The Tension Developed by Human Muscles at Different Velocities of Shortening

Fenn, Wallace O.; Brody, Henry; Petrilli, Alexander

doi:10.1152/ajplegacy.1931.97.1.1

Cited by 26 publications

(11 citation statements)

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“…The importance of pretension, before muscle shortening during in vivo research, has been repeatedly demon- strated (18,19,21,28). Regardless of contraction history, if the concentric movement begins from a relatively higher level of force, our results show that this will add to the mechanical work of the muscles measured during the first 300 ms of shortening.…”

Section: Discussionmentioning

confidence: 55%

“…Thus it is argued that the mechanical work performed by the muscle for the early part of the movement is relatively greater for the prestretch condition, irrespective of the possible contributions from other processes. Indeed, it has been acknowledged that allowing a muscle to achieve a state of increased activation before release will significantly increase its ability to perform work during the initial concentric shortening (18).…”

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confidence: 99%

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Stretch-shorten cycle compared with isometric preload: contributions to enhanced muscular performance

Walshe

Wilson

Ettema

1998

Journal of Applied Physiology

121

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To isolate any difference muscular contraction history may have on concentric work output, 40 trained male subjects performed three separate isokinetic concentric squats that involved differing contraction histories, 1) a concentric-only (CO) squat, 2) a concentric squat preceded by an isometric preload (IS), and 3) a stretch-shorten cycle (SSC) squat. Over the first 300 ms of the concentric movement, work output for both the SSC and IS conditions was significantly greater (154.8 +/- 39.8 and 147.9 +/- 34.7 J, respectively; P < 0.001) compared with the CO squat (129.7 +/- 34.4 J). In addition, work output after the SSC test over the first 300 ms was also significantly larger than that for the corresponding period after the IS protocol (P < 0.05). There was no difference in normalized, integrated electromyogram among any of the conditions. It was concluded that concentric performance enhancement derived from a preceding stretch of the muscle-tendon complex was largely due to the attainment of a higher active muscle state before the start of the concentric movement. However, it was also hypothesized that contractile element potentiation was a significant contributor to stretch-induced muscular performance under these conditions.

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Section: Discussionmentioning

confidence: 55%

mentioning

confidence: 99%

Stretch-shorten cycle compared with isometric preload: contributions to enhanced muscular performance

Walshe

Wilson

Ettema

1998

Journal of Applied Physiology

121

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“…Peyton (1986) coupled the forearm to a torsion spring and calculated its inertia from the frequency of the damped oscillations which followed a disturbance. In another method (Fenn, Brody & Petrilli, 1931) the acceleration following the release of a limb undergoing an isometric manoeuvre was measured. The person exerted a known force against a restraint which was abruptly removed.…”

Section: Discussionmentioning

confidence: 99%

Inertia, Resonant Frequency, Stiffness and Kinetic Energy of the Human Forearm

Walsh

Wright

1987

Exp Physiol

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SUMMARYThe biodynamics of the forearm of a number of relaxed human subjects have been investigated using a printed motor as a torque generator. Oscillation in the horizontal plane at the resonant frequency has been maintained by feed-back of a modified velocity signal. By means of negative position feed-back the stiffness could be artificially increased and the resonant frequency accordingly elevated. From these changes it has been possible to calculate limb inertia and muscle stiffness, treating the limb as a torsion pendulum. The correlation of inertia with the fifth power of limb length has been studied, this relationship being predicted on theoretical grounds. A significant correlation was found between resonant frequency and the square root of the reciprocal of inertia, a relationship also predicted on theoretical grounds. As the limb was kept on resonance the motion was limited solely by the damping. When the rate of oscillation was increased by the use of added stiffness the peak velocity increased, indicating that the damping was reduced. The mean inertia and mean stiffness values for the men were higher than those for the women. The kinetic energy of rapid voluntary movements was greater in men than in women.

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“…In concentric actions, the decline in maximal voluntary torque consequential to a velocity increase, has been studied extensively (Fenn et al 1931;Thorstensson et al 1976). The underlying mechanisms have been attributed to either or both chemical and mechanical muscle properties (Hill 1938) and/or motor unit activation by the central nervous system (e.g., Perrine and Edgerton 1978).…”

Section: Introductionmentioning

confidence: 99%

EMG activity and voluntary activation during knee-extensor concentric torque generation

et al. 2002

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This study was designed to re-examine and compare the neural drive of the knee extensors during isokinetic concentric muscular actions by means of the twitch interpolation technique (activation level, AL) and surface electromyographic (EMG) recordings (root mean square, RMS). Torque, AL and RMS amplitudes of three knee extensors and one knee flexor were measured in nine subjects during maximal and sub-maximal voluntary contractions, performed under concentric (60 degrees.s(-1) and 120 degrees.s(-1); Con60 and Con120, respectively) and isometric (Iso) conditions. Mean (SD) maximal voluntary torque was significantly lower ( P<0.01) during concentric contractions [Con60: 208.6 (26.8) Nm and Con120: 184.7 (26.4) Nm] compared with isometric contractions [327.4 (52.0) Nm]. A significantly lower AL ( P<0.05) was recorded during Con60 [80.9 (8.8)%] compared with Iso [87.9 (5.1)%] and Con120 [88.2 (6.6)%] maximal contractions. Simultaneously, a lower knee extensor average RMS amplitudes (av.RMS) was measured during Con60 maximal contractions compared with Iso and Con120 maximal contractions. The antagonist biceps femoris RMS values were not different between maximal Iso, Con60 and Con120 contractions. During sub-maximal voluntary contractions, the RMS/torque relationships were similar whatever the muscle considered (vastus lateralis, vastus medialis or rectus femoris) and the AL/av.RMS relationships did not reveal any noticeable differences between each contractile condition. The results of the present study indicate that av.RMS and AL describe similarly the neural drive during maximal and sub-maximal efforts and indicate that during maximal voluntary efforts, neural drive is dependent upon concentric angular velocity (up to 120 degrees.s(-1)). Thus, our results suggest that when applying different contractile conditions, the torque output is regulated via complex interactions between intrinsic muscular properties and the neural drive.

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The Tension Developed by Human Muscles at Different Velocities of Shortening

Cited by 26 publications

References 0 publications

Stretch-shorten cycle compared with isometric preload: contributions to enhanced muscular performance

Stretch-shorten cycle compared with isometric preload: contributions to enhanced muscular performance

Inertia, Resonant Frequency, Stiffness and Kinetic Energy of the Human Forearm

EMG activity and voluntary activation during knee-extensor concentric torque generation

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