The mechanical properties of cat soleus muscle during controlled lengthening and shortening movements

Abstract

SUMMARY1. By supplying pulses to different subdivisions of the ventral nerve roots in rotation, it was possible to obtain smooth contractions of cat soleus with low rates of stimulation.2. After contracting isometrically the muscle was subjected to constant velocity lengthening or shortening movements.3. During shortening the tension always fell below the isometric value. The fall in tension was usually greatest when low rates of stimulation were used.4. The effect of lengthening on tension depended on the rate of stimulation. At high rates of stimulation the tension during lengthening always rose above the isometric tension. At lower rates of stimulation (5-15 pulses/see) the tension rose at the beginning of an extension, but decreased later in the movement to a level that was often less than the isometric tension corresponding to that muscle length. At these stimulus rates the tension during isometric contraction was usually higher than during a sustained movement in either direction.5. At low rates of stimulation longitudinal vibratory movements of more than 0-1 mm also reduced the tension far below the isometric value, whereas the reduction was quite slight when the rate of stimulation was high.6. The isometric tension during smooth contractions at low stimulus rates was remarkable in the following respects: it developed rather slowly, it was higher than the tension during or immediately after movements, and it was only slowly regained after movement had ceased.7. The results are discussed in relation to the sliding filament theory of muscle contraction, which, with certain assumptions, provides an explanation for many of the findings.

Variation in isometric force after active shortening and lengthening and their mechanisms: a review

“…amount of force obtained in isometric contraction of reference. These speculations are in agreement with the results obtained in some studies (2,6,7,19,32,43).…”

“…On the other hand, for some advocates of FD (2,6,7,19,32,33) subsidies to confirm it, use the analysis of the common features of the phenomenon. They take into consideration that it increases at large amplitudes of shortening, low speed and large amounts of force produced during active shortening.…”

“…stimulation combined with maximum voluntary dynamic contractions (5). Furthermore, devices have relied on complex servo motors coupled to force transducers that bear little resemblance to human movement pattern (2,11,14,15,16,17,18,19,20,21,22,23,24,25,26).…”

In vivo finger flexor tendon force while tapping on a keyswitch

“…Because the flexor muscle contraction is near the maximum value as the release movement begins and because during the release motion the flexor muscle lengthens, its contraction is eccentric. This type of contraction produces higher forces than an isometric or shortening muscle (14). Superimposed on the residual eccentric contraction is the muscle's passive force.…”

Contractile Performance of Striated Muscle

“…This depressant effect of shortening has been demonstrated in both isolated muscle preparations (Jewell & Wilkie, 1960;Edman & Kiessling, 1971;Briden & Alpert, 1972) and muscles in situ in the body (Joyce et al, 1969). This phenomenon, which is unrelated to fatigue, has previously been studied in considerable detail on both intact and skinned muscle fibres (Edman, 1975(Edman, , 1980(Edman, , 1981Ekelund & Edman 1982).…”