scholarly journals Static Loading of the Knee Joint Results in Modified Single Leg Landing Biomechanics

2019 ◽  
Author(s):  
Michael W. Olson
Keyword(s):  
Knee Joint ◽  
Static Loading ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Rate Of Force Development ◽  
External Loading ◽  
Force Development ◽  
Before And After ◽  
Angular Velocities

ABSTRACTBackgroundExternal loading of the ligamentous tissues induces mechanical creep, which modifies neuromuscular response to perturbations. It is not well understood how ligamentous creep affects athletic performance and contributes to modifications of knee biomechanics during functional tasks.Hypothesis/PurposeThe purpose of this study was to examine the mechanical and neuromuscular responses to single leg drop landing perturbations before and after passive loading of the knee joint.Study DesignDescriptive laboratory studyMethodsMale (n=7) and female (n=14) participants’ (21.3 ± 2.1 yrs, 1.69 ± 0.09 m, 69.3 ± 13.0 kg) right hip, knee, and ankle kinematics were assessed during drop landings performed from a 30 cm height onto a force platform before and after a 10 min creep protocol. Electromyography (EMG) signals were recorded from rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), semimembranosus (SM), and biceps femoris (BF) muscles. The creep protocol involved fixing the knee joint at 35° during static loading with perpendicular loads of either 200 N (males) or 150 N (females). Maximum, minimum, range of motion (ROM), and angular velocities were assessed for the hip, knee, and ankle joints, while normalized average EMG (NAEMG), average vertical ground reaction forces (aVGRF), and rate of force development (RFD) were assessed at landing. Rate of force development (RFD) was calculated during the landings using ANOVAs. Alpha was set at 0.05.ResultsMaximum hip flexion velocity decreased (p < 0.01). Minimum knee flexion velocity increased (p < 0.02). Minimum knee ad/abduction velocity decreased (p < 0.001). Ankle ROM decreased (p < 0.001). aVGRF decreased (p < 0.02). RFD had a non-significant trend (p = 0.076). NAEMG was significant between muscle groups (p < 0.02).ConclusionDistinct changes in velocity parameters are attributed to the altered mechanical behavior of the knee joint tissues and may contribute to changes in the loading of the leg during landing.

scholarly journals Age-specific modulation of intermuscular beta coherence during gait before and after experimentally induced fatigue

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Paulo Cezar Rocha dos Santos ◽  
Claudine J. C. Lamoth ◽  
Fabio Augusto Barbieri ◽  
Inge Zijdewind ◽  
Lilian Teresa Bucken Gobbi ◽  
...  
Keyword(s):  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Treadmill Walking ◽  
Beta Band ◽  
Sit To Stand ◽  
Corticospinal Tracts ◽  
Before And After ◽  
Oscillatory Coupling ◽  
Experimentally Induced

Abstract We examined the effects of age on intermuscular beta-band (15–35 Hz) coherence during treadmill walking before and after experimentally induced fatigue. Older (n = 12) and younger (n = 12) adults walked on a treadmill at 1.2 m/s for 3 min before and after repetitive sit-to-stand, rSTS, to induce muscle fatigability. We measured stride outcomes and coherence from 100 steps in the dominant leg for the synergistic (biceps femoris (BF)-semitendinosus, rectus femoris (RF)-vastus lateralis (VL), gastrocnemius lateralis (GL)-Soleus (SL), tibialis anterior (TA)-peroneus longus (PL)) and for the antagonistic (RF-BF and TA-GL) muscle pairs at late swing and early stance. Older vs. younger adults had 43–62% lower GL-SL, RF-VL coherence in swing and TA-PL and RF-VL coherence in stance. After rSTS, RF-BF coherence in late swing decreased by ~ 20% and TA-PL increased by 16% independent of age (p = 0.02). Also, GL-SL coherence decreased by ~ 23% and increased by ~ 23% in younger and older, respectively. Age affects the oscillatory coupling between synergistic muscle pairs, delivered presumably via corticospinal tracts, during treadmill walking. Muscle fatigability elicits age-specific changes in the common fluctuations in muscle activity, which could be interpreted as a compensation for muscle fatigability to maintain gait performance.

Decrease in maximal voluntary contraction by tonic vibration applied to a single synergist muscle in humans

2000 ◽  
Vol 89 (4) ◽  
pp. 1420-1424 ◽  
Author(s):  
Motoki Kouzaki ◽  
Minoru Shinohara ◽  
Tetsuo Fukunaga
Keyword(s):  
Maximal Voluntary Contraction ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Vastus Medialis ◽  
Force Development ◽  
Ia Afferent ◽  
Before And After ◽  
Integrated Emg

The purpose of the study was to examine the effect of prolonged tonic vibration applied to a single synergist muscle on maximal voluntary contraction (MVC) and maximal rate of force development (dF/d t max). The knee extension MVC force and surface electromyogram (EMG) from the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) during MVC were recorded before and after vibration of RF muscle at 30 Hz for 30 min. MVC, dF/d t max, and the integrated EMG (iEMG) of RF decreased significantly after prolonged tonic vibration in spite of no changes in iEMG of VL and VM. The present results indicate that MVC and dF/d t max may be influenced by the attenuated Ia afferent functions of a single synergist muscle.

scholarly journals Functional assessment of muscle response in lower limbs of tumbling gymnasts through tensiomyography

2016 ◽  
Vol 64 (3) ◽  
pp. 505
Author(s):  
Nicolás Rojas-Barrionuevo ◽  
Mercedes Vernetta-Santana ◽  
Jesús López-Bedoya
Keyword(s):  
Delay Time ◽  
High Performance ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Response Speed ◽  
Biceps Femoris ◽  
Lower Limbs ◽  
Muscle Response ◽  
Antagonist Muscles ◽  
Before And After

Introduction: Jumping capacity, a distinctive technical skill of tumbling gymnasts, is associated to a successful performance in training and competition; hence the need for an individualized, precise and localized assessment of the most demanded muscle structures.Objective: To assess muscle response of the flexo-extension structure in the knee joint and the extension of the ankle joint in a sample of 12 high-performance male gymnasts.Materials and methods: An acrobatic training protocol including sets of forward somersault in tumbling track was conducted. The contraction time, delay time and deformation of muscle belly were evaluated, and the muscular response speed was calculated using tensiomyography before and after the training intervention in different periods of time.Results: Significant differences were found (p<0.05) according to the muscle group involved, where rectus femoris and biceps femoris presented greater enhancement and shortening of the contraction and delay time. Major differences appeared between agonist-antagonist muscles (vastus lateralis-biceps femoris) (p<0.05) due to a decrease in the contraction and delay speed in vastus medialis (p<0.001).Conclusions: Tensiomyography allows estimating the states of activation-enhancing of the musculature responsible of jumping in tumblers, as well as planning the training based on the state of muscle fatigue.

Electromyography Activation of the Lower-Limb Muscles Adopting a Physioball and Elastic Band to Stabilize the Knee Joint During Multiple Sets With Submaximal Loads

2017 ◽  
Vol 26 (5) ◽  
pp. 406-414 ◽  
Author(s):  
Gabriel Andrade Paz ◽  
Jason DeFreitas ◽  
Marianna de Freitas Maia ◽  
Jurandir Silva ◽  
Vicente Lima ◽  
...  
Keyword(s):  
Knee Joint ◽  
Study Design ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Crossover Design ◽  
Elastic Band ◽  
Lower Extremity Injuries ◽  
Control Protocol ◽  
Lower Limb Muscles

Study Design:Crossover design.Context:Excessive valgus and varus force which affected the knee joint during dynamic tasks has been often associated to lower extremity injuries. Strategies to increase the resistance against these asymmetries (eg, the use of a physioball between the knees or elastic bands around the knees) are often applied in rehabilitation and conditioning programs.Objective:The purpose of this study was to investigate the effect of performing leg press (LP) 45° using a physioball and elastic band over multiple sets with submaximal loads on electromyographic (EMG) amplitude and fatigue indices.Methods:18 trained females volunteered (age: 24.4 ± 2.1 y; height: 168.1 ± 4 cm; body mass: 65.1 ± 4.4 kg) participated in this study. The 10 repetition maximum (RM) loads were determined for the LP. Then, 3 experimental protocols were followed in a randomized crossover design over 3 nonconsecutive days: control protocol—the participants performed 4 LP sets; physioball between knees—4 LP sets were performed with the physioball between the knees; elastic band—4 LP sets were performed with the elastic band involving the knees. Ten repetitions were performed during each set with 70% of 10-RM loads; EMG spectral indices (CRMS and Cf5) was collected from the biceps femoris (BF), vastus lateralis (VL), vastus medialis obliquus (VMO), and rectus femoris (RF) muscles.Results:Higher levels of CRMS and Cf5 were noted for RF, VL, and VM muscles using the physioball and elastic band when compared with control protocol, respectively. CRMS index of BF muscle was significantly higher using physioball and elastic band protocol versus control condition, respectively.Conclusion:Therefore, both physioball and elastic band can be adopted during LP with the goal to reduce excessive varus and valgus forces, respectively, even performing consecutive sets with submaximal loads. Furthermore, this may be an interesting alternative to increasing quadriceps activation and improving the knee joint stabilization.

scholarly journals Leg Muscle Activity and Perception of Effort before and after Four Short Sessions of Submaximal Eccentric Cycling

2020 ◽  
Vol 17 (21) ◽  
pp. 7702
Author(s):  
Pierre Clos ◽  
Romuald Lepers
Keyword(s):  
Muscle Activity ◽  
Peak Power ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Peak Power Output ◽  
Leg Muscles ◽  
Perception Of Effort ◽  
Before And After ◽  
Power Outputs

Background: This study tested muscle activity (EMG) and perception of effort in eccentric (ECC) and concentric (CON) cycling before and after four sessions of both. Methods: Twelve volunteers naïve to ECC cycling attended the laboratory six times. On day 1, they performed a CON cycling peak power output (PPO) test. They then carried-out four sessions comprising two sets of 1 to 1.5-min cycling bouts at 5 intensities (30, 45, 60, 75, and 90% PPO) in ECC and CON cycling. On day 2 and day 6 (two weeks apart), EMG root mean square of the vastus lateralis (VL), rectus femoris (RF), biceps femoris (BF), and soleus (SOL) muscles, was averaged from 15 to 30 s within each 1-min bout and perception of effort was asked after 45 s. Results: Before the four cycling sessions, while VL EMG was lower in ECC than CON cycling, most variables were not different. Afterwards, ECC cycling exhibited lower RF EMG at 75 and 90% PPO (all p < 0.02), lower VL and BF EMG at all exercise intensities (all p < 0.02), and inferior SOL EMG (all p < 0.04) except at 45% PPO (p = 0.07). Perception of effort was lower in ECC cycling at all exercise intensities (all p < 0.03) but 60% PPO (p = 0.11). Conclusions: After four short sessions of ECC cycling, the activity of four leg muscles and perception of effort became lower in ECC than in CON cycling at most of five power outputs, while they were similar before.

scholarly journals Muscle Activation Differs between Three Different Knee Joint-Angle Positions during a Maximal Isometric Back Squat Exercise

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Paulo Henrique Marchetti ◽  
Josinaldo Jarbas da Silva ◽  
Brad Jon Schoenfeld ◽  
Priscyla Silva Monteiro Nardi ◽  
Silvio Luis Pecoraro ◽  
...  
Keyword(s):  
Knee Joint ◽  
Muscle Activation ◽  
Specific Activity ◽  
Vastus Lateralis ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Joint Angles ◽  
Back Squat ◽  
Squat Exercise

The purpose of this study was to compare muscle activation of the lower limb muscles when performing a maximal isometric back squat exercise over three different positions. Fifteen young, healthy, resistance-trained men performed an isometric back squat at three knee joint angles (20°, 90°, and 140°) in a randomized, counterbalanced fashion. Surface electromyography was used to measure muscle activation of the vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF), biceps femoris (BF), semitendinosus (ST), and gluteus maximus (GM). In general, muscle activity was the highest at 90° for the three quadriceps muscles, yet differences in muscle activation between knee angles were muscle specific. Activity of the GM was significantly greater at 20° and 90° compared to 140°. The BF and ST displayed similar activation at all joint angles. In conclusion, knee position alters muscles activation of the quadriceps and gluteus maximus muscles. An isometric back squat at 90° generates the highest overall muscle activation, yet an isometric back squat at 140° generates the lowest overall muscle activation of the VL and GM only.

Reciprocal Coactivation Patterns of the Lateral and Medial Quadriceps and Hamstrings during Low- and Moderate-Speed Isokinetic Movement

1998 ◽  
Vol 7 (3) ◽  
pp. 182-196 ◽  
Author(s):  
Ronald V. Croce ◽  
John P. Miller ◽  
Robert Confessore ◽  
James C. Vailas
Keyword(s):  
Knee Joint ◽  
Female Athletes ◽  
Vastus Lateralis ◽  
Biceps Femoris ◽  
Median Frequency ◽  
Vastus Medialis ◽  
Mean Square ◽  
Joint Movement ◽  
Surface Electrodes ◽  
Emg Patterns

The purpose of this study was to examine coactivation patterns of the lateral and medial quadriceps and the lateral and medial hamstrings during low- and moderate-speed isokinetic movements. Twelve female athletes performed isokinetic knee assessments at 60 and 180°/s. Root mean square electromyographic (rmsEMG) activity and the median frequency of the EMG (mfEMG) were determined by placing bipolar surface electrodes on the vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), and medial hamstrings (MH). Results of rmsEMG indicated that the VM showed almost twice the coactivation of the VL (p< .05), and that the BF showed almost four times the coactivation of the MH (p <.05). Finally, differences were noted in the mfEMG (p< .05), with the VM displaying different recruitment patterns at 180°/s as an agonist compared to that as an antagonist. Results indicated that when acting as antagonists, the VM and BE display the greatest EMG patterns during isokinetic knee joint movement.

scholarly journals The Importance of Lean Body Mass for the Rate of Force Development in Taekwondo Athletes and Track and Field Throwers

2018 ◽  
Vol 3 (3) ◽  
pp. 43 ◽  
Author(s):  
Angeliki Kavvoura ◽  
Nikolaos Zaras ◽  
Angeliki-Nikoletta Stasinaki ◽  
Giannis Arnaoutis ◽  
Spyridon Methenitis ◽  
...  
Keyword(s):  
Lean Body Mass ◽  
Body Mass ◽  
Vastus Lateralis ◽  
Rate Of Force Development ◽  
Track And Field ◽  
Medial Gastrocnemius ◽  
Lower Body ◽  
Leg Extension ◽  
Force Development ◽  
The Relationship

The rate of force development (RFD) is vital for power athletes. Lean body mass (LBM) is considered to be an essential contributor to RFD, nevertheless high RFD may be achieved by athletes with either high or low LBM. The aim of the study was to describe the relationship between lower-body LBM and RFD, and to compare RFD in taekwondo athletes and track and field (T&F) throwers, the latter having higher LBM when compared to taekwondo athletes. Nine taekwondo athletes and nine T&F throwers were evaluated for countermovement jumping, isometric leg press and leg extension RFD, vastus lateralis (VL), and medial gastrocnemius muscle architecture and body composition. Lower body LBM was correlated with RFD 0–250 ms (r = 0.81, p = 0.016). Taekwondo athletes had lower LBM and jumping power per LBM. RFD was similar between groups at 30–50 ms, but higher for throwers at 80–250 ms. RFD adjusted for VL thickness was higher in taekwondo athletes at 30 ms, but higher in throwers at 200–250 ms. These results suggest that lower body LBM is correlated with RFD in power trained athletes. RFD adjusted for VL thickness might be more relevant to evaluate in power athletes with low LBM, while late RFD might be more relevant to evaluate in athletes with higher LBM.

scholarly journals Regional and muscle-specific adaptations in knee extensor hypertrophy using flywheel versus conventional weight-stack resistance exercise

2019 ◽  
Vol 44 (8) ◽  
pp. 827-833 ◽  
Author(s):  
Tommy R. Lundberg ◽  
Maria T. García-Gutiérrez ◽  
Mirko Mandić ◽  
Mats Lilja ◽  
Rodrigo Fernandez-Gonzalo
Keyword(s):  
Resistance Exercise ◽  
Muscle Hypertrophy ◽  
Vastus Lateralis ◽  
Knee Extensor ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Knee Extensors ◽  
Cross Sectional ◽  
Proximal Site ◽  
Before And After

This study compared the effects of the most frequently employed protocols of flywheel (FW) versus weight-stack (WS) resistance exercise (RE) on regional and muscle-specific adaptations of the knee extensors. Sixteen men (n = 8) and women (n = 8) performed 8 weeks (2–3 days/week) of knee extension RE employing FW technology on 1 leg (4 × 7 repetitions), while the contralateral leg performed regular WS training (4 × 8–12 repetitions). Maximal strength (1-repetition maximum (1RM) in WS) and peak FW power were determined before and after training for both legs. Partial muscle volume of vastus lateralis (VL), vastus medialis (VM), vastus intermedius (VI), and rectus femoris (RF) were measured using magnetic resonance imaging. Additionally, quadriceps cross-sectional area was assessed at a proximal and a distal site. There were no differences (P > 0.05) between FW versus WS in muscle hypertrophy of the quadriceps femoris (8% vs. 9%), VL (10% vs. 11%), VM (6% vs. 8%), VI (5% vs. 5%), or RF (17% vs. 17%). Muscle hypertrophy tended (P = 0.09) to be greater at the distal compared with the proximal site, but there was no interaction with exercise method. Increases in 1RM and FW peak power were similar across legs, yet the increase in 1RM was greater in men (31%) than in women (20%). These findings suggest that FW and WS training induces comparable muscle-specific hypertrophy of the knee extensors. Given that these robust muscular adaptations were brought about with markedly fewer repetitions in the FW compared with WS, it seems FW training can be recommended as a particularly time-efficient exercise paradigm.

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