Effect of fatigue on rate of isometric force development in mouse fast- and slow-twitch muscles

1992 ◽  
Vol 263 (5) ◽  
pp. C1065-C1072 ◽  
Author(s):  
C. J. Barclay
Keyword(s):  
Energy Expenditure ◽  
Extensor Digitorum Longus ◽  
Initial Rate ◽  
Isometric Force ◽  
Rate Of Force Development ◽  
Force Development ◽  
Maximum Isometric Force ◽  
Slow Twitch ◽  
Rapid Activation

Changes in the rate of isometric force development with fatigue were measured in vitro (25 degrees C) using mouse soleus and extensor digitorum longus (EDL) muscles. Muscles were fatigued using 30 tetanic contractions. Rate of force development was determined from the rate constant of an exponential curve fitted to the rising force phase of a tetanus. For both muscles, when the intertetanus interval was 3 s, maximum isometric force and relaxation rate were significantly reduced in the final tetanus relative to the values in the first tetanus. Rate of force development in soleus muscles transiently increased and then decreased a small amount. The final rate was 92.7 +/- 3.3% (n = 4) of the initial rate. In contrast, the rate of force development in EDL muscles increased to 133.7 +/- 3.3% (n = 4) of the initial rate. This increased rate was evident from the second tetanus of the series, was fully established after 5 tetani, and the magnitude of the increase in rate was inversely proportional to intertetanus interval and was independent of presumed energy expenditure. The enhanced rate decayed with a time constant of 14.3 +/- 2.0 s and was independent of presumed energy expenditure. Most of these observations can be explained by the effects of P(i) on cross bridge kinetics. Other possible mechanisms, involving more rapid activation, are also suggested.

scholarly journals Intramuscular fiber conduction velocity, isometric force and explosive performance

2016 ◽  
Vol 51 (1) ◽  
pp. 93-101 ◽  
Author(s):  
Spyridon Methenitis ◽  
Gerasimos Terzis ◽  
Nikolaos Zaras ◽  
Angeliki-Nikoletta Stasinaki ◽  
Nikolaos Karandreas
Keyword(s):  
Conduction Velocity ◽  
Muscle Fiber ◽  
Isometric Force ◽  
Vastus Lateralis ◽  
Rate Of Force Development ◽  
Muscle Fiber Conduction Velocity ◽  
Force Development ◽  
Leg Press ◽  
Explosive Performance ◽  
Maximum Isometric Force

Abstract Conduction of electrical signals along the surface of muscle fibers is acknowledged as an essential neuromuscular component which is linked with muscle force production. However, it remains unclear whether muscle fiber conduction velocity (MFCV) is also linked with explosive performance. The aim of the present study was to investigate the relationship between vastus lateralis MFCV and countermovement jumping performance, the rate of force development and maximum isometric force. Fifteen moderately-trained young females performed countermovement jumps as well as an isometric leg press test in order to determine the rate of force development and maximum isometric force. Vastus lateralis MFCV was measured with intramuscular microelectrodes at rest on a different occasion. Maximum MFCV was significantly correlated with maximum isometric force (r = 0.66, p < 0.01), nevertheless even closer with the leg press rate of force development at 100 ms, 150 ms, 200 ms, and 250 ms (r = 0.85, r = 0.89, r = 0.91, r = 0.92, respectively, p < 0.01). Similarly, mean MFCV and type II MFCV were better correlated with the rate of force development than with maximum isometric leg press force. Lower, but significant correlations were found between mean MFCV and countermovement jump power (r = 0.65, p < 0.01). These data suggest that muscle fiber conduction velocity is better linked with the rate of force development than with isometric force, perhaps because conduction velocity is higher in the larger and fastest muscle fibers which are recognized to contribute to explosive actions.

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.

Injury to skeletal muscle fibers of mice following lengthening contractions

1985 ◽  
Vol 59 (1) ◽  
pp. 119-126 ◽  
Author(s):  
K. K. McCully ◽  
J. A. Faulkner
Keyword(s):  
Skeletal Muscle ◽  
Isometric Force ◽  
Muscle Fibers ◽  
Lengthening Contractions ◽  
Control Value ◽  
Skeletal Muscle Fibers ◽  
Maximum Isometric Force ◽  
Distal Tendon ◽  
Shortening Contractions

We tested the hypothesis that lengthening contractions result in greater injury to skeletal muscle fibers than isometric or shortening contractions. Mice were anesthetized with pentobarbital sodium and secured to a platform maintained at 37 degrees C. The distal tendon of the extensor digitorum longus muscle was attached to a servomotor. A protocol consisting of isometric, shortening, or lengthening contractions was performed. After the contraction protocol the distal tendon was reattached, incisions were closed, and the mice were allowed to recover. The muscles were removed after 1–30 days, and maximum isometric force (Po) was measured in vitro at 37 degrees C. Three days after isometric and shortening contractions and sham operations, histological appearance was not different from control and Po was 80% of the control value. Three days after lengthening contractions, histological sections showed that 37 +/- 4% of muscle fibers degenerated and Po was 22 +/- 3% of the control value. Muscle regeneration, first seen at 4 days, was nearly complete by 30 days, when Po was 84 +/- 3% of the control value. We conclude that, with the protocol used, lengthening, but not isometric or shortening contractions, caused significant injury to muscle fibers.

Acute Physiological Response to Light- and Heavy-load Power-oriented Exercise in Older Adults

2021 ◽  
Author(s):  
Carlos Rodriguez-Lopez ◽  
Julian Alcazar ◽  
Jose Losa-Reyna ◽  
JuanManuel Carmona-Torres ◽  
Aurora Maria Cruz-Santaella ◽  
...  
Keyword(s):  
Older Adults ◽  
Creatine Kinase ◽  
Resistance Training ◽  
Isometric Force ◽  
Rate Of Force Development ◽  
Heavy Load ◽  
Force Development ◽  
Sit To Stand ◽  
Light Load ◽  
Maximal Isometric Force

AbstractThis study investigated the acute responses to volume-load-matched heavy-load (80% 1RM) versus light-load (40% 1RM) power-oriented resistance training sessions in well-functioning older adults. Using a randomized cross-over design, 15 volunteers completed each condition on a leg press. Neuromuscular (maximal isometric force and rate of force development) and functional performance (power during sit-to-stand test), lactate, and muscle damage biochemistry (creatine kinase, lactate dehydrogenase and C-reactive protein serum concentration) were assessed pre- and post-exercise. Performance declines were found after heavy-load (Cohen’s d effect size (d); maximal isometric force=0.95 d; rate of force development=1.17 d; sit-to-stand power =0.38 d, all p<0.05) and light-load (maximal isometric force=0.45 d; rate of force development=0.9 d; sit-to-stand power=1.17 d, all p<0.05), while lactate concentration increased only after light-load (1.7 d, p=0.001). However, no differences were found between conditions (all p>0.05). Both conditions increased creatine kinase the day after exercise (marginal effect=0.75 d, p<0.001), but no other blood markers increased (all, p>0.05). Irrespective of the load used, power training induced non-clinically significant decreases in sit-to-stand performance, moderate declines in maximal isometric force, but pronounced decreases in the rate of force development. Furthermore, the metabolic stress and muscle damage were minor; both sessions were generally well tolerated by well-functioning older adults without previous experience in resistance training.

Relationship Between Isometric Force–Time Characteristics and Sprint Kayaking Performance

2020 ◽  
pp. 1-6
Author(s):  
Danny Lum ◽  
Abdul Rashid Aziz
Keyword(s):  
Bench Press ◽  
Isometric Force ◽  
Rate Of Force Development ◽  
Isometric Strength ◽  
Mean Power ◽  
Force Development ◽  
Peak Rate ◽  
Time To Completion ◽  
Strength Tests ◽  
Force Time

Force–time characteristics obtained during isometric strength tests are significantly correlated to various sporting movements. However, data on the relationship between isometric force–time characteristics and sprint kayaking performance are lacking in the literature. Purpose: The purpose of the study was, therefore, to investigate the relationship between sprint kayaking performance with ergometer performance and measures from 3 isometric strength tests: isometric squat, isometric bench press, and isometric prone bench pull. Methods: A total of 23 sprint kayaking athletes performed all 3 tests, at 90° and 120° knee angles for isometric squat and at elbow angles for isometric bench press and isometric prone bench pull, and a 200-m sprint on-water to attain the fastest time-to-completion (OWTT) possible and on a kayak ergometer to attain the highest mean power (LABTT) possible. Results: There was a significant inverse correlation between OWTT and LABTT (r = −.90, P < .001). The peak forces achieved from all isometric strength tests were significantly correlated with time-to-completion for OWTT and mean power for LABTT (r = −.44 to −.88, P < .05 and .47 to .80, P < .05, respectively). OWTT was significantly correlated with the peak rate of force development during all isometric tests except for the isometric squat at a 120° knee angle (r = −.47 to −.62, P < .05). LABTT was significantly correlated with peak rate of force development from the isometric bench press and isometric prone bench pull (r = .64–.86, P < .01). Conclusion: Based on the observed strong correlations, the mean power attained during LABTT is a good predictor of OWTT time-to-completion. Furthermore, upper- and lower-body maximum strength and peak rate of force development are equally important for on-water and ergometer sprint kayaking performance.

Aminophylline increases submaximum power but not intrinsic velocity of shortening of frog muscle

1992 ◽  
Vol 73 (1) ◽  
pp. 71-74 ◽  
Author(s):  
B. M. Block ◽  
S. R. Barry ◽  
J. A. Faulkner
Keyword(s):  
Skeletal Muscles ◽  
Isometric Force ◽  
Frog Muscle ◽  
Measured Parameter ◽  
Shortening Velocity ◽  
Force Development ◽  
Velocity Of Shortening ◽  
Force Velocity ◽  
Maximum Isometric Force ◽  
Frequency Of Stimulation

We hypothesized that methylxanthines, such as aminophylline, increase the power developed by submaximally activated frog skeletal muscles by increasing the force developed at any given velocity of shortening. Frog semitendinosus muscles were excised and tested at 20 degrees C in oxygenated control and aminophylline Ringer solutions. Force-velocity relationships were determined and power was calculated from muscles stimulated at frequencies of 80 and 300 Hz. The 300-Hz frequency of stimulation produced a maximum rate of force development. In 50 and 500 microM aminophylline, twitch force increased by 25 +/- 12 and 75 +/- 13%, respectively. Aminophylline did not affect maximum isometric force generation or the shortening velocity at any relative load. At 80-Hz stimulation and in the presence of 500 microM aminophylline, power increased by an average of 11% at 10 of 14 relative loads. At maximum frequencies of stimulation, aminophylline had no effect on any measured parameter. We conclude that aminophylline increases the power developed by submaximally activated frog muscles through an increase in the force generated particularly at the lower velocities of shortening.

Muscle fiber composition, jumping performance, and rate of force development adaptations induced by different power training volumes in females

2020 ◽  
Vol 45 (9) ◽  
pp. 996-1006 ◽  
Author(s):  
Spyridon Methenitis ◽  
Thomas Mpampoulis ◽  
Polyxeni Spiliopoulou ◽  
George Papadimas ◽  
Constantinos Papadopoulos ◽  
...  
Keyword(s):  
Muscle Fiber ◽  
Isometric Force ◽  
Fiber Type ◽  
High Volume ◽  
Rate Of Force Development ◽  
Training Volume ◽  
Power Training ◽  
Power Performance ◽  
Force Development ◽  
Low Volume

This study aimed to investigate the effect of 3 different eccentric-only power training volumes on muscle fiber type composition and power performance. Twenty-nine females were assigned into 3 groups and performed 10 weeks of either 3 (low volume), 6 (moderate volume), or 9 (high volume) sets/session of 4 fast-velocity eccentric-only half-squats against 70% of concentric 1-repetition maximum (1RM), followed by 3 maximum countermovement jumps (CMJs) after each set. Half-squat 1RM, CMJ height/power, maximum isometric force, rate of force development (RFD) and muscle fiber cross-sectional area (CSA) were increased in all groups (p = 0.001). Low-volume training induced higher increases in CMJ height/power and early RFD, compared with the moderate- and high-volume training programs (p < 0.001). Significant reductions in type IIx muscle fiber percentages and %CSAs were found after moderate- and high-volume training, with concomitant increases in type IIa fibers (p = 0.001). Significant correlations were found between the changes in type IIa and type IIx percentages, fiber CSA, %CSA, and the changes in performance (r: –0.787 to 0.792; p < 0.05). These results suggest that relatively large eccentric power training volumes may result in detrimental neuromuscular adaptations, minimal changes in early RFD, and a reduction of type IIx muscle fiber percentage. Novelty Low but not high volume of power training maintains type IIx muscle fibers. Early rate of force development increases after a low- or moderate-power training volume, but not after a high-power training volume. Training-induced changes in type IIx muscle fiber percentage is related with changes in early rate of force development.

scholarly journals Decreased specific force and power production of muscle fibers from myostatin-deficient mice are associated with a suppression of protein degradation

2011 ◽  
Vol 111 (1) ◽  
pp. 185-191 ◽  
Author(s):  
Christopher L. Mendias ◽  
Erdan Kayupov ◽  
Joshua R. Bradley ◽  
Susan V. Brooks ◽  
Dennis R. Claflin
Keyword(s):  
Myosin Heavy Chain ◽  
Muscle Mass ◽  
Heavy Chain ◽  
Extensor Digitorum Longus ◽  
Isometric Force ◽  
Muscle Fibers ◽  
Force Production ◽  
Sectional Area ◽  
Cross Sectional ◽  
Maximum Isometric Force

Myostatin ( MSTN) is a member of the transforming growth factor-β superfamily of cytokines and is a negative regulator of skeletal muscle mass. Compared with MSTN+/+ mice, the extensor digitorum longus muscles of MSTN−/− mice exhibit hypertrophy, hyperplasia, and greater maximum isometric force production (Fo), but decreased specific maximum isometric force (sFo; Fo normalized by muscle cross-sectional area). The reason for the reduction in sFo was not known. Studies in myotubes indicate that inhibiting myostatin may increase muscle mass by decreasing the expression of the E3 ubiquitin ligase atrogin-1, which could impact the force-generating capacity and size of muscle fibers. To gain a greater understanding of the influence of myostatin on muscle contractility, we determined the impact of myostatin deficiency on the contractility of permeabilized muscle fibers and on the levels of atrogin-1 and ubiquitinated myosin heavy chain in whole muscle. We hypothesized that single fibers from MSTN−/− mice have a greater Fo, but no difference in sFo, and a decrease in atrogin-1 and ubiquitin-tagged myosin heavy chain levels. The results indicated that fibers from MSTN−/− mice have a greater cross-sectional area, but do not have a greater Fo and have a sFo that is significantly lower than fibers from MSTN+/+ mice. The extensor digitorum longus muscles from MSTN−/− mice also have reduced levels of atrogin-1 and ubiquitinated myosin heavy chain. These findings suggest that myostatin inhibition in otherwise healthy muscle increases the size of muscle fibers and decreases atrogin-1 levels, but does not increase the force production of individual muscle fibers.

Age- and Sex-Related Differences in the Maximum Muscle Performance and Rate of Force Development Scaling Factor of Precision Grip Muscles

Motor Control ◽  
2020 ◽  
Vol 24 (2) ◽  
pp. 274-290
Author(s):  
Talyene G.C. Corrêa ◽  
Stephanie V.S. Donato ◽  
Kauê C.A. Lima ◽  
Ronaldo V. Pereira ◽  
Mehmet Uygur ◽  
...  
Keyword(s):  
Grip Force ◽  
Isometric Force ◽  
Maximum Voluntary Contraction ◽  
Precision Grip ◽  
Voluntary Contraction ◽  
Scaling Factor ◽  
Rate Of Force Development ◽  
Muscle Performance ◽  
Force Development ◽  
Age And Sex

The aim of this study was to explore the effects of age and sex on the rate of force development scaling factor (RFD-SF) and maximum performance (i.e., maximum grip force [GFMax] and maximum rate of grip force development [RGFDMax]) of precision handgrip muscles. Sixty-four subjects, allocated in four groups according to their age and sex, were asked to hold an instrumented handle with the tip of the digits and perform two tests: maximum voluntary contraction and RFD-SF tests. In the maximum voluntary contraction test, GFMax and RGFDMax were assessed. In the RFD-SF test, the subjects generated quick isometric force pulses to target amplitudes varying between 20% and 100% of their GFMax. The RFD-SF and R2 values were obtained from the linear relationship between the peak values of the force pulses and the corresponding peak values of the rate of force development. Younger adults and males produced higher GFMax and RGFDMax and presented higher R2 and RFD-SF than older adults and females, respectively. No correlations between GFMax and RFD-SF and between RGFDMax and RFD-SF were observed.

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