Reduced stretch reflex sensitivity and muscle stiffness after long-lasting stretch-shortening cycle exercise in humans

1998 ◽  
Vol 78 (5) ◽  
pp. 403-410 ◽  
Author(s):  
Janne Avela ◽  
Paavo V. Komi
Keyword(s):  
Stretch Reflex ◽  
Muscle Stiffness ◽  
Cycle Exercise ◽  
Stretch Shortening Cycle ◽  
Exercise In Humans

Changes in the soleus muscle architecture after exhausting stretch-shortening cycle exercise in humans

2006 ◽  
Vol 97 (3) ◽  
pp. 298-306 ◽  
Author(s):  
M. Ishikawa ◽  
E. Dousset ◽  
J. Avela ◽  
H. Kyröläinen ◽  
J. Kallio ◽  
...  
Keyword(s):  
Soleus Muscle ◽  
Muscle Architecture ◽  
Cycle Exercise ◽  
Stretch Shortening Cycle ◽  
Exercise In Humans

Reduced stretch-reflex sensitivity after exhausting stretch-shortening cycle exercise

1996 ◽  
Vol 72-72 (5-6) ◽  
pp. 401-409 ◽  
Author(s):  
P. V. Komi ◽  
T. Horita ◽  
H. Kyr�l�inen ◽  
T. E. S. Takala ◽  
C. Nicol
Keyword(s):  
Stretch Reflex ◽  
Cycle Exercise ◽  
Stretch Shortening Cycle

Contributions of motor-unit recruitment and rate modulation of compensation for muscle yielding

1982 ◽  
Vol 47 (5) ◽  
pp. 797-809 ◽  
Author(s):  
P. J. Cordo ◽  
W. Z. Rymer
Keyword(s):  
Motor Unit ◽  
Stretch Reflex ◽  
Muscle Force ◽  
Motor Units ◽  
Muscle Stiffness ◽  
Motor Unit Recruitment ◽  
Reflex Response ◽  
Rate Modulation ◽  
Stimulus Rate ◽  
Wide Range

1. Subdivided portions of the cut ventral root innervation of the soleus muscle were electrically stimulated in 14 anesthetized cats. The stimulus trains imposed on these nerves simulated the recruitment and rate-modulation patterns of single motor units recorded during stretch-reflex responses in decerebrate preparations. Each activation pattern was evaluated for its ability to prevent muscle yield. 2. Three basic stimulus patterns, recruitment, step increases in stimulus rate, and doublets were imposed during the course of ramp stretches applied over a wide range of velocities. The effect of each stimulus pattern on muscle force was compared to the force output recorded without stretch-related recruitment or rate modulation. 3. Motor-unit recruitment was found to be most effective in preventing yield during muscle stretch. Newly recruited motor units showed no evidence of yielding for some 250 ms following activation, at which time muscle stiffness declined slightly. This time-dependent resistance to yield was observed regardless of whether the onset of the neural stimulus closely preceded or followed stretch onset. 4. Step increases in stimulus rate arising shortly after stretch onset did not prevent the occurrence of yield at most stretch velocities, but did augment muscle stiffness later in the stretch. Doublets in the stimulus train were found to augment muscle stiffness only when they occurred in newly recruited motor units. 5. These results suggest that at low or moderate initial forces, the prevention of yield in lengthening, reflexively intact muscle results primarily from rapid motor-unit recruitment. To a lesser extent, the spring-like character of the stretch-reflex response also derives from step increases in firing rate of motor units active before stretch onset and doublets in units recruited during the course of stretch. Smooth rate increases appear to augment muscle force later in the course of the reflex response.

BCAA intake affects protein metabolism in muscle after but not during exercise in humans

2001 ◽  
Vol 281 (2) ◽  
pp. E365-E374 ◽  
Author(s):  
Eva Blomstrand ◽  
Bengt Saltin
Keyword(s):  
Amino Acids ◽  
Recovery Period ◽  
Aromatic Amino Acids ◽  
Branched Chain Amino Acids ◽  
Cycle Exercise ◽  
Placebo Condition ◽  
Muscle Concentration ◽  
Branched Chain ◽  
Sparing Effect ◽  
Exercise In Humans

Branched-chain amino acids (BCAA) or a placebo was given to seven subjects during 1 h of ergometer cycle exercise and a 2-h recovery period. Intake of BCAA did not influence the rate of exchange of the aromatic amino acids, tyrosine and phenylalanine, in the legs during exercise or the increase in their concentration in muscle. The increase was ∼30% in both conditions. On the other hand, in the recovery period after exercise, a faster decrease in the muscle concentration of aromatic amino acids was found in the BCAA experiment (46% compared with 25% in the placebo condition). There was also a tendency to a smaller release (an average of 32%) of these amino acids from the legs during the 2-h recovery. The results suggest that BCAA have a protein-sparing effect during the recovery after exercise, either that protein synthesis has been stimulated and/or protein degradation has decreased, but the data during exercise are too variable to make any conclusions about the effects during exercise. The effect in the recovery period does not seem to be mediated by insulin.

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