Different Muscle-Recruitment Strategies Among Elite Breaststrokers

Purpose:To investigate electromyographical (EMG) profiles characterizing the lower-limb flexion-extension in an aquatic environment in high-level breaststrokers.Methods:The 2-dimensional breaststroke kick of 1 international- and 2 national-level female swimmers was analyzed during 2 maximal 25-m swims. The activities of biceps femoris, rectus femoris, gastrocnemius, and tibialis anterior were recorded.Results:The breaststroke kick was divided in 3 phases, according to the movements performed in the sagittal plane: push phase (PP) covering 27% of the total kick duration, glide phase (GP) 41%, and recovery phase (RP) 32%. Intrasubject reproducibility of the EMG and kinematics was observed from 1 stroke cycle to another. In addition, important intersubject kinematic reproducibility was noted, whereas muscle activities discriminated the subjects: The explosive Pp was characterized by important muscle-activation peaks. During the recovery, muscles were likewise solicited for swimmers 1 (S1) and 2 (S2), while the lowest activities were observed during GP for S2 and swimmer 3 (S3), but not for S1, who maintained major muscle solicitations.Conclusions:The main muscle activities were observed during PP to perform powerful lower-limb extension. The most-skilled swimmer (S1) was the only 1 to solicit her muscles during GP to actively reach better streamlining. Important activation peaks during RP correspond to the limbs acting against water drag. Such differences in EMG strategies among an elite group highlight the importance of considering the muscle parameters used to effectively control the intensity of activation among the phases for a more efficient breaststroke kick.

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Muscle Activation in the Main Muscle Groups of the Lower Limbs in High-Level Dancesport Athletes

Medical Problems of Performing Artists ◽

10.21091/mppa.2018.4034 ◽

2018 ◽

Vol 33 (4) ◽

pp. 231-237

Author(s):

Encarnación Liébana ◽

Cristina Monleón ◽

Raquel Morales ◽

Carlos Pablos ◽

Consuelo Moratal ◽

...

Keyword(s):

Tibialis Anterior ◽

Muscle Activation ◽

Rectus Femoris ◽

Biceps Femoris ◽

Lower Limbs ◽

Gastrocnemius Medialis ◽

Leg Muscles ◽

Relative Activation ◽

Muscle Groups ◽

High Level

Dancers are subjected to high-intensity workouts when they practice dancesport, and according to the literature, they are prone to injury, primarily of the lower limbs. The purpose of this study was to determine whether differences exist in relative activation amplitudes for dancers involved in dancesport due to muscle, gender, and type of dance. Measurements were carried out using surface electromyography equipment during the choreography of a performance in the following leg muscles: rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius medialis. Eight couples of active dancesport athletes (aged 20.50±2.75 yrs) were analyzed. Significant gender differences were found in rumba in the tibialis anterior (p≤0.05) and gastrocnemius medialis (p≤0.05). Based on the different activations, it is possible to establish possible mechanisms of injury, as well as tools for preventing injuries and improving sports performance.

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The Effect of Step Width on Muscle Contributions to Body Mass Center Acceleration During the First Stance of Sprinting

Frontiers in Bioengineering and Biotechnology ◽

10.3389/fbioe.2021.636960 ◽

2021 ◽

Vol 9 ◽

Author(s):

Ruoli Wang ◽

Laura Martín de Azcárate ◽

Paul Sandamas ◽

Anton Arndt ◽

Elena M. Gutierrez-Farewik

Keyword(s):

Lower Limb ◽

Sagittal Plane ◽

Center Of Mass ◽

Gluteus Maximus ◽

Rectus Femoris ◽

Gluteus Medius ◽

Biceps Femoris ◽

The Body ◽

Step Width ◽

Acceleration Analysis

BackgroundAt the beginning of a sprint, the acceleration of the body center of mass (COM) is driven mostly forward and vertically in order to move from an initial crouched position to a more forward-leaning position. Individual muscle contributions to COM accelerations have not been previously studied in a sprint with induced acceleration analysis, nor have muscle contributions to the mediolateral COM accelerations received much attention. This study aimed to analyze major lower-limb muscle contributions to the body COM in the three global planes during the first step of a sprint start. We also investigated the influence of step width on muscle contributions in both naturally wide sprint starts (natural trials) and in sprint starts in which the step width was restricted (narrow trials).MethodMotion data from four competitive sprinters (2 male and 2 female) were collected in their natural sprint style and in trials with a restricted step width. An induced acceleration analysis was performed to study the contribution from eight major lower limb muscles (soleus, gastrocnemius, rectus femoris, vasti, gluteus maximus, gluteus medius, biceps femoris, and adductors) to acceleration of the body COM.ResultsIn natural trials, soleus was the main contributor to forward (propulsion) and vertical (support) COM acceleration and the three vasti (vastus intermedius, lateralis and medialis) were the main contributors to medial COM acceleration. In the narrow trials, soleus was still the major contributor to COM propulsion, though its contribution was considerably decreased. Likewise, the three vasti were still the main contributors to support and to medial COM acceleration, though their contribution was lower than in the natural trials. Overall, most muscle contributions to COM acceleration in the sagittal plane were reduced. At the joint level, muscles contributed overall more to COM support than to propulsion in the first step of sprinting. In the narrow trials, reduced COM propulsion and particularly support were observed compared to the natural trials.ConclusionThe natural wide steps provide a preferable body configuration to propel and support the COM in the sprint starts. No advantage in muscular contributions to support or propel the COM was found in narrower step widths.

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Can non-disabled adults reproduce the stiff-knee gait of individuals with stroke?

10.1101/2020.12.02.20242966 ◽

2020 ◽

Author(s):

Odair Bacca ◽

Melissa Celestino ◽

José Barela ◽

Anna Lima ◽

Ana Barela

Keyword(s):

Lower Limb ◽

Knee Flexion ◽

Muscle Activation ◽

Rectus Femoris ◽

Biceps Femoris ◽

Gait Pattern ◽

Activation Level ◽

Stiff Knee ◽

Mechanical Constraint ◽

Disabled Adults

AbstractThis study investigated whether a mechanical constraint of knee flexion in non-disabled individuals could help with reproducing the gait pattern of individuals with stroke. Eleven non-disabled adults (26.6±6.5 years old) and 12 individuals with stroke (52.0±12.8 years old) walked at a self-selected comfortable speed as kinematic and electromyographic data were acquired. Non-disabled adults also walked with an orthosis that limited to 45 degrees of knee flexion. The hip, knee, and ankle joint angles and the muscle activation of the rectus femoris, vastus medialis and lateralis, tibialis anterior, semitendinosus, biceps femoris, and gastrocnemius medialis and lateralis were analyzed. The results demonstrated that non-disabled adults presented similar lower limb excursion to individuals with stroke that affects most joints, although, they displayed a different muscle activation level for most muscles. These results suggest that a mechanical constraint of knee flexion leads to temporal and joint excursion alterations in the lower limb of non-disabled individuals, thereby enabling the reproduction of a gait pattern similar to individuals with stroke. It is also observed that these individuals use different strategies to control muscle activation, which might be related to the lack of control in coordinating muscle activation during gait that is present in individuals with stroke.

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Timing and Modulation of Activity in the Lower Limb Muscles During Indoor Rowing: What Are the Key Muscles to Target in FES-Rowing Protocols?

Sensors ◽

10.3390/s20061666 ◽

2020 ◽

Vol 20 (6) ◽

pp. 1666

Author(s):

Taian M. Vieira ◽

Giacinto Luigi Cerone ◽

Costanza Stocchi ◽

Morgana Lalli ◽

Brian Andrews ◽

...

Keyword(s):

Lower Limb ◽

Tibialis Anterior ◽

Vastus Lateralis ◽

Rectus Femoris ◽

Biceps Femoris ◽

Sample Surface ◽

Recovery Phase ◽

Lower Limb Muscles ◽

Limb Muscles ◽

Stimulation Of

The transcutaneous stimulation of lower limb muscles during indoor rowing (FES Rowing) has led to a new sport and recreation and significantly increased health benefits in paraplegia. Stimulation is often delivered to quadriceps and hamstrings; this muscle selection seems based on intuition and not biomechanics and is likely suboptimal. Here, we sample surface EMGs from 20 elite rowers to assess which, when, and how muscles are activated during indoor rowing. From EMG amplitude we specifically quantified the onset of activation and silencing, the duration of activity and how similarly soleus, gastrocnemius medialis, tibialis anterior, rectus femoris, vastus lateralis and medialis, semitendinosus, and biceps femoris muscles were activated between limbs. Current results revealed that the eight muscles tested were recruited during rowing, at different instants and for different durations. Rectus and biceps femoris were respectively active for the longest and briefest periods. Tibialis anterior was the only muscle recruited within the recovery phase. No side differences in the timing of muscle activity were observed. Regression analysis further revealed similar, bilateral modulation of activity. The relevance of these results in determining which muscles to target during FES Rowing is discussed. Here, we suggest a new strategy based on the stimulation of vasti and soleus during drive and of tibialis anterior during recovery.

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Modificación de patrones cinemáticos y electromiográficos en extremidad inferior por el uso de celular (Modification of kinematic and electromyographic patterns in the lower limb by the use of cell phones)

Retos ◽

10.47197/retos.v0i39.77730 ◽

2020 ◽

pp. 354-358

Author(s):

Oscar David Valencia Cayupán ◽

María José Hudson ◽

Felipe Carpes ◽

Marcos Kunzler ◽

Fernanda Gándara ◽

...

Keyword(s):

Lower Limb ◽

Cell Phone ◽

Sagittal Plane ◽

Biomechanical Model ◽

Rectus Femoris ◽

Biceps Femoris ◽

Lower Limbs ◽

Emg Activity ◽

Protective Strategy ◽

Hip Flexion

Las lesiones de transeúntes relacionadas al uso de teléfono celular han aumentado en relación con el total de accidentes peatonales. El objetivo de este estudio fue comparar variables cinemáticas y electromiográficas de ambas extremidades inferiores al enfrentar un obstáculo, con (CC) y sin (SC) el uso de celular. Diez mujeres jóvenes fueron evaluadas, las cuales caminaron y enfrentaron un obstáculo CC y SC. Con un modelo biomecánico 3D se evaluó la cinemática de extremidad inferior (plano sagital de cadera, rodilla, tobillo, junto al “toe clearance”). Al mismo tiempo se registró la actividad electromiográfica (EMG) de los siguientes músculos: tibial anterior (TA), gastrocnemio medial (GM), recto anterior (RA) y bíceps femoral (BF). Se calculó la amplitud EMG promedio de cada músculo, y el porcentaje de coactivación muscular entre: TA-GM y RA-BF. Se analizó la estrategia de ambas piernas, considerando un primer (P1) y segundo paso (P2) al cruzar el obstáculo, comparando entre una marcha CC vs CS. Según los resultados, la marcha CC incrementa el toe clearance, flexión de cadera, y la amplitud del GM, observado tanto en P1 como P2 al cruzar el obstáculo. Adicionalmente, el P2 reveló un incremento en la flexión de rodilla y tobillo. Por otro lado, la amplitud del TA y coactivación muscular entre TA-GM también aumentó CC en el P2. En conclusión, las variables cinemáticas y electromiográficas en las extremidades inferiores se modifican al cruzar un obstáculo CC. Estos hallazgos podrían indicar una estrategia protectora durante la tarea dual evaluada, minimizar el riesgo de caída. Abstract. Pedestrian injuries related to the use of cell phone have increased in relation to the total number of pedestrian accidents. The aim of this study was to compare kinematic and electromyographic variables in both lower limbs at facing an obstacle, with (WC) and without (WoC) the use of a cell phone. Ten young women were evaluated, while walking and facing an obstacle WC and WoC. A 3D biomechanical model was used to evaluate the lower limb kinematics (hip, knee, ankle in the sagittal plane, together with “toe clearance”). At the same time, the electromyographic (EMG) activity was registered in the following muscles: tibialis anterior (TA), gastrocnemius medialis (GM), rectus femoris (RF) and biceps femoris (BF). The mean EMG amplitude of each muscle and the muscular coactivation percentage between: TA-GM and RA-BF were calculated. The strategy for both lower limbs considering the first (P1) and the second step (P2) were analyzed when crossing the obstacle, comparing between gait WC vs WoC. According to results, the gait WC increase the toe clearance, hip flexion, and the GM amplitude, observed both in P1 as P2 when the person crossed the obstacle. Furthermore, the P2 revealed an increase in the knee and ankle flexion. On the other hand, the TA amplitude and the muscular coactivation between TA-GM also increased WC in the P2. In conclusion, the kinematic and electromyographic variables in the lower limbs are modified when crossing an obstacle WC. These findings could indicate a protective strategy during the dual-task evaluated, minimizing the risk of falling.

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Healthy subjects with lax knees use less knee flexion rather than muscle control to limit anterior tibia translation during landing

Journal of Experimental Orthopaedics ◽

10.1186/s40634-020-00246-6 ◽

2020 ◽

Vol 7 (1) ◽

Author(s):

Michèle N. J. Keizer ◽

Juha M. Hijmans ◽

Alli Gokeler ◽

Anne Benjaminse ◽

Egbert Otten

Keyword(s):

Knee Flexion ◽

Muscle Activation ◽

Reaction Force ◽

Rectus Femoris ◽

Knee Laxity ◽

Biceps Femoris ◽

Level Of Evidence ◽

Jump Landing ◽

Muscle Activation Patterns ◽

Healthy Participants

Abstract Purpose It has been reported that there is no correlation between anterior tibia translation (ATT) in passive and dynamic situations. Passive ATT (ATTp) may be different to dynamic ATT (ATTd) due to muscle activation patterns. This study aimed to investigate whether muscle activation during jumping can control ATT in healthy participants. Methods ATTp of twenty-one healthy participants was measured using a KT-1000 arthrometer. All participants performed single leg hops for distance during which ATTd, knee flexion angles and knee flexion moments were measured using a 3D motion capture system. During both tests, sEMG signals were recorded. Results A negative correlation was found between ATTp and the maximal ATTd (r = − 0.47, p = 0.028). An N-Way ANOVA showed that larger semitendinosus activity was seen when ATTd was larger, while less biceps femoris activity and rectus femoris activity were seen. Moreover, larger knee extension moment, knee flexion angle and ground reaction force in the anterior-posterior direction were seen when ATTd was larger. Conclusion Participants with more ATTp showed smaller ATTd during jump landing. Muscle activation did not contribute to reduce ATTd during impact of a jump-landing at the observed knee angles. However, subjects with large ATTp landed with less knee flexion and consequently showed less ATTd. The results of this study give information on how healthy people control knee laxity during jump-landing. Level of evidence III

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Modeling of Muscle Activation from Electromyography Recordings in Patients with Cerebral Palsy

Applied Sciences ◽

10.3390/app8122345 ◽

2018 ◽

Vol 8 (12) ◽

pp. 2345

Author(s):

Susmita Roy ◽

Ana Alves-Pinto ◽

Renée Lampe

Keyword(s):

Cerebral Palsy ◽

Reference Values ◽

Muscle Activation ◽

Muscle Force ◽

Rectus Femoris ◽

Biceps Femoris ◽

Force Modeling ◽

Lower Extremity Muscle ◽

Musculus Gastrocnemius ◽

Parameter Dependent

The present study estimated muscle activation from electromyographic (EMG) recordings in patients with cerebral palsy (CP) during cycling on an ergometer. This could be used as an input to the modeling of muscle force following the neuromusculoskeletal modeling technique which can help to understand the alterations in neuromotor processes underlying disabilities in CP. EMG signals of lower extremity muscle activity from 14 adult patients with CP and 10 adult healthy participants were used here to derive muscle activation. With a self developed EMG system, signals from the following muscles were recorded: Musculus tibialis anterior, Musculus gastrocnemius, Musculus rectus femoris, and Musculus biceps femoris. Collected EMG signals were mathematically transformed into muscle activation following a parameter dependent and a nonlinear transformation. Muscle activation values from patients with CP were compared to equivalent reference values obtained from healthy controls. Muscle activation calculated at specific foot positions deviated clearly from reference values. The deviation was larger for patients with higher degree of spasticity. Observations underline the need of muscle force modeling during cycling for individualized cycling training for rehabilitation strategy.

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Effect of Hip Flexion Angle on the Hamstring to Quadriceps Strength Ratio

Sports ◽

10.3390/sports7020043 ◽

2019 ◽

Vol 7 (2) ◽

pp. 43

Author(s):

Eleftherios Kellis ◽

Athanasios Ellinoudis ◽

and Nikolaos Kofotolis

Keyword(s):

Muscle Activation ◽

Rectus Femoris ◽

Biceps Femoris ◽

Knee Extension ◽

Quadriceps Strength ◽

Flexion Angle ◽

Electromyographic Activity ◽

H:Q Ratio ◽

Hip Flexion ◽

Selection Of

The purpose of this study was to compare the hamstring to quadriceps ratio (H:Q) obtained from three different hip flexion angles. Seventy-three young athletes performed maximum isokinetic concentric and eccentric knee extension and flexion efforts at 60 °·s−1 and 240 °·s−1 from hip flexion angles of 90°, 60°, and 120°. The conventional (concentric to concentric), functional (eccentric to concentric) and mixed (eccentric at 30 °·s−1 to concentric torque at 240 °·s−1) H: Q torque ratios and the electromyographic activity from the rectus femoris and biceps femoris were analyzed. The conventional H:Q ratios and the functional H:Q ratios at 60 °·s−1 did not significantly differ between the three testing positions (p > 0.05). In contrast, testing from the 90° hip flexion angle showed a greater functional torque ratio at 240 °·s−1 and a mixed H:Q torque ratio compared with the other two positions (p < 0.05). The hip flexion angle did not influence the recorded muscle activation signals (p > 0.05). For the range of hip flexion angles tested, routine isokinetic assessment of conventional H:Q ratio and functional H:Q ratio at slow speed is not angle-dependent. Should assessment of the functional H:Q ratio at fast angular velocity or the mixed ratio is required, then selection of hip flexion angle is important.

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Effects of Short-Term Training With Uncoupled Cranks in Trained Cyclists

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.7.2.113 ◽

2012 ◽

Vol 7 (2) ◽

pp. 113-120 ◽

Cited By ~ 1

Author(s):

Jack M. Burns ◽

Jeremiah J. Peiffer ◽

Chris R. Abbiss ◽

Greig Watson ◽

Angus Burnett ◽

...

Keyword(s):

Muscle Activation ◽

Vastus Lateralis ◽

Biceps Femoris ◽

Training Group ◽

Recovery Phase ◽

Muscle Recruitment ◽

Short Term ◽

Activation Patterns ◽

Gross Efficiency ◽

Muscle Activation Patterns

Purpose:Manufacturers of uncoupled cycling cranks claim that their use will increase economy of motion and gross efficiency. Purportedly, this occurs by altering the muscle-recruitment patterns contributing to the resistive forces occurring during the recovery phase of the pedal stroke. Uncoupled cranks use an independent-clutch design by which each leg cycles independently of the other (ie, the cranks are not fixed together). However, research examining the efficacy of training with uncoupled cranks is equivocal. The purpose of this study was to determine the effect of short-term training with uncoupled cranks on the performance-related variables economy of motion, gross efficiency, maximal oxygen uptake (VO2max), and muscle-activation patterns.Methods:Sixteen trained cyclists were matched-paired into either an uncoupled-crank or a normal-crank training group. Both groups performed 5 wk of training on their assigned cranks. Before and after training, participants completed a graded exercise test using normal cranks. Expired gases were collected to determine economy of motion, gross efficiency, and VO2max, while integrated electromyography (iEMG) was used to examine muscle-activation patterns of the vastus lateralis, biceps femoris, and gastrocnemius.Results:No significant changes between groups were observed for economy of motion, gross efficiency, VO2max, or iEMG in the uncoupled- or normal-crank group.Conclusions:Five weeks of training with uncoupled cycling cranks had no effect on economy of motion, gross efficiency, muscle recruitment, or VO2max compared with training on normal cranks.

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Mechanism of anterior cruciate ligament loading during dynamic motor tasks

10.1101/2020.03.15.992370 ◽

2020 ◽

Author(s):

Azadeh Nasseri ◽

David G Lloyd ◽

Adam L Bryant ◽

Jonathon Headrick ◽

Timothy Sayer ◽

...

Keyword(s):

Anterior Cruciate Ligament ◽

Lower Limb ◽

Muscle Activation ◽

Sagittal Plane ◽

Cruciate Ligament ◽

Three Dimensional ◽

Whole Body ◽

Activation Patterns ◽

Muscle Activation Patterns ◽

Anterior Cruciate

AbstractThis study determined anterior cruciate ligament (ACL) force and its contributors during a standardized drop-land-lateral jump task using a validated computational model. Healthy females (n=24) who were recreationally active performed drop-land-lateral jump and straight run tasks. Three-dimensional whole-body kinematics, ground reaction forces, and muscle activation patterns from eight lower limb muscles were collected concurrently during both tasks, but only the jump was analyzed computationally, with the run included for model calibration. External biomechanics, muscle-tendon unit kinematics, and muscle activation patterns were used to model lower limb muscle and ACL forces. Peak ACL force (2.3±0.5 BW) was observed at 13% of the stance phase during the drop-land-lateral jump task. The ACL force was primarily developed through the sagittal plane, and muscle was the dominant source of ACL loading. The gastrocnemii and quadriceps were main ACL antagonists (i.e., loaders), while hamstrings were the main ACL agonists (i.e., supporters).

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