Isotonic and isometric forces of forearm flexors and extensors.

Singh, Meenakshi; Karpovich, Peter V.

doi:10.1152/jappl.1966.21.4.1435

Cited by 98 publications

(46 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A factor of´1.8 (Katz 1939: frog and tortoise muscles, 0°C) is widely quoted, although´1.6±1.7 better represents Katz's results in``warm'' conditions (15±20°C). Forces substantially higher than isometric, although never to our knowledge as much as´1.8 higher, have been reported to be developed by human arm muscles when operating eccentrically under voluntary activation (Asmussen et al 1965;Singh and Karpovitch 1965;Komi 1973;Grin et al 1993 and references therein). However, thigh muscles, especially the quadriceps, present a confused picture, particularly when studied ± as is now standard ± by isokinetic dynamometry.…”

Section: Introductionmentioning

confidence: 87%

The effect of strength training on the apparent inhibition of eccentric force production in voluntarily activated human quadriceps

Spurway¹,

Watson²,

McMillan³

et al. 2000

European Journal of Applied Physiology

View full text Add to dashboard Cite

Ten male and ten female young adults trained the knee extensors of one leg eccentrically and those of the other concentrically for 6 weeks, using a gymnasium leg-extension machine. Before and after training, both legs of each subject were tested isometrically for maximum voluntary knee-extensor force, and in both eccentric and concentric isokinetic modes at 30-250 degrees x s(-1) All limbs showed improvements in mean eccentric force (ranging from 18% in the concentrically trained legs of the females to 31% in the eccentrically trained legs of the males, P < 0.01-0.001). Upward trends in isometric and concentric forces were smaller and less- or nonsignificant. In three of the four groups, mean eccentric forces after training were significantly greater than mean isometric forces, a difference that was not evident before training. Ten further subjects of each gender, not trained but tested isometrically and isokinetically three times in 2 weeks, showed no significant improvement over the series of tests. The explanation suggested is that the increased percentage activation ("decreased inhibition"), often regarded as the main mechanism of strength gain in the early weeks of training, had been displayed particularly in the subjects' eccentric performance. This implies that the activation-shortfall, which is reduced by the initial phase of strength training, is largely or completely the same as that responsible for the fact that untrained, voluntary eccentric force is less than that of isolated muscle.

show abstract

Section: Introductionmentioning

confidence: 87%

The effect of strength training on the apparent inhibition of eccentric force production in voluntarily activated human quadriceps

Spurway¹,

Watson²,

McMillan³

et al. 2000

European Journal of Applied Physiology

View full text Add to dashboard Cite

show abstract

“…In the situation where the isometric force is measured separately from eccentric force the isometric force can sometimes exceed the maximal eccentric force of the corresponding joint angle (Komi et al 2000;Singh and Karpovich 1966;Spurway et al 2000;Westing et al 1988). Due to possible neural inhibition it may be difficult to maintain the full activation of the muscles during maximal eccentric action (Babault et al 2001;Seger and Thorstenson 2000;Westing et al 1990).…”

Section: Eccentric Versus Separately Measured Isometric Forcementioning

confidence: 99%

“…When maximal voluntary eccentric force is compared with separately measured maximal voluntary isometric force at the corresponding joint angle, the isometric force is usually lower than the eccentric one (e.g. Asmussen et al 1965;Doss and Karpovich 1965;Komi 1973;Griffin 1987), although in some situations it may also be the opposite (Komi et al 2000;Singh and Karpovich 1966;Spurway et al 2000;Seger and Thorstenson 2000;Westing et al 1988). The later could be due to neural inhibition that has been suggested to occur during maximal voluntary eccentric action (Seger and Thorstenson 2000;Westing et al 1990) and therefore subjects have difficulties to maintain high eccentric force level throughout the motion.…”

Section: Introductionmentioning

confidence: 99%

Maximal force during eccentric and isometric actions at different elbow angles

2006

View full text Add to dashboard Cite

The purpose of this study was to examine a course of force potentiation and/or inhibition during maximal voluntary eccentric action. Maximal voluntary force (MVC) of elbow flexion of ten healthy male volunteers was measured during isometric and isokinetic eccentric action starting from 80 degrees or 110 degrees and ending at 140 degrees elbow angle. Surface EMG was recorded from biceps brachii (BB) and brachioradialis (BR) muscles. Maximal voluntary eccentric force during the first 10 degrees of the movement was higher (P<0.001) than the maximal voluntary isometric preactivation force both in 80 degrees and in 110 degrees starting position at all three velocities (1, 2, and 4 rad s(-1)). The relative force potentiation was velocity dependent being smallest at the lowest stretching speed (P<0.01). Average EMG (aEMG) of BB and BR decreased as the joint angle increased both in eccentric and in isometric actions but the decrease in aEMG towards extension was somewhat higher in eccentric actions as compared to isometric. It was concluded that the force measured during the first 10 degrees of eccentric contraction always exceeded the maximal voluntary isometric preactivation force regardless of the joint angle or of the movement velocity. When maximal voluntary preactivation preceded the stretch, the relative force potentiation seemed to be greater at higher stretching velocities (velocity dependent) while at lower preactivation levels, the velocity dependence was not observed. Decreased muscle activation and lower maximal voluntary force towards the end of the movement suggested inhibition during maximal voluntary eccentric actions.

show abstract

“…This placed triceps brachii at optimal length for generating isometric force. 23 Velcro straps across the fingers and wrist held the limb firmly in place. The force transducer (FT10, Grass Medical Instruments, Quincy, MA) lay in a groove beneath the arm support at approximately wrist level.…”

Section: Methodsmentioning

confidence: 99%