scholarly journals Force production and muscle activation during partial vs. full range of motion in Paralympic Powerlifting

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0257810
Author(s):  
Tanise Pires Mendonça ◽  
Felipe José Aidar ◽  
Dihogo Gama Matos ◽  
Raphael Fabrício Souza ◽  
Anderson Carlos Marçal ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Muscle Activation ◽  
Isometric Force ◽  
Full Range ◽  
Pectoralis Major Muscle ◽  
National Level ◽  
Force Production ◽  
Muscle Thickness ◽  
Pectoralis Major ◽  
Post Exercise

Paralympic Powerlifting is a sport in which the strength of the upper limbs is assessed through bench press performance in an adapted specific bench. It is therefore essential to optimize training methods to maximize this performance. The aim of the present study was to compare force production and muscle activation involved in partial vs. full range of motion (ROM) training in Paralympic Powerlifting. Twelve male athletes of elite national level in Paralympic Powerlifting participated in the study (28.60 ± 7.60 years of age, 71.80 ± 17.90 kg of body mass). The athletes performed five sets of 5RM (repetition maximum), either with 90% of 1RM in full ROM or with a load of 130% 1RM in partial ROM. All subjects underwent both exercise conditions in consecutive weeks. Order assignment in the first week was random and counterbalanced. Fatigue index (FI), Maximum Isometric Force (MIF), Time to MIF (Time) and rate of force development (RFD) were determined by a force sensor. Muscle thickness was obtained using ultrasound images. All measures were taken pre- and post-training. Additionally, electromyographic signal (EMG) was evaluated in the last set of each exercise condition. Post-exercise fatigue was higher with full ROM as well as loss of MIF. Full ROM also induced greater. EMG showed greater activation of the Clavicular portion and Sternal portion of pectoralis major muscle and lower in the anterior portion of deltoid muscle when full ROM was performed. Muscle thickness of the pectoralis major muscle increased post-exercise. We concluded that training with partial ROM enables higher workloads with lower loss of muscle function.

A Comparison of Ballistic-Movement and Ballistic-Intent Training on Muscle Strength and Activation

2007 ◽  
Vol 2 (4) ◽  
pp. 386-399 ◽  
Author(s):  
Nicole A. Dinn ◽  
David G. Behm
Keyword(s):  
Reaction Time ◽  
Muscle Activation ◽  
Isometric Force ◽  
Movement Time ◽  
Force Production ◽  
Training Group ◽  
Pectoralis Major ◽  
Ballistic Movement ◽  
Ctrl Group ◽  
Elastic Resistance

Purpose:Studies have both supported and refuted the concept that it is the intent to perform ballistic contractions that determines velocity-specific gains in resistance training. The purpose of this investigation was to determine whether ballistic intent is as effective as ballistic movement in improving muscle activation, force, movement time, and reaction time.Methods:Subjects completed 8 wk of punch training. A dynamic (DYN) group trained with elastic resistance bands, and the isometric (ISO) group trained with an unyielding strap. A control (CTRL) group was also tested. Pretesting and posttesting measures included isometric force; electromyography (EMG) of triceps, biceps, pectoralis major, and latissimus dorsi; movement and reaction time of both arms; and a quick-hands test of coordination.Results:Triceps iEMG increased by 63% in the ISO group (P = .03). Pectoralis major iEMG increased by 65% in the DYN group (P = .007). Movement time decreased 17.6% in the DYN training group (P = .001). Isometric force did not improve in either training group or in the CTRL group.Conclusions:Because of its specificity of movement, dynamic training might be a more appropriate method to improve punching speed for martial artists and boxers. The intent to contract explosively over a short duration does not appear to be beneficial in increasing force production or speed of movement in punching.

The length dependency of maximum force development in rat medial gastrocnemius muscle in situ

2008 ◽  
Vol 33 (3) ◽  
pp. 518-526 ◽  
Author(s):  
Cornelis J. de Ruiter ◽  
Tinelies E. Busé-Pot ◽  
Arnold de Haan
Keyword(s):  
Muscle Activation ◽  
Isometric Force ◽  
Force Production ◽  
Time History ◽  
Medial Gastrocnemius ◽  
Force Output ◽  
Force Development ◽  
Activation Times ◽  
Maximal Isometric Force

During many movements (e.g., running, jumping, and kicking) there is little time for skeletal muscles to build up force, thus rapid force development is important. The length dependency of isometric force development was investigated in maximally activated rat medial gastrocnemius muscles in situ with intact blood flow at 35 °C. Depending on time available for muscle activation, the length dependency of force development was expected to differ from that of the maximal isometric force (Fmax) reached much later during the contraction. During isometric force development in intact muscle–tendon preparations, the contractile elements actually shortened. Therefore, similar to previous findings on shortening contractions, it was hypothesized that maximal rate of force development (MRFD) would be obtained at a length below the optimum (Lo) for maximal isometric force production. To measure the effect of the entire time history of activation, force time integrals (FTIs) for different activation times (10–50 ms) were also calculated. The highest MRFD was obtained 1.94 ± 0.42 mm below (p < 0.05) Lo. When expressed relative to Fmax obtained at each individual length, the optimum was found at Lo – 4.4 mm. For FTI 10 ms and FTI 20 ms, optimum length was obtained at ~2 and 1 mm above (p < 0.05) Lo, respectively, whereas the optima for FTI 30, 40, and 50 ms were ~1 mm below (p < 0.05) Lo. In addition, at short lengths (< Lo – 4 mm) and for all activation times FTIs were relatively more decreased than Fmax. In conclusion, length dependency of force output during rapid force development differed from that of maximal isometric force; specifically, MRFD was obtained 2 mm below Lo.

scholarly journals Evaluation of Strength and Muscle Activation Indicators in Sticking Point Region of National-Level Paralympic Powerlifting Athletes

2021 ◽  
Vol 6 (2) ◽  
pp. 43
Author(s):  
Felipe J. Aidar ◽  
Filipe Manuel Clemente ◽  
Dihogo Gama de Matos ◽  
Anderson Carlos Marçal ◽  
Raphael Fabrício de Souza ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Isometric Force ◽  
National Level ◽  
Rate Of Force Development ◽  
Static Test ◽  
Force Development ◽  
Intermediate Phases ◽  
Maximum Isometric Force ◽  
Dynamic Time ◽  
Sticking Point

Background: The sticking region is considered an intervening factor in the performance of the bench press with high loads. Objective: To evaluate the strength indicators in the sticking point region in Powerlifting Paralympic athletes. Methods: Twelve Brazilian Powerlifting Paralympic athletes performed maximum isometric force (MIF), rate of force development (RFD), time at MIF, velocity, dynamic time in sticking, and surface electromyography in several distances from the bar to the chest. Results: For velocity, there was a difference between the pre-sticking and sticking region (1.98 ± 0.32 and 1.30 ± 0.43, p = 0.039) and dynamic time between the pre-sticking and the sticking region (0.40 ± 0.16 and 0.97 ± 0.37, p = 00.021). In static test for the MIF, differences were found between 5.0 cm and 15.0 cm (CI 95% 784; 1088; p = 0.010) and between 10.0 cm and 5.0 cm (CI 95% 527; 768; p < 0.001). Regarding the RFD, differences were found (CI 95% 938; 1240; p = 0.004) between 5.0 cm and 25.0 cm and between 10.0 cm and 25.0 cm (CI 95% 513; 732; p < 0.001). In relation to time, there were differences between 5.0 cm and 15.0 cm (CI 95% 0.330; 0.515; p < 0.001), 5.0 cm, and 25.0 cm (CI 95% 0.928; 1.345; p = 0.001), 10.0 cm and 15.0 cm (p < 0.05) and 15.0 cm and 25.0 cm (p < 0.05). No significant differences were observed between the muscles in electromyography, although the triceps showed the highest muscle activation values. Conclusions: The maximum isometric force, rate of force development, time, velocity, and dynamic time had lower values, especially in the initial and intermediate phases in the sticking region.

Work-dependent deactivation of a crustacean muscle

1999 ◽  
Vol 202 (18) ◽  
pp. 2551-2565 ◽  
Author(s):  
R.K. Josephson ◽  
D.R. Stokes
Keyword(s):  
Muscle Activation ◽  
Isometric Force ◽  
Carcinus Maenas ◽  
Stimulus Frequency ◽  
Force Production ◽  
Muscle Length ◽  
Background Level ◽  
Shortening Velocity ◽  
Shortening Deactivation ◽  
Work Done

Active shortening of respiratory muscle L2B from the crab Carcinus maenas results in contractile deactivation, seen as (1) a decline of force during the course of isovelocity shortening, (2) a reduction in the rate of force redevelopment following shortening, (3) a depression of the level of isometric force reached following shortening, and (4) an accelerated relaxation at the end of stimulation. The degree of deactivation increases with increasing distance of shortening, decreases with increasing shortening velocity, and is approximately linearly related to the work done during shortening. Deactivation lasts many seconds if stimulation is maintained, but is largely although not completely removed if the stimulation is temporarily interrupted so that the force drops towards the resting level. Deactivation for a given distance and velocity of shortening increases with increasing muscle length above the optimum length for force production. Stimulating muscle L2B at suboptimal frequencies gives tetanic contractions that are fully fused but of less than maximal amplitude. The depression of force following shortening, relative to the force during an isometric contraction, is independent of the stimulus frequency used to activate the muscle, indicating that deactivation is not a function of the background level of stimulus-controlled muscle activation upon which it occurs. Deactivation reduces the work required to restretch a muscle after it has shortened, but it also lowers the force and therefore the work done during shortening. The net effect of deactivation on work output over a full shortening/lengthening cycle is unknown.

scholarly journals The Effects of Accentuated Eccentric Loading on Mechanical Variables and Agonist Electromyography during the Bench Press

Sports ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 79
Author(s):  
Alexis H. Castro ◽  
Dylan Zangakis ◽  
Gavin L. Moir
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Bench Press ◽  
Pectoralis Major Muscle ◽  
Pectoralis Major ◽  
Electromyographic Activity ◽  
Triceps Brachii ◽  
Lifting Technique ◽  
3D Motion Analysis ◽  
Analysis System

We compared the effects of accentuated eccentric loading (AEL) on mechanical variables and agonist muscle activation using low (30% 1-repetition maximum (1RM)) and high (80% 1RM) upward-phase loading with AEL (100% 1RM during downward phase) to traditional loading schemes (T) in the bench press. Twelve resistance-trained men (26 ± 6 years; 1RM: 134 ± 33 kg) performed sets of two repetitions with three-minute intervals using loading schemes of 30AEL, 30T, 80AEL, and 80T. AEL was applied using weight releasers while force plates and a 3D motion-analysis system were used to measure mechanical variables. Electromyographic activity of the pectoralis major and triceps brachii muscles was also recorded. The greater downward-phase loads experienced during the AEL conditions allowed greater overall mean vertical forces (mean difference ( x ¯ Diff): 118 N, p < 0.001), greater work ( x ¯ Diff: 43 J, p < 0.001), and greater pectoralis major muscle activation ( x ¯ Diff: 27 µV, p = 0.002) compared to the corresponding traditional loading schemes. However, there was little evidence of potentiation of the mechanical variables or muscle activity during the subsequent upward phases caused by the AEL schemes. It is possible that the use of weight releasers may disrupt lifting technique particularly during low AEL schemes thereby diminishing any benefits.

scholarly journals Dynamics of Primate Oculomotor Plant Revealed by Effects of Abducens Microstimulation

2009 ◽  
Vol 101 (6) ◽  
pp. 2907-2923 ◽  
Author(s):  
Sean R. Anderson ◽  
John Porrill ◽  
Sokratis Sklavos ◽  
Neeraj J. Gandhi ◽  
David L. Sparks ◽  
...  
Keyword(s):  
Steady State ◽  
Muscle Activation ◽  
Isometric Force ◽  
Force Production ◽  
Rectus Muscle ◽  
Linear Component ◽  
Abducens Nucleus ◽  
In Series ◽  
Tension Increase ◽  
Movement Parameters

Despite their importance for deciphering oculomotor commands, the mechanics of the extraocular muscles and orbital tissues (oculomotor plant) are poorly understood. In particular, the significance of plant nonlinearities is uncertain. Here primate plant dynamics were investigated by measuring the eye movements produced by stimulating the abducens nucleus with brief pulse trains of varying frequency. Statistical analysis of these movements indicated that the effects of stimulation lasted about 40 ms after the final pulse, after which the eye returned passively toward its position before stimulation. Behavior during the passive phase could be approximated by a linear plant model, corresponding to Voigt elements in series, with properties independent of initial eye position. In contrast, behavior during the stimulation phase revealed a sigmoidal relation between stimulation frequency and estimated steady-state tetanic tension, together with a frequency-dependent rate of tension increase, that appeared very similar to the nonlinearities previously found for isometric-force production in primate lateral rectus muscle. These results suggest that the dynamics of the oculomotor plant have an approximately linear component related to steady-state viscoelasticity and a nonlinear component related to changes in muscle activation. The latter may in part account for the nonlinear relations observed between eye-movement parameters and single-unit firing patterns in the abducens nucleus. These findings point to the importance of recruitment as a simplifying factor for motor control with nonlinear plants.

scholarly journals Sensorimotor Impairments and Reaching Performance in Subjects With Poststroke Hemiparesis During the First Few Months of Recovery

2007 ◽  
Vol 87 (6) ◽  
pp. 751-765 ◽  
Author(s):  
Joanne M Wagner ◽  
Catherine E Lang ◽  
Shirley A Sahrmann ◽  
Dorothy F Edwards ◽  
Alexander W Dromerick
Keyword(s):  
Upper Extremity ◽  
Acute Phase ◽  
Muscle Activation ◽  
Isometric Force ◽  
Force Production ◽  
Subacute Phase ◽  
Healthy Control ◽  
Sensorimotor Impairment ◽  
Isometric Force Production ◽  
Speed Accuracy

Background and Purpose Little is known about the relationship between upper-extremity (UE) sensorimotor impairment and reaching performance during the first few months after stroke. The purpose of this study was to examine: (1) how measures of UE sensorimotor impairment are related to the speed, accuracy, and efficiency of reaching in subjects with hemiparesis during the subacute phase after stroke and (2) how impairments measured during the acute phase after stroke may predict the variance in reaching performance a few months later. Subjects and Methods Upper-extremity sensorimotor impairments and reaching performance were evaluated in 39 subjects with hemiparesis at 2 time points: during the acute phase (8.7±3.6 [X̅±SD] days) and the subacute phase (108.7±16.5 days) after stroke. Ten subjects who were healthy (control subjects) were evaluated once. Regression analyses were used to determine which impairments were the best predictors of variance in reaching performance in the subacute phase after stroke. Results Only a small amount of variance (&lt;30%) in reaching performance was explained at the subacute time point, using either acute or subacute impairments as predictor variables. Of the impairments measured, UE strength deficits were the strongest, most consistent predictors of the variance in reaching performance during the first 3 months after stroke. Discussion and Conclusion Surprisingly, the detailed clinical assessment of UE sensorimotor impairment, measured at the acute or subacute phase after stroke, did not explain much of the variance in reaching performance during the subacute phase after stroke. The findings that UE strength deficits (ie, decreased active range of motion and isometric force production) were the most common predictors of the variance in reaching performance during the first 3 months after stroke are consistent with the current viewpoint that impaired volitional muscle activation, clinically apparent as UE weakness, is a prominent contributing factor to UE dysfunction after stroke.

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