CHANGES IN CHARACTERISTICS OF RECRUITMENT MODES IN HUMAN MOTOR UNITS AT VOLUNTARY MUSCULAR RELAXATION
- VernacularTitle:筋弛緩における単一運動単位の活動参加様式の特性
- Author:
SHIGERU MORIMOTO
;
TOSHIO OHMORI
;
HIDESHI HASEGAWA
;
HIROSHI KURATA
;
MAKOTO MASUDA
- Publication Type:Journal Article
- From:Japanese Journal of Physical Fitness and Sports Medicine
1977;26(2):59-63
- CountryJapan
- Language:Japanese
-
Abstract:
It had been proposed by Kurata that relative threshold value Fth of single motor units depends on the gradient G (kg/sec) of the tension increase of muscle in such a manner as
Fth (≡T.G) =ρGλ
Here T1 is the time interval from the onset of EMG to the moment of recruitment of a motor unit and ρ is a proportional constant. The motor unit with a positive/negative value of λ is characterized to be static/phasic.
Morimoto and Hasegawa reported that the above relation also holds for the relaxation period, provided that Ftn and G are replaced by the tension at the moment of silence and the absolute value of G, respectively. In this case, the motor unit with a positive/ negative value of λ is characterized to be phasic/static.
In order to investigate the characteristics of motor units during relaxation period under the influence of pre-relaxation states, such as the increase of tension up to 4kg at the gradient of 0.5kg/sec and the state sustained at 4.0kg for 30sec. Single motor units of m, vastus medialis were studied by the same method as that of Morimoto and Hasegawa.
The following results were obtained;
1) Both at contraction and relaxation periods, the above relation was confirmed.
2) The motor unit with characteristics of recruitment modes was influenced by the pre-relaxation state, but its tendency was not definite. These results suggest that phasic/static characteristics of motor units are not stationary but fluctuate depending on the pre-relaxation states.
