scholarly journals Neural inhibition during maximal eccentric and concentric quadriceps contraction: effects of resistance training

2000 ◽  
Vol 89 (6) ◽  
pp. 2249-2257 ◽  
Author(s):  
P. Aagaard ◽  
E. B. Simonsen ◽  
J. L. Andersen ◽  
S. P. Magnusson ◽  
J. Halkjær-Kristensen ◽  
...  
Keyword(s):  
Resistance Training ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Quadriceps Strength ◽  
Electromyographic Activity ◽  
Neuromuscular Activation ◽  
Concentric Contractions ◽  
Power Frequency ◽  
Heavy Resistance Training ◽  
Median Power Frequency

Despite full voluntary effort, neuromuscular activation of the quadriceps femoris muscle appears inhibited during slow concentric and eccentric contractions. Our aim was to compare neuromuscular activation during maximal voluntary concentric and eccentric quadriceps contractions, hypothesizing that inhibition of neuromuscular activation diminishes with resistance training. In 15 men, pretraining electromyographic activity of the quadriceps muscles [vastus medialis (VM), vastus lateralis (VL), and rectus femoris (RF)] was 17–36% lower during slow and fast (30 and 240°/s) eccentric and slow concentric contractions compared with fast concentric contractions. After 14 wk of heavy resistance training, neuromuscular inhibition was reduced for VL and VM and was completely removed for RF. Concurrently, electromyographic activity increased 21–52, 22–29, and 16–32% for VL, VM, and RF, respectively. In addition, median power frequency decreased for VL and RF. Eccentric quadriceps strength increased 15–17%, whereas slow and fast concentric strength increased 15 and 8%, respectively. Pre- and posttraining median power frequency did not differ between eccentric and concentric contractions. In conclusion, quadriceps motoneuron activation was lower during maximal voluntary eccentric and slow concentric contractions compared with during fast concentric contraction in untrained subjects, and, after heavy resistance training, this inhibition in neuromuscular activation was reduced.

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

Sports ◽  
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.

scholarly journals Evaluation of the Lower Limb Muscles’ Electromyographic Activity during the Leg Press Exercise and Its Variants: A Systematic Review

2020 ◽  
Vol 17 (13) ◽  
pp. 4626
Author(s):  
Isabel Martín-Fuentes ◽  
José M. Oliva-Lozano ◽  
José M. Muyor
Keyword(s):  
Muscle Activation ◽  
Vastus Lateralis ◽  
Muscular Activity ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Quadriceps Muscle ◽  
Electromyographic Activity ◽  
Full Extension ◽  
Cross Sectional ◽  
Leg Press

The aim of this study was to analyze the literature on muscle activation measured by surface electromyography (sEMG) of the muscles recruited when performing the leg press exercise and its variants. The Preferred Reporting Items of Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed to report this review. The search was carried out using the PubMed, Scopus, and Web of Science electronic databases. The articles selected met the following inclusion criteria: (a) a cross-sectional or longitudinal study design; (b) neuromuscular activation assessed during the leg press exercise, or its variants; (c) muscle activation data collected using sEMG; and (d) study samples comprising healthy and trained participants. The main findings indicate that the leg press exercise elicited the greatest sEMG activity from the quadriceps muscle complex, which was shown to be greater as the knee flexion angle increased. In conclusion, (1) the vastus lateralis and vastus medialis elicited the greatest muscle activation during the leg press exercise, followed closely by the rectus femoris; (2) the biceps femoris and the gastrocnemius medialis showed greater muscular activity as the knee reached full extension, whereas the vastus lateralis and medialis, the rectus femoris, and the tibialis anterior showed a decreasing muscular activity pattern as the knee reached full extension; (3) evidence on the influence of kinematics modifications over sEMG during leg press variants is still not compelling as very few studies match their findings.

scholarly journals Intensity-dependent alterations in the excitability of cortical and spinal projections to the knee extensors during isometric and locomotor exercise

2015 ◽  
Vol 308 (12) ◽  
pp. R998-R1007 ◽  
Author(s):  
J. C. Weavil ◽  
S. K. Sidhu ◽  
T. S. Mangum ◽  
R. S. Richardson ◽  
M. Amann
Keyword(s):  
Evoked Potentials ◽  
Exercise Intensity ◽  
Motor Evoked Potentials ◽  
Vastus Lateralis ◽  
Femoral Nerve ◽  
Rectus Femoris ◽  
Knee Extensors ◽  
Electromyographic Activity ◽  
Dependent Manner ◽  
Cycling Exercise

We investigated the role of exercise intensity and associated central motor drive in determining corticomotoneuronal excitability. Ten participants performed a series of nonfatiguing (3 s) isometric single-leg knee extensions (ISO; 10–100% of maximal voluntary contractions, MVC) and cycling bouts (30–160% peak aerobic capacity, Wpeak). At various exercise intensities, electrical potentials were evoked in the vastus lateralis (VL) and rectus femoris (RF) via transcranial magnetic stimulation (motor-evoked potentials, MEP), and electrical stimulation of both the cervicomedullary junction (cervicomedullary evoked potentials, CMEP) and the femoral nerve (maximal M-waves, Mmax). Whereas Mmax remained unchanged in both muscles ( P > 0.40), voluntary electromyographic activity (EMG) increased in an exercise intensity-dependent manner for ISO and cycling exercise in VL and RF (both P < 0.001). During ISO exercise, MEPs and CMEPs progressively increased in VL and RF until a plateau was reached at ∼75% MVC; further increases in contraction intensity did not cause additional changes ( P > 0.35). During cycling exercise, VL-MEPs and CMEPs progressively increased by ∼65% until a plateau was reached at Wpeak. In contrast, RF MEPs and CMEPs progressively increased by ∼110% throughout the tested cycling intensities without the occurrence of a plateau. Furthermore, alterations in EMG below the plateau influenced corticomotoneuronal excitability similarly between exercise modalities. In both exercise modalities, the MEP-to-CMEP ratio did not change with exercise intensity ( P > 0.22). In conclusion, increases in exercise intensity and EMG facilitates the corticomotoneuronal pathway similarly in isometric knee extension and locomotor exercise until a plateau occurs at a submaximal exercise intensity. This facilitation appears to be primarily mediated by increases in excitability of the motoneuron pool.

scholarly journals Effects of the back-squat exercise on lower limb myoelectric activity in trained men: a systematic review

2021 ◽  
Vol 20 (1) ◽  
pp. 83-92
Author(s):  
Rogério Santos Aguiar ◽  
Juliana Brandão Pinto de Castro ◽  
Andressa Oliveira Barros dos Santos Santos ◽  
Giullio César Pereira Salustiano Mallen da Silva ◽  
Fabiana Rodrigues Scartoni ◽  
...  
Keyword(s):  
Systematic Review ◽  
Resistance Training ◽  
Lower Limb ◽  
Vastus Lateralis ◽  
Experimental Studies ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Myoelectric Activity ◽  
Back Squat ◽  
Squat Exercise

Aim: The aim of this study was to describe the effects of the back-squat exercise on the lower limb myoelectric activity in trained men. Methods: We conducted a systematic review following the recommendations of PRISMA. Medline (PubMed), Scielo, Scopus, SPORTDiscus, and Lilacs databases were searched. The search terms included electromyography, exercise, resistance training, and squat. We included experimental studies that described the back-squat exercise using surface electromyography (EMG) in men experienced in resistance training and back squat exercise at angles from 60º to 90º. Results: Eight studies met the inclusion criteria. The interventions of the included studies ranged from 2 to 7 days. The protocols demonstrated to improve the neuromuscular system and to provide greater acquisition of strength in the muscles involved in performing the back-squat exercise (p < 0.05). Thirty-seven muscles were analyzed, with a predominance of the vastus lateralis, vastus medialis, gluteus maximus, and rectus femoris muscles. Conclusion: The studies investigated in this review showed that the back-squat exercise at angles from 60º to 90º increased the lower limb myoelectric activity recorded in loads of 30% and 100% of 1RM in men experienced in resistance training. However, more studies with higher methodological quality are needed in the analysis of the squat exercise to reduce the risk of bias.

scholarly journals Resistance training with different repetition duration to failure: effect on hypertrophy, strength and muscle activation

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10909
Author(s):  
Lucas Túlio Lacerda ◽  
Rodrigo Otávio Marra-Lopes ◽  
Marcel Bahia Lanza ◽  
Rodrigo César Ribeiro Diniz ◽  
Fernando Vitor Lima ◽  
...  
Keyword(s):  
Resistance Training ◽  
Muscle Activation ◽  
Muscle Hypertrophy ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Angle Measurement ◽  
Knee Angle ◽  
Maximal Voluntary Isometric Contraction ◽  
Cross Sectional ◽  
Emg Amplitude

Background This study investigated the effects of two 14-week resistance training protocols with different repetition duration (RD) performed to muscle failure (MF) on gains in strength and muscle hypertrophy as well as on normalized electromyographic (EMG) amplitude and force-angle relationships. Methods The left and right legs of ten untrained males were assigned to either one of the two protocols (2-s or 6-s RD) incorporating unilateral knee extension exercise. Both protocols were performed with 3–4 sets, 50–60% of the one-repetition maximum (1RM), and 3 min rest. Rectus femoris and vastus lateralis cross-sectional areas (CSA), maximal voluntary isometric contraction (MVIC) at 30o and 90o of knee flexion and 1RM performance were assessed before and after the training period. In addition, normalized EMG amplitude-angle and force-angle relationships were assessed in the 6th and 39th experimental sessions. Results The 6-s RD protocol induced larger gains in MVIC at 30o of knee angle measurement than the 2-s RD protocol. Increases in MVIC at 90o of knee angle, 1RM, rectus femoris and vastus lateralis CSA were not significant between the 2-s and 6-s RD protocols. Moreover, different normalized EMG amplitude-angle and force-angle values were detected between protocols over most of the angles analyzed. Conclusion Performing longer RD could be a more appropriate strategy to provide greater gains in isometric maximal muscle strength at shortened knee positions. However, similar maximum dynamic strength and muscle hypertrophy gains would be provided by protocols with different RD.

scholarly journals Comparação do ciclo alongamento-encurtamento em saltos verticais entre mulheres ativas adultas-jovens e idosas

2018 ◽  
Vol 6 (1) ◽  
pp. 15
Author(s):  
Hyago Bernardes da Rosa ◽  
Igor Martins Barbosa ◽  
Eduardo Porto Scisleski ◽  
Samuel Klippel Prusch ◽  
Luiz Fernando Cuozzo Lemos
Keyword(s):  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Medial Gastrocnemius ◽  
Vastus Lateralis Muscle ◽  
Electromyographic Activity ◽  
Counter Movement Jump ◽  
Vertical Jumping ◽  
Significant Difference ◽  
Stretch Shortening Cycle

PURPOSE: To verify if there is an electromyographic economy and/or an increase in the variables of vertical jumps, both as a function of the use of the Stretch-Shortening Cycle and to compare the findings between young and old women, both active. METHODS: The sample consisted of a group of elderly (GI) and a group of young (GJ), both female. The power was measured through the contact platform and electromyographic activity of the muscles: biceps femoris (BF), rectus femoris (RF), medial gastrocnemius and vastus lateralis, through vertical jumping tests: Squat Jump (SJ) and Counter Movement Jump (CMJ). RESULTS: All the muscles evaluated did not present a statistically significant difference in the electromyographic activation and the comparisons of the mean percentage of use of the Stretch-Shortening Cycle (CAE), but it was observed that for the vastus lateralis and rectus femoris muscles there were significant differences in the comparisons between the two types of jumps of both groups, GI (236.89±115.66 for SJ and 230.45±109.10 for vastus lateralis muscle (VL) CMJ and 155.42±49.06 for SJ and 155 , 45±61.78 for the CMJ of the RF muscle) required greater neuromuscular activation to jump less than GJ (117.40±133.09 for SJ and 133.09±60.71 for VL muscle CMJ and 106.72±34.15 for the SJ and 108.87±38.85 for the CMJ of the RF muscle). CONCLUSIONS: The present study confirms that there was no statistically significant difference in the use of CAE in both groups (GI and GJ). However, when it comes to the skipped height and the power developed, there were statistically significant differences in the comparison of the groups.

scholarly journals Resistance Training does not Induce Uniform Adaptations to Quadriceps Muscles

2018 ◽  
Author(s):  
Gerald T. Mangine ◽  
Michael J. Redd ◽  
Adam M. Gonzalez ◽  
Jeremy R. Townsend ◽  
Adam J Wells ◽  
...  
Keyword(s):  
Resistance Training ◽  
High Intensity ◽  
Repeated Measures ◽  
Vastus Lateralis ◽  
Muscle Thickness ◽  
Rectus Femoris ◽  
Muscle Size ◽  
Fascicle Length ◽  
Cross Sectional ◽  
Resistance Training Program

AbstractResistance training may differentially affect morphological adaptations along the length of uni-articular and bi-articular muscles. The purpose of this study was to compare changes in muscle morphology along the length of the rectus femoris (RF) and vastus lateralis (VL) in response to resistance training. Following a 2-wk preparatory phase, 15 resistance-trained men (24.0 ± 3.0 y, 90.0 ± 13.8 kg, 174.9 ± 20.7 cm) completed pre-training (PRE) assessments of muscle thickness (MT), pennation angle (PA), cross-sectional area (CSA), and echo-intensity in the RF and VL at 30, 50, and 70% of each muscle’s length; fascicle length (FL) was estimated from respective measurements of MT and PA within each muscle and region. Participants then began a high intensity, low volume (4 × 3 − 5 repetitions, 3min rest) lower-body resistance training program, and repeated all PRE-assessments after 8 weeks (2 d · wk−1) of training (POST). Although three-way (muscle [RF, VL] × region [30, 50, 70%] × time [PRE, POST]) repeated measures analysis of variance did not reveal significant interactions for any assessment of morphology, significant simple (muscle × time) effects were observed for CSA (p = 0.002) and FL (p = 0.016). Specifically, average CSA changes favored the VL (2.96 ± 0.69 cm2, pp < 0.001) over the RF (0.59 ± 0.20 cm2, p = 0.011), while significant decreases in average FL were noted for the RF (–1.03 ± 0.30 cm, p = 0.004) but not the VL (–0.05 ± 0.36 cm, p = 0.901). No other significant differences were observed. The findings of this study demonstrate the occurrence of non-homogenous adaptations in RF and VL muscle size and architecture following 8 weeks of high-intensity resistance training in resistance-trained men. However, training does not appear to influence region-specific adaptations in either muscle.

Greater initial adaptations to submaximal muscle lengthening than maximal shortening

1996 ◽  
Vol 81 (4) ◽  
pp. 1677-1682 ◽  
Author(s):  
Tibor Hortobágyi ◽  
Jason Barrier ◽  
David Beard ◽  
John Braspennincx ◽  
Peter Koens ◽  
...  
Keyword(s):  
Vastus Lateralis ◽  
Quadriceps Muscle ◽  
Quadriceps Strength ◽  
Control Group ◽  
Electromyographic Activity ◽  
Eccentric Training ◽  
Before And After ◽  
Cross Education ◽  
Short Term Strength ◽  
Concentric Training

Hortobágyi, Tibor, Jason Barrier, David Beard, John Braspennincx, Peter Koens, Paul Devita, Line Dempsey, and Jean Lambert.Greater initial adaptations to submaximal muscle lengthening than maximal shortening. J. Appl. Physiol.81(4): 1677–1682, 1996.—The purpose of this study was to compare the short-term strength and neural adaptations to eccentric and concentric training at equal force levels. Forty-two sedentary women (age = 21.5 yr) were ranked based on the initial quadriceps strength score, and trios of subjects were randomly assigned to either an eccentric ( n = 14), a concentric ( n = 14), or a nonexercising control group ( n = 14). Training involved a total of 824 eccentric or concentric quadriceps actions at 1.05 rad ⋅ s−1administered in four sets of 6–10 repetitions, four times per week for 6 wk. Before and after training, all subjects were tested for unilateral maximal isometric and eccentric and concentric actions at 1.05 rad ⋅ s−1and for a 40-repetition eccentric and concentric fatigue series of the left and right quadriceps. Surface electromyographic activity of the vastus lateralis and medialis was monitored during testing. Concentric training increased concentric (36%, P< 0.05), isometric (18%, P < 0.05), and eccentric strength (13%), and eccentric training increased eccentric (42%, P < 0.05), isometric (30%, P < 0.05), and concentric (13%) strength. Eccentric training improved eccentric and isometric strength more ( P < 0.05) than did concentric training. The electromyographic adaptations were greater with eccentric training. Cross-education was 6%, and neither training mode modified fatigability. The data suggest that training of the quadriceps muscle with submaximal eccentric actions brings about greater strength adaptations faster than does training with maximal-level concentric actions in women. This greater adaptation is likely to be mediated by both mechanical and neural factors.

scholarly journals Electromyographic Comparison of Five Lower-Limb Muscles between Single- and Multi-Joint Exercises among Trained Men

2021 ◽  
pp. 56-61
Author(s):  
Nicolay Stien ◽  
Atle Hole Saeterbakken ◽  
Vidar Andersen
Keyword(s):  
Resistance Training ◽  
Vastus Lateralis ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Knee Extension ◽  
Knee Extensors ◽  
Vastus Medialis ◽  
Leg Press ◽  
Emg Amplitude

Resistance-training exercises can be classified as either single- or multi-joint exercises and differences in surface electromyography (EMG) amplitude between the two training methods may identify which muscles can benefit from either training modality. This study aimed to compare the surface EMG amplitude of five hip- and knee extensors during one multi-joint (leg press) and two single-joint exercises (knee extension and kickback). Fifteen resistance-trained men completed one familiarization session to determine their unilateral six repetitions maximum (6RM) in the three exercises. During the following experimental session, EMG amplitudes of the vastus lateralis, vastus medialis, rectus femoris, gluteus maximus and biceps femoris of the left leg were measured while performing three repetitions on their respective 6RM loads. The multi-joint exercise leg press produced higher EMG amplitude of the vastus lateralis (ES = 0.92, p = 0.003) than the single-joint exercise knee extension, whereas the rectus femoris demonstrated higher EMG amplitude during the knee extension (ES = 0.93, p = 0.005). The biceps femoris EMG amplitude was higher during the single-joint exercise kickback compared to the leg press (ES = 2.27, p < 0.001), while no significant differences in gluteus maximus (ES = 0.08, p = 0.898) or vastus medialis (ES = 0.056, p = 0.025 were observed between exercises. The difference in EMG amplitude between single- and multi-joint exercises appears to vary depending on the specific exercises and the muscle groups tested. Leg press is a viable and time-efficient option for targeting several hip- and knee extensors during resistance training of the lower limbs, but the single-joint exercises may be preferable for targeting the rectus femoris and biceps femoris.

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