GENDER DIFFERENCES IN SPECIFIC TENSION, VOLUNTARY MUSCLE ACTIVATION AND MUSCLE ARCHITECTURE IN HUMAN KNEE EXTENSORS

2001 ◽  
Vol 33 (5) ◽  
pp. S264
Author(s):  
T Abe ◽  
K Kumagai ◽  
M Ukon ◽  
M Ito ◽  
Y Kawakami ◽  
...  
Keyword(s):  
Gender Differences ◽  
Muscle Activation ◽  
Muscle Architecture ◽  
Knee Extensors ◽  
Specific Tension ◽  
Human Knee ◽  
Voluntary Muscle

scholarly journals Muscle Fatigability After Hex-Bar Deadlift Exercise Performed With Fast or Slow Tempo

2021 ◽  
Vol 16 (1) ◽  
pp. 117-123
Author(s):  
Jay A. Collison ◽  
Jason Moran ◽  
Inge Zijdewind ◽  
Florentina J. Hettinga
Keyword(s):  
Maximal Voluntary Contraction ◽  
Muscle Activation ◽  
Voluntary Contraction ◽  
Knee Extensors ◽  
Maximal Velocity ◽  
Time Data ◽  
Voluntary Muscle ◽  
Fast Tempo ◽  
Bar Velocity ◽  
Slow Tempo

Purpose: To examine the differences in muscle fatigability after resistance exercise performed with fast tempo (FT) compared with slow tempo (ST). Methods: A total of 8 resistance-trained males completed FT and ST hexagonal-barbell deadlifts, consisting of 8 sets of 6 repetitions at 60% 3-repetition maximum, using a randomized crossover design. Each FT repetition was performed with maximal velocity, while each repetition during ST was performed with a 3-1-3 (eccentric/isometric/concentric) tempo (measured in seconds). Isometric maximal voluntary contraction, voluntary muscle activation, and evoked potentiated twitch torque of the knee extensors were determined using twitch interpolation before, during (set 4), and after exercise. Displacement–time data were measured during the protocols. Results: The mean bar velocity and total concentric work were higher for FT compared with ST (995 [166] W vs 233 [52] W; 0.87 [0.05] m/s vs 0.19 [0.05] m/s; 4.8 [0.8] kJ vs 3.7 [1.1] kJ). Maximal voluntary contraction torque, potentiated twitch, and voluntary muscle activation were significantly reduced after FT (−7.8% [9.2%]; −5.2% [9.2%], −8.7% [12.2%]) and ST (−11.2% [8.4%], −13.3% [8.1%], −1.8% [3.6%]). Conclusion: The decline in maximal voluntary force after both the FT and ST hexagonal-barbell deadlifts exercise was accompanied by a similar decline in contractile force and voluntary muscle activation.

scholarly journals Is the Occurrence of the Sticking Region in Maximum Smith Machine Squats the Result of Diminishing Potentiation and Co-Contraction of the Prime Movers among Recreationally Resistance Trained Males?

2021 ◽  
Vol 18 (3) ◽  
pp. 1366
Author(s):  
Roland van den Tillaar ◽  
Eirik Lindset Kristiansen ◽  
Stian Larsen
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Gluteus Maximus ◽  
Knee Extensors ◽  
Force Output ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Prime Movers ◽  
Almost All ◽  
Height Data

This study compared the kinetics, barbell, and joint kinematics and muscle activation patterns between a one-repetition maximum (1-RM) Smith machine squat and isometric squats performed at 10 different heights from the lowest barbell height. The aim was to investigate if force output is lowest in the sticking region, indicating that this is a poor biomechanical region. Twelve resistance trained males (age: 22 ± 5 years, mass: 83.5 ± 39 kg, height: 1.81 ± 0.20 m) were tested. A repeated two-way analysis of variance showed that Force output decreased in the sticking region for the 1-RM trial, while for the isometric trials, force output was lowest between 0–15 cm from the lowest barbell height, data that support the sticking region is a poor biomechanical region. Almost all muscles showed higher activity at 1-RM compared with isometric attempts (p < 0.05). The quadriceps activity decreased, and the gluteus maximus and shank muscle activity increased with increasing height (p ≤ 0.024). Moreover, the vastus muscles decreased only for the 1-RM trial while remaining stable at the same positions in the isometric trials (p = 0.04), indicating that potentiation occurs. Our findings suggest that a co-contraction between the hip and knee extensors, together with potentiation from the vastus muscles during ascent, creates a poor biomechanical region for force output, and thereby the sticking region among recreationally resistance trained males during 1-RM Smith machine squats.

Electrically-induced quadriceps fatigue in the contralateral leg impairs ipsilateral knee extensors performance

2021 ◽  
Author(s):  
Fabio Giuseppe Laginestra ◽  
Markus Amann ◽  
Emine Kirmizi ◽  
Gaia Giuriato ◽  
Chiara Barbi ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Central Fatigue ◽  
Endurance Performance ◽  
Voluntary Exercise ◽  
Peripheral Fatigue ◽  
Knee Extensors ◽  
Motor Drive ◽  
Time To Exhaustion ◽  
Crossover Effect ◽  
The Impact

Muscle fatigue induced by voluntary exercise, which requires central motor drive, causes central fatigue that impairs endurance performance of a different, non-fatigued muscle. This study investigated the impact of quadriceps fatigue induced by electrically-induced (no central motor drive) contractions on single-leg knee-extension (KE) performance of the subsequently exercising ipsilateral quadriceps. On two separate occasions, eight males completed constant-load (85% of maximal power-output) KE exercise to exhaustion. In a counterbalanced manner, subjects performed the KE exercise with no pre-existing quadriceps fatigue in the contralateral leg on one day (No-PreF), while on the other day, the same KE exercise was repeated following electrically-induced quadriceps fatigue in the contralateral leg (PreF). Quadriceps fatigue was assessed by evaluating pre- to post-exercise changes in potentiated twitch force (ΔQtw,pot; peripheral-fatigue), and voluntary muscle activation (ΔVA; central-fatigue). As reflected by the 57±11% reduction in electrically-evoked pulse force, the electrically-induced fatigue protocol caused significant knee-extensors fatigue. KE endurance time to exhaustion was shorter during PreF compared to No-PreF (4.6±1.2 vs 7.7±2.4 min; p<0.01). While ΔQtw,pot was significantly larger in No-PreF compared to PreF (-60% vs -52%, p<0.05), ΔVA was greater in PreF (-14% vs -10%, p<0.05). Taken together, electrically-induced quadriceps fatigue in the contralateral leg limits KE endurance performance and the development of peripheral fatigue in the ipsilateral leg. These findings support the hypothesis that the crossover-effect of central fatigue is mainly mediated by group III/IV muscle afferent feedback and suggest that impairments associated with central motor drive may only play a minor role in this phenomenon.

Effects of fatigue on lower limb, pelvis and trunk kinematics and muscle activation: Gender differences

2017 ◽  
Vol 32 ◽  
pp. 9-14 ◽  
Author(s):  
Giovanna Camparis Lessi ◽  
Ana Flávia dos Santos ◽  
Luis Fylipe Batista ◽  
Gabriela Clemente de Oliveira ◽  
Fábio Viadanna Serrão
Keyword(s):  
Gender Differences ◽  
Lower Limb ◽  
Muscle Activation ◽  
Trunk Kinematics

Functional Roles of the Leg Muscles When Pedaling in the Recumbent Versus the Upright Position

2004 ◽  
Vol 127 (2) ◽  
pp. 301-310 ◽  
Author(s):  
Nils A. Hakansson ◽  
M. L. Hull
Keyword(s):  
Gravity Field ◽  
Muscle Activation ◽  
Upright Position ◽  
Knee Extensors ◽  
Muscle Coordination ◽  
Activation Patterns ◽  
Functional Roles ◽  
Leg Muscles ◽  
Surface Electromyograms ◽  
Pedaling Rate

An understanding of the coordination of the leg muscles in recumbent pedaling would be useful to the design of rehabilitative pedaling exercises. The objectives of this work were to (i) determine whether patterns of muscle activity while pedaling in the recumbent and upright positions are similar when the different orientation in the gravity field is considered, (ii) compare the functional roles of the leg muscles while pedaling in the recumbent position to the upright position to the upright position and (iii) determine whether leg muscle onset and offset timing for recumbent and upright pedaling respond similarly to changes in pedaling rate. To fulfill these objectives, surface electromyograms were recorded from 10 muscles of 15 subjects who pedaled in both the recumbent and upright positions at 75, 90, and 105rpm and at a constant workrate of 250W. Patterns of muscle activation were compared over the crank cycle. Functional roles of muscles in recumbent and upright pedaling were compared using the percent of integrated activation in crank cycle regions determined previously for upright pedaling. Muscle onset and offset timing were also compared. When the crank cycle was adjusted for orientation in the gravity field, the activation patterns for the two positions were similar. Functional roles of the muscles in the two positions were similar as well. In recumbent pedaling, the uniarticular hip and knee extensors functioned primarily to produce power during the extension region of the crank cycle, whereas the biarticular muscles crossing the hip and knee functioned to propel the leg through the transition regions of the crank cycle. The adaptations of the muscles to changes in pedaling rate were also similar for the two body positions with the uniarticular power producing muscles of the hip and knee advancing their activity to earlier in the crank cycle as the pedaling rate increased. This information on the functional roles of the leg muscles provides a basis by which to form functional groups, such as power-producing muscles and transition muscles, to aid in the development of rehabilitative pedaling exercises and recumbent pedaling simulations to further our understanding of task-dependent muscle coordination.

scholarly journals Differences in Hip Joint Biomechanics and Muscle Activation in Individuals With Femoroacetabular Impingement Compared With Healthy, Asymptomatic Individuals: Is Level-Ground Gait Analysis Enough?

2018 ◽  
Vol 6 (5) ◽  
pp. 232596711876982 ◽  
Author(s):  
Derek J. Rutherford ◽  
Janice Moreside ◽  
Ivan Wong
Keyword(s):  
Femoroacetabular Impingement ◽  
Hip Joint ◽  
Muscle Activation ◽  
Gluteus Maximus ◽  
Knee Extensors ◽  
Joint Function ◽  
Asymptomatic Group ◽  
Level Walking ◽  
Hip Function ◽  
Asymptomatic Individuals

Background: Femoroacetabular impingement (FAI) is a recognized cause of hip and groin pain and a significant factor in hip joint function during sport. Objective tests for understanding hip function are lacking in this population. Purpose: To determine whether biomechanical and electromyographic features of hip function during level-ground walking differ between a group diagnosed with FAI and those with no symptoms of FAI. Study Design: Controlled laboratory study. Methods: A total of 20 asymptomatic individuals and 20 individuals with FAI walked on a dual-belt instrumented treadmill at self-selected walking velocities. Sagittal and frontal plane joint motions, moments, and muscle activation for the gluteus medius, gluteus maximus, rectus femoris, and medial and lateral hamstrings were analyzed. Discrete measures were extracted from each biomechanical waveform, and principal component analysis was used to determine hip joint muscle activation and hip adduction moment patterns. Statistical significance was determined by use of Student t tests with Bonferroni adjustments for multiple comparisons (α = .05). Results: Individuals with FAI walked more slowly ( P = .015) and had lower self-reported function ( P < .001). No differences in muscle strength were found between the symptomatic and contralateral legs in the FAI group ( P > .017), but those with FAI had lower strength in the knee extensors and flexors and the hip extensors, flexors, and adductors compared with the asymptomatic group ( P < .017). Individuals with unilateral symptomatic FAI walked with similar biomechanical and hip muscle electromyographic results bilaterally. The only differences found were a greater amplitude of gluteus maximus activation in the FAI symptomatic leg compared with the asymptomatic group and greater medial hamstring activation than lateral hamstring activation in the FAI group in both limbs compared with the asymptomatic group. Conclusion: Individuals with FAI were generally deconditioned and reported significantly more functional limitations. No biomechanical differences existed between groups during level walking, yet hamstring and gluteus maximus activation differed when the symptomatic group was compared with the asymptomatic group. Clinical Relevance: The field lacks objective testing of hip joint function to understand implications of FAI for dynamic movements, particularly with applications to biomechanics and electromyography. Level walking was of limited value for understanding FAI hip function, and the development of a more challenging gait assessment is warranted.

scholarly journals Torque-producing capacity is affected by moment arm in the human knee extensors

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Miyuki Hori ◽  
Tadashi Suga ◽  
Masafumi Terada ◽  
Yuto Miyake ◽  
Akinori Nagano ◽  
...  
Keyword(s):  
Knee Extensors ◽  
Moment Arm ◽  
Human Knee
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