scholarly journals Do neuromuscular adaptations occur in endurance-trained boys and men?

2010 ◽  
Vol 35 (4) ◽  
pp. 471-479 ◽  
Author(s):  
Rotem Cohen ◽  
Cam Mitchell ◽  
Raffy Dotan ◽  
David Gabriel ◽  
Panagiota Klentrou ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Endurance Training ◽  
Muscle Activation ◽  
Peak Torque ◽  
Metabolic Effects ◽  
Electromechanical Delay ◽  
Time To Peak ◽  
Neuromuscular Adaptations ◽  
Health Related ◽  
Isometric Torque

Most research on the effects of endurance training has focused on endurance training's health-related benefits and metabolic effects in both children and adults. The purpose of this study was to examine the neuromuscular effects of endurance training and to investigate whether they differ in children (9.0–12.9 years) and adults (18.4–35.6 years). Maximal isometric torque, rate of torque development (RTD), rate of muscle activation (Q30), electromechanical delay (EMD), and time to peak torque and peak RTD were determined by isokinetic dynamometry and surface electromyography (EMG) in elbow and knee flexion and extension. The subjects were 12 endurance-trained and 16 untrained boys, and 15 endurance-trained and 20 untrained men. The adults displayed consistently higher peak torque, RTD, and Q30, in both absolute and normalized values, whereas the boys had longer EMD (64.7 ± 17.1 vs. 56.6 ± 15.4 ms) and time to peak RTD (98.5 ± 32.1 vs. 80.4 ± 15.0 ms for boys and men, respectively). Q30, normalized for peak EMG amplitude, was the only observed training effect (1.95 ± 1.16 vs. 1.10 ± 0.67 ms for trained and untrained men, respectively). This effect could not be shown in the boys. The findings show normalized muscle strength and rate of activation to be lower in children compared with adults, regardless of training status. Because the observed higher Q30 values were not matched by corresponding higher performance measures in the trained men, the functional and discriminatory significance of Q30 remains unclear. Endurance training does not appear to affect muscle strength or rate of force development in either men or boys.

scholarly journals Child–adult differences in muscle strength and activation pattern during isometric elbow flexion and extension

2009 ◽  
Vol 34 (4) ◽  
pp. 609-615 ◽  
Author(s):  
Bareket Falk ◽  
Charlotte Usselman ◽  
Raffy Dotan ◽  
Laura Brunton ◽  
Panagiota Klentrou ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Muscle Activation ◽  
Motor Units ◽  
Elbow Flexion ◽  
Peak Torque ◽  
Electromechanical Delay ◽  
Cross Sectional ◽  
Rate Of Torque Development ◽  
Torque Development ◽  
Flexion And Extension

Muscle strength and activation were compared in boys and men during maximal voluntary elbow flexion and extension contractions. Peak torque, peak rate of torque development (dτ/dτmax), rate of muscle activation, and electromechanical delay (EMD) were measured in 15 boys (aged 9.7 ± 1.6 years) and 16 men (aged 22.1 ± 2.8 years). During flexion, peak torque was significantly lower in boys than in men (19.5 ± 5.8 vs. 68.5 ± 11.0 Nm, respectively; p < 0.05), even when controlling for upper-arm cross-sectional area (CSA), and peak electromyography activity. Boys also exhibited a lower normalized dτ/dτmax (7.2 ± 1.7 vs. 9.5 ± 1.6 (Nm·s–1)·(Nm–1), respectively; p < 0.05) and a significantly longer EMD (75.5 ± 28.4 vs. 47.6 ± 17.5 ms, respectively). The pattern was similar for extension, except that group differences in peak torque were no longer significant when normalized for CSA. These results suggest that children may be less able to recruit or fully utilize their higher-threshold motor units, resulting in lower dimensionally normalized maximal torque and rate of torque development.

scholarly journals Different Muscle Action Training Protocols on Quadriceps-Hamstrings Neuromuscular Adaptations

2018 ◽  
Vol 39 (05) ◽  
pp. 355-365 ◽  
Author(s):  
Cassio Ruas ◽  
Lee Brown ◽  
Camila Lima ◽  
G. Gregory Haff ◽  
Ronei Pinto
Keyword(s):  
Muscle Activation ◽  
Muscle Thickness ◽  
Muscle Quality ◽  
Muscle Size ◽  
Muscle Action ◽  
Short Term ◽  
Electromechanical Delay ◽  
Neuromuscular Adaptations ◽  
Before And After ◽  
Training Protocols

AbstractThe aim of this study was to compare three specific concentric and eccentric muscle action training protocols on quadriceps-hamstrings neuromuscular adaptations. Forty male volunteers performed 6 weeks of training (two sessions/week) of their dominant and non-dominant legs on an isokinetic dynamometer. They were randomly assigned to one of four groups; concentric quadriceps and concentric hamstrings (CON/CON, n=10), eccentric quadriceps and eccentric hamstrings (ECC/ECC, n=10), concentric quadriceps and eccentric hamstrings (CON/ECC, n=10), or no training (CTRL, n=10). Intensity of training was increased every week by decreasing the angular velocity for concentric and increasing it for eccentric groups in 30°/s increments. Volume of training was increased by adding one set every week. Dominant leg quadriceps and hamstrings muscle thickness, muscle quality, muscle activation, muscle coactivation, and electromechanical delay were tested before and after training. Results revealed that all training groups similarly increased MT of quadriceps and hamstrings compared to control (p<0.05). However, CON/ECC and ECC/ECC training elicited a greater magnitude of change. There were no significant differences between groups for all other neuromuscular variables (p>0.05). These findings suggest that different short-term muscle action isokinetic training protocols elicit similar muscle size increases in hamstrings and quadriceps, but not for other neuromuscular variables. Nevertheless, effect sizes indicate that CON/ECC and ECC/ECC may elicit the greatest magnitude of change in muscle hypertrophy.

scholarly journals Rate of Muscle Activation in Power-and Endurance-Trained Boys

2011 ◽  
Vol 6 (1) ◽  
pp. 94-105 ◽  
Author(s):  
Cameron Mitchell ◽  
Rotem Cohen ◽  
Raffy Dotan ◽  
David Gabriel ◽  
Panagiota Klentrou ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Peak Torque ◽  
Surface Emg ◽  
Knee Extension ◽  
Endurance Athletes ◽  
Group Differences ◽  
Electromechanical Delay ◽  
Cross Sectional ◽  
Isometric Knee Extension ◽  
Muscle Cross Sectional Area

Previous studies in adults have demonstrated power athletes as having greater muscle force and muscle activation than nonathletes. Findings on endurance athletes are scarce and inconsistent. No comparable data on child athletes exist.Purpose:This study compared peak torque (Tq), peak rate of torque development (RTD), and rate of muscle activation (EMG rise, Q30), in isometric knee extension (KE) and fexion (KF), in pre- and early-pubertal power- and endurance-trained boys vs minimally active nonathletes.Methods:Nine gymnasts, 12 swimmers, and 18 nonathletes (7–12 y), performed fast, maximal isometric KE and KF. Values for Tq, RTD, electromechanical delay (EMD), and Q30 were calculated from averaged torque and surface EMG traces.Results:No group differences were observed in Tq, normalized for muscle cross-sectional area. The Tq-normalized KE RTD was highest in power athletes (6.2 ± 1.9, 4.7 ± 1.2, 5.0 ± 1.5 N·m·s–1, for power, endurance, and nonathletes, respectively), whereas no group differences were observed for KF. The KE Q30 was significantly greater in power athletes, both in absolute terms and relative to peak EMG amplitude (9.8 ± 7.0, 5.9 ± 4.2, 4.4 ± 2.2 mV·ms and 1.7 ± 0.8, 1.1 ± 0.6, 0.9 ± 0.5 (mV·ms)/(mV) for power, endurance, and nonathletes, respectively), with no group differences in KF. The KE EMD tended to be shorter (P = .07) in power athletes during KE (71.0 ± 24.1, 87.8 ± 18.0, 88.4 ± 27.8 ms, for power, endurance, and nonathletes), with no group differences in KF.Conclusions:Pre- and early-pubertal power athletes have enhanced rate of muscle activation in specifically trained muscles compared with controls or endurance athletes, suggesting that specific training can result in muscle activation-pattern changes before the onset of puberty.

scholarly journals Strength training with repetitions to failure does not provide additional strength and muscle hypertrophy gains in young women

2017 ◽  
Vol 27 (2) ◽  
Author(s):  
Saulo Martorelli ◽  
Eduardo Lusa Cadore ◽  
Mikel Izquierdo ◽  
Rodrigo Celes ◽  
André Martorelli ◽  
...  
Keyword(s):  
Resistance Training ◽  
Muscle Strength ◽  
Young Women ◽  
Muscle Hypertrophy ◽  
Muscle Thickness ◽  
Peak Torque ◽  
Muscular Endurance ◽  
Short Term ◽  
Neuromuscular Adaptations ◽  
Repetitions To Failure

This study investigated the effects of a 10-week resistance training to failure on neuromuscular adaptations in young women. Eighty-nine active young women were randomly assigned to one of three groups: 1) repetitions to failure (RF; three sets of repetitions to failure); 2) repetitions not to failure with equalized volume (RNFV; four sets of 7 repetitions); and 3) repetitions not to failure (RNF; three sets of 7 repetitions). All groups performed the elbow flexor exercise (bilateral biceps curl) and trained 2 days per week using 70% of 1RM. There were significant increases (p&lt;0.05) in muscle strength after 5 (15.9% for RF, 18.4% for RNF, and 19.9% for RNFV) and 10 (28.3% for RF, 26.8% for RNF, and 28.3% for RNFV) weeks of training, with no significant differences between groups. Additionally, muscular endurance increased after 5 and 10 weeks, with no differences between groups. However, peak torque (PT) increased significantly at 180°.s-1 in the RNFV (13.7%) and RNF (4.1%) groups (p&lt;0.05), whereas no changes were observed in the RF group (-0.5%). Muscle thickness increased significantly (p&lt;0.05) in the RF and RNFV groups after 5 (RF: 8.4% and RNFV: 2.3%) and 10 weeks of training (RF: 17.5%, and RNFV: 8.5%), whereas no significant changes were observed in the RNF group (3.9 and 2.1% after 5 and 10 weeks, respectively). These data suggest that short-term training of repetitions to failure do not yield additional overall neuromuscular improvements in young women.

scholarly journals Effects of muscular endurance training on musculoskeletal disorders in teachers

2015 ◽  
Vol 28 (3) ◽  
pp. 535-544
Author(s):  
Elisângela Valevein Rodrigues ◽  
Anna Raquel Silveira Gomes ◽  
Ana Tereza Bittencourt Guimarães ◽  
Bianca Drabovski ◽  
Rosana Rox ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Endurance Training ◽  
Repeated Measures ◽  
Goodness Of Fit ◽  
Peak Torque ◽  
Lower Limbs ◽  
Musculoskeletal Symptoms ◽  
Lumbar Region ◽  
Muscular Endurance ◽  
Goodness Of Fit Test

AbstractIntroduction Physical exercise is indicated to reduce the incidence of musculoskeletal symptoms in teachers.Objective To evaluate the effects of muscular endurance training on muscle strength and musculoskeletal symptoms related to the lower limbs of public elementary school teachers.Materials and methods Thirty-one female teachers were divided into two groups: control (CG, n = 15) and muscular endurance training (TG, n = 16). The training consisted of two sets of 15 repetitions of exercises for quadriceps and hamstring muscle groups, twice a week, for 7 weeks, which were conducted with 50% of 10 repetition maximum(10RM) (first to fourth week) and 60% of 10 RM (fifth to seventh week). Musculoskeletal symptoms (Nordic Musculoskeletal Questionnaire), isometric peak torque (Load cell) and muscle strength (10RM) were assessed before and after intervention. ANOVA for repeated measures and Tukey post hoc were used to analyse strength and peak torque of quadriceps and hamstrings and Chi-square goodness-of-fit test were used to analyse the frequency of occurrence of osteomuscular symptoms.Results The highest incidence of symptoms was found in the lumbar region in both groups. Training caused increased muscle strength of the quadriceps and hamstrings, but there were no significant differences in either the peak torque in the quadriceps and hamstrings or in the reduction of musculoskeletal symptoms.Conclusion The exercise program performed in this study increased the dynamic strength in the TG in relation to the CG, but did not alter the incidence of symptoms in the lumbar region and lower limbs in neither of the groups. Thus, results suggest that the duration of intervention may not have been enough to increase peak torque and decrease musculoskeletal symptoms.

Comparison of single and multiple joint muscle functions and neural drive of trained athletes and untrained individuals

2021 ◽  
pp. 1-11
Author(s):  
Kale Mehmet
Keyword(s):  
Muscle Activation ◽  
Time Windows ◽  
Knee Extension ◽  
Electromechanical Delay ◽  
Neural Drive ◽  
Lower Limb Muscles ◽  
Explosive Force ◽  
Biarticular Muscle ◽  
Voluntary Contractions ◽  
Maximum Voluntary Force

BACKGROUND: There is insufficient knowledge about the rate of force development (RFD) characteristics over both single and multiple joint movements and the electromechanical delay (EMD) values obtained in athletes and untrained individuals. OBJECTIVE: To compare single and multiple joint functions and the neural drive of trained athletes and untrained individuals. METHODS: Eight trained athletes and 10 untrained individuals voluntarily participated to the study. The neuromuscular performance was assessed during explosive and maximum voluntary isometric contractions during leg press and knee extension related to single and multiple joint. Explosive force and surface electromyography of eight superficial lower limb muscles were measured in five 50-ms time windows from their onset, and normalized to peak force and electromyography activity at maximum voluntary force, respectively. The EMD was determined from explosive voluntary contractions (EVC’s). RESULTS: The results showed that there were significant differences in absolute forces during knee extension maximum voluntary force and EVC’s (p< 0.01) while trained athletes achieved greater relative forces than untrained individuals of EVC at all five time points (p< 0.05). CONCLUSIONS: The differences in explosive performance between trained athletes and untrained individuals in both movements may be explained by different levels of muscle activation within groups, attributed to variation in biarticular muscle function over both activities.

scholarly journals The effects of 12 weeks of static stretch training on the functional, mechanical, and architectural characteristics of the triceps surae muscle–tendon complex

2021 ◽  
Author(s):  
Stefano Longo ◽  
Emiliano Cè ◽  
Angela Valentina Bisconti ◽  
Susanna Rampichini ◽  
Christian Doria ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Maximum Voluntary Contraction ◽  
Muscle Stiffness ◽  
Triceps Surae ◽  
Maximum Force ◽  
Passive Stiffness ◽  
Electromechanical Delay ◽  
Fascicle Length ◽  
Generating Capacity ◽  
Plantarflexor Muscles

Abstract Purpose We investigated the effects of 12 weeks of passive static stretching training (PST) on force-generating capacity, passive stiffness, muscle architecture of plantarflexor muscles. Methods Thirty healthy adults participated in the study. Fifteen participants (STR, 6 women, 9 men) underwent 12-week plantarflexor muscles PST [(5 × 45 s-on/15 s-off) × 2exercises] × 5times/week (duration: 2250 s/week), while 15 participants (CTRL, 6 women, 9 men) served as control (no PST). Range of motion (ROM), maximum passive resistive torque (PRTmax), triceps surae architecture [fascicle length, fascicle angle, and thickness], passive stiffness [muscle–tendon complex (MTC) and muscle stiffness], and plantarflexors maximun force-generating capacity variables (maximum voluntary contraction, maximum muscle activation, rate of torque development, electromechanical delay) were calculated Pre, at the 6th (Wk6), and the 12th week (Wk12) of the protocol in both groups. Results Compared to Pre, STR ROM increased (P < 0.05) at Wk6 (8%) and Wk12 (23%). PRTmax increased at Wk12 (30%, P < 0.05), while MTC stiffness decreased (16%, P < 0.05). Muscle stiffness decreased (P < 0.05) at Wk6 (11%) and Wk12 (16%). No changes in triceps surae architecture and plantarflexors maximum force-generating capacity variables were found in STR (P > 0.05). Percentage changes in ROM correlated with percentage changes in PRTmax (ρ = 0.62, P = 0.01) and MTC stiffness (ρ = − 0.78, P = 0.001). In CTRL, no changes (P > 0.05) occurred in any variables at any time point. Conclusion The expected long-term PST-induced changes in ROM were associated with modifications in the whole passive mechanical properties of the ankle joint, while maximum force-generating capacity characteristics were preserved. 12 weeks of PST do not seem a sufficient stimulus to induce triceps surae architectural changes.

The Effects of Tourniquet Application in Total Knee Arthroplasty on the Recovery of Thigh Muscle Strength and Clinical Outcomes

2020 ◽  
Author(s):  
Omer Ayik ◽  
Mehmet Demirel ◽  
Fevzi Birisik ◽  
Ali Ersen ◽  
Halil I. Balci ◽  
...  
Keyword(s):  
Total Knee Arthroplasty ◽  
Muscle Strength ◽  
Clinical Outcomes ◽  
Knee Arthroplasty ◽  
Peak Torque ◽  
Thigh Muscle ◽  
Controlled Study ◽  
Total Work ◽  
Isokinetic Muscle Strength ◽  
Total Knee

AbstractThe present randomized controlled study aims to evaluate whether tourniquet application during total knee arthroplasty (TKA) has an effect on (1) thigh muscle strength (quadriceps and hamstring muscle strength) and (2) clinical outcomes (postoperative knee range of motion [ROM], postoperative pain level, and Knee Society Score [KSS]). The effects of tourniquet application during TKA were investigated in 65 patients randomly allocated to one of two groups: TKA with a tourniquet and TKA without a tourniquet. Patients in both groups were comparable in terms of the demographic and clinical data (p > 0.05 for age, number of patients, sex, radiographic gonarthrosis grade, American Society of Anesthesiologists [ASA] classification, and body mass index [BMI]). All patients in both groups were operated by the same surgeon using one type of prosthesis. Isokinetic muscle strength (peak torque and total work) of knee extensors (quadriceps) and flexors (hamstrings) was measured in Newton meters (Nm) using a CYBEX 350 isokinetic dynamometer (HUMAC/CYBEX 2009, Stoughton, MA). The combined KSS (knee score + function score), visual analog scale (VAS), and knee ROM were measured preoperatively and at 1 and 3 months postoperatively to evaluate clinical outcomes. There were no significant differences between the two groups in preoperative and postoperative values of isokinetic muscle strength (peak torque and total work) and aforementioned clinical outcomes (p < 0.05). The present study has shown that quadriceps strength and clinical outcomes were not improved in the early postoperative period (3 months) when a tourniquet was not used during TKA.

scholarly journals Elbow Joint Fatigue and Bench-Press Training

2014 ◽  
Vol 49 (3) ◽  
pp. 317-321 ◽  
Author(s):  
Yen-Po Huang ◽  
You-Li Chou ◽  
Feng-Chun Chen ◽  
Rong-Tyai Wang ◽  
Ming-Jer Huang ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Upper Extremity ◽  
Athletic Training ◽  
Cycle Time ◽  
Elbow Joint ◽  
Muscle Activation ◽  
Bench Press ◽  
Lateral Force ◽  
Joint Force ◽  
Muscle Strengthening

Context: Bench-press exercises are among the most common form of training exercise for the upper extremity because they yield a notable improvement in both muscle strength and muscle endurance. The literature contains various investigations into the effects of different bench-press positions on the degree of muscle activation. However, the effects of fatigue on the muscular performance and kinetics of the elbow joint are not understood fully. Objective: To investigate the effects of fatigue on the kinetics and myodynamic performance of the elbow joint in bench-press training. Design: Controlled laboratory study. Setting: Motion research laboratory. Patients or Other Participants: A total of 18 physically healthy male students (age = 19.6 ± 0.8 years, height = 168.7 ± 5.5 cm, mass = 69.6 ± 8.6 kg) participated in the investigation. All participants were right-hand dominant, and none had a history of upper extremity injuries or disorders. Intervention(s): Participants performed bench-press training until fatigued. Main Outcome Measure(s): Maximal possible number of repetitions, cycle time, myodynamic decline rate, elbow-joint force, and elbow-joint moment. Results: We observed a difference in cycle time in the initial (2.1 ± 0.42 seconds) and fatigue (2.58 ± 0.46 seconds) stages of the bench-press exercise (P = .04). As the participants fatigued, we observed an increase in the medial-lateral force (P = .03) and internal-external moment (P ≤ .04) acting on the elbow joint. Moreover, a reduction in the elbow muscle strength was observed in the elbow extension-flexion (P ≤ .003) and forearm supination-pronation (P ≤ .001) conditions. Conclusions: The results suggest that performing bench-press exercises to the point of fatigue increases elbow-joint loading and may further increase the risk of injury. Therefore, when clinicians design bench-press exercise regimens for general athletic training, muscle strengthening, or physical rehabilitation, they should control carefully the maximal number of repetitions.

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