Effect of Ankle Position on EMG Activity and Peak Torque of the Knee Extensors and Flexors during Isokinetic Testing

1997 ◽  
Vol 6 (4) ◽  
pp. 335-342 ◽  
Author(s):  
John P. Miller ◽  
Kerriann Catlaw ◽  
Robert Confessore
Keyword(s):  
Female Athletes ◽  
Peak Torque ◽  
Knee Extension ◽  
Knee Extensors ◽  
Emg Activity ◽  
Isokinetic Testing ◽  
Surface Electrodes ◽  
Activity Peak ◽  
Peak Knee ◽  
Healthy Female

The purpose of this study was to examine the effect of ankle position on the electromyographic (EMG) activity, peak torque, and peak knee flexion to extension torque ratio during isokinetic testing of the knee. Twelve healthy female athletes performed six maximal knee extension and flexion repetitions with their dominant legs at 60 and 180°/s with the ankle in a plantar flexed position and again in a dorsiflexed position. Root mean square EMG (rmsEMG) activity was determined by placing bipolar surface electrodes on the quadriceps and the hamstrings. Ankle position had no effect on the rmsEMG activity of the quadriceps or the hamstrings at either 60 or 180°/s. Significant differences were noted for peak flexor torque at 607s (p <.001) and 180°/s (p<.01) and for peak torque flexor/extensor ratio (p <.01), with higher values observed with ankle dorsiflexion. This suggests that ankle position affects knee flexor torque and flexor/extensor ratio but not hamstring activity during isokinetic testing of the knee.

Effect of Submaximal Repetitive Exercise on Knee Coactivation in Young and Middle-Aged Women

2014 ◽  
Vol 30 (2) ◽  
pp. 269-275 ◽  
Author(s):  
Joanne N. Hodder ◽  
Tova E. Plashkes ◽  
Regan A. Franklin ◽  
Heather K. Hickey ◽  
Monica R. Maly
Keyword(s):  
Young Women ◽  
Biceps Femoris ◽  
Peak Torque ◽  
Young Group ◽  
Knee Extension ◽  
Contact Forces ◽  
Knee Extensors ◽  
Middle Aged ◽  
Peak Knee ◽  
Coactivation Ratios

Coactivation of the knee extensors and flexors increases knee joint contact forces, which may lead to degradation of the articular surfaces. This study investigated the effect of neuromuscular fatigue induced by submaximal, repetitive, dynamic contractions on coactivation of knee musculature in young and middle-aged women. Data from 10 young women (24.6 ± 1.8 years) and 8 middle-aged women (55.4 ± 4.2 years) were analyzed. Measures included peak knee extension and flexion torques and the average amplitude of surface electromyography of rectus femoris and biceps femoris. Coactivation ratios were calculated from these activations. To induce fatigue, participants completed up to ten sets of 50 concentric knee extension and flexion contractions at 60°/s. A two-factor analysis of variance was used to determine the effect of age and fatigue. The young group showed higher peak torque compared with the middle-aged group (P< .001). During flexion, biceps femoris activity increased after fatigue when both groups were considered together (P= .018). During extension, biceps femoris activity was higher in the middle-aged than young group (P= .043). Middle-aged women exhibited a trend for greater coactivation during knee extension compared with young women (P= .066). This coactivation likely contributed to extension torque decrements in middle-aged women.

Can Hip Joint Position affect Quadriceps Muscle Responses during Knee Extension Exercise?

2020 ◽  
Vol 41 (13) ◽  
pp. 929-935
Author(s):  
Denis César Leite Vieira ◽  
Marco Aurélio Araujo Dourado ◽  
Lucas Ugliara ◽  
Joao Luiz Quagliotti Durigan ◽  
Brad J. Schoenfeld ◽  
...  
Keyword(s):  
Vastus Lateralis ◽  
Muscle Thickness ◽  
Rectus Femoris ◽  
Peak Torque ◽  
Quadriceps Muscle ◽  
Knee Extension ◽  
Knee Extensors ◽  
Work Output ◽  
Before And After ◽  
Knee Extension Exercise

AbstractThis study investigated the acute effects of seated and supine knee extension exercise on muscle swelling, torque, and work output. Twelve resistance-trained men performed two isokinetic concentric-only knee-extension training protocols at different hip positions in a counter-balanced order. They completed the knee extension exercise in the seated (hip angle at 85°) and supine (hip angle at 180°) positions. The torque and work output were assessed during each set. Moreover, muscle thickness of the middle and proximal vastus lateralis and rectus femoris were evaluated before and after each protocol and used as an indicator of muscle swelling. Middle rectus femoris and proximal vastus lateralis thickness increased significantly (p=0.01) with no difference between exercise variations. However, the middle vastus lateralis thickness increased (p=0.01) only after the seated knee extension exercise (~7%). Knee extensors’ peak torque and work output were approximately 8% higher (p=0.04) in the seated when compared to the supine hip position. There was a similar decrease in torque and work output throughout both protocols (p=0.98). In conclusion, seated knee extension exercises produced greater torque, work output, and muscle swelling in the vastus lateralis when compared to the supine knee extension exercise.

scholarly journals The effects of feedback in isokinetic dynamometry: Effects of visual feedback and verbal encouragement on peak torque and total work values in knee extensors testing

1996 ◽  
Vol 52 (4) ◽  
pp. 88-90 ◽  
Author(s):  
Guy Van Herp ◽  
Ahmad Shah
Keyword(s):  
Visual Feedback ◽  
Peak Torque ◽  
Knee Extensors ◽  
Motivating Factors ◽  
Total Work ◽  
Isokinetic Testing ◽  
The Moment ◽  
Effects Of Feedback ◽  
Verbal Encouragement ◽  
Male Subjects

The purpose of this study was to examine the effects of visual feedback and verbal encouragement on peak torque and total work measurements during maximum isokinetic concentric activation of knee extensors. Twenty-seven healthy male subjects between the age of 19 and 42 completed the two test sessions 14 days apart using an isokinetic dynamometer at 60°/s and 450°/s. Visual feedback was provided as real-time display of the moment output. Verbal encouragement was done using a standardised procedure. With visual feedback and verbal encouragement peak torque and total work at both speeds were significantly greater than without.These findings suggest that combined visual and verbal encouragement are strong motivating factors. It is therefore recommended to use feedback and verbal encouragement as part of a standardised procedure during isokinetic testing.

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.

scholarly journals Test-Retest Reliability and the Learning Effect on Isokinetic Fatigue in Female Master’s Cyclists

2018 ◽  
Vol 6 (4) ◽  
pp. 1
Author(s):  
Jordan M. Glenn ◽  
Michelle Gray ◽  
Nicole E. Moyen ◽  
Jennifer L. Vincenzo ◽  
Kylie K. Harmon ◽  
...  
Keyword(s):  
Learning Effect ◽  
Female Athletes ◽  
Peak Torque ◽  
Knee Extension ◽  
Intra Class Correlation ◽  
Retest Reliability ◽  
Time To Peak ◽  
Flexion Extension ◽  
And Performance ◽  
Test Retest Reliability

Background: Isokinetic exercise is commonly used as a benchmark for strength and performance. Objective: The purpose of this investigation was to establish isokinetic fatigue test-retest reliability and examine the learning effect when testing without familiarization. Methods: 22 masters-aged [53±5 years), competitive female cyclists completed 3 separate 50-repetition knee flexion/extension tests on a Biodex, separated by one-week with no familiarization. Test-retest reliability [intra-class correlation [ICC]), 95% confidence intervals [CI), technical error of measurement [TEM) were calculated. Results: ICCs between trials exhibited excellent reliability during extension [.93–.97) and flexion [.93–.97) for all variables except time to peak torque [ICC=.35 and.45 for extension and flexion, respectively) and fatigue index [ICC=.47 for flexion). Relative TEM was minimal for extension between trial 1 and trial 2 [0.27%–0.97%) and between trial 2 and trial 3 [0.27%–1.45%) for all variables. Similar results were observed for flexion between trial 1 and trial 2 [0.87%–2.45%) and between trial 2 and trial 3 [0.54%–1.10%). No differences [Wilks Λ>.05) existed between trials, indicating no learning effect associated with the tests. Conclusions: There was strong test-retest reliability in masters-aged, female athletes and no learning effect was associated with the Biodex during a knee extension/flexion fatigue protocol.

scholarly journals Changes in Isokinetic Muscle Strength in Adolescent Soccer Players after 10 Weeks of Pre-Season Training

2017 ◽  
Vol 10 (1) ◽  
pp. 27-36 ◽  
Author(s):  
Michal Lehnert ◽  
Petr Stastny ◽  
James J. Tufano ◽  
Pavel Stolfa
Keyword(s):  
Soft Tissue Injuries ◽  
Peak Torque ◽  
Soccer Players ◽  
Knee Extensors ◽  
Future Research ◽  
Isokinetic Strength ◽  
Isokinetic Testing ◽  
Apparent Lack ◽  
Weight Room ◽  
Knee Flexors

Background:During soccer-specific movements, the strength of knee extensors and flexors is of great importance and achieving certain strength ratios between the two has been identified as an important parameter for reducing the risk of soft tissue injuries around the knee.Objective:The aim of the study was to evaluate changes in isokinetic strength of the knee flexors and extensors and their strength ratios in elite adolescent soccer players.Methods:Before and after 10 weeks of standard pre-season soccer training with progressive eccentric hamstring exercises, the players (n=18; age 17.1±0.4 years) participated in isokinetic testing to assess concentric and eccentric peak torque at 60°·s-1.Results:After 10 weeks of training, the peak eccentric torque of the non-dominant quadriceps increased (p=0.018; ω=0.24). Additionally, the average eccentric work increased in the dominant hamstrings (p=0.007; ω=0.23), dominant quadriceps (p=0.02; ω=0.31), non-dominant hamstrings (p=0.003; ω=0.25 and non-dominant quadriceps (p=0.01; ω=0.37). Lastly, the isokinetic functional ratio (eccentric hamstrings-to-concentric quadriceps) increased in favor of eccentric hamstring strength in the non-dominant limb (p=0.04; ω=0.31).Conclusion:The results of the study indicate that pre-season training induced suboptimal changes in the isokinetic strength of the knee flexors and extensors in elite adolescent soccer players. However, the lack of injuries combined with an apparent lack of preparedness explained by slow velocity isokinetic testing indicates that future research should investigate other forms of strength testing to determine soccer-specific preparedness such as isokinetic dynamometry at higher speeds (i.e.180°.s-1or 240°.s-1) and traditional weight-room testing such as 1RM tests.

Obese Youth Demonstrate Altered Landing Knee Mechanics Unrelated to Lower-Extremity Peak Torque When Compared With Healthy Weight Youth

2020 ◽  
pp. 1-9
Author(s):  
Matthew S. Briggs ◽  
Claire Spech ◽  
Rachel King ◽  
Mike McNally ◽  
Matthew Paponetti ◽  
...  
Keyword(s):  
Lower Extremity ◽  
Knee Flexion ◽  
Peak Torque ◽  
Knee Extension ◽  
Knee Flexion Angle ◽  
Healthy Weight ◽  
Knee Mechanics ◽  
Landing Mechanics ◽  
Peak Knee ◽  
Hip Extension

Obese (OB) youth demonstrate altered knee mechanics and worse lower-extremity performance compared with healthy weight (HW) youth. Our objectives were to compare sagittal plane knee landing mechanics between OB and HW youth and to examine the associations of knee and hip extension peak torque with landing mechanics in OB youth. Twenty-four OB and 24 age- and sex-matched HW youth participated. Peak torque was measured and normalized to leg lean mass. Peak knee flexion angle and peak internal knee extension moment were measured during a single-leg hop landing. Paired t tests, Pearson correlation coefficients, and Bonferroni corrections were used. OB youth demonstrated worse performance and lower knee extension (OB: 12.76 [1.38], HW: 14.03 [2.08], P = .03) and hip extension (OB: 8.59 [3.13], HW: 11.10 [2.89], P = .005) peak torque. Furthermore, OB youth demonstrated lower peak knee flexion angles (OB: 48.89 [45.41 to 52.37], HW: 56.07 [52.59 to 59.55], P = .02) and knee extension moments (OB: −1.73 [−1.89 to −1.57], HW: −2.21 [−2.37 to −2.05], P = .0001) during landing compared with HW youth. Peak torque measures were not correlated with peak knee flexion angle nor internal knee extension moment during landing in either group (P > .01). OB youth demonstrated altered landing mechanics compared with HW youth. However, no associations among peak torque measurements and knee landing mechanics were present.

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.

Skeletal muscle fatigue, strength, and quality in the elderly: the Health ABC Study

2005 ◽  
Vol 99 (1) ◽  
pp. 210-216 ◽  
Author(s):  
Andreas Katsiaras ◽  
Anne B. Newman ◽  
Andrea Kriska ◽  
Jennifer Brach ◽  
Shanthi Krishnaswami ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fatigue ◽  
Knee Flexion ◽  
Peak Torque ◽  
Older Men ◽  
Knee Extension ◽  
Muscle Quality ◽  
Knee Extensors ◽  
Men And Women ◽  
Skeletal Muscle Fatigue

We examined the muscle fatigue characteristics in older men and women and determined whether these were related to the size, strength, or quality of muscle. A total of 1,512 men and women aged 70–79 yr from the Health, Aging, and Body Composition Study participated in this study. Muscle cross-sectional area and attenuation were determined with computed tomography. Skeletal muscle fatigue and strength (peak torque) of the knee extensors and flexors were measured using isokinetic dynamometry. Men were more fatigue resistant than women for both knee extension (fatigue index: 70.4 ± 15.3 vs. 66.9 ± 14.3%; P < 0.05) and knee flexion (67.9 ± 16.4 vs. 64.9 ± 17.6%; P < 0.05). Peak torque and muscle quality (specific torque) were higher in men than women for knee extension (99.6 ± 28.2 vs. 63.0 ± 16.8 N·m and 1.62 ± 0.43 vs. 1.51 ± 0.39 N·m/cm2; both P < 0.05) and for knee flexion (74.0 ± 26.4 vs. 49.6 ± 15.9 N·m and 2.47 ± 1.29 vs. 2.22 ± 0.78 N·m/cm2; both P < 0.05). Total work and power output was greater in men compared with women for both the quadriceps (1,353 ± 451 vs. 832 ± 264 J and 87.7 ± 33.5 vs. 53.3 ± 19.2 W; both P < 0.05) and the hamstrings (741 ± 244 vs. 510 ± 141 J and 35.4 ± 16.0 vs. 23.7 ± 10.2 W; both P < 0.05). In both genders, the quadriceps was able to perform more work with greater power compared with the hamstrings. Those who were stronger actually had greater fatigue after adjusting for age, race, physical activity, and total body fat. In conclusion, older men were more fatigue resistant than women, although in both men and women greater fatigue was not related to muscle weakness.

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