VMO:VL Ratios and Torque Comparisons at Four Angles of Knee Flexion

1995 ◽  
Vol 4 (4) ◽  
pp. 264-272 ◽  
Author(s):  
Teddy W. Worrell ◽  
Steven Connelly ◽  
John Hilvert
Keyword(s):  
Measurement Error ◽  
Future Study ◽  
Isometric Contraction ◽  
Knee Flexion ◽  
Vastus Medialis ◽  
Maximal Voluntary Isometric Contraction ◽  
Knee Position ◽  
Significant Difference ◽  
Intraclass Correlations ◽  
Asymptomatic Subjects

The purpose of this study was to determine the intrasession and intersessionreliabilityof EMG vastus medialis oblique:vastus lateralis (VMO:VL) ratios at four knee positions (0, 45, 60, and 90°) at 100 and 60% of maximal voluntary isometric contraction (MVIC). Once reliability was established, the second purpose was to determine VMO:VL ratios and torque at each knee position. Thirty-two subjects participated in two sessions; 19 subjects were tested at 100% MVIC and 13 were tested at .60% MVIC. Results revealed the following intraclass correlations: 100% MVIC intrasession .40-.80, intersession .40-.70; 60% MVIC intrasession .60-.90, intersession .50-.80. A significant difference in torque occurred at all knee positions except 60 versus 90°. No significant difference existed in VMO:VL ratios at the four positions of knee flexion. Pain and measurement error significantly increased during 100% MVIC testing. It was concluded that no selective VMO recruitment occurred as revealed by the VMO: VL ratios in asymptomatic subjects. Future study is needed that reports EMG reliability data during exercises that theorize selective VMO recruitment.

Comparison of Force and Peak EMG during a Maximal Voluntary Isometric Contraction at Selected Angles in the Range of Motion for Knee Extension

1996 ◽  
Vol 83 (3) ◽  
pp. 976-978 ◽  
Author(s):  
Roger M. Zabik ◽  
Mary L. Dawson
Keyword(s):  
Isometric Contraction ◽  
Knee Flexion ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Vastus Medialis ◽  
Joint Motion ◽  
Maximal Voluntary Isometric Contraction ◽  
Motor Recruitment ◽  
Larger Sample

For 5 adults maximal isometric strength at 110°, 90°, 70°, 50°, and 30° of knee flexion for the vastus medialis, rectus femoris, and vastus lateralis varied across angles but EMG responses were similar. That motor recruitment patterns were similar throughout the range of joint motion requires replication on a larger sample.

The Effects of Ankle Position on Torque and Muscle Activity of the Knee Extensor During Maximal Isometric Contraction

2020 ◽  
Vol 29 (1) ◽  
pp. 37-42
Author(s):  
Dae-Hyun Kim ◽  
Jin-Hee Lee ◽  
Seul-Min Yu ◽  
Chang-Man An
Keyword(s):  
Isometric Contraction ◽  
Vastus Lateralis ◽  
Plantar Flexion ◽  
Isometric Exercise ◽  
Rectus Femoris ◽  
Peak Torque ◽  
Emg Activity ◽  
Neutral Position ◽  
Vastus Medialis ◽  
Maximal Voluntary Isometric Contraction

Context: It is very important to empirically determine the optimal ankle position for the quadriceps femoris (QF) strengthening during isometric exercises. Objective: To examine the effect of different ankle positions on torque and electromyography (EMG) activity of QF during maximal isometric contraction. Study Design: Within-subject repeated measures. Setting: University laboratory. Participants: Thirty-six healthy volunteers (15 males and 21 females). Main Outcome Measures: The isometric strength of the QF was measured at 3 different ankle positions: active dorsiflexion (AD), active plantar flexion (AP), and neutral position (NP). Simultaneously, 3 different ankle positions were assessed for EMG activity of the vastus medialis, vastus lateralis, and rectus femoris muscles during maximal voluntary isometric contraction. Results: The peak torque per body weight and average peak torque were significantly higher in AD than in AP and NP (P < .01). The vastus medialis and rectus femoris maximal voluntary isometric contraction EMG activity were significantly higher in AD than in AP and NP (P < .01). The vastus lateralis maximal voluntary isometric contraction EMG activity was significantly higher in AD than in AP and NP (P < .01), and was significantly higher in AP than in NP (P < .05). Conclusions: These results indicate that the 3 different ankle positions affect the QF torque and EMG activity. In particular, AD position may be more efficient for improving QF strength than AP and NP position. Future studies should prove whether long-term duration QF isometric exercise effects muscle strength and functional performance in different ankle positions.

Ultrasound Imaging of the Vastus Intermedius and Vastus Medialis Oblique Thickness for Assessment of Early Torque Development During Knee Extension

2020 ◽  
Vol 10 (7) ◽  
pp. 1557-1561
Author(s):  
Jaeho Yang ◽  
Yong Woo An ◽  
Eunwook Chang
Keyword(s):  
Isometric Contraction ◽  
Muscle Thickness ◽  
Peak Torque ◽  
Quadriceps Muscle ◽  
Knee Extension ◽  
Vastus Medialis ◽  
Maximal Voluntary Isometric Contraction ◽  
Rate Of Torque Development ◽  
Vastus Intermedius ◽  
Torque Development

The purpose of this study was to investigate relationships between knee extension torque (rate of torque development and peak torque) and quadriceps muscle thickness in healthy males and females. Thirty-six recreationally active and healthy individuals participated in the study. Portable ultrasound was used to image the dominant side of each quadriceps muscle (rectus femoris, vastus intermedius, vastus lateralis, vastus medialis, vastus medialis oblique). After muscle thickness measurement, participants performed knee extension maximal voluntary isometric contraction. Rate of torque development was calculated from 0 to 50 (RTD50) and 0 to 200 (RTD200) milliseconds after onset of torque generation and peak torque was defined as maximum torque during maximal voluntary isometric contraction trials. A higher RTD50 value was found to be associated with greater vastus intermedius and vastus medialis oblique thicknesses, and a higher RTD200 with the thickness of all quadriceps muscles (p < 0.05). Finally, vastus medialis and vastus medialis oblique thicknesses were associated with a higher peak torque (p < 0.05). According to these results, the findings suggest to coaches that vastus intermedius and vastus medialis oblique thicknesses are critical to torque development during the early phase of knee extension contraction (RTD50), which is essential for executing athletic tasks and preventing injuries.

scholarly journals Myocardial load at 30% and 50% of Maximal Voluntary Isometric Contraction in healthy individuals with Active and Sedentary Lifestyle

2020 ◽  
Vol 4 (1) ◽  
pp. 7-11
Author(s):  
Samrudhi Singh ◽  
◽  
Mariya Jiandani ◽  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Systolic Blood Pressure ◽  
Isometric Contraction ◽  
Sedentary Lifestyle ◽  
Rate Pressure Product ◽  
Care Hospital ◽  
Hemodynamic Parameters ◽  
Maximal Voluntary Isometric Contraction ◽  
Significant Difference

Background: Activities of daily living consists of isometric & isotonic contraction. Isometric contraction is a static contraction that exerts pressure overload on the heart. Studies have been carried out demonstrating hemodynamic effects of isotonic exercises however limited studies are available on myocardial load with isometric exercises. Aims and Objectives: To study the myocardial load at 30% and 50% of maximal voluntary isometric contraction (MVIC) in individuals with active and sedentary lifestyle. Study design and setting: Observational cross-sectional study was carried out in a tertiary care hospital. Materials and Methods: 140 healthy subjects (70 each in active & sedentary group) were recruited for the study. Baseline demographics of both groups were comparable. Hemodynamic parameters were taken at rest. Subject performed 30% and 50% MVIC and hemodynamic parameters were recorded during and post contraction. Statistical Analysis: Paired t test was used to compare the myocardial load between 30% and 50% MVIC in both groups. Repeated measures ANOVA was used to compare the myocardial load between active & sedentary groups at 30% and 50% MVIC. Result: There was a statistically significant difference in heart rate, systolic blood pressure &rate pressure product between 30% and 50% in active as well as sedentary groups. There was statistically no significant difference in heart rate, systolic blood pressure & rate pressure product between active & sedentary groups at 30% and 50% MVIC. Conclusion: The myocardial load during activities at submaximal intensities (<50%) is within the physiological limits and can be performed safely in individuals with active and sedentary lifestyle.

Evidence of nonlocal muscle fatigue in male youth

2017 ◽  
Vol 42 (3) ◽  
pp. 229-237 ◽  
Author(s):  
Aymen Ben Othman ◽  
Anis Chaouachi ◽  
Raouf Hammami ◽  
Mehdi M. Chaouachi ◽  
Sofien Kasmi ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Knee Flexion ◽  
Knee Extensor ◽  
Knee Extensors ◽  
Control Group ◽  
Elbow Flexors ◽  
Maximal Voluntary Isometric Contraction ◽  
Contralateral Knee ◽  
Significant Difference ◽  
Isokinetic Torque

Evidence for nonlocal muscle fatigue (NLMF) has been inconsistent in adults, with no studies investigating youth. The objective was to examine NLMF in youth. Forty-two young males (age, 10–13 years) were tested for maximal voluntary isometric contraction (MVIC) force of the ipsilateral and contralateral knee extensors at 90° and 120° knee flexion, elbow flexors at 90°, handgrip, knee extensor isokinetic torque (300°·s−1 analyzed at 90° and 120° knee flexion), as well as a unilateral countermovement jump (CMJ) and Y Balance test (YBT). Isokinetic fatigue group (n = 15) had unilateral fatigue induced with 10 sets of 20 repetitions of maximal isokinetic knee extensor contractions at 300°·s−1. Isometric fatigue group (n = 15) used 10 repetitions of 6-s knee extensor MVIC whereas the control group (n = 12) were not fatigued. There was no significant difference in the response to the isometric- or isokinetic-fatigue intervention protocols. Main time effects indicated that NLMF was evident with the contralateral knee extensor MVIC at 90° (p = 0.008; 8.9%), knee extensor isokinetic torque at 90° (p < 0.001; 11.4%), and 120° (p = 0.05; 5.4%), CMJ (p = 0.02; 11.5%), handgrip (p = 0.06; 4.5%), elbow flexors (p < 0.001; 7.7%), and YBT (p = 0.001; 5.6%). Ipsilateral NLMF deficits occurred with handgrip (p < 0.001; 7.3%), elbow flexors MVICs (p < 0.001; 10.7%), CMJ (p = 0.02; 12.2%), and YBT (p = 0.002; 3.8%). NLMF with similar relative fatigue-induced deficits of fatigued and nonfatigued limbs suggest that youth fatigue is highly dependent upon the extent of activation or inhibition of the nervous system. Coaches of young athletes might consider developing technical motor skills before fatiguing exercise components, which might hinder the proficiency of their performance.

Poststretch Isometric Contractions of the Hamstrings: Just a Brief Stretch to Achieve Supramaximal Isometric Force

2021 ◽  
pp. 1-7
Author(s):  
Neil Chapman ◽  
John William Whitting ◽  
Suzanne Broadbent ◽  
Zachary Crowley-McHattan ◽  
Rudi Meir
Keyword(s):  
Isometric Contraction ◽  
Knee Flexion ◽  
Isometric Force ◽  
Biceps Femoris ◽  
Isometric Contractions ◽  
Maximal Voluntary Isometric Contraction ◽  
Hamstring Strain ◽  
Long Head ◽  
Biceps Femoris Long Head ◽  
Knee Flexors

Hamstring strain injuries are common in sport. Supramaximal eccentric or high-intensity isometric contractions are favored in hamstring strain injury prevention. The effect of combining these contraction modes in such prevention programs as a poststretch isometric contraction is unknown. Poststretch isometric contractions incorporate an active stretch and result in greater final isometric force than isometric contractions at comparable joint angles. This study compared torque and muscle activation levels between maximal voluntary isometric contraction and maximal poststretch isometric contractions of the knee flexors. Participants (n = 9) completed baseline maximal voluntary isometric contraction at 150° knee flexion and maximal poststretch isometric contractions at 120° knee flexion actively stretching at 60°/s to 150° knee flexion for final isometric contraction. Torque of the knee flexors and surface electromyography root mean square (sEMGRMS) of biceps femoris long head were simultaneously recorded and compared between baseline and poststretch isometric at 150° knee flexion. Torque was 14% greater in the poststretch isometric condition compared with baseline maximal voluntary isometric contraction (42.45 [20.75] N·m, 14% [22.18%], P < .001) without increase in sEMGRMS of biceps femoris long head (−.03 mV, ±.06, P = .130, d = .93). Poststretch isometric contractions resulted in supramaximal levels of poststretch isometric torque without increased activation of biceps femoris long head.

EMG Analysis of the Vastus Medialis/Vastus Lateralis Muscles Utilizing the Unloaded Narrow- and Wide-Stance Squats

1998 ◽  
Vol 7 (4) ◽  
pp. 236-247 ◽  
Author(s):  
Ricky Anderson ◽  
Carol Courtney ◽  
Eli Carmeli
Keyword(s):  
Knee Flexion ◽  
Healthy Subjects ◽  
Vastus Lateralis ◽  
Emg Activity ◽  
Vastus Medialis ◽  
Significant Difference ◽  
The Difference

The purpose of this study was to see if vastus medialis oblique/vastus lateralis (VMO:VL) ratios could be increased by widening the squat stance and if the VMO activity increases with deeper ranges of knee flexion. Fifteen healthy subjects performed unloaded narrow and wide stance squats through three ranges of knee flexion: 30°, 60°, and 90°. The two squat stances were compared using a 2 × 3 ANOVA to see if the wide-stance squat had any significant difference in EMG activity for VMO: VL ratios compared to the narrow-stance squat. The difference in EMG activity of the VMO between the various angles for both squat stances was also compared. The ANOVA revealed no significant differences between the squat stances for VMO:VL ratios but did show the VMO:VL ratios to be significantly higher with increasing knee flexion angles. These findings suggest that the VMO is active throughout the 90° range and that increasing knee flexion angles can elicit greater activity of the VMO relative to the VL.

scholarly journals Blastocystis sp. Carriage and Irritable Bowel Syndrome: Is the Association Already Established?

Biology ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 340
Author(s):  
Fernando Salvador ◽  
Beatriz Lobo ◽  
Lidia Goterris ◽  
Carmen Alonso-Cotoner ◽  
Javier Santos ◽  
...  
Keyword(s):  
Irritable Bowel Syndrome ◽  
Microscopic Examination ◽  
Parasitic Infection ◽  
Diagnostic Technique ◽  
Control Group ◽  
Cross Sectional ◽  
Significant Difference ◽  
Blastocystis Sp ◽  
Irritable Bowel ◽  
Asymptomatic Subjects

Background: The aim of the present study is to describe the occurrence of Blastocystis sp. detection among asymptomatic subjects and patients with irritable bowel syndrome in order to evaluate the potential association between irritable bowel syndrome and the parasitic infection. Methods: Cross-sectional study where adult patients with irritable bowel syndrome diagnosed according to Rome IV criteria were included. A control group was formed by asymptomatic subjects older than 18 years. Exclusion criteria were: immunosuppressive condition or having received any drug with demonstrated activity against Blastocystis sp. within the last 6 months before study inclusion. Epidemiological and clinical information was collected from all included participants. Two stool samples were obtained from all participants: one sample for microscopic examination and one sample for Blastocystis sp. PCR detection. Blastocystis sp. infection was defined by the positivity of any of the diagnostic techniques. Results: Seventy-two participants were included (36 asymptomatic subjects and 36 patients with irritable bowel syndrome). Thirty-five (48.6%) were men, and median age of participants was 34 (IQR 29–49) years. The overall rate of Blastocystis sp. carriage was 27.8% (20/72). The prevalence assessed through microscopic examination was 22.2% (16/72), while the prevalence measured by PCR was 15.3% (11/72). When comparing the presence of Blastocystis sp. between asymptomatic subjects and IBS patients, we did not find any statistically significant difference (36.1% vs. 19.4% respectively, p = 0.114). Conclusions: regarding the occurrence of Blastocystis sp., no differences were found between asymptomatic participants and patients with irritable bowel disease irrespective of the diagnostic technique performed.

scholarly journals Effects of posterior tibial slope on the mid-term results of medial unicompartmental knee arthroplasty

Arthroplasty ◽  
2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Zhijie Chen ◽  
Kaizhe Chen ◽  
Yufei Yan ◽  
Jianmin Feng ◽  
Yi Wang ◽  
...  
Keyword(s):  
Knee Flexion ◽  
Tibial Slope ◽  
Posterior Tibial ◽  
Significant Difference ◽  
Medial Unicompartmental Knee Arthroplasty ◽  
Group 3 ◽  
Group 2 ◽  
Postoperative Knee ◽  
Group 1

Abstract Objective To evaluate the effect of medial posterior tibial slope (PTS) on mid-term postoperative range of motion (ROM) and functional improvement of the knee after medial unicompartmental knee arthroplasty (UKA). Methods Medical records of 113 patients who had undergone 124 medial UKAs between April 2009 through April 2014 were reviewed retrospectively. The mean follow-up lasted 7.6 years (range, 6.2–11.2 years). Collected were demographic data, including gender, age, height, weight of the patients. Anteroposterior (AP) and lateral knee radiographs of the operated knees were available in all patients. The knee function was evaluated during office follow-up or hospital stay. Meanwhile, postoperative PTS, ROM, maximal knee flexion and Hospital for Special Surgery (HSS) knee score (pre−/postoperative) of the operated side were measured and assessed. According to the size of the PTS, patients were divided into 3 groups: group 1 (<4°), group 2 (4° ~ 7°) and group 3 (>7°). The association between PTS and the knee function was investigated. Results In our cohort, the average PTS was 2.7° ± 0.6° in group 1, 5.6° ± 0.9° in group 2 and 8.7° ± 1.2° in group 3. Pairwise comparisons showed significant differences among them (p < 0.01). The average maximal flexion range of postoperative knees in each group was 112.4° ± 5.6°, 116.4° ± 7.2°, and 117.5° ± 6.1°, respectively, with significant difference found between group 1 and group 2 (p < 0.05), and between group 1 and group 3 (p < 0.05). However, the gender, age, and body mass index (BMI) did not differ between three groups and there was no significant difference between groups in terms of pre−/postoperative HSS scores or postoperative knee ROM. Conclusion A mid-term follow-up showed that an appropriate PTS (4° ~ 7°) can help improve the postoperative flexion of knee. On the other hand, too small a PTS could lead to limited postoperative knee flexion. Therefore, the PTS less than 4° should be avoided during medial UKA.

Influence of submaximal isometric contractions of the hamstrings on electromyography activity and force while functioning as hip extensors

2020 ◽  
pp. 1-8
Author(s):  
Dasom Oh ◽  
Wootaek Lim
Keyword(s):  
Prone Position ◽  
Supine Position ◽  
Isometric Contraction ◽  
Muscle Length ◽  
Biceps Femoris ◽  
Emg Activity ◽  
Isometric Contractions ◽  
Significant Difference ◽  
Extension Force ◽  
Long Head

BACKGROUND: Although the medial and lateral hamstrings are clearly distinct anatomically and have different functions in the transverse plane, they are often considered as one muscle during rehabilitation. OBJECTIVE: The purpose of the study was to compare the electromyographic (EMG) activity between the prone position and the supine position during maximal isometric contraction and to additionally confirm the effect of submaximal isometric contractions on EMG activity of medial and lateral hamstrings, and force. METHODS: In the prone position, EMG activities of the long head of biceps femoris (BFLH) and semitendinosus (ST) were measured during the maximal isometric contraction. In the supine position, hip extension force with EMG activity were measured during the maximal and the submaximal isometric contractions. RESULTS: EMG activity in the prone position was significantly decreased in the supine position. In the supine position, there was a significant difference between the BFLH and ST during the maximal isometric contraction, but not during the submaximal isometric contractions. CONCLUSIONS: The dependence on the hamstrings could be relatively lower during hip extensions. When the medial and lateral hamstrings are considered separately, the lateral hamstrings may show a more active response, with increased muscle length, in clinical practice.

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