Strength and Contractile Adaptations in the Human Triceps Surae after Isotonic Exercise

1993 ◽  
Vol 2 (2) ◽  
pp. 104-114 ◽  
Author(s):  
Crayton L. Moss ◽  
Scott Grimmer
Keyword(s):  
Relaxation Time ◽  
Repeated Measures ◽  
Peak Force ◽  
Contractile Properties ◽  
Triceps Surae ◽  
Type I ◽  
Muscle Twitch ◽  
Time To Peak ◽  
High Repetition ◽  
Isotonic Exercise

The purpose of this study was to determine whether twitch contractile properties and strength of the triceps surae could be altered by 8 weeks of low-repetition or high-repetition isotonic exercise. Subjects were randomly assigned to either the low- or high-repetition group. Before- and after-training measurements were recorded for strength and contractile properties. The contractile variables of the muscle twitch were latency, time to peak force, peak force, half-contraction time, and half-relaxation time. Strength measurements were determined utilizing a one repetition maximal (1-RM) heel-raise testing device. A two-way ANOVA with repeated measures was used to test the effect of training on each variable. Both groups showed a significant increase in 1-RM and half-relaxation time and a decrease in electrical stimulation current after the 8-week training period. It was concluded that if high-repetition exercises develop slow-twitch Type I muscle fibers and low-repetition exercises develop fast-twitch Type II fibers, training programs must be designed specifically according to the desired outcome.

Sag During Unfused Tetanic Contractions in Rat Triceps Surae Motor Units

1999 ◽  
Vol 81 (6) ◽  
pp. 2647-2661 ◽  
Author(s):  
J. S. Carp ◽  
P. A. Herchenroder ◽  
X. Y. Chen ◽  
J. R. Wolpaw
Keyword(s):  
Relaxation Times ◽  
Motor Units ◽  
Contractile Properties ◽  
Triceps Surae ◽  
Initial Increase ◽  
Tetanic Stimulation ◽  
Twitch Contraction ◽  
Time To Peak ◽  
Single Motor Units ◽  
Initial Force

Sag during unfused tetanic contractions in rat triceps surae motor units. Contractile properties and conduction velocity were studied in 202 single motor units of intact rat triceps surae muscles activated by intra-axonal (or intra-myelin) current injection in L5 or L6 ventral root to assess the factors that determine the expression of sag (i.e., decline in force after initial increase during unfused tetanic stimulation). Sag was consistently detected in motor units with unpotentiated twitch contraction times <20 ms. However, the range of frequencies at which sag was expressed varied among motor units such that there was no single interstimulus interval (ISI), with or without adjusting for twitch contraction time, at which sag could be detected reliably. Further analysis indicated that using the absence of sag as a criterion for identifying slow-twitch motor units requires testing with tetani at several different ISIs. In motor units with sag, the shape of the force profile varied with tetanic frequency and contractile properties. Simple sag force profiles (single maximum reached late in the tetanus followed by monotonic decay) tended to occur at shorter ISIs and were observed more frequently in fatigue-resistant motor units with long half-relaxation times and small twitch amplitudes. Complex sag profiles reached an initial maximum early in the tetanus, tended to occur at longer ISIs, and were more common in fatigue-sensitive motor units with long half-relaxation times and large twitch amplitudes. The differences in frequency dependence and force maximum location suggested that these phenomena represented discrete entities. Successive stimuli elicited near-linear increments in force during tetani in motor units that never exhibited sag. In motor units with at least one tetanus displaying sag, tetanic stimulation elicited large initial force increments followed by rapidly decreasing force increments. That the latter force envelope pattern occurred in these units even in tetani without sag suggested that the factors responsible for sag were expressed in the absence of overt sag. The time-to-peak force (TTP) of the individual contractions during a tetanus decreased in tetani with sag. Differences in the pattern of TTP change during a tetanus were consistent with the differences in force maximum location between tetani exhibiting simple and complex sag. Tetani from motor units that never exhibited sag did not display a net decrease in TTP during successive contractions. These data were consistent with the initial force decrement of sag resulting from a transient reduction in the duration of the contractile state.

Isometric contractile properties and instantaneous stiffness of amphibian skeletal muscle in the temperature range from 0 to 20 °C

1981 ◽  
Vol 59 (6) ◽  
pp. 548-554 ◽  
Author(s):  
Bernard H. Bressler
Keyword(s):  
Relaxation Time ◽  
Elevated Temperatures ◽  
Bufo Bufo ◽  
Contractile Properties ◽  
Temperature Range ◽  
Time To Peak ◽  
Intracellular Ca ◽  
Cross Bridges ◽  
Isometric Twitch ◽  
Toad Bufo

The isometric contractile properties of frog (Rana pipiens) and toad (Bufo bufo) sartorii have been studied over the temperature range from 0 to 20 °C. The isometric twitch tension was found to vary considerably between these two species and between muscles in the same species. Between 0 and 4 °C ther was very little change in maximum isometric twitch tension. Between 4 and 12 °C several muscles from frog or toad showed a potentiation of twitch tension whereas others showed a decline. Over this temperature range the toad sartorii consistently demonstrated a greater potentiation. By 12 °C a steady decline in twitch tension in both muscles was seen as the temperature approached 20 °C. The maximum isometric tetanic tension recorded between 18 and 20 °C increased fractionally to an average of 1.504 ± 0.029 (n = 4) for frog sartorii and to 1.377 ± 0.008 (n = 5) for toad sartorii. The time to peak twitch tension and the half-relaxation time decreased markedly with an increase in temperature. Moreover, the half-relaxation time was reduced by a greater proportion than the time to peak twitch tension. Measurements of instantaneous stiffness by controlled velocity releases from the plateau of isometric tetani revealed that the large increase in isometric tetanus tension as the muscle was warmed was not accompanied by a corresponding increase in the total number of active cross-bridges. The possibility that a decreased availability of intracellular Ca2+ ions at the contractile sites contributing to the fall of isometric twitch tension at elevated temperatures is discussed. The possibility exists that at elevated temperatures a change in the intrinsic-contractile ability of the muscle occurs which produces an increased tension per cross-bridge.

The Effects of Immobilization, after Lower Leg Fracture, on the Contractile Properties of Human Triceps Surae

1984 ◽  
Vol 66 (3) ◽  
pp. 277-282 ◽  
Author(s):  
M. J. White ◽  
C. T. M. Davies
Keyword(s):  
Lower Leg ◽  
Voluntary Contraction ◽  
Contractile Properties ◽  
Triceps Surae ◽  
Anthropometric Measurement ◽  
Muscle Fibres ◽  
Type I ◽  
Cross Sectional ◽  
Tension Development ◽  
Lower Leg Fracture

1. The contractile properties of the triceps surae were evaluated in 11 patients after unilateral fracture of the lower leg and subsequent immobilization for 135 ± 68 days. Calf muscle cross-sectional area (plus bone: CSA) was assessed from anthropometric measurement. 2. It was shown that the injured leg had a faster time to peak tension and increased half-relaxation time (1/2RT); twitch force (Pt) was reduced by 25%. Evoked maximal tetanic tensions (P0) at 10 and 20 Hz were reduced by 51% and 46% respectively compared with the uninjured leg. The force of a maximal voluntary contraction (MVC) was also reduced, by 50%, but calf circumference and CSA were only 5% and 16% respectively lower in the injured leg. 3. It was concluded that the changes in contractile speed may indicate a relatively greater atrophy of slow (type I) muscle fibres. 4. The relationship between CSA and tension generation in the injured limb was shown to be poor after immobilization and during recovery. Anthropometric estimation of CSA does not appear to reflect the degree of muscle wasting, as indicated by reduced tension development after immobilization.

Effects of 22 °C muscle temperature on voluntary and evoked muscle properties during and after high-intensity exercise

2007 ◽  
Vol 32 (6) ◽  
pp. 1043-1051 ◽  
Author(s):  
Eric J. Drinkwater ◽  
David G. Behm
Keyword(s):  
High Intensity ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Contractile Properties ◽  
Muscle Temperature ◽  
Plantar Flexors ◽  
Muscle Properties ◽  
Time To Peak ◽  
Cohen’S D ◽  
Cohen's D

The purpose of this study was to investigate the effect of 22 °C local muscle temperature of intact human plantar flexors performing fatiguing contractions on evoked and voluntary contractile properties before and after fatigue. Twelve subjects were tested on plantar flexor voluntary torque, percent muscle activation derived from twitch interpolation, integrated electromyographic (iEMG) activity, and evoked torque and temporal characteristics of maximal twitch and tetanic stimulations before fatigue and 1, 5, and 10 min after intermittent, high-intensity, isometric fatigue under both normothermic and hypothermic conditions. Hypothermic and normothermic changes between time points were analysed by repeated-measures analysis of variance. Normothermic fatigue induced small to large effects (Cohen’s d: 0.29–3.06) on voluntary and evoked contractile properties, whereas most effects of unfatigued hypothermia were limited to rate-dependent processes (Cohen’s d: 0.78–1.70). Most tetanic properties were potentiated 1 min after normothermic fatigue, but remained unchanged by hypothermic fatigue, resulting in significant differences between the two conditions. Soleus iEMG significantly declined 1 min after normothermic fatigue (–29%), but not after hypothermic fatigue. Twitch torque was potentiated by 29% one minute after fatigue while normothermic, but was potentiated by 46% while hypothermic; rate of twitch torque development and time to peak twitch were potentiated by 39% and 10% while normothermic, but 89% and 28% while hypothermic. Although voluntary contractile properties are generally impaired soon after normothermic fatigue, most were not after hypothermic fatigue. Furthermore, evoked contractile properties were generally higher 1 min after hypothermic fatigue. We conclude that the hypothermic condition slows the recovery of potentiated evoked contractile properties back to baseline values.

Effects of hypoxia and Freon 12 on mechanics of cardiac contraction

1976 ◽  
Vol 230 (6) ◽  
pp. 1701-1707 ◽  
Author(s):  
SM Kilen ◽  
WS Harris
Keyword(s):  
Relaxation Time ◽  
Peak Force ◽  
Cardiac Contraction ◽  
Myocardial Tissue ◽  
Papillary Muscles ◽  
Shortening Velocity ◽  
Subsequent Recovery ◽  
Time To Peak ◽  
Adequate Oxygenation

Data are presented which indicate that the mechanism of tension depression and subsequent recovery from dichlorodifluoromethane (Freon 12), an aerosol gas recently described as a potent cardiac depressant agent, differs from that of hypoxia. To analyze these differences, 22 rat papillary muscles, contracting isometrically in a myograph, were studied during and subsequent to 15-min interventions of of hypoxia. Freon 12 with adequate oxygenation, or Freon 12 combined with hypoxia. During each of the three interventions the developed force (F) was markedly depressed, while peak shortening velocity (Vpm) was selectively more depressed by Freon and Freon combined with hypoxia than by hypoxia alone. While hypoxia shortened the time to peak force (TTP) and one-half relaxation time (RT1/2) markedly, Freon 12 with adequate oxygenation slightly shortened RT1/2 (P is less than 0.001) but failed to shorten TTP significantly. In contrast, Freon 12 administered during hypoxia shortened TTP and RT1/2 significantly (P is less than 0.001), more than did hypoxia or Freon 12 alone. Posthypoxic prolongation of TTP and RT1/2 was not seen during recovery from Freon 12. This prolongation was depressed during recovery from Freon 12 given either during hypoxia or during recovery from hypoxia. The results indicate that Freon 12 and hypoxia act synergically, although the mechanisms through which they mediate their actions on myocardial tissue are not identical.

Inhibition of carbonic anhydrases in type I muscle fibers influences contractility

1989 ◽  
Vol 67 (6) ◽  
pp. 645-649 ◽  
Author(s):  
C. Côté ◽  
D. Tremblay ◽  
H. Riverin ◽  
P. Frémont ◽  
P. A. Rogers
Keyword(s):  
Relaxation Time ◽  
Carbonic Anhydrase ◽  
Soleus Muscle ◽  
Extensor Digitorum Longus ◽  
Specific Inhibitor ◽  
Contractile Properties ◽  
Extensor Digitorum ◽  
Female Rats ◽  
Type I ◽  
Significant Difference

We tested the effects of inhibiting the carbonic anhydrase activity of rat soleus and extensor digitorum longus muscles on the isometric contractile properties and the resistance to fatigue. SOL and EDL muscles from female rats were incubated in vitro in the presence of methazolamide, a specific inhibitor of carbonic anhydrase, before determining their contractile properties. Methazolamide had no effects on the contractile properties of the soleus muscle (10−5 or 10−3 M) and extensor digitorum longus (10−3 M), except for the half-relaxation time of the soleus muscle which increased significantly. Values for half-relaxation time were significantly increased with both concentrations of the inhibitor. Muscles were then submitted to a fatigue protocol lasting 30 min. During the fatigue test, no significant difference was observed between control and 10−5 M methazolamide soleus muscles. In presence of 10−3 M methazolamide however, the soleus muscle showed a significantly increased resistance to fatigue compared with control preparations. No significant effect was observed with the extensor digitorum longus muscle exposed to 10−3 M methazolamide. Results are discussed in terms of the presence of two different isoforms of carbonic anhydrase that may be associated with calcium uptake and energy metabolic processes, respectively.Key words: carbonic anhydrase, skeletal muscle, contraction, fatigue, soleus muscle.

One Size Fits All?

Methodology ◽  
2012 ◽  
Vol 8 (1) ◽  
pp. 23-38 ◽  
Author(s):  
Manuel C. Voelkle ◽  
Patrick E. McKnight
Keyword(s):  
Repeated Measures ◽  
Structural Equation ◽  
Type I Error ◽  
Equation Modeling ◽  
Type I ◽  
Finite Sample ◽  
Traditional Methods ◽  
Repeated Measures Anova ◽  
Special Cases ◽  
Latent Curve

The use of latent curve models (LCMs) has increased almost exponentially during the last decade. Oftentimes, researchers regard LCM as a “new” method to analyze change with little attention paid to the fact that the technique was originally introduced as an “alternative to standard repeated measures ANOVA and first-order auto-regressive methods” (Meredith & Tisak, 1990, p. 107). In the first part of the paper, this close relationship is reviewed, and it is demonstrated how “traditional” methods, such as the repeated measures ANOVA, and MANOVA, can be formulated as LCMs. Given that latent curve modeling is essentially a large-sample technique, compared to “traditional” finite-sample approaches, the second part of the paper addresses the question to what degree the more flexible LCMs can actually replace some of the older tests by means of a Monte-Carlo simulation. In addition, a structural equation modeling alternative to Mauchly’s (1940) test of sphericity is explored. Although “traditional” methods may be expressed as special cases of more general LCMs, we found the equivalence holds only asymptotically. For practical purposes, however, no approach always outperformed the other alternatives in terms of power and type I error, so the best method to be used depends on the situation. We provide detailed recommendations of when to use which method.

scholarly journals Changes in Maximal Strength and Home Run Performance in NCAA Division I Baseball Players Across 3 Competitive Seasons: A Descriptive Study

2021 ◽  
Vol 6 (1) ◽  
pp. 4
Author(s):  
W. Guy Hornsby ◽  
Abigail L. Tice ◽  
Jason D. Stone ◽  
Justin J. Merrigan ◽  
Joshua Hagen ◽  
...  
Keyword(s):  
Ncaa Division I ◽  
Repeated Measures ◽  
National Collegiate Athletic Association ◽  
Descriptive Study ◽  
Peak Force ◽  
Division I ◽  
Maximal Strength ◽  
Baseball Players ◽  
Repeated Measures Analysis ◽  
Division 1

The purpose of this longitudinal, descriptive study was to observe changes in maximal strength measured via isometric clean grip mid-thigh pull and home runs (total and home runs per game) across three years of training and three competitive seasons for four National Collegiate Athletic Association (NCAA) Division 1 baseball players. A one-way repeated measures analysis of variance (ANOVA) was performed, revealing significant univariate effects of time for peak force (PF) (p = 0.003) and peak force allometrically scaled (PFa) (p = 0.002). Increases in PF were noted from season 1 to season 2 (p = 0.031) and season 3 (p = 0.004), but season 2 was not significantly different than season 3 (p = 0.232). Additionally, increases in PFa were noted from season 1 to season 2 (p = 0.010) and season 3 (p < 0.001), but season 2 was not significantly different than season 3 (p = 0.052). Home runs per game rose from the 2009 (0.32) to 2010 season (1.35) and dropped during the 2011 season (1.07). A unique aspect of the study involves 2010 being the season in which ball-bat coefficient of restitution (BBCOR) bats were introduced to the NCAA competition.

Control of Rapidly Executed Forces to a Target

1987 ◽  
Vol 65 (3) ◽  
pp. 827-836
Author(s):  
Donald Siegel
Keyword(s):  
Visual Feedback ◽  
Predictor Variable ◽  
Peak Force ◽  
Important Predictor ◽  
Force Amplitude ◽  
Time Curve ◽  
Time To Peak ◽  
Hand Grip ◽  
Rapid Responses ◽  
Force Time

The purpose of the present study was to determine whether initial measures of impulse (i.e., area under the force-time curve) could be used to predict peak force (PF) in hand grip responses of 5- and 10-kg amplitude executed as rapidly as possible. 12 subjects performed 75 practice and 25 test contractions in each condition, with and without visual feedback. The time to peak (PT) for the 5-kg responses was 41 msec., while the 10-kg condition averaged 56 msec. Analyses demonstrated no effect for visual feedback. Correlational analyses of cumulative impulse sections from 5 msec., to PF within conditions showed that early measures of force within a response were not very good predictors of final force amplitude. Indeed, for both conditions upwards of 85% of a reponse needed to have occurred before 50% of PF variance could be predicted. Analyses across conditions demonstrated that 50% of PF variance could be predicted between 15 and 20 msec. PT was also an important predictor variable. By using PT along with cumulative impulse 50% of the variance in PF could be predicted prior to 10 msec., at 5 kg (25% of PT) and at about 15 msec., for 10 kg (27% of PT). Across conditions, 85% of the variance in PF was predictable by 5 msec. Such results suggest that either more refined response indices are needed in predicting response outcome or that even for very rapid responses some lower level “tuning” probably occurs after initiation.

scholarly journals Peak force and maximal shortening velocity of soleus fibers after non-weight-bearing and resistance exercise

1997 ◽  
Vol 82 (1) ◽  
pp. 189-195 ◽  
Author(s):  
Jeffrey J. Widrick ◽  
Robert H. Fitts
Keyword(s):  
Resistance Exercise ◽  
Elevated Level ◽  
Fiber Diameter ◽  
Weight Bearing ◽  
Normal Weight ◽  
Peak Force ◽  
Type I ◽  
Shortening Velocity ◽  
Adult Rats ◽  
Cross Sectional

Widrick, Jeffrey J., and Robert H. Fitts. Peak force and maximal shortening velocity of soleus fibers after non-weight-bearing and resistance exercise. J. Appl. Physiol. 82(1): 189–195, 1997.—This study examined the effectiveness of resistance exercise as a countermeasure to non-weight-bearing-induced alterations in the absolute peak force, normalized peak force (force/fiber cross-sectional area), peak stiffness, and maximal shortening velocity ( V o) of single permeabilized type I soleus muscle fibers. Adult rats were subjected to one of the following treatments: normal weight bearing (WB), non-weight bearing (NWB), or NWB with exercise treatments (NWB+Ex). The hindlimbs of the NWB and NWB+Ex rats were suspended for 14 days via tail harnesses. Four times each day, the NWB+Ex rats were removed from suspension and performed 10 climbs (∼15 cm each) up a steep grid with a 500-g mass (∼1.5 times body mass) attached to their tail harness. NWB was associated with significant reductions in type I fiber diameter, absolute force, normalized force, and stiffness. Exercise treatments during NWB attenuated the decline in fiber diameter and absolute force by almost 60% while maintaining normalized force and stiffness at WB levels. Type I fiber V oincreased by 33% with NWB and remained at this elevated level despite the exercise treatments. We conclude that in comparison to intermittent weight bearing only (J. J. Widrick, J. J. Bangart, M. Karhanek, and R. H. Fitts. J. Appl. Physiol. 80: 981–987, 1996), resistance exercise was more effective in attenuating alterations in type I soleus fiber absolute force, normalized force, and stiffness but was less effective in restoring type I fiber V oto WB levels.

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