex-associated differences of repeated isokinetic knee extension and flexion. Fifty one participants, 30 young children (16 boys and 14 girls; aged 11 and 12 years) and 21 adults (9 males and 12 females; aged 18–35 years), agreed to participate in the study. Isokinetic concentric peak knee extension (PET) and flexion (PFT) torque were measured using a calibrated Biodex System 3. Participants performed 4 concentric extension–flexion cycles with maximum effort; after a 2 min rest, 50 continuous concentric cycles were performed at 1.56 rad·s–1. Total work of the extensors (WKEX) and flexors (WKFL) for the complete 50 repetitions was recorded. Average peak torque and average work for the first and last 3 repetitions were calculated to represent the percentage decline in torque and work. There were no significant differences between groups in the peak torque generated during the pretrial and endurance task, suggesting that participants gave a maximal effort at the start of the endurance task. There was a significant interaction effect in the total work done for both extensors and flexors, with adult males producing the greatest amount of work (6622 and 3444 J, respectively). When total work was divided by body mass, there were no significant sex effects, only main effects for group. The percentage decline for PET (40% vs. 60%), PFT (50% vs. 65%), WKET (43% vs. 61%), and WKFL (60% vs. 69%) demonstrated significant main effects for group, with greater fatigue in adults. We found no significant sex effect for fatigue. This study concludes that females do not resist fatigue from repeated isokinetic muscle actions to a greater extent than males, and that the greater fatigue in adults than in children is probably a product of greater initial torque production and work performed.

Effects of Hydraulic Resistance Strength Training on Isokinetic Measures of Leg Strength in Men with Mental Retardation

1995 ◽  
Vol 12 (4) ◽  
pp. 377-387 ◽  
Author(s):  
Rory Suomi ◽  
Paul R. Surburg ◽  
Peter Lecius
Keyword(s):  
Mental Retardation ◽  
Hydraulic Resistance ◽  
Peak Torque ◽  
Knee Extension ◽  
The Other ◽  
Isokinetic Strength ◽  
Total Work ◽  
Trained Subjects ◽  
Leg Strength ◽  
Hip Abduction

The purpose of this study was to determine the effects of hydraulic resistance (HR) training on total work and peak torque measures of isokinetic strength for tests of knee extension and hip abduction on men with mental retardation (MR). The subjects, 22 men with mild to moderate MR, were randomly assigned to two groups; 11 subjects trained three times a week for 12 weeks using HR exercise machines, while the other 11 served as controls. Prior to and after the 12 weeks of training, all subjects were assessed on isokinetic tests of knee extension at 60 deg/s and hip abduction at 30 deg/s. The strength trained subjects exhibited significant increases in total work scores on knee extension and hip abduction tests for both legs ranging from 25.0 to 177.1%. Significant increases ranging from 50.1 to 82.7% were also noted on two of the four peak torque measures. The control subjects did not exhibit significant changes in total work or peak torque scores on either muscle test between test sessions.

scholarly journals KNEE BIOMECHANICS AND PHYSICAL PERFORMANCE;

2017 ◽  
Vol 24 (12) ◽  
pp. 1921-1926
Author(s):  
Hafiz Muhammad Manan Haider Khan ◽  
Tahir Masood
Keyword(s):  
Body Weight ◽  
Physical Performance ◽  
Martial Arts ◽  
Average Power ◽  
Weight Ratio ◽  
Peak Torque ◽  
Knee Biomechanics ◽  
Performance Tests ◽  
Total Work ◽  
Body Weight Ratio

Introduction: A 29-year old male athlete (body mass: 64 kg; height: 172 cm)sustained complete ACL rupture of the right knee. He was a martial-arts player and the injurywas repetitive, overuse in nature due to cyclic unilateral loading and unloading of the rightknee during training sessions. Rupture was diagnosed through detailed patient history, clinicalphysical examination and was confirmed through magnetic resonance imaging (MRI) of theright knee. Surgical reconstruction of the ACL was planned and a patellar tendon graft wasused. His baseline isokinetic data was recorded 4 months after the surgery. Objective: Thiscase study describes the effects of isokinetic strength training on knee biomechanics andphysical function of an ACL-reconstructed martial-arts athlete. Setting: Pakistan Sports BoardIslamabad. Study period: 40 days. Materials and Methods: Biodex System 3 Pro was used totrain the athlete for 15 sessions on alternate day basis. Average peak torque, average power,total work and peak torque to body weight ratio were recorded for hamstring and quadricepsbefore and after isokinetic rehabilitation. The athlete was positioned in the dynamometer withupright back while hip and knee were flexed to 90 degrees. Unilateral isokinetic contractionswere performed according to a premeditated exercise protocol. Both hamstring and quadricepswere tested isokinetically at five different movement speeds (30deg/sec, 90deg/sec, 150deg/sec, 210deg/sec, and 270deg/sec). Five contractions were performed at each speed duringboth knee flexion and extension. At baseline, average peak torque was higher at lower speedsfor both hamstring and quadriceps. Results: As a result of rehabilitation, average peak torquefor hamstring and quadriceps significantly improved at speeds of 150deg/sec and 90deg/secrespectively. Average power, peak torque to body weight ratio, total work was also improved forboth hamstring and quadriceps. Two physical performance tests - agility run test and verticaljump test - were used to assess the effects of training and both performance tests improved 51%and 100% respectively. Conclusion: Isokinetic training improved the strength of quadricepsand hamstring after ACL reconstruction. Hamstring muscle demonstrated greater traininginducedincrements in torque production compared to quadriceps at all contraction velocities.

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 Four-week of local electromyostimulaiton training on fingerboard increases the isokinetic wrist strength and endurance

2020 ◽  
Vol 24 (3) ◽  
pp. 127-134
Author(s):  
Dicle Aras ◽  
Selçuk Gül ◽  
Fırat Akça ◽  
Mehmet Gülü ◽  
Özkan Güler ◽  
...  
Keyword(s):  
Body Weight ◽  
Physical Therapy ◽  
Essential Role ◽  
Average Power ◽  
Peak Torque ◽  
Muscular Fitness ◽  
Physically Active ◽  
Left Wrist ◽  
Before And After ◽  
Flexion And Extension

Background and Study Aim: Electromyostimulaiton (EMS) has been used for both physical therapy and strength improvements for a few decades. This study aimed to investigate the effects of a four-week local-EMS training performed on a fingerboard (FT) in wrist strength and endurance. Material and Methods:  Sixteen physically active, non-climber students were divided into EMS+FT and FT groups. Each group performed the same training program about 25 min a day, 3 days a week for four weeks. The EMS+FT implementation was performed with a signal width of 260 ms and a frequency of 60 Hz. Before and after training, isokinetic measurements were collected. The parameters used in the research during flexion and extension at 60 and 180°/sec were; Peak Torque (PT), Peak Torque/Body Weight (PT/BW), and Average Power (AP). Results: The EMS+FT group showed statistically significant alterations in all of the parameters (p<0.01 and p<0.05) except in the left wrist AP during flexion and extension at 180°/sec. However, the FT group showed significant changes in only wright wrist AP during extension at 60°/sec, and wright and left wrist AP during flexion at 180°/sec, and left wrist PT during extension at 180°/sec. Conclusions: Accordingly, it could be inferred that FT done by using EMS for four weeks improve the isokinetic wrist strength and endurance significantly. Muscular fitness has an essential role in climbing performance, and this study points that EMS trainings on fingerboard could be used to enhance the climbing performance.

Acute Enhancement of Jump Performance, Muscle Strength, and Power in Resistance-Trained Men After Consumption of Caffeinated Chewing Gum

2019 ◽  
Vol 14 (10) ◽  
pp. 1415-1421 ◽  
Author(s):  
Sandro Venier ◽  
Jozo Grgic ◽  
Pavle Mikulic
Keyword(s):  
Vertical Jump ◽  
Average Power ◽  
Peak Torque ◽  
Knee Extension ◽  
Whole Body ◽  
Chewing Gum ◽  
Jump Performance ◽  
Squat Jump ◽  
Rowing Ergometer ◽  
Ergometer Test

Purpose: To explore the acute effects of caffeinated chewing gum on vertical-jump performance, isokinetic knee-extension/flexion strength and power, barbell velocity in resistance exercise, and whole-body power. Methods: Nineteen resistance-trained men consumed, in randomized counterbalanced order, either caffeinated chewing gum (300 mg of caffeine) or placebo and completed exercise testing that included squat jump; countermovement jump; isokinetic knee extension and knee flexion at angular velocities of 60 and 180°·s−1; bench-press exercise with loads corresponding to 50%, 75%, and 90% of 1-repetition maximum (1RM); and an “all-out” rowing-ergometer test. Results: Compared with placebo, caffeinated chewing gum enhanced (all Ps < .05) (1) vertical-jump height in the squat jump (effect size [ES] = 0.21; +3.7%) and countermovement jump (ES = 0.27; +4.6%); (2) knee-extension peak torque (ES = 0.21; +3.6%) and average power (ES = 0.25; +4.5%) at 60°·s−1 and knee-extension average power (ES = 0.30; +5.2%) at 180°·s−1, and knee-flexion peak torque at 60°·s−1 (ES = 0.22; +4.1%) and 180°·s−1 (ES = 0.31; +5.9%); (3) barbell velocity at 50% of 1RM (ES = 0.30; +3.2%), 75% of 1RM (ES = 0.44; +5.7%), and 90% of 1RM (ES = 0.43; +9.1%); and (4) whole-body peak power on the rowing-ergometer test (ES = 0.41; +5.0%). Average power of the knee flexors did not change at either angular velocity with caffeine consumption. Conclusions: Caffeinated chewing gum with a dose of caffeine of 300 mg consumed 10 min preexercise may acutely enhance vertical-jump height, isokinetic strength and power of the lower-body musculature, barbell velocity in the bench-press exercise with moderate to high loads, and whole-body power.

Relationships among Muscle Endurance, Explosiveness, and Strength in Circum-Pubertal Boys

1998 ◽  
Vol 10 (1) ◽  
pp. 48-56 ◽  
Author(s):  
Kensaku Suei ◽  
Leslie McGillis ◽  
Randy Calvert ◽  
Oded Bar-Or
Keyword(s):  
Body Mass ◽  
Vertical Jump ◽  
Peak Torque ◽  
Knee Extension ◽  
Muscle Performance ◽  
Muscle Endurance ◽  
Total Work ◽  
Endurance Strength ◽  
Isometric Knee Extension ◽  
Pubertal Boys

We assess relationships among muscle endurance, strength, and explosiveness in forty-eight 9.6- to 17.0-year-old males divided into 3 maturational groups (Tanner Stages I, II-IV, and V). Peak torque during isometric knee extension and flexion was averaged to reflect strength. Mechanical power in the Sargent vertical jump was taken as explosiveness, and total work in the Wingate test reflected muscle endurance. Correlations (3 groups combined) among the variables, expressed in absolute terms, were r = .82 to .92, but only -.11 to .70 when expressed per body mass or lean thigh size. These correlations were distinctly lower in the Tanner V boys than in the 2 less-mature groups, which may suggest that specialization into discrete muscle performance characteristics does not occur before late puberty.

scholarly journals A 12-Week Randomized Double-Blind Placebo-Controlled Clinical Trial, Evaluating the Effect of Supplementation with a Spinach Extract on Skeletal Muscle Fitness in Adults Older Than 50 Years of Age

Nutrients ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 4373
Author(s):  
Silvia Pérez-Piñero ◽  
Vicente Ávila-Gandía ◽  
Jacobo A. Rubio Arias ◽  
Juan Carlos Muñoz-Carrillo ◽  
Pilar Losada-Zafrilla ◽  
...  
Keyword(s):  
Spinacia Oleracea ◽  
Peak Torque ◽  
Knee Extension ◽  
Muscle Quality ◽  
Moderate Intensity ◽  
Total Work ◽  
Double Blind ◽  
Repetition Maximum ◽  
Spinacia Oleracea L ◽  
Muscle Fitness

The aim of a 12-week randomized double-blind placebo-controlled study was to assess the effect of daily supplementation with a natural extract of Spinacia oleracea L. (4 × 500 mg capsules/day; total 2 g per day) combined with a moderate-intensity training program (1 h session/3 times a week) on skeletal muscle fitness in adults over 50 years of age. Muscle strength assessed by isokinetic and isometric dynamometry improved significantly in the experimental (n = 23) and the placebo (n = 22) groups, but the magnitude of improvement was higher in the experimental group, with between-group differences in almost all variables, including isokinetic at 60° s−1 in knee extension, peak torque (p < 0.007); total work per repetition maximum (p < 0.009); isokinetic at 180°s−1 in knee extension, peak torque (p < 0.002); total work (p < 0.007); total work per repetition maximum (p < 0.005); average power (p < 0.027); isometric in knee extension, peak torque (p < 0.005); and average peak torque (p < 0.002). Similar findings were observed for muscle quality. Changes in quality of life (SF-36) were not found, except for improvements in the role physical (p < 0.023) and role emotional (p < 0.001) domains, likely as a result of the physical training sessions. A nutritional survey did not revealed changes in dietary habits. No adverse events were recorded. In subjects over 50 years of age, moderate-intensity strength training combined with daily supplementation for 12 weeks with a natural extract of Spinacia oleracea L. improved muscle-related variables and muscle quality. Maintaining muscle health is a key component of healthy aging.

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