scholarly journals The influence of temperature on ryanodine sensitivity and the force-frequency relationship in the myocardium of rainbow trout

1992 ◽  
Vol 167 (1) ◽  
pp. 47-60 ◽  
Author(s):  
L. Hove-Madsen
Keyword(s):  
Rainbow Trout ◽  
Mammalian Species ◽  
Rest Period ◽  
Rate Of Force Development ◽  
Force Frequency ◽  
Maximal Rate ◽  
Force Development ◽  
Time To Peak ◽  
Influence Of Temperature On ◽  
Frequency Relationship

The relationship between stimulation frequency and contraction was established for ventricular strips from rainbow trout heart at 5, 15 and 25 degrees C. Compared to mammalian species, changes in temperature had little impact on force development in trout ventricle at physiologically relevant stimulation frequencies. However, the force-frequency relationship was changed from a biphasic response with a minimum around 0.2 Hz at 5 and 15 degrees C to a monophasic decline in force with increasing frequency at 25 degrees C. Ryanodine reversed the negative force-frequency relationship at 25 degrees C. Potentiation of twitch force after a 5 min rest period was increased from 121 +/− 4% at 15 degrees C to 209 +/− 12% at 25 degrees C. A similar augmentation was seen for the maximal rate of force development. Rest potentiation of both force and maximal rate of force development (dF/dT) was abolished by ryanodine at both 15 and 25 degrees C. The ryanodine concentration causing a half-maximal reduction in rest potentiation of force was 51 nmol l-1 at 25 degrees C and 483 nmol l-1 at 15 degrees C. Rest potentiation was maximally reduced by 10 mumol l-1 ryanodine to 50 and 79% of the value in the absence of ryanodine at 25 and 15 degrees C, respectively. At 5 degrees C, rest potentiation was similar to that at 15 degrees C. At 5 degrees C, there was no rest potentiation of dF/dT and ryanodine did not reduce rest potentiation of force. Instead, rest potentiation was correlated with a potentiation of time to peak tension (TPT) at 5 degrees C. Thus, in trout ventricle, force correlates with TPT at 5 degrees C and seems to be regulated by a ryanodine-insensitive mechanism, while at 25 degrees C force is correlated with the maximal rate of force development and the sarcoplasmic reticulum appears to contribute significantly to excitation-contraction coupling.

scholarly journals INTERPRETATION OF PROPULSIVE FORCE IN TETHERED SWIMMING THROUGH PRINCIPAL COMPONENT ANALYSIS

2018 ◽  
Vol 24 (3) ◽  
pp. 178-181 ◽  
Author(s):  
Rodrigo Maciel Andrade ◽  
Aylton José Figueira Júnior ◽  
Vanessa Metz ◽  
Alberto Carlos Amadio ◽  
Júlio Cerca Serrão
Keyword(s):  
Principal Component Analysis ◽  
Principal Component ◽  
Component Analysis ◽  
Peak Force ◽  
Rate Of Force Development ◽  
Impulse Generation ◽  
Force Development ◽  
Time To Peak ◽  
Force Time ◽  
Minimum Force

ABSTRACT Introduction: Propulsive force in swimming, represented through impulse, is related to performance. However, since the as different biomechanical parameters contribute to impulse generation, coaches have a difficult task when seeking for performance improvement. Objective: Identify the main components involved in impulse generation in the front crawl stroke. Methods: Fourteen swimmers underwent a 10-second all-out fully tethered swimming test. The following parameters were obtained from the force-time curve: minimum force, peak force, mean force, time to peak force, rate of force development and stroke duration. This stage was followed by a principal component analysis. Results: The principal component analysis showed that component 1, predominantly kinetic, was composed of peak force, mean force and rate of force development, and accounted for 49.25% of total impulse variation, while component 2, predominantly temporal, composed of minimum force, stroke duration, and time to peak force, represented 26.43%. Conclusion: Kinetic parameters (peak force, mean force, and rate of force development) are more closely associated with impulse augmentation and, hypothetically, with non-tethered swimming performance. Level of Evidence II; Diagnostic studies - Investigating a diagnostic test.

scholarly journals You are as fast as your motor neurons: speed of recruitment and maximal discharge of motor neurons determine the maximal rate of force development in humans

2019 ◽  
Vol 597 (9) ◽  
pp. 2445-2456 ◽  
Author(s):  
Alessandro Del Vecchio ◽  
Francesco Negro ◽  
Ales Holobar ◽  
Andrea Casolo ◽  
Jonathan P. Folland ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Rate Of Force Development ◽  
Maximal Rate ◽  
Force Development ◽  
Maximal Discharge

scholarly journals Upper body rate of force development and maximal strength discriminates performance levels in sport climbing

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0249353
Author(s):  
Nicolay Stien ◽  
Vegard Albert Vereide ◽  
Atle Hole Saeterbakken ◽  
Espen Hermans ◽  
Matthew Peter Shaw ◽  
...  
Keyword(s):  
Rate Of Force Development ◽  
The Other ◽  
Upper Body ◽  
Relative Time ◽  
Force Development ◽  
Absolute Time ◽  
Time To Peak ◽  
Maximal Force ◽  
Sport Climbing ◽  
Time Periods

The aim of this study was to assess and compare the maximal force and rate of force development (RFD) between intermediate, advanced and elite climbers using several different methods for calculating RFD. Fifty-seven male climbers (17 intermediate, 25 advanced, and 15 elite) performed isometric pull-ups on a climbing-specific hold while the RFD was calculated using several absolute (50, 100, 150, 200, and 250 ms from onset of force) and relative time periods (25, 50, 75, 95, and 100% of time to peak force). The maximal force was higher among elite climbers compared to advanced (ES = 1.78, p < 0.001) and intermediate climbers (ES = 1.77, p < 0.001), while no difference was observed between intermediate and advanced climbers (P = 0.898). The elite group also showed higher RFD than the other two groups at all relative time periods (ES = 1.02–1.58, p < 0.001–0.002), whereas the absolute time periods only revealed differences between the elite vs. the other groups at 50, 100 and 150 ms from the onset of force (ES = 0.72–0.84, p = 0.032–0.040). No differences in RFD were observed between the intermediate and advanced groups at any time period (p = 0.942–1.000). Maximal force and RFD, especially calculated using the longer periods of the force curve, may be used to distinguish elite climbers from advanced and intermediate climbers. The authors suggest using relative rather than absolute time periods when analyzing the RFD of climbers.

Rat myocardial mechanics during pressure-induced hypertrophy development and reversal

1975 ◽  
Vol 229 (2) ◽  
pp. 355-364 ◽  
Author(s):  
P Jouannot ◽  
PY Hatt
Keyword(s):  
Isometric Force ◽  
Muscle Mechanics ◽  
Muscle Thickness ◽  
Left Ventricular ◽  
Force Frequency ◽  
Aortic Constriction ◽  
Shortening Velocity ◽  
Time To Peak ◽  
Prolonged Duration ◽  
Frequency Relationship

Moderate cardiac hypertrophy (CH) was produced in rats by abdominal aorta constriction for 5, 8, 15, 21, and 28 days. Aortic constriction release after 5, 8, and 15 days led to CH regression, which was complete within 15 days. A study of left ventricular papillary muscle mechanics during CH development demonstrated an early but transitory decrease in both maximum isometric force (Po) and maximum muscle shortening velocity (max V); in addition, the time-to-peak tension increased, and there was a decrease in isometric relaxation rate and in force-frequency relationship (negative staircase.) After CH regression, isometric relaxation and negative staircase were similar to controls, whereas the prolonged duration of contraction persisted. After release of the aortic constriction at 8 and 15 days, Po and max V were normal; however, after the earlier release (5 days), Po was higher than control, when muscle thickness was taken into consideration. These findings suggest 1) that an alteration in muscle mechanics may be related to the hypertrophy itself; 2) that anomalous excitation-contraction coupling might persist after CH regression.

Intra- and inter-rater reliability of the rate of force development of hip abductor muscles measured by hand-held dynamometer

2017 ◽  
Vol 22 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Kazuya Takeda ◽  
Shigeo Tanabe ◽  
Soichiro Koyama ◽  
Tomoko Nagai ◽  
Hiroaki Sakurai ◽  
...  
Keyword(s):  
Rate Of Force Development ◽  
Rater Reliability ◽  
Force Development ◽  
Hip Abductor

scholarly journals Influence Of Acidic pH On The Rate Of Force Development In Cardiac Muscle

2009 ◽  
Vol 96 (3) ◽  
pp. 621a
Author(s):  
Frederick S. Korte ◽  
Michael Regnier ◽  
Todd E. Gillis
Keyword(s):  
Cardiac Muscle ◽  
Rate Of Force Development ◽  
Acidic Ph ◽  
Force Development
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