ON SOME INDICATORS OF THE CAPABILITY TO EXERT MUSCLE FORCE OF HUMAN BODY FROM THE STAND POINT OF THE TIME COURSE OF TENSION DEVELOPMENT OF ISOMETRIC TETANUS
Reiji NatoriChotaro IsojimaS. TsubotaYoshiki UmazumeHiroshi KurataAkihito YanagimotoYoshiro MorishitaNaomichi YamamotoReizo Ishii
6
Citation
4
Reference
10
Related Paper
Abstract:
1) The time course of nearly isometrical tension development of human voluntary muscular contraction was analyzed for the purpose of finding some desirable indicators of the capability of human body to exert maximal muscle force as fast as possible.2) The isometric tension curves of maximal exertion of hand gripping, arm and indexfinger bending recorded, the linear relation between Pmax-P, which is a difference between its maximal tension and each value of tension in the time course, and log t, which is the logarithm of time corresponding to each value of tension, was found in each of three portions of a whole curve of time course of tension, the three portions being a range from P0 (log t0) to P1 (log t1), from P1 (log t1) to P2 (log t2) and from P2 (log t2) to Pmax (log tmax.) respectively.3) The range from P1 (log t1) to P2 (log t2) is a phase in which the tension increases most rapidly from an initial small tension to a large tension and is, therefore, regarded as a most characteristic one with respect to the time course of muscle force development exerted voluntarily as fast as possible.4) The angles of intersection of the line connecting P1 (t1) with P2 (t2) or P1 (log t1) with P2 (log t2), with the abscissa in the tension-time or tension-log t curve, which are denoted as or respectively, were found to be able to be adopted as indicators of the capability of human body to exert maximal muscular force for a short period of time.5) The tension curves were found to be nearly the same each other when they were recorded three or four times in the interval of 30 seconds with one and the same subject. If the difference is small between the first and the second record of the time course of a given subject, either of them may be adopted, but if not so, one have to only record the third curve and adopt either of the two resembling each other among the three records.6) Concerning the subjects of the same age, the difference between Pmax and P2 was small and the tan was large with a subject whose P was large. The tan ψ or tanθ was as a rule smaller with subjects of middle and high ages than with younger ones.7) The Pmax decreased with lapse of time when the maximal effort of contraction whose duration was one second was repeated in the interval of three seconds for two minutes. Under this condition the tan ψ increased in some cases, but did not in other cases. Also there were some cases in which t1 remained constant in spite of a decrease in the Pmax with subjects of middle and high ages, P1 of them decreased with decreasing t1. In short the change of the characteristics of the tension curves due to fatigue showed some individual variation.8) The decrease in the Pmax during a continuation of maximal effort of contraction was more remarkable than in the case of repeated contraction mentioned above, but the changes of the values of indicators were nearly the same in both cases.9) The Pmax of hand gripping and index-finger bending decreased to some extent when examined immediately after the effort of contraction had been continued under the condition that the blood stream in the fore-arm was stopped by applying the maximal blood pressure by a manchette of sphygnomanometer. The change of the values of the indicators under this condition was nearly the same as under the condition without the application of pressure, but under the former condition there were some cases in which a portion of the tension curve corresponding to P1 (log t1) deviated from the intersection of the lines, or some cases in which the records of oneKeywords:
Tension (geology)
Isometric contractions of the handgrip muscles were exerted by eight male subjects (age range 19-24 yr) to determine the relationship between fatiguing and nonfatiguing isometric contractions. In a first series of experiments, subjects exerted fatiguing isometric contractions at tensions of 25, 40, or 70% of the maximum strength of the subjects (MVC) following a contraction at a nonfatiguing tension of 5 or 10% MVC for 3, 7, or 20 min. In a second series of experiments, subjects exerted pairs of fatiguing isometric contractions at the same tensions; however, during the 3-, 7-, or 20-min interval between the contractions the subjects either rested or exerted a contraction at 5 or 10% MVC. Nonfatiguing isometric contractions exerted prior to fatiguing contractions had little influence on the endurance for the fatiguing static effort. In contrast, when contractions at nonfatiguing tensions were exerted in the recovery interval following an isometric contraction at a fatiguing tension, the recovery of endurance was dramatically reduced.
Cite
Citations (5)
Objective To determine the test-retest reliability of functional squat system (FSS) isometric muscle strength tests for patients with knee osteoarthritis. Methods The isometric muscle strength of thirty patientswith knee osteoarthritis (21 males and 9 females; age 45 to 89 years, mean age 68.73 ± 12.19 years) was tested twice within 1 week by the same tester. Three test results were obtained: maximum isometric extension strength, the time to initiate isometric extension and the average isometric extension strength. Intra-class correlation coefficients (ICCs) for the three tests were computed to evaluate their retest reliability. Results The ICCs of the maximum isometric extension strength and average isometric extension strength of the uninvolved and involved extremities were respectively 0.87, 0.88, 0.92 and 0.89. The ICCs of the initiation time for the uninvolved and involved legs were respectively 0.25 and 0.41. Conclusion In these tests of patients with knee osteoarthritis using the functional squat system, both the maximum isometric extension strength and the average isometric extension strength had very good test-retest reliability. These two test results could be used as reliable guidance for treatment and rehabilitation of osteoarthritic knees.
Key words:
Knee osteoarthritis; Isometric muscle strength; Tests; Retest reliability
Squat
Cite
Citations (0)
The elbow flexor muscles of four men were trained using maximal voluntary isometric contractions. Thirty contractions a day were performed for five weeks. The four men and four control subjects were tested once a week: measurements of the supramaximally stimulated isometric twitch force, the time taken for the twitch force to peak and the tetanic force were carried out; simultaneously, measurements of the force of maximal voluntary isometric contraction and resistance to fatigue were made. The testing sessions produced no training effect on control subjects. Training produced a 20 per cent increase in the force of maximal voluntary isometric contraction after five weeks, but the forces of electrically evoked twitch and tetanus showed no increase. It was concluded that the increase in the force of maximal voluntary isometric contraction must be related to factors other than the force-generating capacity of the muscle fibres themselves.
Elbow flexion
Plantar flexion
Flexor muscles
Turnover
Cite
Citations (57)
This study was designed to investigate the effect of muscle fiber distribution and pretension at various submaximal contraction levels on the isometric force-time curve during knee extension. Thirteen male physical education students volunteered as subjects. They were instructed to react to an auditory and light signal by extending their right knee as quickly and forcefully as possible. The contractions were performed from seven pretension levels ranging from 0% to 70% of maximal voluntary contraction value (MVC). The isometric force-time curves were analyzed for their maximal rate of isometric force production. Preliminary tension was found to have statistically significant, decreasing effects on isometric maximal strength produced from the pretension levels of 20%, 30%, and 40% of MVC and on the rate of isometric force production (RFD). Relatively, the decrease was greater for the RFD than for the maximal strength. The effect of the 20% preliminary tension on the RFD was greater (P less than 0.05) for subjects rich in fast-twitch muscle fibers in their m. vastus lateralis than for subjects rich in slow-twitch fibers. At the other preliminary tension levels, the intergroup differences did not reach the level of statistical significance.
Cite
Citations (23)
Hamstring strain injuries are common in sport. Supramaximal eccentric or high-intensity isometric contractions are favored in hamstring strain injury prevention. The effect of combining these contraction modes in such prevention programs as a poststretch isometric contraction is unknown. Poststretch isometric contractions incorporate an active stretch and result in greater final isometric force than isometric contractions at comparable joint angles. This study compared torque and muscle activation levels between maximal voluntary isometric contraction and maximal poststretch isometric contractions of the knee flexors. Participants (n = 9) completed baseline maximal voluntary isometric contraction at 150° knee flexion and maximal poststretch isometric contractions at 120° knee flexion actively stretching at 60°/s to 150° knee flexion for final isometric contraction. Torque of the knee flexors and surface electromyography root mean square (sEMGRMS) of biceps femoris long head were simultaneously recorded and compared between baseline and poststretch isometric at 150° knee flexion. Torque was 14% greater in the poststretch isometric condition compared with baseline maximal voluntary isometric contraction (42.45 [20.75] N·m, 14% [22.18%], P < .001) without increase in sEMGRMS of biceps femoris long head (-.03 mV, ±.06, P = .130, d = .93). Poststretch isometric contractions resulted in supramaximal levels of poststretch isometric torque without increased activation of biceps femoris long head.
Knee flexion
Hamstring muscles
Cite
Citations (3)
Cite
Citations (0)
Fatiguing contractions change the force-velocity relationship, but assessment of this relationship in fatigue has usually been obtained after isometric contractions. We studied fatigue caused by isometric or isotonic contractions, by assessment of the force-velocity relationship while the contractions maintaining fatigue were continued. This approach allowed determination of the force-velocity relationship during a steady condition of fatigue. We used the in situ rat medial gastrocnemius muscle, a physiologically relevant preparation. Intermittent (1/s) stimulation at 170 Hz for 100 ms resulted in decreased isometric force to ~35% of initial or decreased peak velocity of shortening in dynamic contractions to ~45% of initial. Dynamic contractions resulted in a transient initial increase in velocity, followed by a rapid decline until a reasonably steady level was maintained. Data were fit to the classic Hill equation for determination of the force-velocity relationship. Isometric and dynamic contractions resulted in similar decreases in maximal isometric force and peak power. Only V max was different between the types of contraction ( P < 0.005) with greater decrease in V max during isotonic contractions to 171.7 ± 7.3 mm/s than during isometric contractions to 208.8 mm/s. Curvature indicated by a/Po (constants from fit to Hill equation) changed from 0.45 ± 0.04 to 0.71 ± 0.11 during isometric contractions and from 0.51 ± 0.04 to 0.85 ± 0.18 during isotonic contractions. Recovery was incomplete 45 min after stopping the intermittent contractions. At this time, recovery of low-frequency isometric force was substantially less after isometric contractions, implicating force during intermittent contractions as a determining factor with this measure of fatigue. NEW & NOTEWORTHY The force-velocity relationship was captured while fatigue was maintained at a constant level during isometric and dynamic contractions. The curvature of the force-velocity relationship was less curved during fatigue than prefatigued, but within 45 min this recovered. Low-frequency fatigue persisted with greater depression of low-frequency force after isometric contractions, possibly because of higher force contractions during intermittent contractions.
Cite
Citations (9)
The purposes of this study were to investigate of the effective hip joint angle during quadriceps isometric exercise by electromyophic analysis. All participants performed quadriceps isometric exercise with knee flexion 60° by Cybex7000. The EMG activity of three knee extensor, vastus lateralis(VL), rectus femoris(RF), and vastus medialis(VM), in the subject' s isometric exercise(maximal voluntary isometric contraction, MVlC) was monitored using bipolar surlace electrodes. The magnitude of the average peak iEMG for each muscle monitored during the stactic motion is calculated as a percentage of the normalized peak iEMG during the MVIC. And the results were follows 1) Statistical analysis demonstrated significantly different maximal isometric force of quadriceps during changes of hip angle.(P＜.05) 2) Between 100° and 130° at hip angles, isometric force of quadriceps increased. Between 130° and 160° at hip angles, isometric force of quadriceps decreased. 3) Maximal isometric force of quadriceps was significantly increasing rate between 100° and 110° at hip angle.(P＜.05) 4) Maximal isometric force of quadriceps was significantly decreasing rate between 140° and 150° at hip angle.(P＜.05) 5) The isometric force of rectus femoris during changes of hip angle was significantly different (P＜.05) 6) The VL/RF, VL/VM, RF/VM iEMG ratios during changes of hip angle was significantly different(P＜.05)
Vastus medialis
Quadriceps muscle
Knee flexion
Cite
Citations (0)
Abstract Thirty-six male college students served as subjects in a study that examined the relationship between isometric strength and relative isometric endurance of the right forearm flexor muscles. The percentages of maximum isometric strength used for the endurance tests were 30, 45, 60, and 75. Three equal groups were formed based on the strength level of the subjects, and an analysis of variance test was used to determine the existence of significant differences. Significant negative correlations were found between isometric strength and relative isometric endurance. The weak subjects performed significantly better than the strong subjects on the light weight loads, with no difference existing between the endurance performances on the heavy loads.
Cite
Citations (24)